Unconventional M1 Garand barrel?

[Toscano]

I'm at the end of my rope . I have an SA M1 barrel with standard markings but atypical rifling...that is to say, that instead of the "normal" 1 turn in 10" rifling this barrel has a 1 turn in 12" twist. I've measured it over and over...from the muzzle, from the breech, it still flags as a 1 in 12 and no-one seems to know where this originated or what program it might have belonged to. It isn't like a 1 in 12 is broached by accident; these things are planned. Any insight to this little thing? Was there only one produced? I doubt it...why were they made? The date stamped is 7/64...any information would appreciated...

[Dirtbiker]

Have you shot it?

Your sure it's a 30-06 and not maybe rebarreled for 308?

[Toscano]

Yes, it has been fired, many times. Even if it was a .308 it would still be 1 in 10". It doesn't like 168gr slugs but it is wicked with 155's.

[Tillers_Rule]

Brownells sells replacement barrels, the .30-06 are 1/10 twist and the .308 are 1/12:

http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=16634&title=M1%20GARAND%20STANDARD%20GRADE%20BARREL

A definite improvement in quality and accuracy over the standard, military-issue barrel found on so many shooter Garands. 4 groove, 30-06 RH 1-10" twist, .308 RH 1-12" twist. Button rifled from 4140, ordnance quality steel blanks, then stress relieved and heat treated for long bore life and dependability. Bores are held to .0002" maximum tolerance from throat to muzzle. Blued, matte finish and short chambered in .30-06 and .308. Requires gunsmith installation and finish chambering.

[CSDGuy]

Looks like a Springfield Armory barrel with drawing number F6535448. I have a barrel from 1954 with that same drawing number. Perhaps someone goofed during the rifling process and gave yours a 1 in 12 twist rate...

[Toscano]

Tillers Rule:
They are REPLACEMENT barrels...not USGI issued SA barrels. This one is.

[Toscano]

CSDGUY:
I believe that might have been the post war drawing number...I really am not sure...as I stated, "It isn't like a 1 in 12 is broached by accident;" Too complicated of a procedure.

[EOD Guy]

If you ask at the Culver's CSP M1 forum, I'm sure someone there can answer your question. See the link.

CSP M1 page

[Toscano]

I might have an answer to the conception of this barrel...if and when I get permission from the source, I'll post his answer. In short, it might have been part of another production.

[Toscano]

FWIW...Here's what I was able to find out about this barrel so far...This was offered by a collector...

That is a 1954 SA barrel, if you look very closely at the top of the "6" it is flat and not rounded which makes it a pooprly stamped "5" (could have been a worn stamp or a poor stamping operator) the F-Series drawing number and MD 41 heat lot code along with the uneven DAS stamp is common for SA rifles and especially from the 1954 time period (by Dec 1954 they where on MD 45 heat lot code). There are plenty of examples of the drawing number and other numbers being offset, Duff has an example of one on page 95 of his Post War Garand book. I have examples of offset, double stampings and poorly marked or partially obscured drawing number, date and heat lot codes all these barrels are on CMP purchased rifles which I wouldn't think would be using faked barrels.

During this mid 1954 time period they where working on the examples of the T44E4 (later to become the M14 rifle) so it is possible the barrel rifling was cut on a machine that was being used to make T44E4 barrels, as this was to be an automatic rifle chambered for the 7.62 Nato round the barrel parameter was changed to 4 groove and 1:12" twist vice the 1:10" twist normally found on the M1 Garand. As with most barrels manufactured the final outside contour cuts would not have been made until the rifling was completed to maintain alignment of the bore and it would be easy to have a 1:12 rifled blank put on the line to be final contoured as a Garand barrel rather than as a T44E4 barrel. Mistakes happen even at Springfield Armory, they where making 2 types of rifles at the same time.

You have a unique barrel which I would bet is 99% original and not a fake, enjoy it.

Jeff