450/577 to 45 LC adapter

I made one and tried it but terrible accuracy. I did not expect much because the bore of a 450-577 is only about .001" smaller than the bullet. Some people use adaptors made for 45-70 shells which are not too bad for accuracy but depending on the fit of the adapter to the chamber, the 45-70 shells can be hard to remove. I also made an adapter for a 45-70 shell shortened so that it ends at the shoulder of the adapter --- that means that the adapter does not expand to fit the chamber and the shells are much easier to remove. The issue of how well the adapter fits the chamber is that if you try to make a universal adapter, it is going to be loose in some chambers

cheers mooncoon
 
CMichaud said:
Not sure. I always heard that they were not that great to be honest.

Part of the issue is the bullet of the MH varies from .460 up
Click to expand...

British martinis need at least a .468" bullet that said these work ok and close ranges with .45 colt id like to get my hands on some .455 webley bullets with a hollow base to try
 
mooncoon said:
I made one and tried it but terrible accuracy. I did not expect much because the bore of a 450-577 is only about .001" smaller than the bullet. Some people use adaptors made for 45-70 shells which are not too bad for accuracy but depending on the fit of the adapter to the chamber, the 45-70 shells can be hard to remove. I also made an adapter for a 45-70 shell shortened so that it ends at the shoulder of the adapter --- that means that the adapter does not expand to fit the chamber and the shells are much easier to remove. The issue of how well the adapter fits the chamber is that if you try to make a universal adapter, it is going to be loose in some chambers

cheers mooncoon
Click to expand...

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This topic has come up periodically. I have an adaptor, bought from Del Selins. I've shot at 25 and 50 yards, using soft (.45ACP) 200gr LSWC and (.45LC) 250gr RNFP bullets, in .45 LC cases loaded with a fast powder, e.g. 8-10 gr Unique or Trail Boss. The 250gr bullets work best. At 50 yards, they are not tumbling, and accuracy is not terrible, i.e. 6-inch group at 50 yards, a lot of the spread is due to old eyes +open sights. I haven't tried out to 100 yards mainly for that reason.
YMMV, depends what you plan on using the rifle for. I'm not using it to win any precision matches, but neither am I aimlessly flinging lead down-range. Using soft cast, aloxed projectiles does work with my MH's.
 
antiqueguy said:
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Click to expand...

to explain what the problem is; the neck area of the martini chamber adapter is fairly thin. When a full loaded 45-70 shell is fired in it, if the neck of the adapter is not tight in the chamber, it will bulge slightly. That means that the 45-70 shell becomes slightly flared at the case mouth and for that reason is difficult to remove. Not impossible but needs to be tapped out with a rod. The adapter is thick enough in the main body that it does not bulge even though it is slightly loose and that means that a shell which does not extent into the neck portion of the adapter can be removed much more easily

cheers mooncoon
 
mooncoon said:
to explain what the problem is; the neck area of the martini chamber adapter is fairly thin. When a full loaded 45-70 shell is fired in it, if the neck of the adapter is not tight in the chamber, it will bulge slightly. That means that the 45-70 shell becomes slightly flared at the case mouth and for that reason is difficult to remove. Not impossible but needs to be tapped out with a rod. The adapter is thick enough in the main body that it does not bulge even though it is slightly loose and that means that a shell which does not extent into the neck portion of the adapter can be removed much more easily

cheers mooncoon
Click to expand...

that was more about the part I made bold
 
antiqueguy said:
British martinis need at least a .468" bullet that said these work ok and close ranges with .45 colt id like to get my hands on some .455 webley bullets with a hollow base to try
Click to expand...

Not correct. From BMF

Specific bore dimensions and bullet diameters


W.R./ Francotte ZAR (and Henry Rifled commercial units in #2 Musket)
... bore diameter, 0.449" ... groove diameter, 0.463" ... recommended bullet diameter, 0.460" to 0.463"


MK I rifles
MK II rifles
MK III rifles
MK I Cavalry Carbines
MK I Garrison Carbines
MK I Artillery Carbines
MK II Artillery Carbines
MK III Artillery Carbines
... bore diameter, 0.449" ... groove diameter, 0.465" to 0.467" ... recommended bullet diameter, 0.465" to 0.467"


MK IV A pattern rifles
MK IV B pattern rifles
MK IV C pattern rifles
... bore diameter, 0.453" ... groove diameter, 0.470" to 0.472" ... recommended bullet diameter, 0.470" to 0.472".
 
Last edited:
CMichaud said:
Not correct. From BMF

Specific bore dimensions and bullet diameters


W.R./ Francotte ZAR (and Henry Rifled commercial units in #2 Musket)
... bore diameter, 0.449" ... groove diameter, 0.463" ... recommended bullet diameter, 0.460" to 0.463"


MK I rifles
MK II rifles
MK III rifles
MK I Cavalry Carbines
MK I Garrison Carbines
MK I Artillery Carbines
MK II Artillery Carbines
MK III Artillery Carbines
... bore diameter, 0.449" ... groove diameter, 0.465" to 0.467" ... recommended bullet diameter, 0.465" to 0.467"


MK IV A pattern rifles
MK IV B pattern rifles
MK IV C pattern rifles
... bore diameter, 0.453" ... groove diameter, 0.470" to 0.472" ... recommended bullet diameter, 0.470" to 0.472".
Click to expand...

just about everyone uses a .468" bullet for the British guns while yes the mkIV likes a bigger bullet it works ok with the .468" bullet
 
'Nuff said.
Myself I could probably mess with it but he likely won't, not if it's that quirky to make work.
Thanks for the input all, much appreciated.
Tokguy
 
antiqueguy said:
that was more about the part I made bold
Click to expand...

British rifles use bore diameter rather than groove diameter in describing their cartridges (usually). A 450-577 means that the bore is .450 (plus or minus manufacturing tolerance) and 45 auto as well as 45 long colt have a bullet diameter of .451. That means that there is virtually no engraving of the rifling on the projectile, particularly with jacketed slugs. I will accept that there is some obturation with soft lead slugs but still very little engagement of the rifling

cheers mooncoon
 
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