British .455 Mk II with M1917 .45 ACP Cylinder - value and shooting performance

[StrawHat]

Thanks you two for added comments. I think I am seeing the lug now and added a couple of pictures. Never knew what it was called, but my converted 455 still has it and it works as designed on both the 45 ACP and the 455s?? Just a bigger space. I always thought is was part of the frame forging?

Anyway, let me know if that is what you are describing. Interesting how many little things affect the functioning of these revolvers, but I am not just not seeing the need to remove that part of my converted 455??

Gary,

Your first photograph shows the cylinder out of battery and lined up with the frame lug. The top revolver has a very minor gap between the cylinder and the lug. The cylinder will hardly move before the lug catches it and the cartridges start to eject.

The bottom revolver has a much larger gap and as such the cylinder gets a running start at the lug. Eventually the repeated “taps” will cause mushrooming of the lug or damage to the cylinder. How long until it happens? Who knows.

When I reworked the 28-2 there was about 1/8” gap, .125”, not much. But when I hit the ejector rod, I hit it hard. Within a year I saw damage in the form of peening on the lug and cylinder. I cleaned everything up and replaced the lug. 30 years later, good as factory!

Kevin

 

[Hondo44]

The factory barrel dimensions were the same for 455 MKII & 45 COLT in pre war guns, which are:

Pre war Smiths with 45 Colt chamberings were so few, Smith used the same groove and bore sizes as their .455.

bore (land) diameter - .447" to .448"; groove diameter - .457” to .458"


Their 1917 45 ACP barrels & post war to current Smith .45 Cal barrels became the same.

bore (land) - .445"; groove - .451”


THREE 45 Caliber CYL CONVERSIONS, NOTING SAFETY CONCERNS:

The preferred method of conversion to accommodate 45 Colt cartridges in a 455 cyl for a 455 and 45 Colt dual cartridge cyl is to ream the chambers for 45 Colt and including a .015" case head recess. Since the .455 case rim is larger in diameter than the Colt, it will not fit down into the recess and thereby maintain its original proper headspace. And ignite both cartridges reliably.

1st option: to convert 45 ACP/AR cyl for dual cartridge cyl including 45 Colt, the ACP cyl chambers are reamed to move the shoulder deeper for the longer Colt cases BUT NOT deep enough for the Colt case rims to touch the cyl face, just deep enough for the Colt Rim to set back off the cyl face .030", to maintain the same headspace as the ACP rims in clips and the AR rims. First, to make sure the colt chamber shoulders are not reamed too deeply, grind the rim off of a 45 Colt case to make it rimless, than use it to verify that your chamber shoulders do not get reamed too deep while reaming to extend the shoulder.
Depending on the reamer used, the shoulder can be cut round for standard 45 Colt roll crimped cases or cut square like the ACP/AR for use with taper crimped 45 Colt cases.

2nd option: to convert a 45 Colt cyl to also safely shoot ACP (only with clips) and 45 AR, as well as the 45 Colt, face off the rear cyl face .030". NOTE: if an outer ring is left on the cyl face, you’ll keep the original cyl serial # and the frame lug will not need replacing, but you’ll need to use full moon clips for ACP that fit inside the cyl face ring.

3rd option: to convert a 455 cyl for a three cartridges; 455, 45 Colt, and 45 AR: with a chamber recess of .050" cut, it'll also shoot 45 AR. With the 45 Colt CHAMBER shoulder left .030" short for its rim to seat in the .050" AR recess, the cyl will shoot 45 Colt, 45 AR, and again the 455 can still be shot because it's larger diameter rim won't fit in the chamber mouth recess so it's headspace is still proper. One cyl can then safely shoot three different 45 cartridges.

Note: the 45 AR cartridge with its 14,000 pressure rating is safer to shoot in 455 non-heat treated cyls than the 45 ACP with its 19,000 pressure. The 455/45 Colt/45 AR pressure ratings are all about the same.

 

[glowe]

Jim, glad you identified the factory dimensions for the $%% barrels. Now I need to find out what the dimensions are for my #*_$$ Target barrel!

The cast unsized HB bullets coming out of my RCBS 455 mold run between .456" to .459" and leave strong rifling imprints on recovered bullets.

My solution to the 45ACP converted revolvers and accuracy problems. Using my RCBS HB 455 bullets, cast with soft lead, I load them in my 45ACP cases with Trail Boss and get identical accuracy to my original 455s. One can purchase these bullets from time to time online, but buying the mold is best if serious about shooting your old 45ACP in the 455 bores. Somewhere between 3 - 3.5 grains works for me, but test your own loads carefully before loading quantities.

 

[steelslaver]

A .451 or .452 will most certainly engage the rifling in a 455 barrel as the bore is .447. But there may be some slippage and probably some blow by.

Ball should be less apt to slip than lead. AA lead hollow based bullet would work as it should upset and engage well. Using a larger bullet might not help if the gun has a 117 cylinder if the 1917 has .452 throats. As the .454 bullet would get squeezes to .452 before it hit the bore.

The advantage of a 1917 cylinder over 455 cylinder with the rear face shaved is 2 things. The 1917 cylinder will have tighter throats for the smaller acp bullets, so they start out the cylinder straighter. Plus, the 1917 cylinder received a heat treatment to handle the 45acps high pressure while the 455 cylinder did not.

 

[StrawHat]

...Jim, glad you identified the factory dimensions for the $%% barrels. Now I need to find out what the dimensions are for my #*_$$ Target barrel!...

Exactly what I was thinking.

Kevin

 

[Hondo44]

Jim, glad you identified the factory dimensions for the $%% barrels. Now I need to find out what the dimensions are for my #*_$$ Target barrel!

Exactly what I was thinking.
Kevin

Yeah, the 38-44:

.346" bore with groove depth of .0055 (each side) for a groove diameter of .357".

 

[glowe]

NO. 38-44 Target!

 

[Hondo44]

NO. 38-44 Target!

Oh, that 38-44. It threw me off when you asked about the 38-44 Target barrel; I thought you meant the 38-44 Outdoorsman. But of course you'd know that! My mental gears not meshing again, need my syncros replaced. Sorry.

The 38-44 Target cartridge barrel bore and groove is the same as the 38 S&W which preceded it by about 20 years; Bore .354" plus the groove depth of .0035" per side gives the groove diameter of .361". And I would slug the barrel to confirm.

As you certainly know but for other readers:
The 38-44 full length case enclosing the ball or bullet requires a cyl with 'charge holes' (like cap and ball cyls) with no 'shoulders', hence not 'chambers'.