The Firing Line Forums - View Single Post - Chambering problems-250 Improved(Ackley)

bfoster · October 11, 1999, 09:50 AM

You might measure the head diameter despite there being no signs if pressure. Other things to check are the neck diameter of loaded rounds and also look for burrs (with a magnifying glass) at the case neck: it doesn't take much of a burr to cause a problem. It might also be possible that the brass has taken a "set" (if you have been using really high pressure loads- in better lots of current brass it takes a peak pressure of very near 80,000 psi M43 to cause visible signs of overpressure in some rifles). If you have been shooting "hot" loads I'd check for case thinning just ahead of the web, and measure case length with a Stoney Point comparator or something similar. The problem is that sometimes a full length die needs to be readjusted or have a couple thousandths ground off to size stretched brass enough to chamber properly. An alternative is to grind the shellholder.

A second line of thought is that it might not have anything to do with the case. If you have been using a slow burning rate ball powder it is sometimes possible for deposits to form in the throat and first inch or two of the barrel. If the cases held the bullets snugly & there were deposits you would notice tight chambering. It can be tough to see deposits without a borescope, but if you were to run a very snug fitting patch through the bore and noticed that the rod was considerably easier to push & pull through all of the barrel except the first inch or two you do have a problem. These deposits aren't at all easy to clean out.

October 11, 1999, 09:50 AM	#2
bfoster Senior Member Join Date: October 13, 1998 Location: N. of Fords Switch, OK, USA Posts: 297	You might measure the head diameter despite there being no signs if pressure. Other things to check are the neck diameter of loaded rounds and also look for burrs (with a magnifying glass) at the case neck: it doesn't take much of a burr to cause a problem. It might also be possible that the brass has taken a "set" (if you have been using really high pressure loads- in better lots of current brass it takes a peak pressure of very near 80,000 psi M43 to cause visible signs of overpressure in some rifles). If you have been shooting "hot" loads I'd check for case thinning just ahead of the web, and measure case length with a Stoney Point comparator or something similar. The problem is that sometimes a full length die needs to be readjusted or have a couple thousandths ground off to size stretched brass enough to chamber properly. An alternative is to grind the shellholder. A second line of thought is that it might not have anything to do with the case. If you have been using a slow burning rate ball powder it is sometimes possible for deposits to form in the throat and first inch or two of the barrel. If the cases held the bullets snugly & there were deposits you would notice tight chambering. It can be tough to see deposits without a borescope, but if you were to run a very snug fitting patch through the bore and noticed that the rod was considerably easier to push & pull through all of the barrel except the first inch or two you do have a problem. These deposits aren't at all easy to clean out.