Here is something for those who don't use pressure testing equipment: After you get a barrel clean, velocity will usually stabilize by 5 firings. It takes 12-15 for pressure to stabilize.
Yes...velocity can be stable and pressure still having some significant swings.
Charlie
In a separate post on barrel cleaning, Mr. Charlie Sisk mentioned the above quote. I'm curious what is happening in this scenario, and how it is expressed in pressure testing. Also, sort of percentage changes in velocity and pressure are testers seeing from the first shot from a clean barrel to stabilization?
What I have experienced is this: lets say you are running a cartridge/powder/primer/bullet at an even 60,000 psi and 3000 fps.
A very good load will have less than 600 psi swings and less than 20 fps extreme spread on velocity. That's with a barrel with that has not been cleaned. Then clean it very good, all the carbon and copper removed. Usually velocity will stabilize in 5 or so shots. But it takes about 12 to 15 for pressure to stabilize, usually 2000 psi or so swings.
But....some loads and barrels may take longer. I have experienced some factory barrels (not match grade) that from a clean barrel to a fouled barrel could change 10,000 psi. Depends on the barrel. And how in particular it was fouled.
And here again I will include this part that pisses everyone off: pressure is described in PSI or CUP, not with adjectives or adverbs.
Don't think that you can measure pressure with eyesight, it wont work. And looking at primers (even if its blown), doesn't absolutely mean anything. Or measuring case heads. And sometimes just because the bolt is hard to lift, because sometimes other things can cause that. Like a front action screw that's too long and hitting the bolt lug.
Now to be fair, I have done very little testing with factory barrels. And that experience has shown me that factory barrels are not as good as match grade barrels. Its that "kinda get what you pay for" thing.
And this: I don't have much experience with cleaning factory barrels. I usually am cleaning match grade barrels with properly cut chambers. That's a whole different ballgame.
Charlie
