Home Forums Hunting & Shooting AR and Tactical Rifles Fire-Lapping the LR-308

Just read that fire-lapping a chrome-lined barrel will remove the chrome. I went to the DPMS website and it says my barrel is "Chrome Moly" but doesn't specify if its a Chrome-lined barrel, only that this is an option. I just bought the Wheeler's system, but didn't want to screw up my barrel. I've fire-lapped several of the barrels on my other guns with fantastic results, but got a little concerned when I read that. I know that this was the base-model and I don't believe that any further "options" were included, but didn't want to take any chances. Any advice would be appreciated.

Lapping compound wont jack up your gasser will it?

Don't fire lap that barrel! Why in the world would you do that?

It's one thing on a revolver barrel with a constriction at the barrel threads or something that will only shoot cast bullets, but don't do it to a rifle barrel.

I'm talking about grit-embedded bullets like that Wheeler kit here. A polishing kit like Tubb's final finish is a different story, and while still debatable if it's helpful or not, at least that won't hurt your barrel. That Wheeler kit definitely can, and probably will. Don't do it!

I would use fire lapping as a last resort. On a factory DPMS barrel I wouldn't even consider it. If it doesn't shoot, just replace the barrel with a good one.

If you do try it, I would shoot the Tubb bullets and not touch the Wheeler stuff.

chrome moly is not chrome lined.

Why do you want to lap it?

Gunner500, I hadn't considered the gas system! This is the only gun I have that is gas operated and completely overlooked it.

Yondering and wareagle700, I used the Tubbs bullets on several other of my guns and, especially my Swedish Mauser benefitted greatly. After the completed process my Swede makes consistent sub-moa groups and, with my handloads, sub-1/2 moa regularly. I did not, however, consider that there may be a difference between Tubbs and Wheeler. It was purely economics. The Tubbs system is roughly $35 per gun while the Wheeler is $50 for the whole kit that treats several guns. Regardless, I've definitely reconsidered and will not be fire-lapping my AR's (I was going to lapp my son's 5.56, also).

Thanks for the advice!

rost495, it was only for optimization. I hadn't considered that there could be negatives, I thought at worst, there would be no appreciable gain if the bore was already good. I'm setting this one up for longer-range (roughly 800 yards is where it will go sub-sonic) and just wanted to remove variables.

YOu never lap unless accuracy shows its needed. IMHO.

I"d ultra bore coat any barrel I had, before I shot it, regardless though.

But lapping is if there is a problem...

Gas system vs lapping? Wouldn't bother me in the least. Pull the gas tube and lap away.

I've fixed one problem barrel by fire lapping it with a Wheeler kit, so they can work well.

But no chrome plated and chrome moly are not the same thing. Plating is just that, a thin coating on the bore - and lapping likely would damage it. Chrome moly refers to a type of steel composition, throughout the metal.

I would not lap a barrel that shoots well as you are removing metal. Nor would I try to lap a Chrome plated barrel, nor a nitrided barrel.

I get the economics.

However, the Tubbs kit uses very fine polishing rouge. The Wheeler kit is essentially different grades of valve grinding compound (I have it too, for other uses) and it will remove steel, even with the finest grit.

I have often wished to know what exactly the polishing compounds in the Tubbs kit are, to be able to duplicate it for barrels and other steel polishing.

Last thing I would ever do to a barrel.

It's worthwhile when you've tried everything else, and say the heck with it, I need a new barrel.

Any metal with any high Chrome content is the hardest metal you will ever work with. Hard to cut with about anything except an abrasive cutter. If Fire-Lapping would hurt Chrome lining in a barrel, I can't help but wonder the harm it does to a chrome-moly barrel itself. But I really have no experience with Fire-Lapping, just wondering out loud.

Hmm?? You're right about lapping hurting a barrel, but the rest? Chrome-moly steel is not that hard to cut, either with machine tools or a lowly hacksaw. Not sure what kind of steel you're thinking of, but it isn't barrel steel.

I know barrel steel isn't that hard, that was my point. If fire-lapping is safe enough for Chrome-moly, not sure why it would be so bad for a much harder metal such as a Chrome lining in a barrel? In spite of being named Chrome-moly, barrel steel has anywhere of .4 to .9 percent actual Chrome content, whereas Chrome lining has much higher percentage of Chromium.