455 conversion to 45 auto question

[quinn]

On the WWI era British S&Ws made in 455 (either first or second version) what was done later to convert the cylinder to 45 acp/moons or 45 autorim? The case diameters of all these cartridges appear to be pretty close to the same diameter (.476+/- a few thou). The case/cartridge lenghts are different, however. Was the chamber just lengthened? Was the cylinder shaved to change headspace? Can you still fire 455 in a converted gun? Thanks

 

[snoopdawg45]

455 to 45 acp

Randy:
The one I have, the cyl. was shaved to accept 45 acp or 45 auto rim.
John

 

[glowe]

Tha standard modification to the 455 was to convert to 45 Auto-Rim or 45 Long Colt. The cylinder was shaved to accept the thicker rims and I think both required some chamber rework, since both casings are longer than the 455.

I am sure that you could chamber 455 in them, unless the cylinder was adapted to take moon-clips, but the chambers might be a little big, so a split case could be a possibility. Other problem is that the firing pin might not hit the primer with enough force, given it would be farther away with the shortened cylinder

 

[lebomm]

The best of the .455/.45 Colt conversions were done by deepening the chamber AND cutting a rim counterbore at the rear without shortening the cylinder. These guns will still fire the .455 without difficulty, as its rim is somewhat larger than the Colt, and using the counterbore preserves the .455's headspace. The ACP/AR conversions are usually shaved, and no longer handle the .455.

Larry

 

[Waidmann]

Larry has nailed it. Good description.

Bill

 

[Oyeboteb]

Too...the Bullets normally associated with present day .45 Colt, or, .45 ACP ( especially when they are Hardball ) tend to be a little too small for the Barrel Bores of the .455 S&W or Colt Revolvers.

So, if one has such an old 'Conversion' and wishes to take it seriously, it is good to measure the inside diameter of the Cylinder Bores, and, of the Barrel, to decide what diameter Bullets to be loading into one's Cartridges for it.

Mine seem to like .454 pure Lead Bullets...while, recovered .452 Hardball show barely any whisps of Rifeling impressions, so, the usual .45 ACP fare is too small for mine...and, this even hold true often enough for the .45 ACP Pistols as such - their Bores were often enough too large from the get-go for the kind of Bullets which would be normally fired in them.

 

[Hondo44]

Larry has nailed it. Good description.

Bill

Yes!

Any 455 to ACP/AR conversion would still allow the use of 455 Mark II since they are slightly longer than 455 Colt. And since the case mouth would headspace on the original chamber shoulder, once faced off, the case head would extend out of the chamber slightly and have the same relationship to the firing pin for reliable ignition.

If I were to convert one to ACP/AR I'd leave a slight rim on the circumference of the cylinder face to eliminate the need for a new cylinder stop in the lower corner of the cylinder window. Or better yet recess the chambers for the AR like for the 45Colt to retain the original cylinder serial number. I could still shoot ACP individually w/o moon clips since I hate them anyway.

 

[jhvaughan2]

Does anyone have experience with the conversion being done through the relieving of the recoil shield? This seems very risky to me. Would the cylinder then not need to be changed?

 

[Hondo44]

I've read about them done that way on this forum and it does avoid the need to modify the face of the cylinder but the chambers would still have to be lengthened if converted to 45 Colt; not so for ACP/AR.

IIRC there was discussion surmizing that if the gun was sent to the factory for the conversion, that's the way it was done.

 

[Jack Flash]

Does anyone have experience with the conversion being done through the relieving of the recoil shield? This seems very risky to me. Would the cylinder then not need to be changed?

There was an article in an old Guns & Ammo that suggested this approach. The idea was that very little material needs to be removed from the recoil shield to convert from .455 to .45 Colt. As I recall, the article said if you're lucky, you may not have to remove any metal at all. You still had to ream out the chambers, obviously.

Of course, .45 Auto Rim would be a different story, requiring a lot more material to be removed, I do suppose.

 

[Muley Gil]

"I could still shoot ACP individually w/o moon clips since I hate them anyway."

But would .45 ACP headspace on the .455 chamber mouth?

 

[Hondo44]

"I could still shoot ACP individually w/o moon clips since I hate them anyway."

But would .45 ACP headspace on the .455 chamber mouth?

Well I've never had a shaved 455 cylinder to actually try, I'll admit. But I have shortened 45 Colt cases, primed them and fired them reliably in a 45 ACP unmodified cylinder. What that told me was that although there is excess headspace for the 45 Colt, there was enough leeway in the firing pin travel to reliably ignite them.

So when I lined up 455 Colt, 455 Mk II and ACP cartridges, with the small difference in extra length of the 455 MK II over the ACP it appeared that the leeyway in firing pin travel would ignite the ACP. Although theoretical on my part.

Hopefully someone with an unmodified 455 cylinder could drop in an ACP and see how far it sticks out when headspaced on the 455 chamber shoulder.

 

[Muley Gil]

I don't have a S&W .455, but I do have a Webley & Scott MK V that has been converted to .45 ACP/AutoRim. I dropped in a .45 ACP and it sank slightly below the edge of the faced off cylinder.

 

[Oyeboteb]

I had a fun thing happen - bought a 1914 Colt 'New Service' in .455 which the Seller said had been converted to .45 ACP and Moon Clips.

Nice old Gun, so I figured what-the-heck.

I get home, and, I find that .45 ACP and Moon Clips will not permit the Cylinder to Close.

I try .45 ACP CArtridges by themselves, and, they fit well, the Cylinder Closes well, and, I suppose they would fire fine, as their Head Space appears to be about right...but, one would have to eject them with a Pencil or something.

.45 Colt is too long.

A little time goes by, and, I am at a Gun Show and a guy has a Box of .455 Cartridges and I buy them...I get home, and, "Bingo", they fit perfectly, and, the Cylinder closes perfectly, but appearently, the old Colt Cylinder was shaved just a little, and, it does allow .45 ACP to fit with no Moon Clips, ( whether the shaving had anything to do with it or not, I do not know ) so, there is yet one more variation on the theme.

If I put a .45 ACP Cartridge into the Muzzle, so the Bullet itself is in the Bore, it goes in all they way to the Cartridge Case mouth, so, this suggests to me that again, as usual, a .45 ACP Bullet is way too small for a .455 Barrel.

 

[Hondo44]

Well, to be completely honest now I'm confused.

Oyeboteb, my expectation was like your experience with your New Service. If your Colt cylinder still has the serial number on the rear face, perhaps the cylinder wasn't shaved/converted at all.

And Muley Gil, I'm baffled by your experience. Your cylinder was shaved and the ACP still went all the way into the chamber. I wonder if since the 455 headspaces on the rim that the Webley's chamber shoulder has a looser tolerance than the Colts or Smiths. It would be interesting to know how far a 455 would drop in with the rim removed.

Thank you both for your test results.

 

[Jack Flash]

Oyeboteb, I have a New Service much like yours, still in its original .455 Colt chambering. (".455 Colt" is what Colt called the cartridge; I doubt the Brits ever used that designation, but that's what Colt put on the barrel).

IIRC, I shortened some .45 Colt cases in an attempt to see if they would function without thinning the rim. I found that I could put one of these cases in a chamber and position it so it was at the lowest point (farthest away from the barrel) and I could close the cylinder just fine. The problem was, the cylinder would bind when the action was cycled. So the .45 Colt rims are just too thick, at least in my Colt.

I found that .45 ACP cartridges had excessive headspace, and that if I put them in moon clips it was impossible to close the cylinder.

My brother was kind enough to thin the rims of some .45 Colt cartridges and then shorten the cases to the correct "Mark I" length (0.890") and I use these modified cartridges for loading .455 Colt cartridges for this old war horse. It used to be possible to buy similar modified .45 Colt cases from Buffalo Arms, but I haven't been to their website in years so I can't say they are still available. Last time I went to their website, it was really hard to find anything.

 

[deadin]

Ready for a long winded response????

I don’t even know just where to start when considering .455 conversions….
First, realize that nearly all .455 chambers are designed to accept either the .455 MkII cartridge or the .455 MkI cartridge (aka .455 Colt in Canada). The main dimensional difference in these rounds is case length with the MkI being longer then the MkII. The 45 ACP and 45 AR are both shorter and have a smaller head diameter than the .455 so there is no need to deepen the chamber. A .45 ACP will drop into an unmodified .455 chamber and fall .100 below the chamber mouth. (measured in a .455 TL) The difference in head diameters between the two are around .004 which can cause a little swelling of the case, but shouldn’t be a deal breaker unless loading hot rounds. (which no one should be doing in a conversion in the first place.) The .45 Colt has a slightly larger head diameter so this problem shouldn’t quite as pronounced. At the same time the .45 Colt case is longer and the chambers will need to be deepened in order to accept it.
Now we get to headspace… I can’t find what headspace is recommended for the rounds under discussion, so I am going to consider that normal headspace ranges from about .004 to .013. Anything less than .004 can cause hang-ups in cylinder rotation and anything over .013 can cause case stretching, misfires, and a whole symphony of undesirable results. (Especially with an already too small head diameter.) So, in order to accommodate the thicker rim of the .45ACP/45AR , (the AR being designed to allow its use without clips), so rim thickness can be considered the same for both cartridges. Remember the 45ACP is designed to headspace on the case mouth, not the rim. (1917 S&W had a headspace shoulder built in so one could use 45ACP without clips, but extraction had to be done with a stick. 45AR works just fine.) The .455 chamber does not have this shoulder so all headspacing is dependent on the rim of the case. This means that something will have to give to get either the 45ACP/AR or the 45 Colt to fit. The given remedies are shorten the cylinder, shave the standing breach (recoil plate), rebate the charge holes or a combination of the above. The various rim thicknesses are: .455 = .035, 45 Colt = .055 and the 45 ACP (w/clips)/45AR = .085. To allow use of ACP or AR will require that app. .050” of metal be removed somewhere. However this will also add .050 to the headspace requirements for the .455 which is way over the recommended max. A suggested way around this is to rebate the charge holes to allow the smaller rim diameter of the 45AR (.516) to drop in far enough to headspace and still allow the .455 rim (.535) enough cylinder face to headspace. (This will also allow the 45 Colt rim (.510) to fit if the charge hole has been deepened.) The only problem with this is that it precludes using clips on 45ACP as they will try to headspace on the same surface as the .455, which was the original problem. (Remember, no shoulder for the ACP to headspace on.) If you are willing to give up 45ACP, this is a pretty elegant solution as it doesn’t change any external dimension of the gun, the cylinder stop is still within specs, it retains the cylinder serial number, etc. The only problem is that it will add around .030” to the headspace of the .45 Colt. (The difference in rim thickness between it and the Auto Rim). This is outside the recommended range, but as long as the loads are kept in the lower range, shouldn’t cause many problems. So, if you want to keep the ability to use 45ACP in clips, it’s pretty much shave the cylinder or breech face with all of the inherent problems included, the main one of pretty much writing off safely using .455. (I suppose one could try making up some kind of a .050 “moon shim” that could be placed on the back of the cylinder and have the .455 rounds placed through it.)
Now, I have seen a few .455’s that will close on a 45 Colt rim, but they have to be loose to the point of being way out of spec as the Colt rim is .020 thicker than the .455

 

[2152hq]

Great post deadin!
I will only add a couple of pics I was going to post anyway.

This of how far GI 45acp ammo drops into an un altered S&W 455 chambered cylinder.

..and a couple of a Smith 455 cylinder altered to take 45 (Long) Colt ammunition. Not a very well done job but it shows what is done in the process.
The other pic shows the fresh cut lengthened chamber w/original blued throat.
This cylinder has an 'in the white' extractor fitted. No ser#'s on either part.
Maybe some NOS parts never fitted that someone intended to make up a conversion with.

 

[Oyeboteb]

Oyeboteb, I have a New Service much like yours, still in its original .455 Colt chambering. (".455 Colt" is what Colt called the cartridge; I doubt the Brits ever used that designation, but that's what Colt put on the barrel).

IIRC, I shortened some .45 Colt cases in an attempt to see if they would function without thinning the rim. I found that I could put one of these cases in a chamber and position it so it was at the lowest point (farthest away from the barrel) and I could close the cylinder just fine. The problem was, the cylinder would bind when the action was cycled. So the .45 Colt rims are just too thick, at least in my Colt.

I found that .45 ACP cartridges had excessive headspace, and that if I put them in moon clips it was impossible to close the cylinder.

My brother was kind enough to thin the rims of some .45 Colt cartridges and then shorten the cases to the correct "Mark I" length (0.890") and I use these modified cartridges for loading .455 Colt cartridges for this old war horse. It used to be possible to buy similar modified .45 Colt cases from Buffalo Arms, but I haven't been to their website in years so I can't say they are still available. Last time I went to their website, it was really hard to find anything.

Hi Jack Flash,


What fun!


Mine says "NEW SERVICE 455 ELEY" for the Barrel Stamping text.

My Cylinder has been 'shaved' a little, and looks like it...but just what was accomplished by this, I do not know.


I think I paid like $36.00 for a Box of factory .455 Cartridges at the Gun Show, some non-ammo seller who had a few odd Boxes of this and that, and, I figured I'd save the Brass ( if I ever shoot it enough to do so, ) and, then, re-Load them.

It was not that long ago, that one could not hardly give away any .455 Colt New Service or S&W 2nd Model Hand Ejector, and no one wanted them.

I am glad I wised up enough in time to get myself one of each ( Colt, and, S&W ), just to have for fun, before they went quite so pricey as they are now.

Next time I go to the Range, I will try mine with some every day K-Mart .45 ACP Cartridges, and, see how they fire.

I expect they will fire just fine, even with their slight excess of Head Space...and even with the Bullets being too small for the Barrel and so on.

I have a few old Boxes of factory loaded .45 Auto-Rim, and, several old Boxes of factory primed Cases, and, I should dig those out and see how - or if - they fit, too.

Have you tried those with yours?

 

[Oyeboteb]

I have an S&W 2nd Mdl HE which was originally chambered for the .455 ELEY, and, which had been modified to chamber .45 Colt AND .45 ACP.

Well, golly, what is a boy or girl to do with that?

What I did, for it and for an other New Service I have, both of which have Cylinder Bores and Barrel Bores which really need something of about .454 in diameter for the Bullet...

What I did, was to modify some .45 Colt Cases, at their annular incised 'groove' at the Rim, by slightly widening and deepening the groove, for them to fit nicely into the usual Full Moon Clips, and, I loaded those Cartridges then with some nice, soft pure Lead Bullets of .454 diameter.

Well, this worked just dandy, and, looks really cool also.

As much as one may enjoy the look and convenience of the Full Moon Clip full of .45 ACP, having them in .45 Colt is just all the more fun.

Easy to do, and works like-a-charm, and, satisfied the Head Space issue of .45 Colt when just by itself, and, obliges the need for a .454-ish Bullet...and, eliminates Bullet Jump associated with the use of the .45 ACP Cartridge in Moon Clips in those Revolvers also able to chamber the .45 Colt.