7.62x39mm ammo tested in bbl lengths from short to long


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R.W.Dale
November 28, 2008, 06:42 PM
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 first.

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 Stevens 200 were as follows
154grn Wolf 1.2"
123grn Monarch 1.37"
125grn Remington 1.0"

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Winston_Smith
November 28, 2008, 09:34 PM
Nice data. I just stocked up on some monarch from academy so this is nice data to have. The monarch looks to be pretty hot stuff. Thank for your efforts.

jpwilly
November 28, 2008, 09:45 PM
Rem is way underloaded! Curious why Wolf Military Classic Ammo wasn't also tested in 122gr or Winchester White Box from Wally World? Would like to have seen those included. Otherwise good info. Thanks.

R.W.Dale
November 28, 2008, 09:50 PM
Rem is way underloaded! Curious why Wolf Military Classic Ammo wasn't also tested in 122gr or Winchester White Box from Wally World?

Two reasons

Even though I had a box of mil classic on hand my AR15 will not ignite the stuff.

I didn't have any win ammo on hand, the ammo tested was what I happened to have.

I'm most impressed with the Monarch fodder especially the combination of accuracy and velocity from the Bench gun. Just over MOA for less than $5 a box and at a smoking velocity too. I wish I had bought another 1K

XD-40 Shooter
November 28, 2008, 10:11 PM
With my Yugo SKS, which is a 24" barrel with the grenade launcher, I'm getting 2450-2500 fps with the 122 grain Wolf FMJ and I'm getting 2150-2200 with the 154 grain Wolf SP's. The extra 4" of length is giving me 75-100 fps. The grenade launcher acts like an expansion chamber, its not rifled, but it still contains the gas from the powder.

Mike U.
November 28, 2008, 10:42 PM
I've been hoping someone with a chrony and weapons in 7.62x39 with different barrel lengths would do this type of testing.
Thank you, krochus. :)

IIRC, someone mentioned in another thread that Monarch is a re-badged version of Sapsan. Anybody know if this is true?




Hmmm...haven't been to Arfcom's dark side in a couple of weeks. Better mosey on over and catch up. ;)

R.W.Dale
November 28, 2008, 10:43 PM
IIRC, someone mentioned in another thread that Monarch is a re-badged version of Sapsan. Anybody know if this is true?


All indication point to the stuff being rebranded Barnual, which is very good stuff

gvnwst
November 29, 2008, 04:42 PM
Nice data krochus. Can you get some ballistics charts up for this info?

R.W.Dale
November 29, 2008, 04:54 PM
I could calculate them up using my "POINT BLANK" program, but I'd be completely lost as to how to post em in a readable format. I really struggled with the HTML needed for this small collection of numbers.

I'll see what I can do for a simple 100 200 and 300yd energy and trajectory table

gvnwst
November 29, 2008, 05:03 PM
Cool, thanks.

R.W.Dale
November 29, 2008, 06:07 PM
as best I can calculate the ballistics are as follows, based on a 200yd ZERO

154 grain Wolf SP, ballistic coefficient .3302

range........elevation........velocity........energy

16.5" bbl

100yds........+4.64"........1813fps........1124 fpe
200yds........+0.00"........1614fps........890 fpe
300yds........-17.78".......1432fps........701 fpe


20" bbl

100yds........+4.20"........1891fps........1223 fpe
200yds........+0.00"........1685fps........971 fpe
300yds........-16.39".......1497fps........766 fpe


26" bbl

100yds........+3.46"........2029fps........1407 fpe
200yds........+0.00"........1811fps........1121 fpe
300yds........-14.35".......1612fps........888 fpe



123 grain Monarch FMJ, ballistic coefficient .257?

range........elevation........velocity........energy

16.5" bbl

100yds........+3.44"........2042fps........1139 fpe
200yds........+0.00"........1765fps........850 fpe
300yds........-14.72".......1517fps........628 fpe


20" bbl

100yds........+3.12"........2118fps........1225 fpe
200yds........+0.00"........1833fps........918 fpe
300yds........-13.74".......1578fps........680 fpe


26" bbl

100yds........+2.66"........2268fps........1404 fpe
200yds........+0.00"........1971fps........1061 fpe
300yds........-11.71".......1701fps........790 fpe


125 grain Remington SP, ballistic coefficient .267

range........elevation........velocity........energy

16.5" bbl

100yds........+3,93"........1941fps........1046 fpe
200yds........+0.00"........1684fps........787 fpe
300yds........-16.15".......1454fps........587 fpe


20" bbl

100yds........+3.57"........2012fps........1124 fpe
200yds........+0.00"........1747fps........847 fpe
300yds........-15.02".......1510fps........633 fpe


26" bbl

100yds........+2.97"........2157fps........1292 fpe
200yds........+0.00"........1879fps........980 fpe
300yds........-13.11".......1629fps........736 fpe

ByAnyMeans
November 29, 2008, 07:17 PM
Krochus:

Did you see a big difference in your groupings when using 308 diameter bullets in the guns. I ask because I am looking into reloading 7.62x39 for my AK and it would be easiest and cheapest to use the .308 diamter I have for my .308 bolt gun. I heard everything from "it will be a tackdriver in the bolt gun and okay in the AK, hey it's an AK anyway who cares" to "if you do that you will blow your AK up in your face. You seem to be very knowledgable in this department so any info you could share would be appreciatted.

R.W.Dale
November 29, 2008, 07:30 PM
In all the .310 bored rifles I've tried .308 bullets in none showed the slightest reduction in accuracy because of it. Many reloading dies for 7.62x39 come with two expander balls for .308 and .310 diameter bullets just for this reason.

I have however noted that with low pressure loadings the smaller bullets tend to produce somewhat lower velocities, but this disparity all but disappears when full throttle loads are used.

many don't realize that .310 bores tend to have deeper rifling than STD american .30 caliber. guns. While the BORE may be .002" larger typically the measurement between the lands will still mic .300 just like any 30 cal. This means that you still have plenty of grip on .308 bullets in a .310 bore. I theorize that between the bullet jacket material displaced by the rifling and bullet obturation there's more than ample bullet seal generated to prevent any significant amount of gas blowby

that or......

when it comes right down to it .002 just isn't very darn much

ByAnyMeans
November 29, 2008, 07:44 PM
Thanks for the reply and figured you were the one to ask. I never thought about the dies and your right all the ones I looked at had both 308 and 310

Dr. Tad Hussein Winslow
November 29, 2008, 08:05 PM
Very interesting; thank you!

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