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MAS .308 conversions

Posted: Sat Aug 12, 2017 4:53 pm
by wpflgun
Does anyone have one of the .308 conversions that actually works decently?

Re: MAS .308 conversions

Posted: Sat Aug 12, 2017 6:41 pm
by indy1919a4
My friend has a mas 49/46 maybe a jam every 70-80 rounds... its pretty good..

I have seen several that were crap... shot 20 rounds, then a jam o matic

Re: MAS .308 conversions

Posted: Sun Aug 13, 2017 11:00 am
by ghostdevilguy
I had one that I was lucky if it ran three rounds in a row without a failure to extract. I ran 70 rounds through it before I had enough and traded it off, I think the most it went with no problems was 5 rounds.

Re: MAS .308 conversions

Posted: Sun Aug 13, 2017 8:32 pm
by capt14k
Buy the original 7.5 French. If you already have one in .308 and don't want to sell it there was a guy who used to make an adjustable gas system that supposedly fixed a lot of the problems.

Sent from my XT1585 using Tapatalk


Re: MAS .308 conversions

Posted: Sun Aug 13, 2017 9:46 pm
by Polock
A friend had one--the only ammo it would consistently work with was Indian 7.62 dated (IIRC) early nineties--USGI ball, etc would not
get thru a mag w/o problems.

Re: MAS .308 conversions

Posted: Thu Sep 14, 2017 10:48 am
by wombat12
Good news-you can get your >308 MAS running with little work and treasure. A few areas overlooked by Century need to be addressed:

1)Recoil spring. For reasons unknown, the recoil spring was shortened. In conjunction with the shortened gas tube, the action of recoil is quite violent. The
recoil spring can be replaced with an original (new) spring available from Gunparts, Inc for $7.95.

2)Extractor. The extractor is set up for the 7.5 MAS round with a larger rim diameter than the 7.62N/.308. This is why the extractor tends to rip the rims off the .308 rounds. The extractor can be modified to provide a better grip on the .308 case:
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File carefully, reinstall the extractor and test by placing the .308 under the extractor, visually inspect and give it a little shake. The .308 case should be held by the extractor.

3) Gas valve. As stated above, the gas system of the MAS49/56 is seriously over gassed for reliability under adverse conditions. Member Starmetal on Gunboards.com offers an adjustable gas valve that is a simple replacement for the original for $40 shipped. I liked mine so well that I ordered one for my 7.5 version. I now don't bother shooters 25 feet down the shooting line!

If the above is more than you care to do, I've had several owners tell me that their problem rifles run great with steel case ammo. If you run into other problems, post them up and I'll be glad to help.

Re: MAS .308 conversions

Posted: Thu Sep 14, 2017 2:32 pm
by indy1919a4
Many Thanks Wombat12, I will try the steel case fix first... That would be pretty neat

Re: MAS .308 conversions

Posted: Tue Feb 05, 2019 1:40 am
by Rex_in_OTZ
It seems like $38 plus postage would be one the fixes my Century 49/56 needs.
Then the extractor and recoil spring.
I noticed one end looks cut
Is there a bolt buffer for the MAS?

Re: MAS .308 conversions

Posted: Wed Mar 20, 2019 11:26 pm
by Rex_in_OTZ
The replacement adjustable gas valve adjusts with a allen wrench, is supposed to be a very close fit.
The fella making them sells them for $40 thats including the $1 postage.
I sent off my postal money order snail mail and in about 2.5 weeks the new valve arrived!
(Tennessee to NW Alaska)

Re: MAS .308 conversions

Posted: Thu Apr 04, 2019 12:58 pm
by Prudhomme
Mine runs perfectly now. Years ago I bought a new extractor, spring and firing pin from Brownells. Cost about $30.00 for everything. Filed the new extractor according to instructions from this forum. Filed the tip of the new firing pin to flatten the point a little bit. Threw away the old cut spring and replaced it with the new one. I kept the original pin and extractor as they were in a small zip lock bag. The original Mags work fine as they are.
I believe Century cut the spring to prevent slam fires with softer primers, used in commercial ammo. I shoot only military 7.62 ammo so I probably didn't need to replace/modify the pin.
There is a lot of miss information about the conversion, i.e., rough chambers, gas pressure, tearing the rim from the cartridge, etc.
If Century would have filed the extractor to grip the .308 rim properly, left the spring alone and flattened the tip of the pin a tiny bit for commercial ammo we wouldn't need to touch it at all.
Anyway, I love this rifle. The size, caliber (power), stout engineering, accuracy and quality materials combine to make it a favorite.
And thanks to Kelt for being a great resource. He has seen the elephant, as some vets like to say.
Prudhomme out.

Re: MAS .308 conversions

Posted: Fri May 03, 2019 3:02 pm
by Pricate
Mine cycles and ejects fine, only had one slam fire once when I used Winchester Ammo, needless to say, I don’t use it anymore I have not had issues with anything else.