Relining old Colt 1903 pocket hammer (.38 ACP) barrel

Hello,

Does anyone know if it is possible to reline an old .38 ACP barrel from an old colt? Chamber is dimensionally identical to .38 super, and bore is the same as a 9mm (same liner).

Aside from the bad bore, the pistol is fully functional and in good shape internally.

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I'm having a hard time finding a replacement barrel unit- they come up sometimes, but not often.

Thanks!

-Dave

I would consider taking another 9mm barrel and turning it down to make a liner.
Not being restricted to manufacturer's dimensions might make it possible to select a barrel reamer from what is on hand.
Barrel, 9mm/.380Cal, Blank, Pistol, 9-1/8'' Long x .555'' OD. Blued. | Gun

I have one of those too and was surprised to find the firing pin to be a bronze material, said to be beryllium copper, so I suspect that the period just after 1900 was nearing the end of the most corrosive primer period.
That might account for the poor barrel bore.

I have one of the Baby Brownings in 25 ACP with same problem- bore completely gone and keyholes at 15' while second-hand barrels are a bit tough to find.
In the case of the Browning there have been a couple of companies which offered copies and barrels from those makers are available.
One sort of low quality and one too expensive to consider for my old beat up pistol.

saki302 said:

Hello,

Does anyone know if it is possible to reline an old .38 ACP barrel from an old colt? Chamber is dimensionally identical to .38 super, and bore is the same as a 9mm (same liner).

Aside from the bad bore, the pistol is fully functional and in good shape internally.

Imgur: The magic of the Internet

I'm having a hard time finding a replacement barrel unit- they come up sometimes, but not often.

Thanks!

-Dave

Click to expand...

How does it shoot? Are you shooting lead bullets? Badly pitted bores strip lead bullets eventually turning the barrel into a "smooth bore".

Often times a badly pitted bore will still shoot jacketed bullets or something plated like Berry's acceptably.

Liners need a minimum wall thickness for safety. Even if the bore has the minimum wall thickness the chamber might not. Getting the minimum wall thickness in the chamber area might leave the barrel too thin.

UncleFrank said:

How does it shoot? Are you shooting lead bullets? Badly pitted bores strip lead bullets eventually turning the barrel into a "smooth bore".

Often times a badly pitted bore will still shoot jacketed bullets or something plated like Berry's acceptably.

Liners need a minimum wall thickness for safety. Even if the bore has the minimum wall thickness the chamber might not. Getting the minimum wall thickness in the chamber area might leave the barrel too thin.

Click to expand...

If its too thin, maybe a stub job is called for. Cut off barrel at the locking breach, bore it and thread it, thread custom made liner, intall.

Liners need a minimum wall thickness for safety. Even if the bore has the minimum wall thickness the chamber might not. Getting the minimum wall thickness in the chamber area might leave the barrel too thin.

Click to expand...

Can you supply some numbers or references?
I would have thought that a liner would not burst if properly fitted inside the original barrel.
I understand this concept if it is applied to cylinders for an internal combustion engine, but in that case the liner may supply the strength and not the aluminum finned castings that house them.

Kurt Learning said:

Can you supply some numbers or references?
I would have thought that a liner would not burst if properly fitted inside the original barrel.
I understand this concept if it is applied to cylinders for an internal combustion engine, but in that case the liner may supply the strength and not the aluminum finned castings that house them.

Click to expand...

I have the same interest as well as this has rushed right over my expertise.
I assumed the same with my Baby Browning that the barrel did not have enough wall thickness to re-line.

Open question - how does the hoop strength vary between a cylinder of single wall and that comprised of one or more nested cylinders.
I have no ideal but would assume some point is reached where a pressure wave would burst each "hoop" in turn if in a failure if the constraints of design are not met- for instance a chamber made from a roll of even high tensile foil seems to be far short of the solid in strength.

The engineering must be well established on this point..


"Velocity and range of artillery vary directly with pressure of gunpowder or smokeless powder gases pushing the shell out of a gun barrel. A gun will deform (or explode) if chamber pressures strain the barrel beyond the elastic limit of the metal from which it is made.[1] Thickness of homogeneous cast metal gun barrels reached a useful limit at approximately one-half caliber. Additional thickness provided little practical benefit, since higher pressures generated cracks from the bore before the outer portion of the cylinder could respond, and those cracks would extend outward during subsequent firings.[2]

Claverino's 1876 treatise on the "Resistance of Hollow Cylinders" was published in Giornale d'Artiglieria.[3] The concept was to give exterior portions of the gun initial tension, gradually decreasing toward the interior, while giving interior parts a normal state of compression by the outer cylinders and wire windings.[4] Theoretical maximum performance would be achieved if the inner cylinder forming the rifled bore were compressed to its elastic limit by surrounding elements while at rest before firing, and expanded to its elastic limit by internal gas pressure during firing.[5]

Built-up gun - Wikipedia"

I don't have any specific remaining thickness numbers; they likely vary according to cartridge/barrel design and max pressure.

I'd contact a few liner mfrs, tell them what you are attempting to do and see what they recommend as a minimum remaining barrel/chamber thickness. They might know some gunsmiths that have already done something similar.

I have no idea but would assume some point is reached where a pressure wave would burst each "hoop" in turn if in a failure if the constraints of design are not met- for instance a chamber made from a roll of even high tensile foil seems to be far short of the solid in strength.

What happens is the inner layer cracks and lets high pressure gas infiltrate the outer layer. Then the outer layer cracks because it is no longer strong enough to resist the pressure.

This is a serious problem with high pressure cartridges; it is harder to quantify for lower pressure ones. I am not familiar with the M1903 in .38 ACP; I think I worked on one in .32 ACP a long time ago and my recollection is that the barrel seemed integral with the frame, but I didn't really get into it deeply.

Ok- thank you.
I see in the .22 long rifle world a reline is a seemingly casual undertaking.
It must be as you state that the pressure wave is easily met with the comparatively robust cylinder walls in that cartridge.

I actually would like to reline my old Baby Browning at some point if it were advisable.
I think I would be looking at stoping the sleeve just forward of chamber?

This would leave the hoop strength intact at breech and the nuance of reamed alignment being absent in a pocket pistol as I can setup in lathe to around .0001" TIR

I'd be concerned sleeving from the muzzle to chamber mouth would leave a potential gas escape path along the lines of what GGaskill noted above. I know it's been done before, usually sleeving the chamber. But I think only on 22's and black powder guns IIRC.

Barlow's formula shows a yield pressure of about 15k PSI for a 1/2" dia liner, over the .384 chamber. Assuming annealed 4130. SAAMI spec for 38 ACP is 26,500. But a forged liner (TJ's) is probably going to be harder than that, and there's the added 'support' of the case itself. A .625 liner would get you to about 25k.

And that's for a static pressure. An impulse from a cartridge is a different matter. Better? Worse?

Soooooo ...... there's the details of the original barrel dimensions to account for. A good experiment might be to build up a breech to use a bare .5" liner, and see if you could shoot 38 Super +P in it without incident. If nothing else, it could result in a fun display piece ;-)

Bottom line, I don't know the answer, obviously. I have a 32-20 rifle that needs a liner. I think my calc's suggested a 1/2" liner was more or less sufficient, but the muzzle of the barrel is only .550. A 7/16" liner, maybe available special order, doesn't make me feel comfortable at the chamber end. So I'm contemplating stepping it down several inches forward of the chamber, which slightly complicates boring it out. And I'd have to turn the liner down. Step one is seeing what that does to the bore dimensions.

Ive sleeved a number of 303s that had the DP cross chamber drill hole.......Ive also listened to lots of complex procedures involving heating ,freezing,shrinking etc.......and done none of these ...just made the sleeve insert a thumb push fit ...fire one test shot and the whole lot is locked together......Relining 32/20 s is childs play...even read of owners doing the rebore with a hand held lekky drill...........I m guided by Hatchers reports of work at Springfield Arsenal where barrels of service model1903 rifles were turned down as thin as 1/16" ,and still held service ammunition pressure reliably,and needed a 75,000 psi proof round to burst them.

If you want to turn down a rifled liner to a very thin wall,fill it with cerometal first,then the job is simple and the bore wont be swaged in,and leave the cerrometal in the bore until the liner is fixed in place .....if your work is to any acceptable standard ,the liner will be a thumb push fit,and the job entirely successful.........Use a 4140 liner ,and it will have much superior yield strength to the soft steel barrels used in old pistols.

A friend of mine ended up trading me for the old pistol- I found a better one for a little more with a good barrel.

Boring and threading the front and rear and threading them onto a good barrel is probably the best/strongest choice. I'll mention that to my friend- perhaps in a different caliber like .380.
One company experimented with a .380 conversion which worked well but was not economically viable to produce. The power curve was enough to cycle the pistol with commercial ammo yet not over stress it. I'm not sure if magazine mods were needed to help it feed.

As for the old bore- a 9mm 124gr plated projectile would fall straight through (not quickly, but smoothly), so the rifling was likely 'cleaned' away with a power tool to 'remove the pitting' I'd guess!

-Dave

You missed your chance- you could have sold it for top dollar listed with "clean bore"...

Saki has discovered a universal truth in guns....buy a good one and sell the dud one for the same money.....Incidentally,I believe a pistol with the bore reamed smooth is illegal in the US without a registration and tax stamp.