Need barrel counterboring or recessing work done

[Patton]

I just recently traded for an American Derringer in 45 Win Mag. Oddly enough I almost bought this gun years ago but passed because of the odd chambering. Someone bought it and resold it to a different shop. I don't think they even realized what an odd caliber it was when they, the pawn shop, bought it. It was just cheap enough I was able to justify it.

I looked into having it rechambered to 45colt before, but now I think I would do better just counterboring the barrel to accept the 45 auto rim cartridge. The 45 win mag is a lengthened 45 acp so all that should be needed is the recessing for the rim. Does anyone see an issue or have any recommendations. This modification should even allow the use of 45 win mag if still desired. Believe it or not, but 45 auto rim ammo which I have a line on is actually easier to find than 45 win mag.

[Sidecarist]

Easiest way to do it would be to rent the reamer. I would want to check the reamer prints to make sure the pilot was long enough to guide it...

I'm a little concerned that the bullet has a long jump past the sharp edge used to head space the 45 win mag. This isn't quite like 38spl & 357mag.

[Patton]

Yeah, that jump is 3/10" of an inch. I wonder what actually happens in that scenario. How much velocity loss is caused by the escaping gases around the free bore? I know that the Judge and Governors do not loose too terribly much. Edited February 24, 2016 by Patton

[Sidecarist]

I wouldn't be concerned about velocity loss, I'm more concerned that pressure could spike with the bullet having to transition across the square chamber headspace edge.

This MAY not be an issue if the bullet has enough length to span from the auto rim case mouth to the bore. These chambers do not have a cone shaped mouth like revolver chambers do...

[Patton]

I see what you are saying. I need to research to see what the inside of the 4.10/45LC barrels look like.

[Dolomite_supafly]

Get a 45 Long Colt reamer and do it by hand. The difference between the two is .027" which isn't a whole lot. I seriously doubt you are going to have issues if you ream it to 45 Long Colt even if it doesn't get rid of the WinMag chamber 100% but honestly I think it will.

 

It is really, really early but it looks like the 45 LC reamer will clean up the edge of the chamber to where it will not be an issue. It looks like it will clean up all of the existing 45 WinMag chamber when you ream using a 45 Long Colt reamer. The real difference is not the loaded ammunition but the chamber specs and the WinMag chamber will clean up to 45 LC specs.

 

The end of the WinMag chamber is at 1.198" with a diameter of .474". The LC chamber is 1.295" long with a straight diameter of .480". The base of the WinMag is .4807" and the LC is .4862". Looks like all the critical areas of the WinMag are smaller than the LC so the 45LC reamer should clean up all traces of the WinMag chamber.

 

The ONLY issued I could see is if someone decided to load to modern pressures or decide to buy some loads for Rugers. The max pressure for a 45 WinMag is 38,400 PSI, 45 Long Colt is 13,400 and the "modern" 45 Colt is 30,300. So you could definitely shoot the original specification ammunition and you could probably shoot modern LC cartridges but I would not want to test fire it.

 

Here are the various dimensional drawings for the loaded ammunition and the chamber specificaitons.

http://www.saami.org/pubresources/cc_drawings/Pistol/45%20Winchester%20Magnum.pdf

http://www.saami.org/pubresources/cc_drawings/Pistol/45%20Colt.pdf

 

And personally, I would just rent a reamer and do it by hand. The difference is small enough that you do not need a lathe but it will take a little longer. Just make sure to go slow and check fitment often. The Long Colt head spaces on the rim so you could use a fired case to set the headspace. Just make sure it is either sized or it is chopped 1/4" ahead of the rim so it doesn't want to headspace on an swollen casing.

Edited February 24, 2016 by Dolomite_supafly

[Dolomite_supafly]

One more thing, if you do ream it to 45 Long Colt make sure to obliterate the original caliber and remark it with the new caliber. Down the road it might same someone some grief trying to figure out the caliber.

[Patton]

That probably is my best option. I think I may still see what it would cost just to have someone do it. A 45 LC remear is probably pretty common and in the toolbox of some gunsmiths.

[Dolomite_supafly]

Actually probably not. Not too many uses for it other than specialty work. I honestly cannot think of any reason to have a 45 LC reamer. That is unless you are building one off guns and not too many smiths in Tennessee building guns from the ground up, and especially in 45 LC.

 

It really isn't that hard and even if it is not perfect it will still be useable because that is not some sort of match gun needing every ounce of accuracy squeezed out of it.

[Sunfish]

If I could find some Win mag brass and dies I would just load down to ACP and leave the chamber alone.

[Patton]

I broke down and bought 100 pieces of virgin brass. I figured I may not shoot but 100 rounds through it in a lifetime anyway. I will shoot the first group tomorrow through the chronograph.

[xsubsailor]

I broke down and bought 100 pieces of virgin brass. I figured I may not shoot but 100 rounds through it in a lifetime anyway.

 

I'm sure this is a true statement  :D . I have an American Derringer in .357 and I consider it my "life and death" gun because it hurts so much when I shoot it. Factory loads (357) puts powder burns on the target a 7 yds. .38s are unpleasant to shoot but .357s are downright painful   :eek: 

 

I had a friend that had one in 45-70 and tried his best to talk me into trying it. Being the smart person that I am (disregarding the 357) I told him no.

[Dolomite_supafly]

I'm sure this is a true statement  :D . I have an American Derringer in .357 and I consider it my "life and death" gun because it hurts so much when I shoot it. Factory loads (357) puts powder burns on the target a 7 yds. .38s are unpleasant to shoot but .357s are downright painful   :eek: 

 

I had a friend that had one in 45-70 and tried his best to talk me into trying it. Being the smart person that I am (disregarding the 357) I told him no.

 

I read an article by a prominent gun writer when I was young. He talked about have arthritis in his wrist and elbow. He then said he can tell you the day it happened. He said he was testing a new derringer in 444 Marlin for an article. He said after the first shot his elbow started hurting then after a few more his wrist.

 

I could not imagine those things with a 357 Magnum.

[Patton]

To my surprise the 45 win mag was not unpleasant. A friend and I shot various loads today and both of us were impressed. I plan to load some more and hit the range again soon. I loaded one round that I kept referring to as the bad boy and even it was not too bad.

I plan to push it a little harder. Remember, all of this is through a 3" barrel. I think I will try a 260 gr bullet with 10gr of Unique.
A little size comparison with a Buck 110 and a S&W model 60.

Edited March 9, 2016 by Patton