Sizing to fit cylinder chambers

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Makeminea45

Bearcat
Joined
Nov 5, 2009
Messages
6
Just looking for a few opinions on this subject. My 45 Colt Bisley has a bore that measures .451 I have slugged it twice to be sure. The chambers mouths measure .4545 with 2 that go .455. I can push unsized bullits at .454 through the cylinders with very little pressure. I tried some RCBS 270 SAA that I cast and the results where not that great. I had to size them at .452 because that's the sizer I had on hand at the time. I was able to lube some without sizing but have not tried any yet. I also have a .454 sizer on the way. With the bullit sized this much over bore would I run into any problems with pressure spikes or anything else I should know? I would like to work up 2 loads for this gun. One around the 1000 fps mark and the other in the 1250 fps range. I've chrono'd some of the loads I have shot and I am within this range. Thanks.
 

Ale-8(1)

Moderator
Staff member
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Oct 24, 2007
Messages
11,063
The closer you can get the lead bullets to the throat size, the better. Those .454's will swage down to the .451" bore.

Work up your loads in stages.

JMHO

:)
 

J Miller

Blackhawk
Joined
Sep 30, 2000
Messages
977
Makeminea45":3srt3isd said:
Just looking for a few opinions on this subject. My 45 Colt Bisley has a bore that measures .451 I have slugged it twice to be sure. The chambers mouths measure .4545 with 2 that go .455. I can push unsized bullits at .454 through the cylinders with very little pressure. I tried some RCBS 270 SAA that I cast and the results where not that great. I had to size them at .452 because that's the sizer I had on hand at the time. I was able to lube some without sizing but have not tried any yet. I also have a .454 sizer on the way. With the bullit sized this much over bore would I run into any problems with pressure spikes or anything else I should know? I would like to work up 2 loads for this gun. One around the 1000 fps mark and the other in the 1250 fps range. I've chrono'd some of the loads I have shot and I am within this range. Thanks.

You won't run into any pressure problems. I have a S&W 25-5 with .457" throats and a .4515" bore. I have bought hard cast 265 gr Keith SWCs from Beartooth Bullets sized to .457" and shot them with no problems at all from that pistol. As a matter of fact the leading problem ceased and the accuracy improved dramatically. Since then I've been shooting my own Lyman 454424 bullets at .455" from it due to the fact I can't find a .457" sizer. They work OK.

As Ale-8(1) said, work up slowly to your desired loads.

Joe
 
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