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Captain Morgan

Discussion in 'Uncategorized Threads' started by maclellan1911, Mar 15, 2008.

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  1. maclellan1911

    maclellan1911 TS Member

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    I read several post of all subjects and I like the fact that someone gets loads tested. I load Clays,1oz,sts hulls,Rem tgt12 at the low end of presure and FPS so I am not really worried about my loads. My Question is Have you done any testing to do with the quality of the crimps and the performance of the shell? I see so many dished and domed crimps. It took me a long time to get my crimps looking like factory. I tried loading 3/4oz loads and had a very time getting a quality crimp. always a bit dished and heavy swirl. After playing around for a while I went back to 1oz shot, re adjusted and fine. So will a poor crimp domed or dished heavy swirled or slight hole in the middle affect shell performance?
     
  2. Capt. Morgan

    Capt. Morgan TS Member

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    I've never had tests run specifically to analyze the effect of a crimp on ballistics, but after reading the article linked above, I've tried to make sure that my crimps all stay in the same depth range: .035" to .045". Getting a "factory" crimp usually requires careful attention to the component combination; bulky powders and tall or stiff wads equal domed crimps while fine-grained powders and short wads result in dishes. Swirls are usually a machine adjustment matter...too much pre-crimp usually. Some data just won't produce nice-looking shells because the components don't work well together.

    In talking with Kevin at Down Range regarding the results of my tests, he has alluded to a minimal effect on pressure and velocity from concave crimps. But concave crimps indicate a short component stack and possibly a bit of air above the powder charge. That causes low chamber pressure, low velocity and poor patterning (bloopers!)

    Domed crimps, on the other hand, usually indicate a compressed component stack, too much wad pressure, a partially collapsed wad and, consequently, a weak crimp. I've let shells with domed crimps lay on their sides on my loading bench (as they would in a shell box) for a week and watched the crimps gradually open and the crimp shoulders virtually disappear as the compressed wad inside gradually returns to its normal shape. This would result in considerably lower chamber pressure and lower shot velocity than the data called for. I've also noticed that domed crimps also indicate that the petals of the wad may be curled within the crimp shoulder and that is not good for a pattern either.

    I keep detailed records of each shell I send for testing...weight of each component and description of each crimp including depth and appearance. I've sent batches of shells that included normal crimps, slightly swirled crimps and even a few with a tiny hole in the middle and have not noticed that any of those characteristics have caused serious problems for either pressure or velocity. (I can't say, though, what the effect on the pattern was.) In other words, it wasn't obvious that the shell with the tiny hole in the crimp produced a lower pressure and velocity or that the swirled crimp produced higher numbers. But Kevin will start to measure my crimp depths as soon as one of my test shells records an over-pressure and he'll list the crimp depth of each shell in the result data. That tells me that the depth is important, and the Tom Armbrust article above bears that out (crimp discussion, about mid-page).

    Morgan
     
  3. maclellan1911

    maclellan1911 TS Member

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    Thank you, I just hate seeing poor crimps. Also most have the guys haveing the problems also have the poorest crimps.
     
  4. Capt. Morgan

    Capt. Morgan TS Member

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    I was at a club last week watching the line and one of the shooters put a shell into his break gun while the barrel was still resting on the pad. When he lifted the muzzle to close the gun, a little mound of pellets appeared on the pad. He removed the shell and closed the partially-open crimp with his fingers, mounted and fired and broke the target. At the end of the round he showed his squadmates another collection of loose shot in the shell box. The shell was probably only half full when he shot it.

    You've aroused my interest in dished crimps but I don't know how to test the effect without introducing an additional component into the mix that might alter the results. I've tried a 1 1/8 oz. load using Top Gun hulls, Federal primers and wads and Clay Dot powder. Apparently Federal uses a bulkier powder in these shells because the combination results in some seriously dished crimps. I think I need to find a taller wad suitable for straight-walled hulls but don't know where to look. Maybe this is a combination I should just forget about?

    Morgan
     
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