Cleaning and abrasives and Fire Lapping
- By MikeMiller
- Bolt Action Rifles
- 39 Replies
Dang that fired a couple of brain cells in my headHere is another good one for ya....
Back when we did a ton of R&D barrels for Remington for the MSR rifles I get a phone call out of the blue from one of the engineers. They were down in TX doing testing. Also had military guys there from what I remember. Caliber was 338 Lapua if I remember correctly. Might have been 300wm. Anyways both guns are just being hammers with box ammo. Then he tells me... the next day one of the guns just quite shooting. I forget the distance but it was at long range. He said the day before the gun was shooting .7moa or better with box ammo and the next day rounds wouldn't even hit paper. Wild shots going every where! Low round count on the barrel as well. I said, The gun just doesn't quit shooting like that. Some body did something somewhere. I asked the normal questions... same lot of ammo, scope issues, was it cleaned and what and how etc... he said the gun wasn't in they're control/possession the whole time. I said... better start asking questions and digging into it. The other rifle was still pounding nice small groups.
Turned out someone ended up fire lapping the barrel on that one gun! Here's your sign!
I was once teaching a class of 20 police snipers all with the same 26” REM 700 PSS’s. I took one case of Fed 175’s in 308 and did ten rds in each on chronograph. The average velocity ranged from 2450 to 2650. Guess which guns were slower? The couple DIY fire lapping Not a big sample and was told they shot better after fire lapping but the fire lapping bullets I had bought to try have not been used in twenty years because of it
I understand a true smith doing a touch up on lapping to get final machine marks out because he knows what he is doing but I put DIY lapping barrels with DIY crowning. Don’t do it yourself. Leave to professionals