Well I finally finished the grand firelapping experiment. I figure I'd throw out the results since others have hotly debated the wisdom of such a drastic thing to do to a barrel. Some background:

-Factory New (Feb, 2006) Ruger M77MKII in 280 Rem
-A good 100 rounds of factory stuff and 250+ round of reloads without anything shooting under 1.5-2" groups.
-I pillar bedded and floated it.
-1-2 rounds leaves visible copper streaking at the muzzle.
-accuracy, such as it was, deteriorated rapidly after 10+ rounds.
-There were visible ring grooves from tooling/rifling/whatever down the length of the bore. Explanations ranged from a bad/rough reamer used for the bore to oversized reamer before hammerforging.

Now after shooting the Tubb system firelapping, all 50 rounds, I took the best of the previous loads out ot the range. I tweaked it .5 grain up and down, and shot the same 5 rounds first 5 and last 5 to check for fouling effects. All shots were without cooling time, and I only waited 10 minuted or so between groups. The top left and bottom right have pulled shots...discount them.

150 grain Nosler BT, 57 grains H4831SC, 100 yards


Yeah, I'm f'in happy with the results! I still get a bit of copper right against the rifling, but the vast majority of the grooves are clear after 20 rounds.

It changed a trash rifle to a serious keeper. That makes it fully worth the effort and cost! As usual, YMMV.

Many thanks to Rusty Marlin and the rest of the AR guys for answering several inane questions and helping convince me to give it a try!

Just curious, did you measure the distance to the lands before and after the fire-lapping?

Looks like the effort paid off. Glad to see it worked for you!

Length to lands for this bullet (150 NBT) increased from 3.35 to 3.42". I wonder if there was a burr or tight spot left over from chambering that was wiped out by the firelapping. I tested for accuracy after the first 2 sets and got a 25/32" group. That tells me there was likely bullet damage leading to (or at least greatly contributing to) the accuracy problems.

Since it was so short throated I didn't mind the extra wear. I still need to slug the barrel, but there was no measurable difference at the muzzle after the first 2 sets.

Looks like you got good results!
I wonder how much was due to the bedding and how much firelapping?

Is the crown in good shape?
I've seen Rugers in magazines with close up pictures of the crown showing burrs.

gunmaker

I had similar results when I fire lapped my Savage a few years back.

Funny thing, I was at the range a few weeks ago merrily banging away, when I looked at some of my older notes. Before the Tubb polish, I had to stop after 10 rounds and clean out the copper or accuarcy would suffer. That day, I had 25 rounds through and no drop off in accuracy, and it cleans easier also.

quote:

Originally posted by gunmaker:
Looks like you got good results!
I wonder how much was due to the bedding and how much firelapping?

Is the crown in good shape?
I've seen Rugers in magazines with close up pictures of the crown showing burrs.

gunmaker

The bedding didn't help measurably...I did that and shot for groups before firelapping.

The crown shows a good symmetrical fouling pattern and no burrs.

CDH, congratulations! Your results mirror mine with firelapping. I've never seen it do anything negative, unless pushing on the throat a few thou pisses you off, if the rifle shoots better, then I figure that's a moot point.

Thanks for sharing your intel.

Regards--Don