gcf
.30 Stingray
South Texas
Posts: 274
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Post by gcf on Jan 28, 2022 13:40:15 GMT -5
... The abrasive compound applied into the forcing cone, first bit of barrel with cut in half cue tip swabs. A soft RN or RNFP bullet and light charge used. The method I've used successfully (careful NOT to over do a good thing) in the past, as follows: 1. Embed soft alloy bullets as heavily as possible w/ Beartooth compound. 2. Prime & charge (very light load / fast powder) fired / un-sized brass. Smear fresh compound liberally on the (soft alloy / preferably long bearing surface) lapping bullet bearing surface - also filling lube grooves (but avoiding bullet base) w/ compound, then seat & clean excess from outside of brass. 3. Lube clean bore w/ CLP. 4. Fire full cylinder of lapping loads. 5. Clean all chambers & bore fully after each cylinder of lapping loads - removing all lead, carbon, etc.. 6. Check bore for tight spots, re-lube, & repeat as required - monitoring accuracy results. 7. When complete, lightly polish bore w/ fresh compound on a snug cloth polishing bob, then clean up the entire mess THOROUGHLY. 8. Check accuracy with normal loads, & check for lead buildup. Yeah it's a real mess, & a long process - as I normally limit each lapping session to 12 - 24 rounds max. Stretches out the process, but better that - then over doing it. A guy can always come back for a bit of touch up later - if needed... The process you describe is interesting. Sounds like you just use a "normal" light, soft alloy CB load, & do not embed the bullet with compound. Is that correct? The bullet embedding process is IMHO, a royal pain. Also, do you clean and / or lube the bore between shots? As mentioned, I've always used Beartooth Bullets lapping compound, but as it appears that he has retired from the business, it occurs to me that if I need to undertake another bore lapping project in the future (nothing planned currently), I may need to find another source for suitable compound. Wondering if anyone might have a recommendation? Thanks in advance!
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edk
.375 Atomic
Posts: 1,108
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Post by edk on Jan 28, 2022 15:02:27 GMT -5
As mentioned, I've always used Beartooth Bullets lapping compound, but as it appears that he has retired from the business, it occurs to me that if I need to undertake another bore lapping project in the future (nothing planned currently), I may need to find another source for suitable compound. Wondering if anyone might have a recommendation? Veral Smith of LBT bullets is a source of lapping compound.
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bamagreg
.327 Meteor
Woodstock, GA
Posts: 856
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Post by bamagreg on Jan 28, 2022 15:52:17 GMT -5
As mentioned, I've always used Beartooth Bullets lapping compound, but as it appears that he has retired from the business, it occurs to me that if I need to undertake another bore lapping project in the future (nothing planned currently), I may need to find another source for suitable compound. Wondering if anyone might have a recommendation? Veral Smith of LBT bullets is a source of lapping compound. I wonder if bore lapping compound is basically valve grinding compound that you can buy at your local auto parts store?
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Post by bradshaw on Jan 28, 2022 20:18:25 GMT -5
"I wonder if bore lapping compound is basically valve grinding compound that you can buy at your local auto parts store?” ----bamagreg
*****
Valve lapping compound is, I believe, carborundum, in grits coarser than desirable for bore lap. The finest grit valve lap might work for stainless, which abrades slower than chromoly. Each barrel which starts life with less-than-perfect gun-drill & rifling, or is damaged by subsequent operations, is a unique barrel, requiring individual treatment if it can be saved.
Old time lapping techniques use very fine diamond. Coarse abrasives may correct one problem, while creating another.
When Ruger introduced the S410N Super Blackhawk with 10-1/2” barrel in 1979, Bill, Jr., sent me two. My shooting partner, Ed Verge, drilled & tapped the topstrap of one to mount a Leupold 4x28mm EER. The other Silhouette Super got aimed at IHMSA silhouette. The barrel of the siron sight Super quickly copper-fouled. Shot straight as fury, but fouled. I cleaned the bore with JB Bore Paste on patches of cotton flannel, placed over a jag carved in the end of a 3/8” hardwood dowel. At conclusion, groove diameter measured .428-inch. A superbly accurate, broach rifled barrel by George Wilson in Connecticut (Ruger barrel maker). JB Bore Paste is a fine grit, soft abrasive that breaks down very quickly.
Metal fouling ceased after treatment with JB Bore Paste. Had I used coarse, hard valve lapping compound, that barrel might have been ruined. (The original barrel had no tight or loose spots; no such barrel could be doctored to its accuracy. David Bradshaw
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Post by northerngos on Jan 28, 2022 23:25:26 GMT -5
"I wonder if bore lapping compound is basically valve grinding compound that you can buy at your local auto parts store?” ----bamagreg ***** Valve lapping compound is, I believe, carborundum, in grits coarser than desirable for bore lap. The finest grit valve lap might work for stainless, which abrades slower than chromoly. Each barrel which starts life as less-than-perfect is an individual, requiring individual treatment if it is to be saved. Old time lapping techniques use very fine diamond. When Ruger introduced the S410N Super Blackhawk with 10-1/2” barrel in 1979, Bill, Jr., sent me two. My shooting partner, Ed Verge, drilled & tapped the topstrap to mount a Leupold 4x28mm EER. The other got aimed at IHMSA silhouette. The barrel of the silhouette gun quickly copper-fouled. Shot straight as fury, but fouled. I cleaned the bore with JB Bore Paste on patches of cotton flannel, placed over a jag carved in the end of a 3/8” hardwood dowel. At conclusion, groove diameter measured .428-inch. A superbly accurate, broach rifled barrel by George Wilson in Connecticut (Ruger barrel maker). JB Bore Paste is a fine grit, soft abrasive that breaks down very quickly. Metal fouling ceased after treatment with JB Bore Paste. Had I used valve lapping compound, that revolver may not have down its wonderful shooting. This revolver had no tight or loose spots, and I doubt any such barrel could be brought up to its accuracy. David Bradshaw Mr. Bradshaw, I have consistently thoroughly enjoyed gleaning insight from your posts. For clarification (this is all new to me), were the patches pushed through the muzzle, or was the Rowen run through the barrel and used to pull the patch out from the cylinder window? I am waiting for some push through slugs from lbt to check a couple of revolvers, I look forward to learning more about this. Kind regards, Joel
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Post by bradshaw on Jan 29, 2022 1:07:44 GMT -5
northerngos.... thank you for the kind words.
JB Bore Paste is a fine-grit, very soft abrasive. My method on that early S410N Silhouette Super was, first, to clean with Hoppe’s #9 on cotton flannel patch. A jag whittled on a hardwood dowel holds the flannel patch, which is pushed into the muzzle. and carefully pushed through to barely protrude from the barrel face. I’ll leave Hoppe’s in the bore overnight or days on end. Aggressive ammonia dopes don’t sit in the bore more than a minute, and that includes stainless.
JB Paste is rubbed into the flannel patch. It blackens in a few strokes. Discard. Take care in reversing the stroke at breech and muzzle. Finish with Hoppe’s.
The M1 Garand and M-14 are cleaned from the muzzle. I used the Marbles 3-piece brass rods and GI 7-piece steel rods. Never wore out a muzzle. Just have to be careful. David Bradshaw
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Post by bula on Jan 29, 2022 8:26:54 GMT -5
GCF, that is correct. A "soft" cowboy action type bullet, RN or RNFP. No rolling on a plate to embed abrasive. I used Trail Boss powder, but light charge of bullseye or such would do. I did clean between shots. The S.S. BSBH 480's showed improvement 75-100 shots down the road. A dozen or so in a batch, per session. YMMV..
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cmillard
.375 Atomic
MOLON LABE
Posts: 1,943
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Post by cmillard on Jan 30, 2022 9:00:48 GMT -5
For my lapping adventures, I have 3 different compounds. I have also used the Tubb lapping bullets once to great success. My lapping compounds are as follows: wheeler 320 grit, NECO 800 grit, NECO 1200 grit.
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Post by rleprechaun on Jan 30, 2022 12:34:41 GMT -5
Wheeler bore lapping Kit
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Post by cas on Feb 5, 2022 10:05:03 GMT -5
Question is, what happens if you do not STOP? 20+ years ago I had a Vaquero that was a total dog. Among it's many issues was a barrel with a lot of choke and a horrible looking barrel with lots of machine marks in the rifling. I fire lapped it a lot. I figured I had nothing to lose honestly, the gun had so much wrong I thought about cutting it up. (there were times I regretted not doing that, rather than continuing to sink boat loads of time , work and money into it to make it useful.) Anyway I had it at one of our informal shooting get togethers and a friend had his tools for cutting 11º forcing cones. Well what the heck, go to it. He went to cut mine and found there was very little left of the factory "specs", I'd lapped to lord knows what degree and length.
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Post by northerngos on Feb 5, 2022 23:10:11 GMT -5
northerngos.... thank you for the kind words. JB Bore Paste is a fine-grit, very soft abrasive. My method on that early S410N Silhouette Super was, first, to clean with Hoppe’s #9 on cotton flannel patch. A jag whittled on a hardwood dowel holds the flannel patch, which is pushed into the muzzle. and carefully pushed through to barely protrude from the barrel face. I’ll leave Hoppe’s in the bore overnight or days on end. Aggressive ammonia dopes don’t sit in the bore more than a minute, and that includes stainless. JB Paste is rubbed into the flannel patch. It blackens in a few strokes. Discard. Take care in reversing the stroke at breech and muzzle. Finish with Hoppe’s. The M1 Garand and M-14 are cleaned from the muzzle. I used the Marbles 3-piece brass rods and GI 7-piece steel rods. Never wore out a muzzle. Just have to be careful. David Bradshaw That makes sense, thanks much for the information!
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jgt
.327 Meteor
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Posts: 782
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Post by jgt on Feb 6, 2022 12:28:10 GMT -5
JB Bore Paste is fine for polishing. It will help a barrel clean up better, but it would take many, many hours to lap a bore with it. The process for bore lapping is to start out the same way you do when sanding grips. You use a coarse grit for a while, then a medium, then fine. Once you are to the fine you can go as fine as you like, even JB Bore Paste. You shoot a group. Clean the bore. Shoot five to ten bullets that you have rolled between two steel straps/plates to imbed the lapping compound. Then you stop, clean the bore. Shoot another group. Clean the bore. Shoot some more lapping impregnated bullets. Once you see a little progress with the group, you go to a finer grit compound and repeat the process. Most carbon steel barrels take about thirty rounds depending on thread squeeze/roll mark tightness and grit used. Stainless can take up to fifty. I keep five different grits from wheeler and NECO. The cylinder throats must be address before you begin or you are just spinning your wheels. The process has been explained many times. A little research will get you a better explanation.
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Post by bradshaw on Feb 7, 2022 10:45:45 GMT -5
Hi All, I've fire lapped several guns in the past and had very good luck with the process after reading some of the works of Hoover and Garza whom I thank very much for their efforts. I'm left with a question though, I recall both gentleman stating that when the group size shrinks noticeably that you should STOP which I have done with stellar results. Question is, what happens if you do not STOP? Can you create an over bore situation, does the accuracy fall off within like 3 more rounds, has anybody taken it too far for the sake of science? ***** chieftjs.... lapping can be taken too far. As we’ve discussed, bore & rifling must be good enough to be saved. Lapping won’t correct a bore compressed by heavy stamping, or a wavy-drilled bore. Over-aggressive stroking of lap compound may loosen or egg-shape where the patch or slug is reversed, especially at the muzzle. Soft polish or cleaning compound, such as JB Paste, cleans copper fouling and minute roughness, without lapping. No harm in careful use of pin gauges on a bore; just don’t jam one in the lands. I relay on a lead slug driven through the lightly-oiled bore, re-indexed. and pushed through again, to check for tight and loose spots. A tight or loose spot is located via cleaning rod. Inferior barrels have been put on expensive guns, which is reason enough to evaluate accuracy on an individual basis. IHMSA silhouette brought this little secret home like nothing anyone had written before. That target out yonder is a cold critic. David Bradshaw
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Post by ChiefTJS on Feb 9, 2022 8:53:23 GMT -5
I think it's a valuable tool to use for certain instances and will continue to do it in moderation when called for. I've used both processes, imbedding the bullet as well as placing JB in the forcing cone. To date I've only used JB on rimfires as I wasn't impressed with trying to imbed loaded rounds. Thank you all so much for the insights!
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Post by rkcohen on Mar 4, 2022 9:08:12 GMT -5
...i love discussions like "fire lappring" almost as much as arguing over motor oil!!
and yes, fire lapping does work - in most cases - when done correctly - as outlined here..
to much, and you have a smooth, smooth bore!
regarding patches/cleaning semi-autos, years ago when i was in germany, a bundeswehr armorer explained to us (american gi types) why the germans only used pull thru cleaning tools on their weapons......
a little common sense and patience can go a long, long way... whether fire lapping or taking care of semiauto rifles/shotguns..
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