Chamber Pressures?

[ZVP]

I was just thinking about how much of a load is placed on the frame (Brass or Steel) between two navy framed revolversm loaded to factory recommended charges, One in .44 caliber, and the other in.36 cal..
If loaded with a standard weight ball and wad would the .36 with it's smaller barrel. and chamber put more pressure on the frame tham an equally safe loaded .451 Ball and powder charge?
Brass frames are notorious for stretching and if a guy wanted to keep his revolver shooting longest, which Caliber should he consider?
I have one of the Brass Framed .36's and really like it! The Brass frame feels self-lubricated and cocks like butter as does the trigger action!
I normally load a .451 pure Lead Ball with aPistol wad and a little filler (COW), and have experienced no problems yet. i think the load is weak enough and It only gets fired about15 to 20 shots occasionally. Maybe once every month.
It's a pretty accurate charge and ball, a real fun gun to shoot!
I'm just wondering if i'd have been better off buying the .36 for longitibitys sake and strain on the frame?
Thanks
ZVP

 

[damoc]

i was also wondering if the smaller calibers would be safe in brass frames long term
for shooting stout loads.

 

[Don McDowell]

Brass frames are prone to "stretch" more than the steel frames.
Get ahold of a pre Fadala edited Lyman Blackpowder Handbook, they have more pressure data than you can shake a stick at.

 

[elhombreconnonombre]

I suppose some degreed material scientist/engineer on the forum could hook up a brasser with strain gauges and figure this out.

 

[J-Bar]

Small calibers can have surprisingly high chamber pressures:

http://www.lasc.us/SAAMIMaxPressure.htm

Note that the .22 LR has a higher (24,000 PSI) max. chamber pressure than a .38 Special (17,000 PSI) or .45 Colt (14,000 PSI).

So, if chamber pressure is the key factor in causing stretch, the smaller caliber may not automatically be the best choice.

But I don't know if chamber pressure is the culprit. The heavier ball hitting the barrel opening might contribute more to stretch than the lighter ball. The usual recommendation for keeping powder charges moderate to low in a brass frame revolver could be intended to reduce the momentum of the ball, rather than the chamber pressure.

In any case, it's an interesting question from an experimental design perspective, but my recommendation would be to buy the gun that excites you, shoot the hell out of it, and if you wear it out buy another. Life is short. Enjoy.

 

[ZVP]

Well now we have a "maybe" onthe chamber pressures against the frame!
I see too that the ball forcing it's way at high pressure, being swaged down to barrel size, then to riflong sizes. It all makes sense!
I just wondered for several reasons:
#1 there are many .44 cal Brassers on the market today as opposed to almost NO .36/"s.
#2 I don't know if the US market is responsible, but the old bigger is better philosophy prevlant here, mifgr have influenced the large bore preferance?
#3
Just maybe the manufacturers did some engineering and found that indeed the .44 puts less strain on the frame ( lengthens lifetime) than a .36 and gives the manufacturer better reputation?
#4 Maybe all the old Westerns with songs about their"old 44's" influenced it?
Personally I like the .36 caliber, very flat shooting, economical on propellants, and it has a high velocity and good penetration.
However, my Piettia .44 "Navy" is a great shooting gun! It cocks like butter, the trigger pull is smooth and has no rough spots anywher, making it a real sweet shooter! I do think that the brass adds a beasing-like surface for parts to work against.

I wish I'd have counted the shots, but mo, I just shot it, at first I fired some pretty stout rounds (maybe 20), just for the bang, and then I wised-up and took it easy @ 18 to 20 gr charges.
Yea when I wer it out, I'll probablly buy another. This time, one with a 5 1/2" BBL! I like short revolvers!
I would really like to know which caliber is best for Brass though?
ZVP

 

[rodwha]

The Spiller & Burr is brass, and the Remington Pocket .31 can be had in brass too.

I really like the Spiller, but am reluctant to purchase a brass frames pistol. I'm told by a few it would likely hold up to a lifetime of ~20 grn 3F Swiss/Olde E/T7.

 

[Prairie Dawg]

From the Lyman Black Powder Handbook:
.36 1851 -- 7.5"
Gearhart Owen FFFg black powder
.375 Roundball

14 grains -- 6900 LUP -- 752 FPS
17 grains -- 7200 LUP -- 879 FPS
20 grains -- 8300 LUP -- 967 FPS
23 grains -- 8560 LUP -- 1017 FPS
26 grains -- 8600 LUP -- 1079 FPS
29 grains -- 9440 LUP -- 1097 FPS
************************
.36 1851
Gearhart Owen FFFFg black powder
.375 Roundball

14 grains -- 6900 LUP -- 884 FPS
17 grains -- 7240 LUP -- 924 FPS
20 grains -- 8460 LUP -- 1006 FPS
23 grains -- 8640 LUP -- 1027 FPS
26 grains -- 8820 LUP -- 1033 FPS
29 grains -- 9660 LUP -- 1090 FPS
******************
.44 1860 -- 8" barrel
Gearhart Owen FFFg black powder
.451 Roundball

19 grains -- 5540 LUP -- 706 FPS
22 grains -- 5540 LUP -- 752 FPS
25 grains -- 5780 LUP -- 805 FPS
28 grains -- 6380 LUP -- 885 FPS
31 grains -- 7060 LUP - 933 FPS
33 grains -- 7340 LUP -- 979 FPS
37 grains -- 7940 LUP -- 1032 FPS
********************
.44 1860 -- 8" barrel
Gearhart Owen FFFFg black powder
.451 Roundball

19 grains -- 5240 LUP -- 772 FPS
22 grains -- 5420 LUP -- 797 FPS
25 grains -- 6080 LUP -- 868 FPS
28 grains -- 6320 LUP -- 881 FPS
31 grains -- 6500 LUP -- 859 FPS
34 grains -- 7240 LUP -- 953 FPS
37 grains -- 7420 LUP -- 960 FPS
********************

With Colt-style guns, the big worry is that the guns will "shoot loose" with constant heavy loads.
Remember that the projectile slams into the forcing cone when the gun fires, and the barrel is pinned to the frame via the arbor.
The higher energy the round ball has, the more it tugs on the arbor.

If you like brass-framed guns--shoot them, but keep the loads on the lighter side.

In my experience, cap guns are more accurate with lighter loads anyway.

In my case, (Cowboy Action Shooting), I'm just shooting steel plates and there is no reason to shoot heavy loads.

--Dawg

 

[Willie Sutton]

Pressure doesn't stretch a frame. Thrust does.

Thrust is pressure multiplied by the surface area of the rear of the cylinder.

Small calibers might have higher pressures, but less surface area at the rear of the chamber, and thus less total force exerted on the frame.

Willie

.

 

[Hellgate]

The frame itself doesn't really stretch. The threads that hold the arbor get stripped or pulled by the barrel pushing forward and the recoil ring at the back of the recoil shield gets indented by the steel cylinder slamming backward causing further denting of that thin, raised brass ring. Combine the two and the cylinder increasingly slides back and forth on the arbor and the frame appears to be "stretched" but it is just the arbor pulled forward and the recoil ring peened backward with the frame dimensions the same.

 

[rodwha]

So is this not quite an issue with a Remington or Spiller & Burr?

 

[Crawdad1]

I don’t see how it could be with the barrel screwed into the frame like it is on the Reminton. For occasional use, like once a month or once every two months for shooting beer cans or putting holes in paper a brass framed Colt is just fine. But, if you’re going to use it hard like for hunting or for competition then you almost have to get steel frame.

 

[Hellgate]

Rodwha,
The brass framed Remingtons can also "shoot loose" but what happens is the cylinder eventually peens into the rear of the frame causing an indentation that allows the cylinder to move farther to the rear and the gap opens up. Due to the greater surface area of contact it should take a bit longer to affect a Remington than a Colt. The Colt recoil ring that the cylinder contacts is only about 1/8" wide so it gets beaten out of shape easier.

 

[rodwha]

I really like the Spiller & Burr and since it only comes in brass it has sat on Dixie's shelf for some time now…

Though full tilt loads may not be necessary I just see it as silly to have something that you can't shouldn't shoot it's potential loads. I do like thunder, and generally shoot 30-35 grn 3F charges from my .44/.45 cal pistols. But those I certainly do intend on hunting with.

I've asked and been told that a Spiller ought to be able to handle a lifetime of 20 grn 3F Olde E/T7 charges. Brass still leaves me uncertain though.