moly bullets

buster

buster

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left coast,home of the latte drinking granola eate
question;do moly coated bullets cause an increase in barrel preasure?" i recently tried 5 different loads for my m1 garand;imr4895,168gr hpbt moly from hornady,federal primer,rp brass.made loads starting from 44gr to 46 gr in half grain incraments.loading manual lists 47gr as max load so i kept it to 46 for starters. at 45.5gr some of the primers were showing signs of excess preasure.unfortunately,i change three variables with this load 1] switched to 168gr bullet 2] moly coated 3] imr4895 powder.at 45.5 and 46gr the peimers were protuding out from the base.the worst thing about this is the 46gr was producing the best groupings[or maybe i was improving my site picture by the time i got to these] does anyone have some input?sry forgot to mention 30-06 ,308dia bullet
 
All things equal, molly will reduce pressure as the bullet slides down the bore with less friction(chrony same loads moly and not moly, moly load will lose velocity over the non moly bullet). Protruding primers would be more a sign of a headspace issue in my opinion. Perhaps the gun should be checked for headspace and a measurement of a freshly sized case would be a good idea, could be setting the shoulder back to far with the sizing die.

Andy

Andy
 
Protruding primers aren't generally considered to be a sign of excess pressure. If the primer is protruding, then there is obviously room for extra length. Therefore there might be an excess headspace situation as Andy has suggested. Could be that the rifle is off-spec, or the brass is sized a bit short. Might be a good idea to check. If a rifle has excess headspace, high pressures will force the casehead against the boltface, and the primer will be squashed into place, perhaps being flattened in the process.
 
I agree with the post above.....

Flattened primers can be caused by slight headspace.....

Take one of your primed cases with no powder and fire it..... the primer will back up an show the amount of headspace you have.
 
thank you,seems i would be on the wrong track,i'll check my brass dimensions and adjust if off.i'm curious about using a case with just a primer ,the primer alone has the ability to push back if excessive headspace?" i'll try it and see.on a gas operated semi auto would this require a replacement bolt if it proves true?
 
I would not make a habit of running moly'd bullets through your M1, the coating will probably raise hell with the gas system. I am sure those here on the board with vaster realms of knowledge in the M1 area will chime in soon.
 
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