Fire lapping for 50 BMG Tac Rifle
Anyone know of a source for bullets, abrasives or loaded rounds for fire lapping a rough 50 BMG barrel? Anyone experienced in performing this operation on this caliber?
Thanks for any help.
Thanks for any help.
0
-
Both Brownells and Midway sell abrasive kits.
I've never done a 50 cal. bbl., but regardless "fire lapping" is the last resort that I use.
Consider using slightly worn cleaning brush wrapped with cleaning cloth coated with valve polishing compound. Run the patch through half dozen times, then change it out and repeat. Keep doing that and after say 8-10 patches clean well and try firing it to check improvement.
There are some other abrasive pastes out there that are coarser than valve polishing compound. Generraly you can get them through a machine shop supply house (or a local machine shop), but be real careful with the coarser stuff. And what ever you do, don't let anyone talk you into attaching a drill to you cleaning rod/polishing setup ... you are looking for the back and forth (along the bore axis) not around and round.
If your bore is so rough that you have no luck, then try fire lapping because at that point there is nothing to loose.
If you only have time to do two things so-so, or one thing well ... do the one thing!0 -
Hi oughtsix,
You can buy lapping compound from www.midwayusa.com.
Regards,
Heavyiron[8D]0 -
I agree strongly with what CM says here. I use USP Bore paste personally as it seems to be VERY consistant and not overly abrasive. I would only use the fire-lapping method as a last resort also, having done irreperable damage to a slightly rough 225 Winchester recently that wound up being worse abraded than when I started; sure wish I had stuck with my own best advice and just kept at it with the USP as the 225's are not easy to find anymore!
"When I cease learning...I'm dead"(Me)
"Power corrupts...Absolute power corrupts absolutely"(Descartes?)
"History is written by winners"(Patton)
"You get a lot farther with a kind word and a gun than you do with a kind word alone!"(Al Capone)
"There is nothing lower than the human race...except the French" (Samuel Clemens)0 -
oughtsix,
I do not recommend "fire lapping" because it puts the most pressure, lapping compound, & erosion in the chamber throat area. This is the area that erodes/wears on a barrel the fastest because of a combination of heat from burning powder & pressure required to broach the bullet into the rifling. In essence "fire lapping" has the potential to greatly reduce your barrel life. This is why Contender Man is right on the mark when he said it is a last ditch effort.
For hand lapping a barrel, I use a soft lead slug that is tapped & formed to fill the bore. The lead is soft enough to embed & hold the grit & tough enough to hold it. Lapping a barrel is tedious & time consuming, so if your barrel needs polishing to extend the number of shots between cleaning intervals to maintain accuracy, lapping is the way to go. If a snignificant improvement in accuracy is the goal, look at crown problems, bebbing problems, or send the barrel back to the manufacturer.
"all I really need to know I learned in kindergarten" Robert Fulghum
anyone who says "nobody needs a full auto" has never been in front of a brown bear charge0 -
Thanks for the input guys.
The bore in question belongs to a client who jammed three different cleaning rods into the barrel and the expansion chamber of the muzzle brake. One of these rods was steel. Some pretty obvious damage was done in getting the mess out.
I'm familiar with lapping techniques but there seems no good way to cast a molten lap onto a rod in the bore due to the (huge) muzzle break. Guess I'll just swage one in from the chamber end as suggested by cussedemgun.
I've never used fire lapping and thought it would be the easiest thing to do, but the advice here and research into the cost elsewhere has dissuaded me from that option.
Thanks again.0 -
You think he would learn anything about cleaning and proper barrel care after he get's the bill for a new barrel installation?
Dosn't the brake unscrew from the barrel?
Some guys like a mag full of lead, I still prefer one round to the head.0 -
Big difference if smoothing out a bore with polishing/lapping and trying to repair one that has been damaged.
Wish you would have just come out and said what the problem was at the start as that would have helped those of us that are trying to help you. Now a good part of the response limit to your post has been used up. However, you can always do another "Part-2" post.
You can see the damage, we can't ... but now that you have the bore cleared of the obstruction you can try lapping out the rough edges and then test fire it to see what, if any, the accuracy degradation is. Beyond that it's "new barrel city".
And to the comment about the brake being readily removable, that depends on the mfg. which is another thing we don't know.
If you only have time to do two things so-so, or one thing well ... do the one thing!0 -
Big difference if smoothing out a bore with polishing/lapping and trying to repair one that has been damaged.
...but now that you have the bore cleared of the obstruction you can try lapping out the rough edges and then test fire it to see what, if any, the accuracy degradation is. Beyond that it's "new barrel city".
Understood all that already, and just what I intend to do. Just wanted opinions and info on fire lapping as an alternative.
Unfortunately, this kid has no real baseline accuarcy data or standard (having fired it only at 100 yds, and not much) so we will only know whether it shoots decent or not. I couldn't believe the
totally inadequate rods he was trying to use and his general lack of knowledge of his toy. And, yes, he's about to get a monitary penalty to go with the earful he's already had from me to hopefully good effect.
Thanks again.0
Please sign in to leave a comment.
Comments
8 comments