After reading threads on this subject and not being a reloader I'm trying to understand the nuances of these guns. Mine is an 8 3/8" nickel plated specimen, 45 LC, pinned barrel with a late N prefix, SN: N904xxx. I mic'd the chambers at the forward face of the cylinder and came up with a nominal .450-.451, although it's difficult to get consistent measures. I don't have anything but my digital micrometer to measure. The gun is pretty accurate with all the factory loads I have tried. What should I be looking for as to what is good and what isn't, in a layman's terms. Thanks in advance.

Hmmmmmm, shoot it and see if it groups well.
If you're not going to shoot it then it's a moot point.

To see if cylinder chamber throats are good I use a jacketed .452 bullet
( Speer gold dot 250.gr.) and a lead .454 bullet to see which
passes through .

Allen

__________________
NRA cert.instructor&R.S.O.

The gun is probably more accurate than what I am able to produce. The target below was shot from 25 yards. The top 6 were before I adjusted sights and the 6 in the black are after. That's a 4" bulls eye. I don't have any loose bullets but I have loaded ammo. Blazer 200 gr JHP/.440, Winchester 255 gr LRN/.434, WW LRN (weight unknown)/.432 and all the bullets fit into the front of the chambers up to their cases, so I believe they will all pass through (guess). None of the bullets measure .452-.454" but I am measuring loaded bullets just above the cases which is probably not the proper place to measure. Again, I don't know and that's why I'm asking the questions.

I can always go down to the LGS to see of they will let me use some bullets of the diameter you mentioned and do the drop through test. Thanks Allen.

Attached Images

M25 45 LC.jpg (56.5 KB, 16 views)

If you'd like more accuracy than digital caliper you can buy some pin gages around the sizes you expect and try them.They normally sell them in .001" increments. They can be bought through MSC. Better yet if you know anyone who is a machinist in your area just remove the cylinder and bring it to him and have him use an inside mic or hole gage.

All my machinist friends are up in Dayton, OH, but I do know a lot of aircraft machanics around here. They would have the tools you mentioned and would let me use them. Thanks.

I bought a 25-5 last fall... Hornady XTP's were a tight fit through the chambers. I was very excited after all the horror stories I've heard- but still haven't shot it yet.

+1 on thebullet test- if the the bullet you plan to use drops through....uh-oh....you'll need bigger bullets.