.38S&W Leading problems Help

[Argentino]

Pictures below are from an old (circa 1909) Colt Police Positive chambered in .38 Colt New Police/.38 S&W.

After 25 shots I´ve noticed leading over the topstrap above the forcing cone (over the fouling cup these old revolvers have). No leading in the barrel; just over the fouling cup.

I was shooting light loads (2.0 grains of HP38 under a 148 gn. WC boolit- Lyman 358495 at around 450 fps)

Boolits were sized to 0.359" since bore is 0.358" (tight for a .38S&W). The throats however are somewhat larger at 0.363".

I guess this might be related with boolits sized at .359" which are OK for bore dimensions but are too small for throat dimensions (0.363")

Any help regarding what might be causing this type of leading (and how to clean it) will be much appreciated.

Thanks,
Argie.

[onelight]

You may be getting some flame cutting from loose fit of bullet to the throats I am sure someone has a better idea but I take a 22 mag case flatten out the mouth and use it for a scraper to remove the heavy lead buildup on the top strap and around the barrel and the front of the cylinder I would think it would have leaded also.

[Larry Gibson]

What alloy?

What lube?

[FergusonTO35]

Does this happen with other powders? HP-38 can produce crusty gray fouling that looks like that. Was shooting some 9mm yesterday with this powder, and noticed a fair amount of silver-gray "leading" on the lands of the bore after 20 rounds. However, accuracy was superb and some no. 9 and a quick pass with the brush removed it.

[Argentino]

You may be getting some flame cutting from loose fit of bullet to the throats I am sure someone has a better idea but I take a 22 mag case flatten out the mouth and use it for a scraper to remove the heavy lead buildup on the top strap and around the barrel and the front of the cylinder I would think it would have leaded also.

Thanks for the input. Using a .22 case as a scraper sounds like a good idea: I´ll try that.

And yes, the front of the cylinder is also leaded. I thought they were just burn rings but I´m seeing some leading there too.

[Argentino]

What alloy?

What lube?

Larry,

I´m using 90%Pb + 10% Lino. Sized at 0.359" and tumbled lubed with BLL´s. Lyman#358495.

I miked the barrel at 0.358" so I thought of using this mold (almost no sizing required, since 0.359" is the "as cast" diameter for this particular mold and alloy).

But all throats are 0.363" so maybe this is where the leading is coming from.

Thanks

[Argentino]

Does this happen with other powders? HP-38 can produce crusty gray fouling that looks like that. Was shooting some 9mm yesterday with this powder, and noticed a fair amount of silver-gray "leading" on the lands of the bore after 20 rounds. However, accuracy was superb and some no. 9 and a quick pass with the brush removed it.

I´m afraid I did n´t have the chance of trying other powders yet. This is the first time I reload for this revolver.

I´m used to HP 38 in other calibers and I agree with you: it burns dirty and leaves considerable fouling. However I´m pretty sure that what appears in pictures is lead, since I managed to remove some particles of it from the fouling cup and yes, it is all lead.

Thanks,
Argie.

[reddog81]

I'd size the bullet as large as possible up to .363. The barrel will size the bullet down to .358 without issue.

If the leading is limited to the area shown in the pictures, it's really of little concern and more a visual nuisance than anything else.

[35remington]

Try a .363” bullet if possible and see what happens.

[Ozark mike]

I run my revolvers at or over chamber dia even if bore dia is smaller. You may even pick up some accuracy

[Larry Gibson]

Argentino

Since there's no leading in the bore it appears to me, as you surmise also, the leading is from gas cutting around the bullet in the cylinder throats. You might try using just plain Pb alloy or find some tin and mix a 40-1 alloy. The linotype has to much antimony, even at that low amount. At the low pressure of your load the bullet isn't obturating at all. A double coat of BLL or a single coat of LLA should be sufficient. Upping the powder charge to 2.4 or 2.7 gr HP38 may also help to obturate the bullet a bit.

[Walks]

I use an old Ideal 1cav #358311. Unsized lubed with 45-45-10, cast with LINO. Drops at .361

This works well in both my OLD H&R breaktop and S&W M&P 5" surplus. Never measured the cylinder mouths or slugged the bore of either revolver.

A Cowboy Shooter friend gave me the mold and a bottle of what I think was liquid alox about 25odd yrs ago. Told me about the unsized tumble-lube for the 1st time. Gave me 100rds of ammo.

And I proceeded to lose the bottle of lube between the range and home. So I just shot the rounds he gave in Sidematches using my Grandmother's H&R .38S&W breaktop. At 20ft they shot dead on with a light load of BullsEye.

Never cast any until I learned about the benefits of Tumble-Lube after joining CBA.

The bullets dropped .361 and TL'ed don't shoot as well in the old Smith. Plan a good polish of the bore and getting a hollow based mold from N.O.E. in .361+Dia.

Those should shot very well in the old M&P. But I gotta measure the chamber mouths first.

When I find the time.

Good Luck with yours.

[mattw]

BTW, that is not an excessive amount, but it is not a trivial amount either. I have an old 32 Short that will do that as well, it is a timing issue with the gun and is not worth fixing as it has no blue left and has a bunch of external pits. Was not stored properly for only God knows how many years.

One thing not mentioned... measure you cylinder gap with a feeler gauge. That old girl may have a lot of wear in the front side. As suggested by others, when the cylinders are that large you will really want to find a bullet that fits the cylinder properly. With proper lube they will pass thru the barrel and leave minimal lead and may even shoot better. Another thing... the timing could be off a little and causing some misalignment at time of firing. Read up on it, and you will see how it affects the pistol.

I decide what size bullet I will use in a revolver by test fitting them thru the cylinder. I really like a front side fit that requires at least minimal pressure to fit them thru the chamber. It can be a pain, for example, I shoot 4 different 38's and 4 or 5 different 357's. I have to size some to .358, .3595 and .360. But, it really does help with accuracy when this is done correctly. At least you do not have the flip side where the chamber is much tighter than the bore, then you have to have the chambers worked on.

[243winxb]

Cast with linotype/lead 50/50 , lube , no sizing, unless larger then . 363"

.359" ain't never gonna bump up to .363" lol

Pulled bullet from old factory round.

[DougGuy]

OP I think you answered your own question in the last of your original post. You know the throats are .363" and the boolits are admittedly .359" and you are shooting very light charges, not enough pressure to obturate the boolit to the throat, but plenty enough to push burning gases past the sides of the too small boolit, here is where your leading is coming from. The reason it doesn't lead the bore, is because it is just large enough to seal once it makes it into the bore.

Your throat diameters pretty much dictate what diameter boolits you would need to fill them. I would size to a light drag fit in the throats and shoot the thing..

Apologize to Larry Gibson I hadn't seen his post until I posted mine, but hey says about the same thing right?

[243winxb]

You alloy is soft.

[Outpost75]

I have a great deal of experience loading for the .38 S&W in 1920s era Colts and S&Ws, Webley & Scott, S&W Victory and Ruger India contract models.

Throat fit is vital. So is soft alloy and soft lube which can coat the bore. If you do not have a mold that drops not smaller than .362" in 8 BHN 1:40 tin-lead alloy, the easiest solution which works is to use factory, soft-swaged 148-grain HBWC bullets from Remington or Speer. Lube these with 45-45-10 or Lee Liquid Alox on top of what is already on them. Use RCBS .38 S&W Cowboy dies and seat bullet out to 1.20 OAL, crimping in top lube groove, with 2.7 grains of Bullseye or TiteGroup, 3 grains of 231, HP38, 452AA, or WST or 3.5 grains of Unique, Universal or AutoComp. What you are doing is loading a .38 Special wadcutter charge in a .38 S&W case. The hollowbase bullet will upset to fill the cylinder throats and the load will be accurate and not lead.

Otherwise, buy a mold from Accurate that "fits", Tom has a bunch suitable for .38 S&W.

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[243winxb]

The antimony in linotype will increase bullet diameter as bullets drop from the mould.

[Outpost75]

The antimony in linotype will increase bullet diameter as bullets drop from the mould.

Yes, but less than 0.001", more like 0.0003-0.0005" and hardness will exceed 10 BHN so bullets will not seal and therefore will lead.

[243winxb]

SAAMI maximum PSI for the 38 S&W is 14,500 . The alloy has to be strong enough so the bullet doesnt encounter Plastic deformation.