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interesting problem !!!

poff6401

Sergeant
Full Member
Minuteman
Oct 26, 2007
125
0
42
Columbus, Ohio
a buddy asked me to put this on here to see if anybody had any thoughts

winchester model 70 action
krieger 1-8.5 twist chambered in 260
hs precision stock

all work performed by krieger

loading 42.5 gr. of H4350
against lands

it was shooting 5/8" groups with no signs of pressure. now the groups have opened up to 2.5" and the primers are being pierced. he is doing nothing different since he got it
 
Re: interesting problem !!!

Weigh the projectiles. I bought a batch of 168 SMK's once only to discover some 190's mixed in.
NOTE... This was an opened batch I bought online so it was just the seller's mistake.
 
Re: interesting problem !!!

Ide chrono the load to see how much faster its shooting. Its going to be something in the reloading process. An odd batch of powder, some bullets with an unusualy long bearing surface...ect...
 
Re: interesting problem !!!

Carbon ring in the throat or case necks stretching into the throat and getting
pinched if it's a tight neck chamber.
 
Re: interesting problem !!!

First a visual inspection and secondly I would have him chrono a few shots, that will be the fastest trouble shooting he could do if he has loaded every bullet he had from the batch already.
 
Re: interesting problem !!!

Also, what is the temperature difference? A hot load at 10 degrees F is going to be way too hot at 90F. Not likely the issue since it is december and cold...
 
Re: interesting problem !!!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: poff762</div><div class="ubbcode-body">a buddy asked me to put this on here to see if anybody had any thoughts

winchester model 70 action
krieger 1-8.5 twist chambered in 260
hs precision stock

all work performed by krieger

loading 42.5 gr. of H4350
against lands

it was shooting 5/8" groups with no signs of pressure. now the groups have opened up to 2.5" and the primers are being pierced. he is doing nothing different since he got it </div></div>

Are you using Lapua brass? They have thicker necks than other brands of 260 Rem causing excessive pressure problems because the neck cannot expand enough to release the bullet correctly.
 
Re: interesting problem !!!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bigwheeler</div><div class="ubbcode-body">Carbon ring in the throat or case necks stretching into the throat and getting
pinched if it's a tight neck chamber. </div></div>
+1
 
Re: interesting problem !!!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steve123</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: poff762</div><div class="ubbcode-body">a buddy asked me to put this on here to see if anybody had any thoughts

winchester model 70 action
krieger 1-8.5 twist chambered in 260
hs precision stock

all work performed by krieger

loading 42.5 gr. of H4350
against lands

it was shooting 5/8" groups with no signs of pressure. now the groups have opened up to 2.5" and the primers are being pierced. he is doing nothing different since he got it </div></div>

Are you using Lapua brass? They have thicker necks than other brands of 260 Rem causing excessive pressure problems because the neck cannot expand enough to release the bullet correctly. </div></div>

Oh and I had ran out of a older 8lb jug of H-1000 and bought a new one. The new jug was giving excessive pressure with the same powder charge as the old. Bolt was very sticky.