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-   -   How critical is Overall Cartridge Length in the M1? (http://forums.thecmp.org/showthread.php?t=255142)

old97dog 11-19-2019 05:20 PM

How critical is Overall Cartridge Length in the M1?
 
I recently purchased a Field Grade M1 from the CMP and I am in the process of loading ammunition for it: H4895 powder and a Speer 150Gr BoatTail bullet (.308 BTSP). With the bullet set to an Overall Cartridge Length of 3.34 inches, there is very little of the bullet being held by the neck of the cartridge case.

Can I set the bullet deeper in the cartridge case, reducing the overall cartridge length? Or, do I need to select a different bullet with a flat base?

Thanks, old97dog

la Fiere 11-19-2019 05:31 PM

My Speer manual shows a COAL of 3.250 for the #2022 (150 gr. / BTSP) bullet.


If that's the bullet you're using consider starting there. 3.34" is too long.

ceresco 11-20-2019 03:32 AM

The exact OAL is not critical. You need enough bullet inside the case neck to hold the bullet firmly. Exceeding the Max OAL OF 3.34" will usually jam the bullet into the rifling....something to be avoided. I am mystified by the bullet choices shooters often make. Most of the CMP M1s are used at 100-200 yards. There is no reason to use heavy or boat tail bullets at these distances. Most shooters would be well served using flat base bullets under 140 grains with starting loads. Cost and recoil will be lowered with no loss of accuracy or function. A search of these forums will produce an abundance of information on this subject. Good Shooting. ..

mac1911 11-20-2019 02:40 PM

Quote:

Originally Posted by ceresco (Post 1887214)
The exact OAL is not critical. You need enough bullet inside the case neck to hold the bullet firmly. Exceeding the Max OAL OF 3.34" will usually jam the bullet into the rifling....something to be avoided. I am mystified by the bullet choices shooters often make. Most of the CMP M1s are used at 100-200 yards. There is no reason to use heavy or boat tail bullets at these distances. Most shooters would be well served using flat base bullets under 140 grains with starting loads. Cost and recoil will be lowered with no loss of accuracy or function. A search of these forums will produce an abundance of information on this subject. Good Shooting. ..

My bullet choices are based on price.
I will by the best deal 125-168s . The 155s often on sale for less than the 125/130s.
i dont see much choices between 130 and 150s for any better prices.

slickshot223 11-21-2019 03:44 PM

The std rule is to have no less than the diameter of the bullet seated in the neck of the brass!

ceresco 11-22-2019 08:25 AM

While that is desireable, many bullets will not allow it. LC M2 Ball is one of them and millions of rounds were produced. I will seat short bullets as deep as possible, that is, until I run out of full .308 diameter. This usually puts 30-06 rounds with 110gr to 130grs bullets at 3.09 to 3.10" overall length. Function will still be 100%. Good Shooting.......


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