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Post by ChiefTJS on Dec 11, 2021 9:51:21 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?
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Post by bradshaw on Dec 11, 2021 21:24:03 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? ***** Would not fire lap without reason. Slug bore----generations ago, this was routine before shooting cast bullets. * Index pure lead slug before tapping through bore with hardwood dowel or taped rod. * Align slug to same grooves/lands. Push through, feeling for loose or tight spots. Mark rod to measure any such spots. * Target minimum 50 feet, preferably farther. I want 50 or 100 yards. Initial targeting may be done before or after slugging. Take it from there. David Bradshaw |
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Post by ChiefTJS on Dec 12, 2021 10:34:16 GMT -5
Absolutely Mr. B! Every gun does not need the procedure done at all, it's usually a last resort for a gun I can't get to shoot after trying multiple other efforts.
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diddle
.30 Stingray
Posts: 470 
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Post by diddle on Dec 12, 2021 15:29:57 GMT -5
IME, it’s not unusual to encounter a Ruger revolver with thread choke that will require remediation in order to shoot lead alloy slugs well. This constriction will exist in varying degrees and may be removed with properly performed “firelapping”. Obviously, the worse the constriction, the more shots will be required. Maybe not so obvious is that the stainless barrels are much more resistant to the firelapping process and will require extra shots. I believe it is also important to start the process with properly sized chamber throats … another common problem among big bore Ruger revolvers.
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Post by needsmostuff on Dec 12, 2021 17:36:58 GMT -5
It is almost S.O.P. for me on a Ruger Single Action.
Of all I have done most shoot much better. A few almost no change. But none shoot worse.
As far as stainless I have never completely got rid of thread choke but have substantially reduced it.
I have also felt choke under all the silly warnings Ruger stamps on the barrels.
There is something to be said for laser marking barrels.
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Post by bradshaw on Dec 13, 2021 7:52:03 GMT -5
IME, it’s not unusual to encounter a Ruger revolver with thread choke that will require remediation in order to shoot lead alloy slugs well. This constriction will exist in varying degrees and may be removed with properly performed “firelapping”. Obviously, the worse the constriction, the more shots will be required. Maybe not so obvious is that the stainless barrels are much more resistant to the firelapping process and will require extra shots. I believe it is also important to start the process with properly sized chamber throats … another common problem among big bore Ruger revolvers. ***** diddle.... once again, when talking tech it is important to be specific: True* Stainless barrel resists lapping, considerably moreso than carbon steel barrel. * Lapping slug must pass through CHAMBER EXIT HOLE (aka throat) without shedding abrasive or compression which renders slug loose in bore. * Lapping must be done with patience & care, and checked frequently on target Untrue* Undersize chamber exits “common problem among big bore Ruger revolvers.” Problem applies to Ruger .45 Colt and .45 ACP cylinders. Emphatically does not apply to Ruger .44 Mag cylinders. Barrel accuracy suffers when:* A barrel made too fast, or with a worn drill or reamer; or rifled with a worn broach, button, or mandrel; * Oversize GROOVE diameter. * Barrel not TIMED to frame threads or tightens too soon BTDC (Before Top Dead Center), resulting in COMPRESSION RING at barrel shoulder/frame junction. * Uneven BORE diameter----tight or loose spots. Just a few of the details which factor into a revolver’s ORCHESTRA of DIMENSIONS. David Bradshaw |
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Post by Encore64 on Dec 13, 2021 7:59:24 GMT -5
I've also experienced very good success with fire lapping. Usually followed by lapping with Corbin's Bore Lap Compound.
Also, agree on Ruger 45s. All but one I've owned came with undersized throats. Some as tight as .449".
The cylinders are sent to be opened up to .452". Clements just did two for me.
Interestingly enough, every 44 Special and 44 Magnum has been .431" on every chamber.
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bamagreg
.327 Meteor
Woodstock, GA
Posts: 856
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Post by bamagreg on Dec 13, 2021 9:46:58 GMT -5
I've also experienced very good success with fire lapping. Usually followed by lapping with Corbin's Bore Lap Compound. Also, agree on Ruger 45s. All but one I've owned came with undersized throats. Some as tight as .449". The cylinders are sent to be opened up to .452". Clements just did two for me. Interestingly enough, every 44 Special and 44 Magnum has been .431" on every chamber. The Ruger 45's I've had that were made from the 90's on were tight chambered. I had one from 1975 that measured .455". Years ago I had an Old Model but that was before I knew anything about measuring chambers. |
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diddle
.30 Stingray
Posts: 470
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Post by diddle on Dec 13, 2021 9:58:51 GMT -5
IME, it’s not unusual to encounter a Ruger revolver with thread choke that will require remediation in order to shoot lead alloy slugs well. This constriction will exist in varying degrees and may be removed with properly performed “firelapping”. Obviously, the worse the constriction, the more shots will be required. Maybe not so obvious is that the stainless barrels are much more resistant to the firelapping process and will require extra shots. I believe it is also important to start the process with properly sized chamber throats … another common problem among big bore Ruger revolvers. ***** diddle.... once again, when talking tech it is important to be specific: True* Stainless barrel resists lapping, considerably moreso than carbon steel barrel. * Lapping slug must pass through CHAMBER EXIT HOLE (aka throat) without shedding abrasive or compression which renders slug loose in bore. * Lapping must be done with patience & care, and checked frequently on target Untrue* Undersize chamber exits “common problem among big bore Ruger revolvers.” Problem applies to Ruger .45 Colt and .45 ACP cylinders. Emphatically does not apply to Ruger .44 Mag cylinders. Barrel accuracy suffers when:* A barrel made too fast, or with a worn drill or reamer; or rifled with a worn broach, button, or mandrel; * Oversize GROOVE diameter. * Barrel not TIMED to frame threads or tightens too soon BTDC (Before Top Dead Center), resulting in COMPRESSION RING at barrel shoulder/frame junction. * Uneven BORE diameter----tight or loose spots. Just a few of the details which factor into a revolver’s ORCHESTRA of DIMENSIONS. David Bradshaw Mr. B, thank you for filling in the holes in my commentary. My experience pales in comparison to yours and I admire, and deeply respect, your advice. I will add, though, that the last 44 Special flat top I bought had as much thread choke as any of my 45’s. But, that’s just one data point. Again, thanks. |
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Post by bradshaw on Dec 13, 2021 11:28:50 GMT -5
Mr. B, thank you for filling in the holes in my commentary. My experience pales in comparison to yours and I admire, and deeply respect, your advice. I will add, though, that the last 44 Special flat top I bought had as much thread choke as any of my 45’s. But, that’s just one data point. Again, thanks.
----diddle
*****
Please note Ruger .44’s don’t suffer tight throats. Which, unfortunately, has nothing to do with a ring of bore compression----caused by over-tightening, or by interference between barrel tenon and frame. Along about thirty years ago Ruger and S&W forgot about THREAD TIMING. Thread timing is the designed relationship between frame threads and barrel threads. Thread timing allows the barrel to be hand tightened within a limited degree range. My preference has the barrel hand tightening to about 10 or 12-degrees BTDC (Before Top Dead Center). With the Ruger Blackhawk/SBH 11/16” x 24 TPI (Threads Per Inch), this snugs the barrel to the frame without forming a compression ring (in the bore) at the barrel shoulder.
Note that the coarser the thread, the more it draws the barrel per degree of rotation. The fine threads on an S&W or Dan Wesson allow more degrees of rotation before distortion. Also, fine threads on the barrel tenon possess greater ROOT DIAMETER----thickness of TENON WALL, aka rim around forcing cone.
The thicker the tenon wall----.38 on .44/.45 frame----the more torque it requires to compress.
David Bradshaw
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Post by bula on Dec 13, 2021 11:47:44 GMT -5
When we discuss "fire lapping", there is more than one way to do it, and ways without firing. I'd like to see that discussed, pros and cons. I had it explained to me, and took out enough of the thread choke in 2 Ruger 480 BSBH's, in a manner that does not risk the throats. 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 by way of respected person here, told to by one of top 'Smiths often mentioned here. I'm not comfortable using name, as info came by PM when I was asking as to remedies to leading in my 480's. It worked.
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Post by 2 Dogs on Jan 28, 2022 9:11:59 GMT -5
When we discuss "fire lapping", there is more than one way to do it, and ways without firing. I'd like to see that discussed, pros and cons. I had it explained to me, and took out enough of the thread choke in 2 Ruger 480 BSBH's, in a manner that does not risk the throats. 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 by way of respected person here, told to by one of top 'Smiths often mentioned here. I'm not comfortable using name, as info came by PM when I was asking as to remedies to leading in my 480's. It worked. I have not seen fire lapping impact cylinder throats to any degree that I could measure. I don’t think the cylinder throats create enough resistance to the lapping slug to do so. Perhaps a bit of smoothing or polishing but no negative impact or dimensional change I could see. I did take one barrel off one sixgun and successfully lap it by pushing a lead slug from the breach end to the muzzle. Other than getting the barrel off the gun it was pretty simple and easy to do. I hope I answered your questions. You know where to find me Sir. |
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Post by bula on Jan 28, 2022 10:28:08 GMT -5
Was offering another option, or at least food for thought. No questions at this time as happy with outcome. Thank You, I know you are more than free with your help and advice.
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edk
.375 Atomic
Posts: 1,108
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Post by edk on Jan 28, 2022 12:18:40 GMT -5
I did take one barrel off one sixgun and successfully lap it by pushing a lead slug from the breach end to the muzzle. Other than getting the barrel off the gun it was pretty simple and easy to do. Was this for the purpose of specifically eliminating thread choke? If so, in an earlier thread there was some speculation the choke might spring back once the barrel was removed. Any evidence of this observed? |
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gman50
.30 Stingray
Posts: 191
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Post by gman50 on Jan 28, 2022 12:49:23 GMT -5
I had a barrel with thread choke on a RSBH 44 magnum that once removed did indeed spring back. This was verified by slugging barrel before and after. This was discussed in a thread sometime back. This was done at Bayou Teche Guns by Mike Brazda whom David knows. Don't remember the exact amount of choke that was there before removal.
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