A 7.62X39 Savage Switch Barrel

Anyone interested in precision shooting no doubt looked down on the mostly Chinese made SKS and AK variant semi-automatic carbines that flooded the surplus market after the end of the cold war. On the other hand, some of the users of these carbines touted the reliability, handling and utility of these controversial little rifles.

One thing that these arms had going for them was the 7.62 X 39mm (also called "short 30 Russian") cartridge. Surplus ammunition was (and to a limited extent still is) dirt cheap. The cartridge had enough power to provide some utility while at the same time low enough recoil for just about anyone to handle. (The straight recoiling semi-autos tend to make what little recoil there is manageable as well.) My own interest in this round is for reduced load cast bullet shooting. The round provides reduced case capacity (for better load density with light loads) in a 30 caliber (pretty much the minimum caliber for trouble free lead casting) round.

Of course, a semi-automatic is a poor choice for cast bullet shooting. There are several reduced size commercial "mini" bolt actions chambered in 7.62 X 39 there are really pleasant to shoot. However, the purpose of reduced loads is economical practice shooting. The best practice is with a full sized rifle - or better yet the actual rifle you will be hunting or competing with. A switchbarrel for the Savage is therefore the logical choice for a bolt gunner, due to its ease of gunsmithing. The following article explains how, for example, a 7.62 X 39 barrel can be put on for a few months of summer practice all the while the original deer caliber can be put back for the fall.

The 7.62 X 39 Cartridge:
Before embarking on this project, the shooter should be aware of several characteristics of the 7.62X 39 cartridge. It is slightly different than just a shorter 30 caliber. For one thing, the groove diameter is slightly larger (.311) compared to most other thirty calibers (.308). Surplus ammunition is loaded to the larger bore diameter. Normally .002 is not enough variation to make a difference, although reloaders find that 308 bullets do not perform well in some military rifles. (Most commercial 7.62 X 39 rifles are made using .308 barrels.) It is noted that Clymer Reamers for 7.62 X 39 also use the .308 throat diameter. Since my plan is the use of cast bullets, I used a .308 barrel as there are a lot more suitable bullet molds available compared to a .311 barrel.

The other nuisance one should be cognizant is case head size. The case head for the Russian round is .448 - the same as the "PPC" cartridges which were derived from a Russian case design. The standard 7mm Mauser/30-06/308 case head size from which most large bore sporting and military cartridges are based is .473 inches. This is a difference of about 25 thousandths. According to literature, when using commercial or reloaded PPC rounds, many rifles (e.g. Remington 700) chambered for standard cases handle the PPC sized cartridges without problems. With this project, it turned out that some additional work was required.

The quickest, cheapest, easiest way to a 7.62 X 39 barrel for Savage is to order and Adams & Bennet (A&B) barrel prethreaded and ready to install from MidwayUSA.com. However, those barrels are apparently made with shooters using surplus ammo in mind and have a .311 bore diameter. Also, A&B barrels have a reputation for roughness - not a good recipe for shooting cast bullets.

Rather than an A&B barrel, or a more costly custom barrel, I decided to make use of the many Remington 700 take offs that show up on Ebay or Gunbroker.com. The hammer forged Remington barrels usually do well with cast bullets. Choosing one of the short (20 or 22 inch) sporter weight barrels also yielded and additional advantage: it was possible to rethread the barrel on an inexpensive mini-lathe. (The usefulness of the mini-lathe for home gunsmithing will be covered in a future article. The re-threading process will be described then.)

For shooters without lathe access, a gunsmith will need to be consulted. I have used Mark Skaggs of Grants Pass, OR. He is about the most reasonable price wise. He can be reached on Ebay as MauserHouser or emailed at Casesc45@aol.com.

There is normally plenty of meat on a Remington barrel for the barrel ahead of the threads to be turned down to 1.07 inches and threaded 20TPI. Then the barrel old shank is removed leaving usually about 1 3/4 to more than 2 inches of usable threads. However, in addition to the M700 barrel threads, just about all of the .308 chamber back of the neck must also be removed. This is due to the more tapered case of the 7.62 X 39 compared to the 308 Win. After this operation, there is a bare minimum of threads. Therefore, care in facing and chambering is required to minimize the amount of barrel removed.

In this operation, the barrel was threaded, and a cut off groove put in approximately 1/4 inch back of the neck. The barrel end was then hacksawed off . (The mini-lathe doesn't have suitable rigidity for parting.) Then the barrel face was faced, taking off just enough metal to reach the part of the shoulder less than .450 inch.

Reaming was done by hand taking care not to over ream so as to not need any more facing cut.When the barrel was fitted there were only about a half dozen threads left for the barrel nut - a bare minimum for keeping the barrel tight in the action.

Fitting and Initial Testing.
For general info on the procedure for barrel swaps on a Savage, see here. In this case, a factory cartridge (with the bullet pulled - powder dumped) was used to headspace the barrel. As always, the first round was fired with a 20' string on the trigger.

Initial testing was performed using a box of commercial 7.62 X 39 Winchester white box economy commercial ammunition. After two fouling shots the first 5 shot group was more than 3 inches at only 50 yards! Worse than the subsonic 308 118 grain plinker loads I use for tin cans. However, after two more groups, the barrel settled down to just under 1 inch at 50 yards. No benchrest winner, but good enough for offhand practice.

Unfortunately, about half the rounds failed to eject (not a real problem since I single load) and two stuck in the chamber (this is a real problem) and had to be knocked out with a cleaning rod. I borrowed a 5 round clip of Yugoslavian surplus - and surprisingly they grouped as good as the commercial stuff, but they all stuck in the chamber after firing.

Extractor Change Out:
Further research on the net showed that there are different PPC and "Standard" bolt faces. A custom bolt head is even available from Sharp Shooter Supply (SharpShooterSupply.com). Fortunately they also have a "PPC Extractor" that will allow the standard bolt head to work with the 7.62 X 39 case head. It has little more reach than the standard and it still will work with standard case head cartridges. I ordered it and after a wait of a few weeks (they apparently make them to order) it showed up in a padded brown envelope.

The SSS extractor is a little longer and in comparison to the standard extractor has a straight rather than a radiused lip that provides greater reach into the cartridge groove. It also seems to have a more pronounced front bevel. Installation is simple, see here.

Final Results:
I hadn't bought anymore 7.62 X 39 ammunition, but testing with the fired Yugoslavian rounds showed they pulled right out every time. The next time I was at the range I was shooting 6mm Rem. The first few times I chambered the rounds there was some resistance and a discernable snapping sound as the new extractor snapped over the case head. I rubbed some graphite on face of the extractor and after a few more rounds, it apparently "wore in" and seemed back to normal.

Still haven't worked up any 7/62 X 39 cast loads yet. A 30/221 (aka 300 Whisper) chamber reamer came up on ebay and I won it. Has even a smaller case capacity along with a longer case neck……

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