Fun with numbers and my accuracy averages, Custom Stevens 200

[R.W.Dale]

YAY! math

I was bored and honestly getting kinda disappointed in my Stevens 200 target rig I guess for no other reason than shooting great groups had gotten to be routine. So what I did was to take my target binder out and average up my 100yd 5 shot group sizes by bullet. The numbers I came up with were quite a bit better than I had expected and honestly have me fired up on this rifle again.

I guess the disappointment just came from only focusing on the bad groups and not giving myself and the rifle enough credit for the good ones. Anyways here's my numbers so far going back to where a started keeping targets just over a year ago

The rifle is a stevens 200 fitted with a Shilen bull bbl originaly chambered for 7.62x39mm and now chambered for an improved version, The stock is a choate "ultimate" varmint, the trigger is a rifle basix SAV1 and the scope is a Leupold 36x

125 grain Speer TNT HP

20 groups total---largest 1.12"------smallest .258" ----avg group size .597"


110 grain Hornady V-Max

8 groups total----Largest 0.832"------smallest .411"---avg group size .632"


110 grain Berger Match HP

4 groups total----Largest .760"----smallest .340---avg group size .511"


100 grain Lapua "cutting edge" HP

4 groups total----Largest .692"----smallest .532"---avg group size .613"

150 grain Speer SP

4 groups total----Largest 1.46"----smallest .930"---avg group size 1.138"


125 grain Sierra Gameking

2 groups total----Largest .882----smallest .750"---avg group size .816"

123grain Monarch (barnual) FMJ factory load

6 groups total----Largest 1.37"----smallest .666" avg group size 1.060"

What does this all tell me? Heck I don't know other than it's a good thing I bought 1000 of those TNT's and that steel cased ammo is only half as accurate as my handloads.......which is honestly disappointing and welcome at the same time. Either way I thought I'd share these results and maybe have a discussion throwing about Ideas of where to go from here to shrink these averages even further

[drdougrx]

Me thinks you have wayyyy toooo much time on your hands!!!!

No really...it's validation and a great argument for record keeping.

[Davemuzz]

I'm gonna go with the way too much time argument.

[EVOC ONE]

Lots of note taking and data.  Plenty of range time.  A ton of fun.  I like it. 

Good work and, as a Savage/Stevens fan, thanks for noting the impressive results.

 

[03A2]

Since you have time and an engineer/techie mindset, why not try some of the painstaking load prep stages you aren't currently trying and quantify their effect on your loads since you have a few of those tnt's left?  You know, turning necks, checking loaded rounds for concentricity, cleaning every primer pocket, weigh sorting your brass and bullets, sacrifices to the gods, whatever else benchresters do.  I would be interested (but much too lazy) to see what their effect on a somewhat normal hobbyist would be. 

[R.W.Dale]

Since you have time and an engineer/techie mindset, why not try some of the painstaking load prep stages you aren't currently trying and quantify their effect on your loads since you have a few of those tnt's left?  You know, turning necks, checking loaded rounds for concentricity, cleaning every primer pocket, weigh sorting your brass and bullets, sacrifices to the gods, whatever else benchresters do.  I would be interested (but much too lazy) to see what their effect on a somewhat normal hobbyist would be. 

Aside from neck turning (I intend to buy the equipment) I do all those things. Thus far specific load tuning COL, charge, burnrate ect ect has done the most to shrink my averages.

In fact I have batches of cases sorted within .5 of a grain that turn out to shoot no tighter groups than haphazardly grabbed cases that vary by almost 2 grains.

I've tried weighing charges to the nth degree of accuracy only to find that if anything accuracy was less than with thrown charges   

[03A2]

I have found COL to greatly affect things for me also, as much as bullet and powder in my limited experience.  I appreciate knowing  that none of the real time consuming tricks have had a great impact for youl.

[Frank46]

I for one would like to know more about your 7.62x39 rifle. I keep all chronograph records and load data for just about every shot fired through the screens. Somme very interesting things tend to present themselves once you have the numbers in hand. Frank

[R.W.Dale]

I for one would like to know more about your 7.62x39 rifle. I keep all chronograph records and load data for just about every shot fired through the screens. Somme very interesting things tend to present themselves once you have the numbers in hand. Frank

OK the rifle started out as a Stevens200 in .223remington. I fitted it with a savage drop in  Shilen select match stainless bull BBL chambered for 7.62x39mm on a .308" bore and a 1-15"twist.  The stock is a Choate ultimate varmint and the trigger is a rifle basix SAV1 adjusted to around 1.5lbs. The scope mounts are just plain old Leupold and the scope is a Leupold 36X

After playing around with the 7.62x39 for awhile and proving my point to folks that 7.62x39 IS NOT an inaccurate cartridge I rechambered the rifle to what I cal 30PPC Largo or 7.62x39 30 degree improved if you will.

This had two benifets,

ONE a slight increase in  case capacity

TWO a much more stable case shape and more positive headspace greatly extending brass life. I have cases that are on their 13th full power loading and still going strong

All ammo is loaded on a Rockchucker press with brass being resized using a Lee 7.62x39 collet neck die

Accuracy however is identical to before the rechambering. But of course I still retain the ability to shoot factory 7.62x39 ammo, even the steel cased stuff.

Look into my sig links for more data and chrony tests

[Frank46]

Did you have to make any special mods so as to have the larger 7.62x39 round feed from the magazine, and what changes were made to the boltface going from .223 to 7.62x38. This has got my interest. I've a small stash of lapua ammo that comes in 30 round boxes so about 3-400 rounds total. Plus about 300 IMI cases sitting around doing absolutely nothing. And I like to shoot cast bullets which in this case should be a natural. Course my savage is a long action in 308 but should not be any real problems in getting the case to feed and fire. Frank

[R.W.Dale]

Did you have to make any special mods so as to have the larger 7.62x39 round feed

Well sorta. I installed a scorehigh benchrest single shot follower on top of the mag follower and then proceeded to forget the magazine existed.

and what changes were made to the boltface going from .223 to 7.62x39.

A .223 boltface was opened up to ppc/7.62x39 specs along with a little hand reprofiling of the extractor with a file. The ejector was also removed

Course my savage is a long action in 308 but should not be any real problems in getting the case to feed and fire. Frank

I wouldn't bet on that

The one time I tried the mag the other day cartridges would literally pop up, out and literally turn round backwards when cycling the bolt. And remember this is an improved version of the cartridge with all the case taper blown out

[dross80]

What bad groups?

[Frank46]

krochus, thanks for the information. Frank

[jeepmann1948]

  A side note on your work, Very nice rifle and record keeping. Nice choice of cartridge too
 As an old time bench shooter, I agree with your method of Powder dispensing. Many years ago benchrest shooters found out thrown loads from a quality, consistent measure was more accurate than weighed charges. As a matter of fact Most of my peers use a micrometer dial equipped measure and don't have a clue what the charge actually reads.(Just what the setting is on the micrometer) this and careful repetitious  procedures make for tiny groups.
 Of course we spend way too much time on case prep, but that is just the nature of the game. Honestly I think that a good smooth flash hole make the ignition more accurate, case neck is important especially if you are shooting a tight necked case.
  Bullet seating depth is  the most critical variable. Just a few thousandths can make a large difference in group size. 
  Happy Trails & Small groups

[moorepower]

If you want to have some more fun, get some Lapua 220 Russian cases with the small flash hole, fire form them and try out some real custom benchrest bullets and get back to us on the results. Did you skim bed the rifle or are you just using the factory bedding block?

[alan in ga]

I fully intended to rebarrel my CZ 7.62x39 Carbine to something else. I pulled the barrel, turned off the rear sight 'knot' and crowned the muzzle in my lathe. Then I put the barrelled action into a CZ American walnut stock to get the advantage of the higher comb they have compared to the origional 'carbine' stock'. It also happened to be a nicely figured stock that many of the early .221 FireBalls came in.
It shoot so well I kept the barrel on it. A friend has the 30 cal reamer and I might just set this barrel back a half turn and run the improved reamer into it.
The 7.62x39 is fine just as it is, too. I'll just keep 'making do' with the .310-.311" bore. I've heard the Sierra 150 gr bullet in .311" is an excellent one for hunting deer and gives excellent accuracy.

[R.W.Dale]

The 150 Sierra is a terrible choice for a hunting bullet for 7.62x39mm.  This projectile will not expand at the impact speeds this round generates. This bullet will simply pencil through deer resulting in an unrecoverable animal. Trust me I found this out for myself.

Forget 150g bullets in this diameter, they're all designed for cartridges with much higher velocities. Instead choose a quality 12x grn bullet fueled by a stiff charge of aa1680 or n120. I always used the 125g .308" nosler b-tip after my 150sierra debacle

[alan in ga]

I have an article that said it expanded very well  in 'test medium'. Guess real animals are not the same!
Thanks for the update.I agree the 125 BT should do great.
I'll post the article later today.