Precision Load for M1A

P

Powderman

New member
Question to all:

I am working my way through a jug of IMR 4895, pulled down powder.

I loaded some trial rounds in .308, using 150 gr. FMJBT for testing and initial zero, and 175 gr. MatchKings for grouping(or so I thought).

For the 150 gr. bullet (also military pulldown) I used 42.0 grains. For the 175 gr. I used 41.0 grains. Both loads used Federal Match primers.

With the light bullets, I just ran the cases through the sizer, wiped them down, hit them with the powder measure, and seated a bullet. No special prep, no extra care. I even had mixed cases!! Crimped the crap out of them with a Lee factory crimp die.

The 175 gr. bullets received the full monte--neck turned, cases weighed, primer pockets uniformed and cleaned, bullets weighed, charged hand trickled. Bullets seated in two steps, no crimp. OAL measured exactly. Fired from clean barrel, 1 round every 5 minutes, wet patch with Hoppes and dry after every round for two, three round groups.

The rifle used is an M1A Nat'l Match, with a Kahles 3-12x56 mounted.

So, what's the rub here?

The Match Kings patterned like a shotgun!!!! 3 inch groups, at 100 yards!!

The 150 grain "plinkers"?

.340 to .509 inch groups at one hundred yards.

What gives? Did I do something wrong--or is it that my rifle doesn't like the load?

Thanks,

Eagle
 
What's the rifling twist? I don't have an M1A but I do have a couple diferent .308 bolt guns and my slower twist barrel (1:12) likes the lighter bullets better. Isn't it a great hobby? Sometimes the exact opposite of what you expect happens. Gotta love it!
 
IMHO, it is the barrel twist. The National Match barrel is 1:11 twist. You may need a 1:10 twist match barrel to stabilize the 175 grain bullets. You might try 155 gr or 168 gr match bullets as well.

I have M1As in all three barrel twists but the best groups are consistently with 150 grain Sierra boattail handloads. Go figure! This might be a M1A reloading secret you stumbled on to! :D
 
Neck turning

Suggest you NOT turn the necks.................semi's are not like bolt's............
They NEED case neck tension, around .003..............
Try again, and do not swab the bore.........wait until you have shot 3-4 5 round groups..........
Still allow cooling, and time.......but every time you swab the bore, you are asking for larger groups..........especially if you are doing it in the middle of groups.........
 
I am not sure with the heavy bullet is the problem. I shoot 174 gr GI boatail bullets at 200yds and can get 4 inch groups with iron sights from prone using 4895 in your powder weights. I don't turn necks nor do any other benchrest type preps. Maybe look at you bench holding technique??

pwiz
 
Try a different powder. I have excellant results (for me) with IMR 4064

I've got a question too...I've been loading 42.0 gr 4064 with a 180 NP, and it shoots great, but I've been told recently to stick with milspec loads for my M1A (147 to 175 gr bullets) or it may give me op rod problems later, and commercial ammo (308) is probably over pressure for this "Mil-Spec" rifle also.

Can anyone expound on these issues for me? I hesitate to think my loads are too much for such a fine rifle, but would like the whole scoop to be sure.

Thanks!
 
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