kalwasart said:
We have had several (3) customers send us their LMT's to check out, we had one customer even drive here from another state to check out his system because he was having pressure issues. We took him to the range with SSA, Hornady and Remington ammunition. All rounds had pressure issues in his weapon, flatten primers, extractor pull marks (really bad) and we also had a few blew primers. All the weapons we had tested had a timing issue and showed signs of over pressure even with our commercial loads. The one guy who drove here had sent his weapon back several times for them to address the issue, final he just replaced the barrel and all his problems went away.
We do not not if this is just a bad patch of barrels or a design issue.
Art-SSA
On CL barrel if the chamber is rough then you will see what appears to be typical over pressure signs with ammo that is even well below normal operating pressure even below 50K.
It seems many producing barrels or handling the tech issues don't have a basic understanding of what happens in a chamber during the ignition sequence of the cartridge.
The primer is hit, the cartridge, if not already, is now pushed forward against the chamber shoulder. The case walls blow out to seal the chamber. The primer protrudes out of the primer pocket from back pressure thru the flash hole(completely normal)and seats against the bolt face. Normally the case would then stretch some about 0.001 an partially re-seat the primer and also would start to releases from the chamber walls and then fully seat back against the bolt face and in doing so fully re-seating the primer. But IF the chamber walls are extremely rough combined with the fact factory ammo is set to give max headspace tolerance and most chambers are set in the middle, the the primer never re-seats. You now have a blown primer. This only takes enough pressure to push the primer out which is much lower then pressures of normal loads. Not only this but becasue the case head has been left unsupported the case head grows in diameter and in length as it stretches rather then being released from the side walls. This leaves you with all the tell tale signs of high pressure without there actually being any at all. You are left with a case that has:
Blown primer
Bulged case head
separation ring above the case head
Hard extraction
Failure to eject
Normally a blown primer is becasue the primer pocket expands excessively from to much pressure and that pressure holds it to the chamber wall. In this case its the rough chamber wall causing the issue and high pressure is not needed to create the issues.
It is understandable why a consumer would think it was a high pressure issue as that is what the normal data tells him but a firearms tech should know what is actually going on in a chamber to figure this out
Then you have the issue of, if the chamber is rough then the bore very well could be as well, as its all one coating process. If there is excessive chrome anywhere, then its very likely there is excessive chrome everywhere. Again it is a matter of understanding a process so you can trouble shoot. If you don't you are at a sever disadvantage in being able to properly diagnose whats wrong.
I think its very telling when you have a ammo manufactures helping to diagnose issues that he knowns are not caused by his ammo. That is what I call great service. I bet if you showed up at one of the "big ammo makers" with a similar issue you wouldn't be taken around to the plant and to a firing range to see what was wrong with a gun from another maker or even their own for that matter.
