Load/test data from my 44Mag.

[twoworms]

I test fired my 44Mag Ruger SBH the other day and found out a few things about it.

First off it makes a big boom with my new Lee 308gr as cast WW cast boolit with out a gas check and 19grains of Little Gun lubed with Felix lube I made myself.

Second, I found more shot to shot varation than I expected with my load in each cylinder to cylinder.

The test data is below.

Cylinder's 1-6, fps 8 yards out.

#1, 1181, 1189, 1185
#2, 1221, 1222, 1226
#3, 1180, 1178, 1175
#4, 1251, 1256, 1254
#5, 1153, 1150, 1156
#6, 1224, 1221, Ran of of ammo.

Shot to shot in each cylinder is good, but whats up with the cylinder to cylinder change? Can this be fixed?

Tim

[Bass Ackward]

[Shot to shot in each cylinder is good, but whats up with the cylinder to cylinder change? Can this be fixed? Tim[/QUOTE]

Tim,

See if you can move your cylinder forward and backward in the window of the frame. Be careful that you aren't seeing side to side play. If it moves, you are changing the B/C gap distance and thus the pressure a little.

I don't see your figures as a real problem. If there is no movement forward and back, then it will even out some as the gun breaks in.

[twoworms]

Bass A,

There is something going on forward/backward but its hard to say how much. I would guess about .005 movement. But its about the same all the way around. Holding the handgun up to the light I can see day light in the gap area. Looks like around .008 to .01 of a inch to me. I don't have anything to check it, maybe a spark plug gap tool could be used?

Tim

[truckboss]

on my friends bh the cyl. throats are 2 thou. different,never crono. it.maybe if there is a diff you could match them.

[twoworms]

truckboss,

Now you tell me... :)

This is going to turn out to be a pain in the ask me later and I'll tell you how much of a pain. I have shot the Ruger for years and never checked the loads speed before.


Tim...

[454PB]

I'd suggest you buy a set of feeler gauges at any automotive store and check the barrel/cylinder gap. All my Rugers run .002" to .0035".

[Bass Ackward]

That was my guess. You can buy spacer washers from Midway for some guns in .002 and .004 sizes and take that out of it. @ $15.

It will actually take that out of it, but it will be a PIA to keep track of every time you disassemble it. You can call Ruger and they make correct it for free. But then they will go all over it and you may not want that. A guy I know sent one in for something and they changed the barrel for him cause it had worn appreciably. He spent years getting it that way to shoot cast. Was he ..... upset!

I really don't see a whole lot of problem. Would hate to see the real problem turn out to be anneal of your brass. Seen that do the same thing as you get different pressures and seals from different ignition. (End play also changes headspace affecting ignition too.)

And as the cylinder moves forward, the bullet has to take a sharper turn to make the bore which can delay time and hold it back to raise pressure. I believe that cylinder misalignment is actually the root cause for end play increasing, but it can be burrs and some other issues too.

So removing end play is a good thing as long as you don't get it too tight or the cylinder won't want to go in or rotate freely either loaded or unloaded. I like no more than .001 to .002. Problem is that it widens the BC gap and may increase flame cutting.

I just got a GP100 that required .004 and I now have a B/C gap of .009. So if I turn out to like the gun, I will take some of that out of it.

[mike in co]

did you slug the cylinder ??

the good news about my cylinder was the variation was very small....
.4325 to .4327

having said that i still see as much as 50fps spreads.

it still shoots under an inch with all the cast boolits i have put thru it at 25yds

[twoworms]

Mike,

I think I'll slug the cylinder and see what I have. It may not be a problem the cyl to cyl gap in fps, but it sure looks odd on paper.

Tim

[fourarmed]

It is pretty common to find that the B/C gap is tightest at one chamber. I have a hard time visualizing how it could alternate between adjacent chambers. My money is on varying throat diameters. Slugging may be accurate enough if you are really careful. If you know somebody with a set of pin gauges, that is really the best way to do it.