Thread: suppressor pressure

Originally Posted by gundoc

I would agree that there is no significant gain in velocity but tests here in NZ have shown that good suppressors have increased velocity by a few fps in .22 rimfire rifles.

Yes, gas pressure is increased after the bullet passes the gas port, but pressure is then equal throughout the barrel. The increased pressure after the bullet passes the gas port means that the cartridge is still gripping the chamber wall when the action starts to open. In extreme cases the extractor will rip through the rim of the case. I have cured many of these problems over the years by making an adjustable gas port that can be tuned to suit each rifle, and in many cases it has also been necessary to bore out the suppressor by up to 1 millimeter to give a faster pressure drop. The bigger the cartridge, the worse the problem. Smaller rounds like the .223 have much less gas volume and lose the pressure quicker, although the higher residual pressure in the bore manifests itself by coating the cases in powder residue. An adjustable gas port addresses this situation fairly easily. The sticking case problem is more common with the .308 or bigger cartridges. I have been sorting these problems for other gunsmiths (who don't want to know about them) for many years, and still get to do them even though I am retired.

Yes I agree if we were talking about cycling issues in a gas gun but that's not the situation.. In his 7mm saum the sticky Bolt lift is long after the bullet and any pressure have gone and wouldnt the stamping on the case head is most likely to have occurred at the top of the pressure curve indicating an overload?
Id be interested to see the rimfire tests showing velocity increases with a supressor, are they on line somewhere?