Consistent velocities and accuracy

[corbanzo]

Ever since I bought my chronograph years ago, I have become a stickler about consistent velocities.  There are some powders that annoy me because of this. (H110 ring a bell??)


One of the first things I do before I even shoot at paper is throw a set over the chronograph to see how my velocities are running.  Usually I will go with my chrono and change my load if I am not getting the consistency I want.  Accuracy kind of comes in far behind this.....


In rifles there is no question, it has to be consistent velocities, especially when considering long range shooting.  Though with rifle powders I usually don't have this problem.  I stay with the newer breeds of powders and have found them to be very consistent even over different lots of powders for the most part.  So I find the few that I like and try to use them across a few different calibers.


Then when it comes to handguns... I try... and try good and hard to make my rules stick... and sometimes it works and sometimes not.  It is true that magnum pistol powders are just harder to make behave no matter what you do.  If you want big velocity.... you usually have to deal with a little bit of inconsistency.  But being as shooting my canons tends to stay within a reasonable off hand range I don't fuss too much... but still try and find that niche I'm looking for between consistent velocity, accuracy, and raw horsepower. 


Of course we all have those days when we wonder exactly how much H110 we can compress in a .454 case over a 180 grain .451 bullet.... but that's a story for another day.   

[stimpylu32]

I've been pissed off sence the day I brought my first ( and only ) Chrono home , loads that were great shooters for me would have a span of up to 50 fps ( Handgun ) and rifles were as much as 100 fps . I spent over a year trying to get the numbers right and came to the conclusion that WHO CARES just how fast its going if it goes were I point it . 
 
stimpy

[corbanzo]

I agree!  And still care... for some #%$^*&^%$$% reason!   

[necchi]

Thanks guys, I appreciate stories like this.
I too have a chrono, it's a good tool for the loader to have, but I've been able to not become obsessed with it and the numbers.
 I do strive to keep the ES and SD down, but stories like the guy that harvested 20 different big game animals on two different continents with his favorite rifle and his best load,, scrapping the load when he fired it over a chrony because it wasn't fast enough,, has helped me keep it real.
 
I still want to enjoy, loading. 

[kynardsj]

Never had a chrony and will echo what stimpylu32 said, if it goes where I point it and does what it's supposed to do when it gets there I really don't care. Kinda like a watch I owned years ago, it had an analog set of hands and above the 6 it had digital time. Kept good time but it drove me crazy if the time on each didn't match to the second. I think a chrony would do the same on these loads that work so well for me. I will be blissful in my ignorance.

[Ranger99]

i have one i bought 12-15 years ago
and mainly used it to check bows
when we were gadget obsessed
and we were all starting to use carbon
arrows. i've used it for some of my
contender loads a long time ago too.
hadn't thought too much about it
for a number of years now and for
the life of me i can't think of exactly
where it might be stashed at.

[stimpylu32]

I know exactly were mine is , buried on the bottom shelf of my gun cleaning supplies rack , don't think I've moved it in 3 or 4 years , just don't see the point anymore , all it does is get me all riled up     kinda like my wife does from time to time when she tells me what I want and don't want . 
 
stimpy

[FPH]

Best thing that happened to mine was my buddy shooting it one day......by by chrony.

[SHOOTALL]

I've been pissed off sence the day I brought my first ( and only ) Chrono home , loads that were great shooters for me would have a span of up to 50 fps ( Handgun ) and rifles were as much as 100 fps . I spent over a year trying to get the numbers right and came to the conclusion that WHO CARES just how fast its going if it goes were I point it . 
 
stimpy
 
++1

[Bigeasy]

Used to obsess over the chrono, striving for minimum deviations in velocity, til I noticed that a lot of loads with high deviation numbers were very accurate.  I still use my chrono when working up loads, mainly in rifles to tell me if I have gone to hot - a load going say, 200 fps faster then shown in the book should be a sign of increased pressure.  By the way, with H-110 / 296 in big bore handguns, I have found a hot primer, full power loads, a good roll crimp, and a tight fit of bullet in the case all contribute to consistent velocities.
 
Larry

[revbc]

Just shot my 454 C H&R carbine today with some 300 gr jfp bullets.  Chrono gave me about 12 fps difference in 3 shots, however; it was about a 6-8" group at 100 yds.  Had some that varied 50-60 fps that shot better.  Go figure.

[FPH]

I am what most people would call "anal" about my reloads.  I don't know what I would change to bring the velocities "closer " if they are inconsistent.

[Siskiyou]

 I think my Chronys have set dormant a couple of years but I am about ready to pull out the one that does not have a bullet hole it.  That’s the one reserved for pistol rounds.  After that traumatic experience of shooting a Chrony Bang-Flop testing pistol velocity is not a priority.
Shooting for effect or consistency?
Four samples:   150-grain Hornady using   H4831 Low 2856 High 2894 Spread 38 fps
                             150-grain Factory Hornady            2776 Low 2831 High Spread 55 fps
                             130-grain Hornady SP                      WW785 Low 3001 High 3051 Spread 50 fps
                             140-grain Hornady BT                     WW785 Low 2983 High 3018 Spread 35 fps

Most accurate load is the 140-grain Hornady BT using WW785.  I consider this my long range deer and antelope load.  The 150-grain Hornady using H4831 is my Oak and Brush Country load.

Surplus/H4831 is a favorite powder and the Chrony help me decide on a load when the 140-grain Hornady came out.  I thought that I could easily work up to 58.0 grains for use in my Savage 110 but I was sorely disappointed.  I had pre-load a number of increments up to 58.0 grains and went to the range.  I never made it to 58.0 grains in my rifle.  I settled on 57.2 grains for a velocity of 2868 fps.  I collected a couple of deer with that load but when I found loads in my newest Hornady and Lyman manuals using WW785 I started a new load development process.  My load development started at 2200 foot elevation in 90 degree weather, and the Chrony testing occurred at 6700 foot in 70˚ temperatures.  The resulting accuracy and results on deer had me thinking this was the best deer load possible out of my Savage 110CL in 270 Winchester.  Then Winchester dropped WW785.  Fortunately I had some on hand.

The Chrony helped prove its value in the testing of the 140-grain Hornady loads.  I confirmed that WW785 was the better powder in my rifle using the 140-grain bullet.  When it comes to the 130-grain bullets results between H4831 and WW785 are similar.  I would have pushed my testing a little more with the 130-grain Hornady and WW785 if I had a Chrony at that time.  Admittedly more velocity was not needed.

I have found that buying more than a pound of powder at a time leads to consistence.  When I went to buy IMR4064 for the .300 Savage I bought three pound of the same Lot number.  A pound of powder goes a long ways in the 300 Savage case.  I believe that should last me the remainder of my lifetime.  After a hard look at the lack of powders on the shelf currently I bought 2-pounds of Mag-Pro for the 270 Winchester.  I bought only 2-pounds because that was the store limit. I have been thinking Mag-Pro fits the 270 Winchester profile for a slow burning powder.  But data for it in the 270 Winchester is limited.  I have started low and working up. 

I am currently trying the Accurate Mag-Pro in the 270 Winchester.  I already know what works and that is the baseline for my development.  Last night a granddaughter and I were talking about loads for her rifle.  I showed her a 150-grain WW Power Point recovered from a Mule deer.     The bullet had expanded to .78 and retained over 76-grains of jacket and lead core for approximate 51%.  The shot was frontal at over 250-yards and the bullet penetrated the chest at the base of the neck, lung, and down the inside of the ribcage penetrating four ribs and stopping in the fifth rib.
I was surprised at the performance because Winchester use to advertise this Super-X load at 2900 fps.  I had bought five boxes at $5.00 each the end of one season on sale.  I stored them away for years because I was happy with my handloads.  But I knew that the time would come that I might need them because of time conflicts.  I did try them in my Remington 760 and they did not provide the accuracy I was seeking.
I planned a shooting session at one of my favorite location at 6700 foot elevation that also duplicates my common hunting areas.  I tested fired the disappointing WWPP loads across the Chrony and was disappointed that my average 15-foot velocity was 2727 fps. I was firing my Remington 700 in 270 Winchester with a 22-inch barrel.  The rifle shot close to a 1” group with this factory load.  My favorite handload that day gave me an average 2876 fps.  Except for the hunt described I have used the 150-grain Hornady interlock out of that rifle with success but have recovered none from behind the shoulder shots.
A hunting partner has had success with the 150-grain Power Point on deer and bear and as a resulted I bought a supply for reloading.

Last night I showed granddaughter #2 the Power Point loads I have set aside for a range session with her and the M760.  I have loaded 130-grain Power Points for her sister’s 270 Winchester A-Bolt.

The real value of the Chrony in my mind was to reestablish that 2900 fps was not absolutely necessary in most of my hunting activities.  Knowing my muzzle velocity and running the numbers with the bullet I am using in the Sierra Infinity Ballistics program allows me to develop a drop chart to tape on my rifle stock.  As a kid I killed bucks up close but missed them at long range.  I had a lot of learning to do and adjusting my sights and my brain to published manufacture charts was counterproductive.  I remember the days when all the 270 Winchester 130-grain ammunition was listed as 3140 fps.  Now days it is listed at 3060 with an exception for Hornady Whitetail that is listed at 2840 fps.  I do not know if this number is printed on the box but down range results might catch a hunter and write miss at 400 yards in the notes.  Two inches at 100-yards is not a big difference but ammunition selection in rural America can be an issue.  Your rifle can be sighted in for a load that in a jam cannot be bought off the shelve.  Or will it?
When I was a 14-yearold hunter I ran out of ammunition.  It had to be my inspiration to become a reloader.  When I make a week or two hunting trip I normally take a green plastic box with fifty rounds in it.   Those old rounds are showing some tarnish now.  This might make me a felon in California next hunting season.

P.S for many years I fired over my Chrony with rifles without incident.  After a session with my pistol firing over the Chrony it had a bullet hole in it.  I was able to repair the broken wire, and it works.  I have decided that if I am foolish enough to test pistol rounds I will do it over the Chrony I shot.  My new Chrony is reserved for rifle testing.

[Siskiyou]

 I made the trip to the range I talked about before.  It was very productive.  The Beta Master Chrony recorded data from every one of the thirty-one rounds I fired across it.

The purpose of the trip was to continue load development for a granddaughter’s 270 Winchester and gather some data from my 30-30 Marlin using the 150-grain Remington C-L as the baseline.  The rangemaster was kind enough to help me in aligning the Chrony.  I had already tape the rods with red and yellow tape to make sure that I did not put a low round into the Chrony.

The average velocity obtained from the Remington ammunition was 2310 fps 15 fifteen feet from the muzzle.  My hand loads used CCI200 primers, 150-grain Hornady RN, 35-grains of BL-C(2) and 37-grains of BL-C(2) powder.  The 35-grain load average was 2290 fps at 15-feet.  The 37-grain load averaged 2413 fps and there was a little primer flow. 
A check of my old records show that 36.5 grains of BL-C(2) with the Hornady 150-grain RN to be accurate.
Member Gun Runner gave me three pounds of BL-C(2) that he had been storing since Columbus was a boy.  The powder has held up very good.  37.0 grains is the maximum charge shown at the Hodgdon’s Data Center for a 150-grain bullet in the 30-30 Winchester.
I checked my 30-30 data sheets from the past and 36.5 showed real promise but I had no record of firing it across the Chrony.

Firing the 30-30 was a test run to make sure that I was lined up for testing 150-grain loads using Mag-Pro powder for the 270 Winchester.  I have a ways to go in the 270 Winchester.  Achieved velocity was below my goal, and I was surprised that the 57.5-grain charge produced lower average velocity then the 57.2 grain charge by 10 fps.  With a Maximum listed charge of 61.0 grains with a 150-grain 270 bullet I feel that I have room to up the charge by .5 and 1.0 grains.  I know my Remington 700 will handle the increase but I want to make sure my granddaughter’s M760 will function smoothly with it.

This is the second time I have used the Chrony Beta Master and it went smoothly.  I believe a key to that was a very bright, sunny day.  When I used my Chrony Alpha Master in the high country I had to deal with shading from tall timber during the day and passing thunderheads. This time of year I would have to deal with snow on the ground plus the other issues. 

Suggest that if you are testing pricy bullets that you first check the alignment of your Chrony with a .22 rifle.  I have found that the black lead bullets out of a .22 record very well.  The 22 LR is also a cheap round when learning the functions of your Chrony.  I do not claim to be an expert, I am amateur user and I have watched a number of people become frustrated with Chrony and other brands.  I suspect many of them are also frustrated with the TV remote. 

A brother is one of those frustrated using the Chrony.   20 + years ago he shot a rod on his Chrony, and he put it away.  I gave him a replacement rod but the Chrony has not seen daylight.  I should note that he also gave his computer away.  Technology and he do not get along.

I have to agree with Bigeasy.   I fired a few rounds loaded with 60-grains of WMR and 140-grain WW Silvertip BT (old style). I was surprised when I got a high of 3028 fps and a low of 2869 fps.  That is 159 fps difference.  The bullet spread was 1/2”.  This load has proven to be accurate over the years and I will have to do some checking but it appears to be accurate enough for most of my hunting.  Just looking at the target I would not know about the difference.  A quick check of old Chrony data does not show this extreme spread. I need to set the Chrony aside and do some 200-yard test firing.

[corbanzo]

Siskiyou-

After all that hard load data you threw out there I wish I had a 270 or 30-30 to use your results off of!

[Siskiyou]

 
Corbanzo:

Working with the 30-30 has reinforced to me what a sweet round the 30-30 Winchester is.  My small groups of hunting buddies are the old, gray haired guys setting in the corner at the coffee shop drinking coffee, talking about hunting rifles and the ladies.  The 30-06 is the most common caliber used but there is ownership of other calibers.  As we have become older the 30-30 is far more respected then it was in our youth.

 

One of my buddies kept encountering a forked horn buck last fall while out hunting Mountain Quail with his M12 twenty.  That got him thinking about a 30-30 truck gun to have in his rig while bird hunting.  Those discussions lead me to show him a couple of pictures of targets I shot with factory and handloads with my 30-30.  There are a number of powders that work with the 30-30 and I have loaded a few of them.  But I wanted to do some testing with B LC-(2) because I have an ample supply.  The chapter in my load binder is thin.  I have had the rifle for a very long time but I normally bought Federal and Remington on sale.  The default ammunition was Remington 150-grain C-L because of its accuracy.

But with this recent firing over the Chrony I feel confident that the 36.5 or 37.0 grain BLC-2 handload is as adequate as the factory Remington 150-grian.  I should note that I have a small supply of 150-grain C-L component bullets that I will also test.

I have five boxes of 150-grain Federal factory loads.  I want to duplicate my recent test with some of them.

On the same day I want to test the Hornady Factory 160-grain LeverEvolution.  I understand the published data for the ammunition is based on a 24-inch barrel.  Admittedly I have put the 30-30 away and taken a 270 on the second day of the hunt because the location presents the opportunity for shots over 200 yards.

 

A hunting partner took a buck with his 30-06 at 266-yards, a week later I took a buck about 100 yards away from his kill at 32-yards with a 270.  (Both kills later measured with a Nikon 800 rangefinder.)  I have hunted the same area with my 30-30.  In theory the 266-yard shot is doable with my Marlin with a 20-inch barrel and a Burris 2-7x Ballistic Plex Crosshair scope.  But the close shot and the longer shots are common in the area we hunt.

 

Knowing the velocity the 160-grain LeverEvolution is producing in my rifle is important to me.  With known velocity data, and using the Sierra Infinity Six ballistics program I can come up with a Dope Card for my Marlin.

 

I still need to work on the Mag Pro loads for the 270 with two granddaughters shooting that caliber.  In addition to that a brother passed a 300WM to one of them with loads.  All I know about the loads are they use magnum primers, and 165-grain C-L bullets.  They are loaded with a mystery powder that might be H4350.  I can only guess the velocity out of the 26-inch barrel is between 3000 and 3200 fps.  I prefer to know then guess.
 
Before I retired I did not have a lot of sparetime.  I think that some shooters become frustrated with Chronys because they are a time consumer.  And they consume money for every round fired.  That is why I recommend a learning session using a 22 rifle.  In my opinion learning to use a Chrony with a 300WM at $3 or $4 a pop is an expensive mistake.  Much better to use a .22LR at two or three cents a round.

[Hairy Chest]

Used to obsess over the chrono, striving for minimum deviations in velocity, til I noticed that a lot of loads with high deviation numbers were very accurate.  I still use my chrono when working up loads, mainly in rifles to tell me if I have gone to hot - a load going say, 200 fps faster then shown in the book should be a sign of increased pressure.  By the way, with H-110 / 296 in big bore handguns, I have found a hot primer, full power loads, a good roll crimp, and a tight fit of bullet in the case all contribute to consistent velocities.
 
Larry

Case tension affects groups. It is better not to mix cases of different tension but to segregate them.  Segregation works. 

[corbanzo]

Yeah, I've always been an -06 man myself.   Up here the 30-30 doesn't have much ground... mostly because of the quarry.  The .270 though is a very popular caliber, I have been beating around the idea of buying one for my love, of course then the 7mag sticks in my head.... choices, choices.


I have to say a win 94 in 30-30 has always been on the list of "must have" rifles when I get around to that point on my long, long list of "must have" firearms. 


That 300 WM is gonna smoke with 165's.  Usually a pretty light load for that cartridge, but for those girls, the recoil of the 165's is going to be more manageable.  The 300WM is one of those cartridges you can definitely hot rod above "standard" factory ammo.  Of course more recently developed factory loads striving to put big numbers on the box are looking to max it out... but a good dose of 4350 will open some eyes.

[Siskiyou]

 
  I clearly understand why the -06 is preferred over the thirty-thirty in most parts of the world.  A lot of people like them but when they have a choice they go out the door with more gun.  I had a Husqvarna 30-06 that my father-in-law bought at the commissary, Fort Greely, Alaska.  He must have stocked up with 180-grain Silvertips at the sametime.  He took moose and caribou with it.  He was stationed at Fort Greely before Alaska became a state.  I inherited the rifle and did some hunting with it when black bear was on the menu.  My SIL had to have a -06 so it is his now.  I still have a few rounds of his Silvertips.  If get the SIL and the -06 around the Chrony I will have to check out the velocity.
 
I have told the granddaughter that the Lead Sled is a good option when we are testing the 300WM rounds over the Chrony.  Makes for a steady rest, takes up the recoil and reduces the risk of shooting the Chrony.  Once we have some empty 300WM brass I am thinking about what I have on hand, keeping the cost down, and reducing the recoil.  It appears that a starting load of 64.0 grains of H414, a 165-grain bullet should produce about 2900+ fps. The recoil should be reduced about 1/3^rd.   The Chrony will give us the velocity out of that rifle. 
 
I am guessing that she will find the 300WM with the 26-inch barrel rather cumbersome compared to the 270 Winchester with a 22-inch barrel out deer hunting.  Far more gun then needed and the 270 will do black bear.  The objective of the 300WM for her is elk hunting in grizzly habitat.
 

 
She is not weak; I have seen her defeat five or six opponents at a martial event in a day.   I might be the weak one in this case. 
 

 
Back in 1960-1 I spent sometime during the summers in the Peace River Country of Alberta.  Neighbor who had a big farming operation was a hunter at heart.  Moose was always on the menu and his wife proved it by serving moose roast and homemade bread for dinner.  He was a fan of an old 30-30 Winchester with an octagon barrel.  He had to upgrade to a .303 British because the 30-30 developed a bulge from snow in barrel.  His big laugh was U.S. hunters coming to the area on guided hunts with 300 Magnums.  His big advantage was living and running a trapline in his youth with the same old family 30-30 in hand. I suspect that he would have loved having a 30-06.
 

 
I know that I did not think of a chronograph in those days, might have read a mention of them in Outdoor Life.
 

 
I have a 7MM Remington Magnum but it normally stays home because I prefer my 270’s or retro to old calibers such as the 300 Savage, and 30-30.  It is a good shooter but like the lighter weight rifles.
 

 
Chrony notes:
 
Load:  Speer 160 grain Spitzer, powder AA8700 WT xx.x grains.  Primer WLMR
 
Group 1+ at 100 yards.  Velocity 3007 fps adjusted for muzzle.  Group 2.5 inches high.  Low shot in 9 ring cause by first shot with 6 o’clock hold.  Use for long range (400 yard) hunting.
 

[mcbammer]

How  do you guys  know  your  chrony  isnt  defective. I  suspect  two  side by  side   would  read  different. Any  one  tested  factory  ammo  for  variations.

[corbanzo]

Well I look for consistancy. If I have or load that my max spread is only 15fps, I know it's not just spitting out bull when in the same day I can test another load and have a max spread of 70 fps, go back to the original  and get similar results as before.

[Siskiyou]

 A recent test of Remington Factory C-L 30-30 shows an average deviation of 16 fps. On the same day an accurate 30-30 handload had an average deviation of 19 fps.

I just checked some .277 Hornady SST pushed by H4831 that I fired in 2011.  The deviation was 20 fps.  I normally let the barrel cool between rounds so this might have been over a two to three hour period.  During that time most likely temperature increase twenty to thirty degrees.
The assumption that two side by side instruments would have a difference would be a safe bet. You can set a half dozen gps units next to each other and there could be difference by a few feet between them. I have notice that the data between my two Chronys is similar. It may not be exactly the same because of the difference in the atmosphere, and altitude.   I doubt side by side testing of the same bullet will produce the same results; inline test will generate slower data in the second unit.  A bullet rapidly decelerates after leaving the muzzle.

The manufacturer's claim: Every SHOOTING CHRONY® measures the speed of bullets, arrows, shotgun & airgun pellets, paintballs, et cetera, from 30/fps. to 7000/fps. and with better than 99.5% accuracy.

I did test two 270 Winchester rifles side by side on the same day with the same lot of handload ammunition using the same lot of Winchester cases, WMR powder, WLR primers and bullets.  The conclusion was that the Savage 110 barrel is 30 fps faster than the Remington 700.  But that is only valid for the two rifles tested.

Unlike the Highway Patrolman's radar unit my Chrony is not tested my certified test equipment and certified technician.   I can accept or discard my data and I can share it, “as is.”  If the data appears fault I can cross check using my other unit, but once a round has been fired it is gone.  The depth of my testing is very shallow.  My testing is limited by my limited pocket book.
I believe that a brand x chronograph with more eyes would give better data.
 

[savage308]

I use my chrony  very little as of late but can tell you that my 44 mag pistols like full loads with mag primers crimped hard to get good groups
I have found that sometimes with faster powders like unique there is primer flash over and fps varies where as with the 4227 loads
the sd numbers were smaller.
 

[lrrice]

I don't have a crony and would probably get all anal if I did.  That said, I have been using the ladder method to work up loads lately and am amazed at the load range of some of the sweet spots.  Sometimes a couple of grain variation around the sweet spot will remain MOA or better.  So, to make a short story long, I'm not nearly as worried about weighing vs dipping charges any more, much less minute variations in speed.

[corbanzo]

That's funny you mentioned that...  I have gotten away from weighing as much as I can.


Throwing is the way to go in my book!


Even my run of the mill uniflow keeps up in the velocity and accuracy book with weighing charges. 

[Siskiyou]

 


mcbammer

Your question regarding accuracy of the units is well taken.  In this day and age it is difficult trusting any source.



I like the ideal of the Oheler35P and so does the U.S. government and the industry.  For years I have read about H.P. White Laboratories.          http://www.hpwhite.com/services/ballistics-testing/  No doubt the gold standard in testing.  Years ago gun writers mentioned them on a regular base, but with the advent of personnel chronographs I have not seen much reference to H.P. White of late. 



I have never used an Oheler 35P but by reputation it is the best.  It appears for the price the purchaser gets a lot.  http://oehler-research.com/cgi-local/SoftCart.15.exe/online-store/scstore/p-M35-P.html?L+scstore+hfhs6677ffc6d9c6+1365531695



I like the idea of the 3^rd channel on the Oehler to check my shot.  But I can do some things with the Chrony to guard against bad data.  Muzzle blast can generate false readings.  I mentioned one in my February 15^th post.

I fired a few rounds loaded with 60-grains of WMR and 140-grain WW Silvertip BT (old style). I was surprised when I got a high of 3028 fps and a low of 2869 fps. That is 159 fps difference



The Oheler with the Proof Screen will alert the user to the fluke.   While my Chrony will save a shot string I do not have a printer attached to the unit.  I record each shot on the Chrony Test Record Sheet.  If an identifiable occurrence happens I can add an asterisk and note to the sheet for that shot.   If I understand the Oheler unit advises the user of the bad shot and it can be eliminated from the shot string.

In the case of the Chrony Beta Master that I am using I press and release the FU until the shot number I want is displayed.  I then hold the button down until the unit flashes and I release the button.  .  I will delete a shot string after I have record the information on the Record Sheet. Frankly I am in the learning stage and do not want to mess up.  I prefer to record the data and make adjustments when I compute it on the work sheet after the shoot.

Muzzle blast generates false readings.  Early in my shoot testing Mag-Pro and the 150-grain bullets I had no incidents.  But the false reading came at the end of the day when testing a hotter load.  At the shot a diffuser and rod popped out of the unit.  At first I thought I had hit the unit.  The unit displayed a high reading.  I have had this happen before when burning 60 or more grains of powder in the 270 and 7MM magnum. 

I needed to delete that shot out of my data string.  If included my average velocity would have been 3028 fps.  By deleting it the average is a more realistic 2923.5 fps on that day.  I looked back and look at some of my old data that was fired at a higher elevation.  Unfortunately conditions were cooler, and I was using 58.1 grains of WMR not the 60.0 grains I fired in my recent testing. 


 Press & release the FU button until the desired shot number is displayed (NOT the velocity). Hold the button in until display flashes. Release immediately when it flashes.

There is lot of Err entries noted in the old data.  I believe the majority of them are due to lightning conditions when shooting in the high country in the summer.  Loss of light from building afternoon thunderstorms and shadows from tall timber as the sun moves during the day.  The loss of direct sunlight because the sun drop behind the mountains.  I tried manufacturing lighting and run it off a 12v battery but that did not work out.  Admittedly I was doing it on the cheap.

I have been disappointed by most factory 7MM ammunition since I bought the rifle.  But I was shocked at the accuracy of the PMC 160-grain ammunition I bought.  I only test fired 8 rounds so from statistical standpoint this is not good data but it still tells me a lot.  I had fired 9 rounds but I toss one result because of muzzle blast and a high reading.  The resulting group is documented in the attach picture.

Average velocity was 2802 fps and average deviation was 16 fps.  I considered this velocity to be rather low but performance on the target was very good.  The best I have received from factory ammunition I have fired.

I decided that I would not use this load on a plan bear hunt.  The PMC factory load was impressive on the accuracy scale but low velocity.  On the same day I tested the Speer 160-grain Spitzer handload.  It averaged 2988 15-feet from the muzzle.

The top picture is the 160-grain Speer and the bottom picture is the 160-grain PMC.  I was planning a bear hunt at between 7000 and 8000 foot elevation.  The country has very good structure for long range shooting.  A bad case of the Shingles cancelled the hunt. 

I realize that I need to do a better job of documentation.

[corbanzo]

You should keep a minimum of 10 yards to get good consistent readings from any chronograph with a firearm.  Dust and blast are a big problem for chronos, they are a very sensitive piece of equipment.   The distance also helps to make sure you have a space to get a point of aim in the backdrop so you don't shoot your chrono!

[Siskiyou]

 I just pulled out and measured the phone type cord that connects the Chrony sensors to the screen-control head on my Chrony Beta Master.  The cord measured approximately 17 ˝ feet with some twist.  Suspect that if it was flat it would be 18-feet long.  When it goes from the bench to the Sensor body it is about 15-ft out allowing slick in the cord between the tripod and the bench.  My manual recommends a minimum of 10-feet from the muzzle.  One of my adult grandchildren has a 300WM.  I believe that will be an interesting day when we test the 300WM ammo.

I have also tapper the end of some small diameter wood dowels to use in place of the metal rods in hope that if I hit one the sensor will not be damaged. I have been known to duct tape the diffusers to the rods/dowels to keep them together.  Sometimes they pop-off from tension and other times from muzzle blast from the cases that hold a lot powder.  No problem with the 30-30 and 243.

Corbanzo you are dead on regarding setup, I am always concerned I will shoot my unit.  There is a notch on the Northern of the unit, I line-up the notch on the Northend and split the “O” in CHROY with the crosshairs.  I have red tape six inches up the rods for crosshair stops, and yellow tape as stops four inches up the rods for iron sight stops.

The nice thing about the “Master” units is the remote control head/LED screen that is normally back on the bench protected from muzzle blast.

[corbanzo]

I shoot prone a lot, my range is a river bottom.  Crony usually sits on the ground, so anything within 10 yards is game for blast and dust.

Easiest way I've found to not shoot is look straight through the chrome at a rock or shrub and keep that as your point of aim every shot.

Luckily I haven't hit one yet.

[Siskiyou]

The remote high country spot I shoot at is an old gravel pit that has not been disturbed in many years.  In fact the trees growing in are reducing my opportunities.  I use to take a couple of saw horses and part of a sheet of plywood up there to use as a table top.  Then I had an old formica table from my Dad's place and I cut it and used the legs to make a small portable bench.  It keeps me out of the dirt.

The club I belong to has nice cement benches on a cement slab with gravel a few feet out from the slab.  This time of the year I wear rubber boots to get to setup targets.  Depending on the weather  a guy could setup a few duck decoys in the pools. Even on a nice sunny day dust is not an issue.
Normally I keep the scopes at 4x or lower.  That way the rods are picked up in the field of view and I can place the cross hairs across the tap on each side and the lower part of the verticle hair  centered on the "O" and the notch.
I am still stun from shooting my first Chrony with a pistol round.  I had avoided test firing the pistol over the Chrony for thirteen or fourteen years.  My brother shoot a rod on his Chrony with a .357 and a good friend had centered his with a 44-magnum.  Clearly the message to me was do not fire a pistol over the Chrony, bad thing will happen.  Kind of like drinking and driving.
I have a couple more sessions with the Chrony coming up and then I do not see any need for a while.  I enjoy going an shooting the 22 rifle every once and while.  I need to take advantage of that time and get in some selve training on my Beta Master Chrony.  It has a few extra functions that I need to use automatically without thinking about it.