7.62x39mm ammo tested in bbl lengths from short to long

[R.W.Dale]

   
Over on AR15.com I offered to compile a bunch of data concerning how 7.62x39 preforms in diffrent bbl lengths. I figured I'd share it with you guy's as well.


The rifles used for this test differed greatly from one another so please don't take this as "one size fits all" data.

The rifles used were as follows

1. A norinco 16.5" paratrooper SKS .310bore

2. is a 20" Model 1 Sales AR15 upper .310bore

3. a custom bolt gun with a 1/15 inch twist bbl that's 26" long and has a .308 bore

All chrony readings were taken at 12 feet with a model F1 without sky screens against a uniformly Grey overcast sky and an air temp of 55 degrees. Perfect chronographing weather.

Part 1 factory loads

154 grain WOLF sp


16' bbl........20" bbl........ 26" bbl
2042............2106............2273
2025............2110............2265
2015............2113............2261
2041............2125............2256
2033............2124............2250

avg velocity
2031............2115............2261



123 grn Monarch FMJ

16' bbl........20" bbl........ 26" bbl
2354............2432............2599
2345............2418............2595
2377............2405............2593
2315............2453............2548
2330............2422............2601

avg velocity
2344............2426............2587


125 grn Remington SP

16' bbl........20" bbl........ 26" bbl
2265............2261............2428
2238............2308............2444
2202............2304............2437
2191............2366............2485
2224............2264............2486

avg velocity
2224............2300............2456


Part 2 hand loads

for these loads the 26" rifle was omitted and the SKS had the gas piston removed due to slamfire and cycling concerns

170grn Sierra .308 diameter 30-30 flat point, magtech SR primer, 28.0grs H335

16' bbl........20" bbl

1921............1968
1924............1967
1931............1970
1936............1970
1896............1985

avg velocity
1921............1972

125 grn nosler b-tip, magtech SR primer, 25.5grs AA1680

16' bbl........20" bbl

2256............2359
2226............2355
2243............2361


avg velocity
2241............2358


The only real loser in all this is the anemic Remington ammo, this stuff just reinforces my assertion that anything METRIC factory loaded in this country is going to suck.

The most interesting find was just how fast and accurate these loads were when fired from as accurate platform as possible through a 26" tube

5 shot groups for the factory loads in the 26" bolt gun were as follows
154grn Wolf 1.2"
123grn Monarch 1.37"
125grn Remington 1.0

[kyelkhunter3006]

How is the barrel fouling with the .310 ammo in a .308 bore?  Any signs of high pressure with it?  I really want to make up an accurate bolt action in 7.62x39, probably on a CZ 527 or the Remington 799 action.  I want a barrel longer than 18.5" on the 527 and the 20" on the 700, with a heavier contour too.  It's almost impossible to find a reasonably priced .310 bore barrel anywhere.  I don't care about match grade accuracy, just would really like a longer heavier barrel.

[bluebayou]

Your speed and accuracy results reinforce my opinion that the 7.62x39 is a maligned cartridge.  It's the platform......SKS and AK that makes everyone sniff at this cartridge.  

Not that the average Rooshan ammo is that great to start with.  

Interesting that you got 200 fps more out of that 26" barrel.  Wouldn't have thought that it was so much with faster powders.  I assume that your handloads are Remington, small primer brass.

Side note, have checked 4 boxes of Remington PSP's at different stores and all four boxes had large primers.  Suck.

Was thinking 125 BT's in the CZ527.  Should be nice.  I have some 150 and 123 311 Hornadys loaded for this week.  I hope that they improve on the Barnaul that I tried.  

You ever tried more speed from the 125 BT's?  Or is that the most accurate load?

[R.W.Dale]

You ever tried more speed from the 125 BT's?  Or is that the most accurate load?

I've gone as high as 28grs in a bolt gun. But beyond 25.5grs in the AR15 and cases start to look a little more worked over than I would like. In the 26" bbl 28grs is good for just over 2700 fps. In an 18/5" cz 527 it would get me appx 2450 fps

How is the barrel fouling with the .310 ammo in a .308 bore?  Any signs of high pressure with it?

Don't know haven't cleaned it yet, this is the first time I've shot factory ammo in this rifle. I doubt it'll be much trouble though what with a hand lapped bore and a bit O sweets 7.62 solvent. After shooting the factory loads I shot a couple of .5" groups using 100grn .308 lapua bullets handloaded to 2850fps.

  You'd never see any pressure signs in this rifle. But it's not like .002 is going to put 7.62x39 above WSM pressures which is what my action can handle.

[kyelkhunter3006]

This is the gun you built on a Stevens 200, right?  Shilen barrel?  I'm not wanting something quite that heavy, more a "walking varminter" (whatever that means ) genre rifle.  I love the 527, but I hate that short light barrel on it.  Same thing with the 799. 

I'll mostly use it for tramping around the woods and for predator hunting.  No more .22 centerfires for me anymore, where I hunt a lot in Eastern KY, I've seen pics on a couple of trail cams this year of a cougar in the area (they don't live in KY, yeah right) and about 10 miles away another guy got a couple pics of a black bear (they only live near the TN line, I was told, yeah right +2). 

Of course, I wouldn't be intentionally hunting either of them, but if one or the other showed up and got aggressive, I'd rather have a 125gr bullet instead of a 50gr bullet to defend myself with.  The easiest thing to do (and who wants to do it the easy way, that's no fun) would be to just take the 30-06 crow and coyote hunting, but I'll be the first to admit that I can't shoot it all day without getting a flinch. 

[R.W.Dale]

This is the gun you built on a Stevens 200, right?  Shilen barrel?  I'm not wanting something quite that heavy, more a "walking varminter"

yes it's built around a stevens200 and is quite heavy, however shilen will do many different contours

[Badnews Bob]

If your building the rifle and reloading for it you have a great selection of .308 bullets why bother with .310? and if by chance you shoot some factory loads it already known to not be a problem. Win win there I think. I know I sure like my little CZ527.