Removing the "Bumps" due to barrel tightning.

[Changeling]

When you have a constriction in a revolver barrel due to the barrel threads being tightened down everyone seems to want to firelap to get rid of the problem.

Why can't a cast slug just be used with some lapping compound to hand lap the constriction out. I hand lapped muzzle loader barrels years ago and it is definitely not as difficult as one is lead to believe by talking to the barrel makers.

[Wally]

To me it makes good sense to hand lap so you don't mess with the cylinder chambers when fire lapping---however, as I understand it hand lapping is a tedious process-- That's probably why so many opt to fire lap I use gas checks and leave the constriction "as is"...

[jhrosier]

If the barrel is fitted properly, there will be no constriction at the receiver.
A crush fit is not appropriate for fitting revolver barrels.
The crush fit is a manufacturing shortcut that results in an inferior product.

Jack

[curator]

Having done both on many revolvers, I prefer fire lapping. It is significantly easier and gives better results if done properly. It doesn't result in sore shoulders and arms either. The actual shooting can be fun. Fire lapping loads are often surprisingly accurate for some reason. When done you end up with a very smooth, tapered bore that shoots cast bullets very well. If you have the proper lapp-bullet hardness (bhn 12 or slightly less) and the correct chamber throat diameters they won't be significantly enlarged. Yes, it often takes 50+ lapping shots. Bullets with a long bearing surface and at least .002 over largest groove diameter will sometimes work with a bit fewer. I clean and tap a pure lead round ball through the bore after every 10-12 shoots to moniter my progress.

[Char-Gar]

Humm... Constrictions at the breech end of some sixgun barrels are indeed real. Folks are indeed determined to get rid of them, after a guru said to do so.

I am not certain they present a real problem to hand held pistol shooting. I have several sixguns with visable constrictions that shoot far far better than I can hold and I am not a shabby pistol shot. I ceased to worry about these constrictions some years ago. I think they are more of a theoritical issue than a practical issue.

[nicholst55]

Taylor Throating is also a popular, relatively inexpensive method of removing these constrictions. Ruger, especially, seems to have a propensity for this.

[missionary5155]

Good morning
I Firelap Every New barrel I become the owner of. Last 3 months of 2009 I firelapped my 2 new .410 barrels or my 414SM Dan Wesson project. Both Barrels Looked very nice to start with. Slugging them showed little variations. After 10 rounds each of a 265 grain .412 sized lubed with Metal Glo ( Metal Polish not a grinding compound) each barrel is without any variations as close as a tight patch can tell me.
Both barrels shoot Excellent. Both barrels do not lead (32 grains 1680, 265 gc WW) & shoot less than an inch at 25 yards iron sights on a cold morning.
I did a Kel-tec Sub 2000 40 S&W with the same process and it shoots cloverleafs at 25 yards me sitting on my larger muscle with a 180grain TC WW over Acc#5.
I also firelap every used revolver IF there is any constriction ESPECIALLY at the throat area.
A constriction at the muzzle I can tolerate some. BUT a constriction at the breach end ... ??? How can an undersized lead bullet shoot to the BEST accuracy possible ? With every revolver I own... I want it to be the best possible shooting iron it can be. Maybe I cannot HOLD it as well as it will shoot... But then I can learn to. A flawed revolver will always be just that. I choose not to be hampered with mediocricy IF there is a solution as simple as 35 or so Cast boolits coated with lapping or polishing compound of some type.
I also ream my cylinder throats IF they are all out of sorts. On my desk right now is my 44-40 New Service. Ugly.. no finish.. but a beautiful .429 barrel. But cylinders that were .424-.427. At 20 yards it shot great pie plate patterns. A year ago I reamed it with a taper reamer (all I had) to .428+ which helped. Now I have a proper reamer and will go to .430.
So when I read that Undersized boolits via a constricted throat "shoots better than I can hold" I am thankful some experimenters are still out there looking for solutions to that constricted throat I have no desire to live with.

[Wally]

Humm... Constrictions at the breech end of some sixgun barrels are indeed real. Folks are indeed determined to get rid of them, after a guru said to do so.

I am not certain they present a real problem to hand held pistol shooting. I have several sixguns with visable constrictions that shoot far far better than I can hold and I am not a shabby pistol shot. I ceased to worry about these constrictions some years ago. I think they are more of a theoritical issue than a practical issue.

I have a no. of Rugers with this phenomenon..they are accurate but they lead up---in the past I merely used a tight patch and aluminum fly screen to remove the lead fouling, after so many shots--now I use gas checked bullets that has solved the problem for me.

[Dan Cash]

I simply avoid Ruger and newer Smith & Wesson handguns.

[dubber123]

I simply avoid Ruger and newer Smith & Wesson handguns.

Good plan, but I have some older S&W's that are a little tight in the frame area too. I just firelapped a Model 14 made in the 60's, as it leaded a tiny amount right after the leade. It shoots spotlessly clean now.

[Wally]

Good plan, but I have some older S&W's that are a little tight in the frame area too. I just firelapped a Model 14 made in the 60's, as it leaded a tiny amount right after the leade. It shoots spotlessly clean now.

I have a Model 27 that leads up due to the barrel constriction--can I ask how you fire lapped the model 14? The Model 27 is quite accurate and I get no leading if I use a GC bullet.

[dubber123]

I have a Model 27 that leads up due to the barrel constriction--can I ask how you fire lapped the model 14? The Model 27 is quite accurate and I get no leading if I use a GC bullet.

I used some Lee .358" wadcutters, and rolled them between 2 steel plates with some 320 grit automotive valve lapping compound on them. You don't have to "crush" the boolits between the plates, just firm pressure. Wipe off the extra, it's the embedded stuff on the boolit surface that does the work. Use fired, but unsized cases, and seat them over a low charge of fast powder. About 2 grains of Bullseye should do in the .357. If you stick one, they tap back out easily. I like to shoot AT something to make sure the boolit exits the bore every time. Don't try to shoot high velocity, slow is what you want. I fired 6, swabbed the bore, fire 6, repeat. I think it took about 36 of them to straighten mine out. I could measure no real change in the cylinder throats, just the bore leading went away.

[Wally]

I used some Lee .358" wadcutters, and rolled them between 2 steel plates with some 320 grit automotive valve lapping compound on them. You don't have to "crush" the boolits between the plates, just firm pressure. Wipe off the extra, it's the embedded stuffi n the boolit surface that does the work. Use fired, but unsized cases, and seat them over a low charge of fast powder. About 2 grains of Bullseye should do in the .357. If you stick one, they tap back out easily. I like to shoot AT something to make sure the boolit exits the bore every time. Don't try to shoot high velocity, slow is what you want. I fired 6, swabbed the bore, fire 6, repeat. I think it took about 36 of them to straighten mine out. I could measure no real change in the cylinder throats, just the bore leading went away.

I thank you---I will try with some Lee 148 grain WC-TL bullets. Where did you obtain the lapping compound? How often did you clean the barrel..in between shots? I also have a SS Ruger .357 Magnum Blackhawk with the same problem---as I understand it it takes more shouts to fire lap it. Have you ever fire lapped one?

[dubber123]

I thank you---I will try with some Lee 148 grain WC-TL bullets. Where did you obtain the lapping compound? How often did you clean the barrel..in between shots? I also have a SS Ruger .357 Magnum Blackhawk with the same problem---as I understand it it takes more shouts to fire lap it. Have you ever fire lapped one?

My compound came from a regular auto parts store. Permatex brand I believe. Many go with a finer grit towards the end, but the 320 produces a better finish that any barrel started with, so I leave it at 320. In the revolvers, I cleaned every 6 rounds. All the guns I have done so far have been blued. You don't have to do it all at one sitting either, especially if you are nervous the first time. Fire a cylinder full or two, and then shoot some regular loads to test your progress. You can spread it out over weeks or months if you like. It's a tedious process.

[Wally]

My compound came from a regular auto parts store. Permatex brand I believe. Many go with a finer grit towards the end, but the 320 produces a better finish that any barrel started with, so I leave it at 320. In the revolvers, I cleaned every 6 rounds. All the guns I have done so far have been blued. You don't have to do it all at one sitting either, especially if you are nervous the first time. Fire a cylinder full or two, and then shoot some regular loads to test your progress. You can spread it out over weeks or months if you like. It's a tedious process.

Thank you---I am sorry, you did say that you cleaned the barrel after every 6 rounds--what I meant to ask is what method/how throughly did you clean it?

[dubber123]

I just used a tight fitting patch on a brush with a little oil on it. The lapping compound I have is oil based, and cleaned out very easily. At the slow speeds you are firing, they don't really foul the bore much.

[Wally]

I just used a tight fitting patch on a brush with a little oil on it. The lapping compound I have is oil based, and cleaned out very easily. At the slow speeds you are firing, they don't really foul the bore much.

After cleaning was there any leading in the barrel---the reason I ask is that I had read that the barrel must be absolutely lead free for the lap to do its' job.

[dubber123]

Starting with a clean bore is correct, no point in the lapping boolit doing it's work on lead buildup rather than the actual constriction. I never noticed any leading during firelapping. The compound I used is oil based, and I have to assume that acts as a lube during the process. That and the very low speeds seemed to preclude any leading. The cleanup between strings took all of a minute.

[Wally]

Starting with a clean bore is correct, no point in the lapping boolit doing it's work on lead buildup rather than the actual constriction. I never noticed any leading during firelapping. The compound I used is oil based, and I have to assume that acts as a lube during the process. That and the very low speeds seemed to preclude any leading. The cleanup between strings took all of a minute.

Thanks again---I'll have to try this as it has worked for you and should do the same for me. My idea is to shoot so many, then try shooting regular cast bullets, to determine if the lead fouling is eliminated.

[Changeling]

Thanks, that really answered my question ! I've decided to use cookie dough and beach sand as directed for my question.