Author Topic: Rifle silhouette loads??? (Read 4904 times)

Hammer47 · « **on:** November 24, 2003, 07:51:10 AM »

Anyone care to share their favorite loads for silhouette for the 7BR? I am shooting a custom actioned, 27inch 8 twist bbl. Loads for standing rifle would be appreciated. Regards... Gary

Arizona Jake · « **Reply #1 on:** November 29, 2003, 04:43:49 AM »

I used the 7mm BR cartridge for HP rifle silhouette for a few years, and achieved the best precision out of 140 gr. Sierra Game King BT bullets with 29.3 grains of AA2520, which is the ball powder equivalent of IMR4895. The same load produced even better precision with Sierra 168 gr. HPBT Match bullets.

Accuracy is the bullet hitting where you aim it. PRECISION is having a series of shots hit the same place, i.e. small groups.

Just my 2-cens worth, but I would switch to the 7 mm-08 cartridge. Any gunsmith can ream a 7 BR chamber to a 7-08 without a problem. In the 6 years I used the 7 mm BR, the bullet failed to topple 1 out of every 4 rams I managed to hit, whether they were hit low in the belly or dead-on. It seemed that only high body hits were reliable. I had at least one 140 gr. bullet fail to knock over a center-punched javelina.

Bottom line, this cartridge is marginal. You may be able to develop faster loads with newer Vihta Voury or Varget powders, but your best bet is to go with a 7-08. You can tailor mild, soft recoil loads that are precise and will get the job done all the way to the turkeys with 140 grain bullets (35.6 to 36.2 grains of varget), and you can safely develop ram loads with 162 or 168 bullets (41.0 - 41.4 grs. of Varget) that will reliably knock the rams down. You will still lose a few ecery now and then, but I've also witnessed rams staying put after being hit soildly with 190 gr. .308 bullets.

The 1-in 8 twist is a little bit faster than necessary, since a 1 in 9 is optimum, but should not hurt.

Best of luck,

drags · « **Reply #2 on:** December 01, 2003, 05:05:26 PM »

Hammer47
I shot a 7br last year at Ridgway and I was very satisfied with it. I use varget powder and ser. 168 and 130gr. matchkings. The velocity for the 168 mtk is 2434 fps. ave. three shots. I never lost a ram yet with this load, and I know two other people that shoot a 7br and they haven't lost a ram at Ridgway last year either they use the same bullets as me but one uses 2230 and the other uses 4895. the 130grs. are going about 2500fps but thats just a guess as I haven't checked it on the chrony yet. They have worked very well on the c,p,t I haven't had any trouble knocking any thing over. So far I'm satisfied,they say they might shoot high power at McDonald next year. If they do I'll use the 7br there as McDonald has a reputation for rams that are hard to knock over. The 7-08 is a great cartridge but has more recoil than the 7br, I seen one 7-08 shooter that had a leather shooting vest a padded shooting shirt and a home made pad that he put between the shirt and vest, you can shoot the 7br in a Tshirt. I don't know if the 7br is better but so far it has done the job for me and the two other shooters I mentioned. Give it a try I think you'll like it. The above powders and others in there burning rate work very well, you wont have an trouble finding a good load for the 7br.
Joe

dave imas · « **Reply #3 on:** December 01, 2003, 08:05:44 PM »

be careful using Ridgway as a determining test for the 7br. or any cartridge for that matter. wonderful range with rams that are most obliging when hit.
dave

drags · « **Reply #4 on:** December 02, 2003, 09:53:40 AM »

I've read my post and I can't see where I used ridgway as a determining factor.
Joe

dave imas · « **Reply #5 on:** December 02, 2003, 01:12:51 PM »

Sorry Joe,

you stated that you were satisfied with the performance of your 7br and only mentioned Ridgway as the range for your testing or matches. please forgive me for assuming too much. my deepest apologies.
dave

drags · « **Reply #6 on:** December 02, 2003, 02:32:22 PM »

Hi Dave
No need to apologize no offense was taken. Out of curiousity why do you think the rams go down farily easy at Ridgway, the reason I ask is I think they do too thats why I wanted to try 7br at the Mcdonald Pa. range as the rams are harder to knock over there. In fact if i had it to do over again I go with the .260 rem. instead of the 7br, reason being is the recoil is about the same and the.260 seems to preform better. JMO Hammer47 sorry if I changed the subject of your post.
Joe

dave imas · « **Reply #7 on:** December 02, 2003, 07:40:05 PM »

Hi Joe,

i've had the opportunity to shoot a few matches around the country and found that the Ridgway rams were well trained and very obedient when compared to sheep at other ranges. it has to do with the wind, stands, and how the rams are set. i think you are right, the .260 is a better bet. comfortable recoil for the short animals and, if necessary, can be cranked up for the rams. i shoot both the .260 and the 6.5x55. two excellent choices. word on the street has it that the 6.5mm bullet is inherently more accurate than the 7mm. any engineers out there to confirm or rebutt?

dave

ajj · « **Reply #8 on:** December 12, 2003, 03:35:04 AM »

I've shot this cartridge for two years and like it very much. Since light recoil is the motivation I try to stress that feature in loading. Speer makes a 115 gr HP that is just spooky accurate and $12.50 per hundred from Midsouth. This is for chickens only. It's too explosive for pigs. The recoil is noticeably less than the 120's I've tried. I know that doesn't make sense...I'm just reporting.
For pigs and turkeys I use a 123 gr rebated boattail made especially for silhouette by Anthony and Lynne Finn in Australia. For rams, the Finns make a hard-cored 145 in a long jacket. Great BC, light enough for the little cartridge to move and I haven't lost a ram yet. I get it up to 2530fps out of a long barrel with a compressed load of VV133. The primer pockets will only take two firings.
If you don't like the idea of ordering bullets from Australia and loading three different cartridges, Hornady makes a 120 flat base in both HP and SP. Both are accurate in my rifle, completly adequate out to turkeys and have the additional advantage of being cheap. (Save a couple of bucks on each box of bullets and in about twenty years you'll have financed a new barrel.) I just don't see the point of the 130 MK except, maybe, wind bucking. It's too light for rams and unnecessarily heavy for the close animals.
There are lots of powders in the correct burning range. I've mentioned the VV133 ram load. For the other animals I just throw 28.5 of AA2015 under the 115 Speer and the 123 Finn. This is a mild load IN MY RIFLE.

longgun · « **Reply #9 on:** December 13, 2003, 07:04:29 AM »

AJJ, I'm confused by your post, I think!..... I thought you were shooting a 6.5 cal. Are you talking about 6.5 cal or 7MM bullets? The thread has veered off so that I am uncertain about what cal we are talking about.

Don Weathersbee

ajj · « **Reply #10 on:** December 15, 2003, 03:12:02 AM »

Hi, Don. My heavy rifle is a 7 BR. My hunter is a 260 Rem, after years with the ADL in 6.5x55.

ajj · « **Reply #11 on:** December 15, 2003, 03:14:42 AM »

Don: I should have re-read MY post before replying to yours. I see what you mean, now. My load and bullet talk was about the 7 BR and I see that I never actually said that. Sorry.

hh4064 · « **Reply #12 on:** November 24, 2004, 02:00:38 PM »

A gentleman I shoot with has a 40X remington looking down a Hart barrel. He shoots Hornady A Max bullets 162gr 29.7 gr of Vihtvouri either N120/N130 NOT SURE which one. He has not lost a ram all year. He is also 67 yrs old and loves the mild report. DO ALITTLE MORE RESEARCH BEFORE USING THIS. remember N120 vs N130 But he loves it

CB · « **Reply #13 on:** November 24, 2004, 03:57:34 PM »

I set my wife up with a 7br few years ago and after spotting the hits for her decided to rebarrel with one myself back in the spring (std gun, htr is still 7-08) both are Douglas 1x9 twist mine 26" hers 25". We've shot 140GK's, 130Speer flat base, 150 &130 MK's, and 139Hornadys, all have done well out to turkeys most have had days in the wind? I have settled on a simplified plan which is to shoot 162AMAX all the way out, recoil is mild and trajectory can easily be studied as well as windage with major reduction in match confusion. especially helpful when turkey shootoffs are up in the wind we had at Raton this year. I'm using IMR-4895 at about 2350 or so, hers 2230data at app same speed.
Ram knockdown? I was fully prepared to lose a few after seeing them slammed with the same bullet in 7-08,,,,,,It hasn't happened!! this year since rebarreling, 54rams at four differant ranges hit the dirt without a ringer. UNTILL!! I went down to shoot with ajj and the Ark gang. reduced course, half size ram at 300mtrs? and I put fraction of a bullet on the back line gouge a finernail chunk of steel out and ring my first ram with the barrel!! go figure.
As for Ridgeway 03 I seem to recall one rainy day when my most infallible elk buster ram load sent one muddy ram straight back on the stands with a center mass hit and he hung there, the impact was impressive and clearly visibly shocked with the naked eye, but he didn't go down, I heard others shooting 260s that rang none, once again,,,go figure.
7BR? I'm very much impressed with the little gun that could, I'm working on the 20 "easy points" I'm leaving standing which are hurting my scores a lot more than an occasional dinger.

drags · « **Reply #14 on:** November 25, 2004, 02:35:11 PM »

CB and hh4064, I'm using the 168 and 130gr sierra matchkings with varget powder in my 7br, have only rung one ram in the last two years shooting at Ridgway only. I like the 7br very much low recoil easy to load for, I used 6br lapua brass and necked them to 7br and turned the necks I trimmed them also and after five firings they haven't streched enough to be trimmed again. I also tried the new 175gr. matchking using varget powder estimated velocity about 2350fps, I only had a sample pack of 10 bullets so I shot 10shot groups at 100yds the smallest was 1/2 inch at 100yds 3 shot groups. My gun is a 9" twist and sierra told me that a 8" twist is needed and even if it would group well at 100yds it would'nt group at 500 meters because the bullet would slow down an lose stability. Has any one tried the 175gr mtk in a 9" twist barrel at 500 meters, any info on this bullet would be appreciated?
Drags

DanDeMan · « **Reply #15 on:** November 25, 2004, 03:40:01 PM »

Drags,

You stated:

My gun is a 9" twist and sierra told me that a 8" twist is needed and even if it would group well at 100yds it would'nt group at 500 meters because the bullet would slow down an lose stability. Has any one tried the 175gr mtk in a 9" twist barrel at 500 meters, any info on this bullet would be appreciated?

If your 175 Sierra MK is punching round holes at 100 yards it will also be punching round holes at 500 meters through a paper target. That means it is stable at 500 meters. Bullets become more stable as they travel down range until they hit the upper transonic region; about 1,250 fps.

The reason this is so is the over-turning moment, that tries to tumble the bullet, is reduced due to the fact that the bullet velocity slows down quicker than its rotation. It is the rotation that stabilizes the bullet. The velocity is related to over-turning moment, the slower the velocity for a given bullet rotation speed the more stable the bullet, so due to the fact that the forward speed of the bullet slows down quicker than the rotational speed the bullet becomes more stable as it flys down range.

Post the 7mm, 175 MK bullet length, ogive length, meplat diameter, boattail length, base diameter and I will give you an estimate of bullet stability at your intended MV.

drags · « **Reply #16 on:** November 26, 2004, 03:00:15 AM »

Dan, If I read your post correctly if the bullet is accurate at 100yds it should be accurate at 500 meters as long as the velocity doesn't go below 1250fops. Have you tried the 175gr sierra mtk in a 9' twist 7mm barrel or know anyone that has? This bullet should make a good ram bullet for the 7br, 7-08, ect. Sierra through me a curve when they said a 8' twist is needed as a 9' twist is the popular twist for the 7mm. As I rethink my conversation with sierra they said the 175mtk might not be accurate in a 9' twist but if it shot good at 100yds it may not shoot well at 500 meters, they even said cold weather would effect accuaacy, your thoughts. The measurments of the 175mtk are bullet lenth, 1.450, ogive lenth, .680, boatail lenth, .228, boatail diameter .232, meplat diameter .070.
Drags

DanDeMan · « **Reply #17 on:** November 26, 2004, 08:07:03 AM »

Drags,

There is a major difference between bullet stability as evidenced by round holes through a paper target and accuracy at 100 yards or 500 meters. After extensive testing, shooting 1,000s of rounds through heavy corrugated cardboard from 50 yards all the way out to 1,000 yards, I can say that, without a doubt, they are NOT the same. Some of the most accurate loads at 100-yards were shot with marginally stable bullets that produced slightly elliptical holes. None of these loads EVER shot well at 500 meters.

The 7mm 175 Sierra MK bullet dimensions have been input into exterior ballistics software, the equations of which were developed by the US Army at the Aberdeen Proving Grounds Ballistics Research Lab. The bullet STABILITY FACTOR (SF) is about 1.348 when the bullet is launched at 2,300 fps from a 9-twist barrel. Bullet STABILITY FACTOR is also called DYNAMIC STABILITY. Typically design SF is 1.5. Even driving the bullet to a MV of 3,000 fps only improves the SF to 1.402, marginal for all-around shooting at silhouette distances. The only way to determine if the 175MK will shoot well at the ram-line is to test it. I design for SFs of 1.5 for HP rifles. You may find that the bullet will shoot just fine in what Id call the upper marginal SF for all-weather-condition, match-quality accuracy. Atmospheric conditions can have a substantial effect of bullet stability. If the SF is too low, a load that will shoot in favorable conditions will produce shotgun patterns in less than favorable conditions. The 175MK SF was calculated at Standard Sea Level Atmosphere: 59 F, 0% humidity, pressure 29.92 at sea level.

As an example, I worked with the 6.5mm, 155 Sierra Long-range bullet extensively in 8-twist barrels. The bullet was capable of producing excellent accuracy at 100-yards when launched in the 2,600-fps to 2,700-fps MV range. At 2,600 fps the SF is about 1.24 under Standard atmospheric conditions. But, the bullet would never group well at the ram-line. I did not do any tests to measure bullet yaw angle, but it was evident that the bullet just would not shoot at 500 meters.

Years ago I shot a 9-twist, 7mm BR. My ram load used the 168 JLK VLD launched at 2,450 fps using a case full of VarGet. It was deadly accurate at rams and had a SF of 1.57 at 2,450 fps. The load never lost a ram and we have some very tough rams in CA. The bullet BC is about 0.605 at 2,450 fps. The 7mm, 175 Sierra MK has a BC of 0.592 at the same MV.

If I was going to specify a 7mm barrel to launch the 175 Sierra MK for HP silhouette use Id go with an 8.5-twist which should produce a SF of 1.529 at a MV of 2,400 fps.

cslcAl · « **Reply #18 on:** November 26, 2004, 09:17:49 AM »

Drags, I agree with Dan on the 8.5 twist. I have a 1-8.5 Kreiger #3 in a 7-08 on my hunter rifle. I had aquired a number of the new 175 MK's right before the nationals. I didn't have enough to test with so I just loaded them with the same powder charge as my 168 MK's.(39.0 grs. of IMR 4064) When I sighted them in at Raton they got to the rams with 1.5 min. less elevation than the 168's. To test for accuracy I shot at the hole in the horn; with all shots hitting near enough to going through to satisfy me. This bullet is a hard hitter. A ram hit anywhere is going down; and the one's hit on the edges or the head get ripped of the stands. I also used these loads at the Pa State match at Ridgway. I want to clarify an earlier comment made in this thread. I shoot at Ridgway almost every month and their rams are not as easy as they used to be. They did a lot of work to the range over the past couple of years and there seems to be a lot of lost rams anymore. I lost some with 168 -7-08's and I know a lot have been lost with 142-260's. Al Foust

Gringo Grizzly · « **Reply #19 on:** November 28, 2004, 12:04:33 PM »

I shot the 7BR for a year way back when it was the rage.

It WAS very accurate in my rifle and I think I used 28.5 H335/168 for all targets.
T Hartman - a darn good silhouette shooter at the time - used 29 gr W748 with the same bullet.

If you try these loads, work up as there's lots of difference between BR chambers.

I think the 7BR was chambered in the Model 7 early in that rifle's life.

I did lose more rams % wise than with the 7/08, and ended up rechambering the same barrel to that cartridge. I did this because with MY rifle I was having trouble getting consistent accuracy at 500 meters with the low velocity 168 from the BR.

Ram target sets around the country vary ALOT in my experience.
They even vary on the same range if the wind is blowing from behind the critters, have mud-caked feet, or are set up on the front of the stands by target-setters, and I'm sure some of you can name some other reasons.

If I were shooting a 7mm of any kind right now, I'd sure give those 175's a try.

Those "flying telephone poles" should be devastating indeed!

Looking forward to see what the PS Writer reveals in his ram check in the next issue using the 6 BR.

I'm hoping he doesn't use bench-shot rams in good conditions on a single day as a performance-indicator.

Gringo