Headspace

[Buck45]

Just got a new M1A. Card in it certifies from SA. 1.631. headspace
SAMMI GO is 1.630..NO GO...1.634. 308 WINCHESTER

Now jump to 7.62x51 go for NATO 1.634 no go 1.645 That no go is .015 over the go of 308Win.

I was reading the sticky on M14/305......Are most of the M14s then really set at no go for 308 Win...when made. At around 1.638 or 1.639.

Some assistance to clear this up might help..as I think I'm looking at this from a wrong position. As 7.62 is reported to be safe in 308 Win but not the other way around. I know 7.62 is around 50k psi where 308 can be 62k.

Springfield states GI SPEC or good commercial that meets GI Specs.

My guess Hungry will need to jump on this one.

 

[M14Doctor]

My loose understanding of reloading tells me you need to size to your chamber.
I can build these rifles, but I'm no professional on the reloading hehehe

 

[Hungry]

Hey that chamber is 1 thou over the SAAMI spec.. nice tight match chamber. Full length re-size your brass. You shooting commercial? Factory .308 works fine. You got access to 7.62mm surplus? Where? That seems so rare these days...

Frankly, I just shot the 7.62mm IVI when I owned an M1A with a tight NM chamber. My #### did not fall off! That's all I know.... That was before 25 Apr 1995 when we had an ammo allotment with the ORA at Base Borden. We shot lots and lots of 7.62mm IVI ball ammo from my M1A and my TRW M14 USGI Isreali surplus! Good times!!

There....does that help?

Cheers,
Barney

 

[Buck45]

Thanks guys I really needed the input....I've reloaded for 35 years now. All bolt action and lever action stuff. Plus revolver and pistol.

I grabbed a M14s awhile back. Then got the M1A. So new venture into semi auto rifle reloading.

I'm going to use factory Hornady loads along with some PRVI ...

My new brass is Hornady Winchester and PRVI. I ordered some Norinco 7.62 for the M14s brass case stuff. When done Hungry I\ll save the norinco 7.62 brass for you ..free. It's crimped and Berdan primed so a chore at fixing the primer pockets.

Years ago I did some military stuff in 45acp . I'll stick to commercial brass now.

Range report on this stuff hopefully by mid May. Winter project maybe getting the Doctor to build me a rifle on the M14s in my safe.

Thanks again....this stuff is addicting. Learning curve is growing.

The last free 7.62 stuff I fired was in the late 60's early 70's. Just dated myself.

 

[sobo4303]

If I read your post correctly, your M1A headspace is 1.631. That is perfect for 308 reloading.

My Norky with a USGI bolt is just a 1.6315.

I full length resize mine. Just watch the case head because the more you reuse, the more the rim get chewed up. I use a precision (diamond) file to fix those when I am short of brass. Found a bunch at the range, so those are in a pile to trim up when I get desperate again.

Also, I use a Lee precision case trimmer (a bit with a standard length trimming guide). All my cases are now standard trim lengths. After the first trim, I have not really taken much off, even after four firings. You would be amazed at how consistent your groups will get with a standard and uniform case lengths.

 

[Rocket Surgery]

^ I second that and found the exact same thing. My groups were less erratic in all calibres once I stopped mixing brass and made sure they were all trimmed to exactly the same length. Many years ago I used to just fire them on the LEE precision trimmer and take them off after one spin thinking they were fine. I never realized that even after you deburr inside and out, you should put them back on the trimmer to make sure they spin freely. Now that I moved to a Lyman case trimmer with collets, I find the job actually gets done better than the LEE but that's just my opinion

 

[Buck45]

Yup it's 1.631 SPRINGFIELD has a certificate for each rifle with the technicians data and date tested attached to the serial number warranty card stuff.

For my bolt action stuff using a Girard case trimmer I think that's how you spell his name. I will keep brass lots together. Thanks for the help.

My Winchester M70 3006 uses nothing but home made loads for moose hunting. Time to branch into 308 now. One thing who carries CC1 34 type primers. I've never seen them here.

 

[Rocket Surgery]

I'm not sure who carries the CCI large rifle, I've actually never seen them for sale. Most people that I know use Fed210m primers for the m1a series rifles, they're widely available.

 

[purple]

1.632 is considered to be about the optimum for a .308 chamber in an M14 type. Altho the specs are different, most 7.62 cartridges will chamber freely in a chamber of this dimension. If you are concerned about 7.62 rounds being too long to prevent the bolt from closing fully on them in this chamber you can trial fit a batch of them by stripping the rifle and bolt and then manually closing the stripped bolt on them.

GI 7.62 brass is preferred when reloading for the M14 types due to it's greater strength/longevity. You can control the headspace and length of brass with your FL resizing die and case trimmer. You can also do a chamber check of your resized brass before reloading it. In addition to establishing the correct length of brass, it is equally important to verify the radial dimension to ensure chambering w/o resistance. This is one area where neck sizing can create a problem.