jgt
.327 Meteor
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Post by jgt on Apr 17, 2019 8:29:08 GMT -5
something I forgot to mention, I use cartridge cases that I deem "sacrificial" as my firelapping cases. These cases are cases that have been reloaded the most. I uses a full 50 round box. Others use the same 10 rounds over and over to keep from sacrificing more cases. Depending on how hard to get or expensive your cases are over there, you get to choose what you do. I just wanted to mention it, because once those cases are used for firelapping, I do not use them for anything but firelapping. I think your cylinder throats are fine according to your measurements. I would not recommend using jacketed bullet though. Bullets cast from wheelweight dropped from the mold into water will be fine. I use mine without even water dropping them. The process is messy, it also take patience, but it is the best method given your circumstances. I think it is superior to hand lapping, because it will come closer to giving you a uniform barrel. The velocity only need to be enough to keep the bullet from sticking in the barrel. You can read an article by Fermin Garza (aka two dogs} at Gunblast.com with his explanation of firelapping. Please continue to keep us updated as you are helping others that have not tried this method yet. Good luck.
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Post by magnumwheelman on Apr 17, 2019 11:26:38 GMT -5
Just curious... I had always thought that a threaded restriction, was most often found on larger bore revolvers, where the barrel tubes are thinner, making it easier to distort with over tightening... smaller bores, with thicker tubes, would be less likely to get a thread based restriction... are these really that common on the 38 / 357 guns???
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Post by mathias on Apr 17, 2019 15:05:04 GMT -5
First of all a big thanks to everybody for all the helpful tips. I will do some more fire lapping and report back when i have been able to go to the range. I will also se if i can get a better rest. There are no benches on the snow free range so it might be my knees again Perhaps shoot some more rounds for a better average ? Best regards
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Post by magpouch on Apr 25, 2019 4:56:07 GMT -5
Great job so far Firelapping certainly takes a leap of faith, it doesn't seem natural to do it, but wow the results are usually impressive. I have a 5" GP100 357 Mag that I shot initially at 25 yards with cast loads to get a baseline, then began to firelap. Every cylinder of firelapp rounds tightened the group, you could actually see improvement on the target. Very impressive actually. So now my usual routine is to measure bore, groove and throats, check for restriction and firelapp on most every revolver I acquire. I have never had a negative experience doing it, but it is a little work. Not every revolver improves by doing it, but my experience shows that most do.
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Post by mathias on Jun 13, 2019 14:04:58 GMT -5
Hi Just letting you guys know that the project still continues admittedly slowly. I have done one more set of fire lapping consisting of 12 rounds with grit 220 (tot 30) 24 rounds with grit 320 (tot 48) 30 rounds with grit 600 (tot 60)
I then tested the precision using the same loads as before and there was very little change in group size, so i wonder if i just keep lapping ? And how many shots of the coarse grit 220 that is safe to fire ? Math
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Post by mathias on Jul 12, 2019 13:31:15 GMT -5
Hi I have done some more lapping and shooting but i don´t think there has been much progress. As of now i have shoot as follows 30 rounds with grit 220 72 rounds with grit 320 60 rounds with grit 600 I start to get worried about the number of abrasive rounds i have fired, is this normal ? Below are my latest test groups, loads are the same as earlier in the thread. I went ahead and bought a pingauge set (minus) a .347 pin goes through the barrel with sliding fit if that means something. I take full responsibility for the flyer in the top group, both grops are 10 rounds fired from a sitting rest at 25m Any thoughts are welcome Regards Mathias
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Post by potatojudge on Jul 17, 2019 18:59:42 GMT -5
I'm no fire lapping expert, but I've sanded a lot of wood and a little metal and I'll say this- the real change you see in dimensions comes from 220 and coarser grit, and the finer grits are mostly for removing scratches left by coarser grits with much less change in dimensions.
I see you're 30 rounds of 220 in and the remaining 130 rounds are finer grits.
You're getting there with a .347 pin sliding down the bore assuming it's uniform end to end. Can you still see strong rifling? If so I'd say keep fire lapping until the bore feels uniform with the pin gauge and slugging.
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Post by bradshaw on Jul 17, 2019 19:34:30 GMT -5
I'm no fire lapping expert, but I've sanded a lot of wood and a little metal and I'll say this- the real change you see in dimensions comes from 220 and coarser grit, and the finer grits are mostly for removing scratches left by coarser grits with much less change in dimensions. I see you're 30 rounds of 220 in and the remaining 130 rounds are finer grits. You're getting there with a .347 pin sliding down the bore assuming it's uniform end to end. Can you still see strong rifling? If so I'd say keep fire lapping until the bore feels uniform with the pin gauge and slugging. ***** potato judge is onto the realm of abrasives. One could polish a lump forever and still have a lump. Last week I braced myself in the rocks, into the roar of a nature-made jacuzzi. Brook hole in a mountain stream. Bowls eroded in rock over thousands of years, some big enough to step your foot to the shin. A revolver shooter can’t wait that long. the danger of fire lapping with very coarse abrasives comes with overdoing it. To slug the bore every 30 rounds or so isn’t a bad idea. That, and a trip to the target board are part of tuning the instrument. David Bradshaw
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Post by mathias on Jul 22, 2019 14:48:52 GMT -5
Hi So if i understand this right i should continue firelapping using 320 grit and slug and test for accuracy often ? And that i have not yet fired to many round with lapping compound on them Thanks for al the help
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Post by mathias on Jan 5, 2020 6:44:43 GMT -5
Hi it has been some time sens my last post, but i now think i am done fire lapping. I have fired 72 more slugs cowered with 320 grit sense my last post. I bought a 3 point micrometer, one with a V-shaped lower part so it measures on three points. A slug driven all the way through barrel comes out 8,97mm A slug was then driven 20mm down the barrel and then pushed back out and measured 8,965mm. (the 5 thousandths is estimated as the line stopped between two marks) I know this sounds wrong as the slugs were both pushed down from the muzzle end. I did this two times (total 4 slugs) and got the same result both times so i guess it might upset 0.005mm on the way out the forcing cone, i used a wood dowel an light taps from a hammer to drive the slugs.
I also got a minus pingauge set and a .347 pin goes smoothly through the barrel whit out resistance, unfortunately so are the gauges too long for me to measure the forcing cone.
I also checked the timing both with my eye and the .347 gauge and found no problem.
All this said and done i am still not happy with how the gun shoots så any thoughts on things i done right or wrong are greatly appreciated
Best regards Mathias
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Post by bradshaw on Jan 7, 2020 12:57:12 GMT -5
Hi it has been some time sens my last post, but i now think i am done fire lapping. I have fired 72 more slugs cowered with 320 grit sense my last post. I bought a 3 point micrometer, one with a V-shaped lower part so it measures on three points. A slug driven all the way through barrel comes out 8,97mm A slug was then driven 20mm down the barrel and then pushed back out and measured 8,965mm. (the 5 thousandths is estimated as the line stopped between two marks) I know this sounds wrong as the slugs were both pushed down from the muzzle end. I did this two times (total 4 slugs) and got the same result both times so i guess it might upset 0.005mm on the way out the forcing cone, i used a wood dowel an light taps from a hammer to drive the slugs. I also got a minus pingauge set and a .347 pin goes smoothly through the barrel whit out resistance, unfortunately so are the gauges too long for me to measure the forcing cone. I also checked the timing both with my eye and the .347 gauge and found no problem. All this said and done i am still not happy with how the gun shoots så any thoughts on things i done right or wrong are greatly appreciated Best regards Mathias ***** Mathias.... since jacked bullets deliver acceptable accuracy, while cast bullets do not, I would shoot jacketed. Without the chance to hold the revolver and target, my ability to evaluate comes up short. In competitive circles, no amount of measurement takes the place of the Firing Line. A few notes* Forcing cone----critical to accuracy. Must be concentric to bore, smooth, and not too long for the angle. The old time standard 11-degree cone allows great accuracy from a dimensionally correct barrel. Cannot measure a forcing cone with pin gauges, and it doesn’t matter. A 5-degree cone is fine: yet, like the 11-degree, it must bnot be cur too deep. A hand tool follows any irregularity and makes the problem worse. * It is possible the barrel is good between frame & muzzle. The rear of the barrel can be recut for a new TENON (barrel stub or shank). The challenge is to cut a new tenon on a barrel shaped by drop forge or cut from billet. Fire lapping is not a cure-all for dimensional irregularity in the bore & groove. (The underlug channel for ejector rod must be recut.) David Bradshaw
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Post by mathias on Jan 7, 2020 14:15:29 GMT -5
Thank you for your thoughts Mr Bradshaw I had sort of come to that conclusion as i also thought i was nearing the amount of fire lapping i was comfortable doing. I still think that i managed to get my barrel more even then it was before i started this and i did not harm anything and that makes this endeavor a win in my book It also looks like it is a bit easier to clean now. I will keep an eye on the forcing cone to see if i can see some Irregularities that needs to be addressed but Great many thanks to all who contributed with thoughts and ideas Happy shooting Mathias
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Post by bradshaw on Jan 7, 2020 16:20:27 GMT -5
Thank you for your thoughts Mr Bradshaw I had sort of come to that conclusion as i also thought i was nearing the amount of fire lapping i was comfortable doing. I still think that i managed to get my barrel more even then it was before i started this and i did not harm anything and that makes this endeavor a win in my book It also looks like it is a bit easier to clean now. I will keep an eye on the forcing cone to see if i can see some Irregularities that needs to be addressed but Great many thanks to all who contributed with thoughts and ideas Happy shooting Mathias ****** Mathias.... FIRE LAPPING indeed should reduce fouling of jacket on LANDS, and lead fouling of LANDS & GROOVES. Did not suggest you have a bad forcing cone. The forcing cone is critical to accuracy. Javen’t seen your M-586 forcing cone, let along the rest of the revolver. You certainly don’t want to disturb a correct forcing cone! A further note on forcing cones: a barrel tenon with thin wall that extends into the frame waindow is susceptible to cracking, most often at 6 ‘clock, where the tenon may be thinned to clear the YOKE on a swing-out cylinder. Please follow up with more reports of your shooting. It’s good to hear of work to fix a sixgun, both success and failure. And, news is welcome from sixgunners outside the USA. Keep shooting. If possible, work your way up to 100 meters. Avoid bullseye shooting at long range. To shoot a plain paper or cardboard target makes it easier to chisel your eye on the top of the front sight----mind on target, eye on sight. A front sight .125-inch wide (3.18mm) covers about 12-inches (305mm/30.5 centimeters) @ 100 meters. Actual subtension----width sight appears to cover on target----depends on EYE RELIEF (distance between eye and front sight). CREEDMOOR has the longest eye relief, with accuracy equal to sandbag rest. Prone has the shortest eye relief. David Bradshaw
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Post by mathias on Jan 8, 2020 3:11:14 GMT -5
When old man winter lets us go and i can get to range again i will put her through a solid testing. I did not plan on doing anything to the forcing cone merely keeping an eye on it. When i have some results worth posting i will do so Best regards Mathias
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Post by bradshaw on Jan 8, 2020 8:40:20 GMT -5
When old man winter lets us go and i can get to range again i will put her through a solid testing. I did not plan on doing anything to the forcing cone merely keeping an eye on it. When i have some results worth posting i will do so Best regards Mathias ***** Mathias..... back to your original post: you slugged the bore of your M-586, to measure 8.95mm, or as Squigz notes .352”. I suggest you go to the SAAMI ( Sporting Arms and Ammunition Manufacturers Institute) website. Look up cartridge and chamber drawings. Scroll to page 44 for the .357 Magnum. SAAMI tolerance variation for bullet diameter, .357 MagLead----.359”, minus to .356” (9.119mm-0.076mm) Jacketed----.358”, minus to .355” (9.093mm-0.076mm) Note SAAMI’s appalling tolerance for “acceptable” bullet diameter! Just because a measurement bears official sanction does not confer accuracy. SAAMI bore & groove diameter, .357 MagBore----.346” (8.79mm) Groove----.355” (9.02mm) SAAMI chamber exit (throat), .357 Mag.3580” (9.093mm) If your M-586 has traditional S&W 5-groove rifling, it is difficult to measure with a micrometer----unless you know exact height of the lands. A digital caliper is much less accurate than a micrometer. I trust a dial caliper more than a digital; yet the caliper is a tool of approximation. A target is much easier to measure. You can throw away your measuring tools but you cannot throw away the target. David Bradshaw
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