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More on the Top-break revolver......

10K views 28 replies 6 participants last post by  Bob Wright 
#1 ·
In my previous post "Thoughts on the Top-Breal revolver......." of about a month ago, we had some discussion on the relative strength of the stirrup latch.

Steve M1911A1 wrote:
"The stirrup latch is joined to the frame of either gun by means of two fairly small screws, one at each side of the stirrup. Thus, these relatively small screws absorb all of the discharge force received by the stirrup latch."

I had no practical knowledge of the Webley other than the occassional firing of other folk's guns. However, in the current (June 2012) "American Rifleman" there is an exploded view of the Webley MK VI revolver. First time I had examined such information. The stirrup latch has two bosses around the screw hole, on the inside of the "legs" of the latch. These slide into recesses in the sides of the standing breech of the revolver. the effect is that these must be sheared off for the latch to fail. In addition, the screw is not two, but rather one through screw. If I remember correctly, this places that screw in double shear, thereby doubling the shear strength of that screw.

I must admit that I am on the edge of going beyond knowing what I'm talking about, but it does seem to me the latch is much stronger than Steve M1911A1 gave it credit for.

Steve, you stated, I believe, that you were a retired mechanical engineer. Does what I've said here make sense?

Bob Wright
 
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#27 ·
I'm not DAN, but the Rhino system would lessen recoil stress by minimizing the upward "whip" by virtue of placing the opposing forces more directly in line. The barrel whip of a revolver in recoil is caused by the rearward force of the fired round (directly rearward) being opposed by the resistance of the hand at the grip being much lower.

Remember the old Russian "Hacksaw Pistol" of a few years back? Recoil was the same, but muzzle flip was lessened.


Bob Wright
 
#28 ·
Yeah, OK, but that "upward whip" of which you wrote would serve to help hold the break-action closed, not to open it.

Nevertheless, the major force involved is the rearward shove from the being-expended cartridge, in Newtonian reaction to the forward-moving bullet.
That tends to violently separate the break-action, and to rip it open. This is why the top-strap is in tension, all of it focussed upon the hole into which the upward projection of the frame fits.
 
#29 ·
I'm about to get in way over myhead here regarding the "upward whip", but here is my experience:

I had a customized Colt Single Action Army .357 Magnum that had had a Smith & Wesson rear sight installed in the top-strap. I was firing some heavy .357 Magnum loads and noticed my groups were climbing out of the black at twenty five yards. I was puzzled by this as to why they should stray. Then, after reloading for another string, the hammer was nearly impossible to cock. I examined my gun and noticed the rear of the cylinder binding against the top strap, and further, the barrel angled down noticably.

After I cleared my gun and left the range, I went to my gunsmith and we analyzed the problem. The inertia of the barrel makes it tend to stay on line with the target as the gun recoils. The top strap, weakened by the milling, stretched under the recoil forces. The standing breech still maintained its correct angle to the lower part of the frame, only the top strap and forward section of the frame "gave."

I thought I had reduced my Colt to a parts gun, but my gunsmith was able to re-align the frame, and I no longer shoot heavy handloads in this Colt.

That is why I assumed the top strap is in tension from "barrel pull" rather than back thrust from the case head.

All of the foregoing is only my surmise, not any educated engineer's calculations.

Sure would like some more authoritative input than I am capable of.



Bob Wright

P.S. Congratulations on that second grand daughter, and hope you have a very pleasant visit!
 
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