O.A.L.

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  • Last Post 05 October 2023
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4895 posted this 04 October 2023

after having trouble getting a decent group in my 308 pre 64 bolt rifle, while using a cast bullet that weighs 180 gr with a check, i Notices the chamber is was short, the gas check on the bullet when  seated is below the neck, i think this is to short of a chamber for cast bullet target shooting. could this be my problem?

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pat i. posted this 04 October 2023

I'm gonna go out on a limb here and say...maybe. What bullet, what load, what alloy, size, what velocity, how far below the neck? Lot of questions I know but knowledge is power.

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OU812 posted this 04 October 2023

I would do a pound cast and measure. Be carefull when seating bullet into tight case neck. Some alloys can be soft enough to expand during seating.

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Ken Campbell Iowa posted this 04 October 2023

ditto on the chamber image ...  it might be surprising how close you are  .. and avoid months of guessing and wasting primers when maybe just a teensy bit of fiddling could get you better groups. 

for instance , it could just be the nose on your bullet is too snug for the bore ...

or just the front band of the fat end of the casting .

****************

for instance , just finished rebuilding my new toy, an old beater Tikka 55 in 308 ... so anxious to shoot this i loaded up several loads with my usual plinking castings for all my 30 cal rifles  ... 0.310 bases, but undersize 0.297 noses, which only work at about 1200 fps ..   6.5 gr of 700X ... ... oh oh, 6 moa ... oh oh ... 

so did a pound cast ... finally ......  after i wasted 150 primers ....

hmmm .. just ahead of the neck i read 0.316 although tapering quickly to 0.308 .. wow ...  my only cast bullets that are even close are just 0.312 base .. so tried these and now groups are an acceptable 2 moa ...  right direction ....

now i need to find another couple thou to clog up the gas squirting by that still loose base ... that way lies glory ...

options are to swage the base bigger or find another mold ...  a shrewd member here also mentioned making longer necked cases from 30-06 brass to reach the tighter spot in the leade ...   ...  might try 3 or 4 of those ...

but at least i see the problem and that carrot is hanging just in front of my nose ...

just some thoughts ... ken

 

 

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Glenn R. Latham posted this 04 October 2023

4895,

   A GC below the neck isn't fatal, I shot a lot of matches like that and did well, but I wasn't "firewalling" the load, a 190 cb at 1520 fps. with 4759.  As others said, bullet fit would be the first place to look.

Glenn

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4895 posted this 04 October 2023

 i'm suffering with P.P.M.S and buy my bullets 500 at a time. my load is 28gr of 4895 that i shot years ago when i was in good shape but now a days ihave to cheat a litte

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pat i. posted this 04 October 2023

Ken the saami specs on a 308 has a .310 .090 long ball seat followed by a taper. For that thing to have a .316 opening to the ball seat is really big. Must have 1000s of rounds through it. 4895 what are your driving bands micing? I assume it's a bore rider so what size is the nose?

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lotech posted this 05 October 2023

I've seen very good accuracy results using the Lyman #314299 with the gas checked bullet base slightly below the neck. I was using this bullet in two .308s. The nose is simply too fat to seat out to where it needs to be. With my recently discovered Eagan taper die, I'll  try to shrink the nose where the bullets can be seated out farther. 

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