Rem 700 7.62x39 Conversion

lejarretnoir

lejarretnoir

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Another project I wanted to do and found the time before I start work next week.

Basically, this Rem 700 started out as me buying a used factory stock 700 BDL .308 Varmint made in the 80's sometime right here on the EE. Upon receiving it I found the headspace bad. It closed easily on the No-Go giving it .006 extra. Not cool, but I found that is within Remington QC so it got the stamp of approval. I decided to test a few rounds and found the brass was shaving off at the ejector plunger hole and causing it to be difficult to open after firing, trigger had lots of creep and stock had a loose fit.

OK, now I see why it got sold. No problem, got a good deal and I had plans for it anyway. Off came the barrel, blueprinted the action, corrected headspace, polished trigger and everything is right as rain. Managed to get sub MOA groups with 154 gr Scenars and some Sierra 150gr GK SP. Not fantastic, but acceptable. Since I have other .308 barrels that shoot better I pulled it off again and set it aside.

Found some more deals on the EE. A damaged bolt where the extractor and nose part had been broken off and an extra BDL varmint stock. A good candidate for a PPC/7.62x39 bolt head conversion. Repaired the bolt and installed a Sako extractor, pillar-bedded the action in.

Since I already own a 7.62x39 reamer throated for a .308 bore I had to measure and see if I could convert the varmint barrel to the Russian round. Almost all the .308 Win chamber had to be removed. Cutting off roughly 1.5" and some made it so I could make a complete chamber. This left just a bit more than .100 for a shoulder and the original 24" barrel finished at 22.5".

Did some testing with Czech surplus, factory PRVI, Mexican match and some handloads all with Hornady .310 123gr. V-Max bullets, 20x Super Sniper scope and trigger set at 2lbs crisp.

Home on the range and my humble benchrest. Not high tech, but it gets my rifles zeroed @ 100yds. :)

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A closeup of the shoulder and recoil lug area. Snugged up nice and tight with lots of meat on the shank.

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Some groups. Not spectacular, but remember the barrel is not either.
Czech Surplus did average around 2 to 3".

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I did manage to pull off one sub MOA group with the handloads and one sub 2MOA with the Czech surplus, but I think the .308 bullets will do better than the .310's in this bore. Of course my testing is minimal at this time, but I will report back later once I reload some other bullets and tweak the loads. There was no tweaking of any load in this short test. The PRVI factory ammo shot a tad better than the Czech Mexican Match V-Max.

In conclusion, I'm satisfied with it. I'm in the process of having a new .308 mag follower delivered and spring to alter for my mag as I only loaded single shot for the test. If I didn't cycle fast enough the loaded rounds would sometimes squeeze out. I shortened the .308 mag body and blocked it like a .223 body, but left it fatter for the 7.62x39 cases as the .223 body would jam the cases being too small. Just need the modify the follower.

Extracts perfectly and no pressure signs whatsoever. I see no problem at all with .310 bullets in .308 bores. May not be the most accurate, but will work and certainly will be fine for short range deer hunting. ;)
 
that's interesting.
Nice to see a guy that's not scared of tearing apart a rifle and modifying it himself to get what he wants. Sounds like you've got the 7.62x39 on the 700 action figured out. I've done 700's with shank OD's as small as 1.14, you don't need much shoulder as long as it's flat and without a large bevel....
Sounds like your magazine mods are similiar to the mods for running the 6BR case....
 
Unfortunate about the original not working out. Would you have had enough meat in the shank, had it not been a heavy barrel to start with?
 
I don't understand why the 7.62x39 seems incapable of decent accuracy. It is ultimately based off the 220 Russian which was also the basis for several of the most accurate cartridges in the world. The 7.62 just seems determined to deny its accurate heritage.

I really wanted to like my 7.62x39 bolt guns but an inaccurate rifle just sucks.
 
Suputin said:
I don't understand why the 7.62x39 seems incapable of decent accuracy. It is ultimately based off the 220 Russian which was also the basis for several of the most accurate cartridges in the world. The 7.62 just seems determined to deny its accurate heritage.

I really wanted to like my 7.62x39 bolt guns but an inaccurate rifle just sucks.
Click to expand...

I have no idea what the standard of accuracy is for M43 ball.
There is no reason why rounds assembled on the 7.62x39 case should not shoot very well indeed, assuming an accurate rifle and quality bullets.
In a .308 barrel, as lejarretnoir has used, I bet the 130gr bullets used in Hunter Benchrest would shoot very well, even though they are generally shot in slower twist barrels.

Years ago I did a M700/7.62x39 conversion, bolt altered to suit, fitted a non-detachable Mini-30 magazine. Worked well. Then my interests changed, and the bolt has a 6PPC barrel in front of it, and the receiver is sleeved.....
 
I remember when I shot DCRA target rifles where we used 7.62 NATO IVI ball. Getting a good lot to shoot 1.25" groups was exceptional, but the term "Flying with IVI" comes to memory. These were match grade barrels too, but it didn't matter. The odd flyer would open that group to 3x the size.

M43 ball is not as well made as IVI is. Steel jacketed, steel core, steel cased with some lead in the tip and little between the jacket and core. I don't believe the Reds were concerned about quality control as much as we in the Western world. 6" @ 100 meters is accurate in a SKS as it was originally intended for. Getting some 2" groups from the boltgun was exactly all I could hope for with the Czech ammo. I tested a Charles Daly Mini-Mauser .310 bore 7.63x39 a friend had that shot horribly. I suspect a bad barrel there.

Let me test some Lapua and Sierra match bullets and see what transpires. .5 MOA is doable with this barrel and 1-12" twist and some good bullets. Unfortunately, most gunmakers are not stepping up to make this round even more accurate in a boltgun. All we see is short barreled carbines, 1-10" twist and .310 bores and no match ammo. Your typical .308 Win and .223 Rem has all the refinements done.

Would I put a $400 dollar match grade barrel on this action to see if it would shoot better? No, but I know I can make it shoot itty bitty groups if I did. I just don't have deep pockets yet. ;)
It's not a cartridge I find suitable for F-Class competition. Great for having fun though. Cheap to shoot and doesn't beat me to death with recoil after 200 rds in a 9lb gun. Besides, I wanted to do this conversion for a long time. Since the 6PPC hit the world the original round has always intrigued me and cheap practice in a centerfire rifle is a solid goal. :)
 
Part 2

After yesterdays groups I was beginning to think my shooting had gone to hell, so I loaded up some 168grs Sierra MatchKings and some Lapua 154grs Scenars. I was able to touch the lands with the Sierras, but could not with the Scenars because of different ogives and the bullet damn near fell out of the case. The throat of the reamer is long because my main goal was to shoot .310 bullets in a .308 bore. I set the depth of the Scenars to the same point of the Sierras.

It didn't take long after a few sighters between cleaning breaks to get zeros and foul the bore with both bullets to see which bullet showed promise. I really wanted the Lapua to tuck em in, but try as I might I could only stay sub MOA. I think the throat is wrong for it and I'll just stick to using it my 0 freebore Palma .308 reamer I have on order. That reamer is designed for all the new Palma bullets coming out.

The clear winner hands down and sub .5 MOA is the old Sierra 168gr. MK. Let's put it to rest that the 7.62x39 cannot be made to shoot accurately. It can and will. These are all 5 shot groups @ 100yds.

After I tried some 165gr Sierra HPBT bullets I had laying around. They also could touch the lands and delivered sub MOA easily, but match bullets they are not. They are at the top left and bottom right. The cartridges are where the foulers and zeroing took place. Each bullet struck at different POI.

OK, my confidence is restored, but I had to quit as the mosquitoes were really bugging me.

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Part 3

A beautiful day at home on the range and another attempt at getting some groups from Czech Lot 1992 and Norinco Lot 74. A series of 5-5 shot groups @ 100yds.

After a couple of sighters, Best group of the day for Czech ammo was 1 1/8", but then a flyer opened a group to 2 13/16". Because of unknown flyers I needed two targets to be sure I could keep them on the paper. Agg is 2.06"

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The Norc ball really came in strong with one group that broke MOA at 15/16". The biggest groups were 1 1/2" and agg is 1.262".

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Let's face it, the Czech stuff is mediocre at best, but cheap. The Norinco surplus rivals factory hunting ammunition in your standard bolt action hunting rifles. I wish we could get could more of it.

It's been fun testing out the 7.62x39 and various ammo in a known varmint barrel capable of .5 groups. I'm positive with a match chamber, barrel, benchrest bullets and everything spec'd for ultimate accuracy this little bugger could put them in one hole like it's offspring.
It's not really new what I accomplished here because the 30PPC has been done for awhile now.

It really is too bad that some guys get a hold of after searching hard and paying a near $1000 sometimes for a 7.62x39 bolt action only to find it's accuracy is horrible. I did test one of the first batches of Norinco Bush Rangers and a Charles Daly many years ago, but was not impressed. 4 to 6" groups should not be happening with bolt actions. I suppose some of those rifles will shoot better than others, but my findings left me frustrated. I've heard good things about the little CZ 527 in this caliber. Perhaps someone could post their groups too.
 
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