7.62x39 in a .308 bbl with adapter?

saands · July 29, 2002, 12:12 AM

I knew that cartridge adapters have been used to convert 30-06 to 308 for some time, but I just ran across an adapter that lets an -06 or a 308 (different adapters of course) chamber 7.62x39 ... see it at http://www.eabco.com/sale8.html ... having reloaded for my 7.62x39, I know that the vast majority (all except some ruger mini-30's) came with .310 or .311 barrels ... so is it safe to shoot standard 7.62x39 ammo out of a rifle so converted ... It seems like the pressure HAS to be elevated ... but then the 308 and the 06 are higher pressure rounds. What do you think ... I have an "extra" Turkington 308 that I made from a Rem700 take-off and a Turk 38 action (Side note: Turkingtons are a addictive habit once you get one right

) and it seems that the versitility of being able to feed it both of the 2 most plentiful centerfire rounds in existance would be nice.

Question #2: The ad states that you can reverse the conversion easily ... once reversed, do you toss the adapter or can you switch at will?

Thanks in advance,
Saands

Gewehr98 · July 29, 2002, 04:36 PM

Cheap, easy way to convert all those Navy M1 Garands to 7.62 NATO, right?

The chamber inserts, even when installed with the super grade LocTite, had an annoying habit of getting extracted with the fired 7.62 NATO rounds, leaving a .30-06 length chamber to accept the next 7.62 NATO round - not a Good Thing.

End of Navy experiment.

People have been asking the same question of the 7.62x39 chamber adapters for the 7.62x45 Czech VZ-52 rifles. I refer them to the Navy's trials and tribulations.

saands · July 29, 2002, 05:10 PM

I can see that the semi-auto application would have a high likelihood of failure due to accidental extraction and subsequent mis-chambering, but what about the more mundane use in a bolt rifle? With the 7.62x39, I was more interested in the pressure increase due to the slightly larger diameter on 7.62x39 ammo versus the standard .308 ... I don't think that the 7.62x39 would stay on the .308 Mauser's boltface if it weren't being constrained by the insert ... so there might not be the same safety issue either.

Saands

Gewehr98 · July 29, 2002, 09:21 PM

on .30-06 pre-64 Winchester Model 70's, using the .308 adapters.

That's not saying it would happen to your own bolt gun, but the possibility's always there.

Here's something else to think about. You're taking a rifle that's chambered for .30-06, aka 7.62x63, and adding a chamber/throat adapter for 7.62x39. That's a minimum of 24mm freebore for the little 123gr bullet to travel before it hits the rifling. Accuracy will be questionable.

Squeezing a .310-.311 bullet down to .308 upon firing might raise the pressures a smidgen, true, but the 7.62x39 is rated at 50K CUP, no greater than the 50K CUP of the .30-06 per SAAMI specs.

James K · July 30, 2002, 08:09 PM

As noted, the .308/.30-'06 adapters have not had a high degree of success, partly because the former round is bigger at the shoulder than the latter is at that point, so it jams into the chamber. Things are better if the adapter is epoxied into the chamber and a .308 reamer run in to cut the shoulder larger, but then it is difficult to convert back. (In a semi auto, other concerns, like gas port size, enter into the picture.)

The 7.62x39/.308 presents some other problems. The main part of the adapter is pretty thin, and if not fully supported (that is if the chamber is a bit oversize) will expand from the pressure with unknown results. Also, as noted, the smaller cartridge is smaller at the base, and may not be gripped by the extractor as it should.

If anyone decides to try this, let us know the results.

Jim

DAVID NANCARROW · July 31, 2002, 01:35 PM

If my feeble brain can remember correctly, Ruger's mini 14/7.62 is a 308 bore with a long tapered leade which allows .311 bullets to pass through it. I was shooting next to a person who owned one last Sunday, and the groups weren't pretty but it was reliable enough. Don't know if it was the shooter or the weapon/ammo. I'm not so certain I'd worry about freebore on the conversion, but would have the throating to compensate for it-Weatherby has been free boring for decades and they have pretty good accuracy in the main. I was shocked when I checked the leade on my Rem VS in 308. My stony point shows a boat tailed 150 barely touching the casemouth, yet it will toss 1/4 inch groups when I do my part, and probably better if I could get out and practice more.

HerbG · August 1, 2002, 08:25 AM

This is a very interesting idea! I noticed that the manufacturer of the adapter says best results come with American factory ammunition and with guns having claw-type extractors. A few rounds of foreign corrosive ammunition would probably lock that adapter in the chamber forever if it wern't promptly removed and cleaned!

If I were absolutely certain that adapter would come out of the gun easily, I'd give one a try in my brand new Remington 7. On the other hand, with my luck.............

July 29, 2002, 12:12 AM	#1
saands Senior Member Join Date: November 14, 1999 Posts: 1,573	7.62x39 in a .308 bbl with adapter? I knew that cartridge adapters have been used to convert 30-06 to 308 for some time, but I just ran across an adapter that lets an -06 or a 308 (different adapters of course) chamber 7.62x39 ... see it at http://www.eabco.com/sale8.html ... having reloaded for my 7.62x39, I know that the vast majority (all except some ruger mini-30's) came with .310 or .311 barrels ... so is it safe to shoot standard 7.62x39 ammo out of a rifle so converted ... It seems like the pressure HAS to be elevated ... but then the 308 and the 06 are higher pressure rounds. What do you think ... I have an "extra" Turkington 308 that I made from a Rem700 take-off and a Turk 38 action (Side note: Turkingtons are a addictive habit once you get one right ) and it seems that the versitility of being able to feed it both of the 2 most plentiful centerfire rounds in existance would be nice. Question #2: The ad states that you can reverse the conversion easily ... once reversed, do you toss the adapter or can you switch at will? Thanks in advance, Saands

July 29, 2002, 09:21 PM	#4
Gewehr98 Senior Member Join Date: June 30, 2000 Location: Token Creek, WI Posts: 4,067	I've seen accidental extraction of those chamber inserts... on .30-06 pre-64 Winchester Model 70's, using the .308 adapters. That's not saying it would happen to your own bolt gun, but the possibility's always there. Here's something else to think about. You're taking a rifle that's chambered for .30-06, aka 7.62x63, and adding a chamber/throat adapter for 7.62x39. That's a minimum of 24mm freebore for the little 123gr bullet to travel before it hits the rifling. Accuracy will be questionable. Squeezing a .310-.311 bullet down to .308 upon firing might raise the pressures a smidgen, true, but the 7.62x39 is rated at 50K CUP, no greater than the 50K CUP of the .30-06 per SAAMI specs. __________________ "Bother", said Pooh, as he chambered another round... Neural Misfires

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July 29, 2002, 04:36 PM	#2
Gewehr98 Senior Member Join Date: June 30, 2000 Location: Token Creek, WI Posts: 4,067	U.S. Navy tried that... Cheap, easy way to convert all those Navy M1 Garands to 7.62 NATO, right? The chamber inserts, even when installed with the super grade LocTite, had an annoying habit of getting extracted with the fired 7.62 NATO rounds, leaving a .30-06 length chamber to accept the next 7.62 NATO round - not a Good Thing. End of Navy experiment. People have been asking the same question of the 7.62x39 chamber adapters for the 7.62x45 Czech VZ-52 rifles. I refer them to the Navy's trials and tribulations. __________________ "Bother", said Pooh, as he chambered another round... Neural Misfires

July 29, 2002, 05:10 PM	#3
saands Senior Member Join Date: November 14, 1999 Posts: 1,573	I can see that the semi-auto application would have a high likelihood of failure due to accidental extraction and subsequent mis-chambering, but what about the more mundane use in a bolt rifle? With the 7.62x39, I was more interested in the pressure increase due to the slightly larger diameter on 7.62x39 ammo versus the standard .308 ... I don't think that the 7.62x39 would stay on the .308 Mauser's boltface if it weren't being constrained by the insert ... so there might not be the same safety issue either. Saands

July 30, 2002, 08:09 PM	#5
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	As noted, the .308/.30-'06 adapters have not had a high degree of success, partly because the former round is bigger at the shoulder than the latter is at that point, so it jams into the chamber. Things are better if the adapter is epoxied into the chamber and a .308 reamer run in to cut the shoulder larger, but then it is difficult to convert back. (In a semi auto, other concerns, like gas port size, enter into the picture.) The 7.62x39/.308 presents some other problems. The main part of the adapter is pretty thin, and if not fully supported (that is if the chamber is a bit oversize) will expand from the pressure with unknown results. Also, as noted, the smaller cartridge is smaller at the base, and may not be gripped by the extractor as it should. If anyone decides to try this, let us know the results. Jim

July 31, 2002, 01:35 PM	#6
DAVID NANCARROW Senior Member Join Date: November 5, 2000 Location: Wyoming Posts: 1,761	If my feeble brain can remember correctly, Ruger's mini 14/7.62 is a 308 bore with a long tapered leade which allows .311 bullets to pass through it. I was shooting next to a person who owned one last Sunday, and the groups weren't pretty but it was reliable enough. Don't know if it was the shooter or the weapon/ammo. I'm not so certain I'd worry about freebore on the conversion, but would have the throating to compensate for it-Weatherby has been free boring for decades and they have pretty good accuracy in the main. I was shocked when I checked the leade on my Rem VS in 308. My stony point shows a boat tailed 150 barely touching the casemouth, yet it will toss 1/4 inch groups when I do my part, and probably better if I could get out and practice more.

August 1, 2002, 08:25 AM	#7
HerbG Senior Member Join Date: January 8, 2000 Posts: 111	This is a very interesting idea! I noticed that the manufacturer of the adapter says best results come with American factory ammunition and with guns having claw-type extractors. A few rounds of foreign corrosive ammunition would probably lock that adapter in the chamber forever if it wern't promptly removed and cleaned! If I were absolutely certain that adapter would come out of the gun easily, I'd give one a try in my brand new Remington 7. On the other hand, with my luck.............