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 Post subject: Rolled vs Folded Crimp
PostPosted: Mon Apr 28, 2003 11:26 pm 
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Friends All.....Recently I have had a lot of email, etc. concerning rolled crimps vs folded crimps on shotshells. There seems to be some confusion on this subject stemming from old data. It was thought for years that the over-shot wad used in rolled crimps cause blown and patchy patterns. There was also a lot of hype from the ammo companies pushing the folded crimp, but the truth is that folded crips worked on the high speed loaders better.....less scrap! When high speed photography came into use, it was found that the blown patterns were caused by the heavy waxed filler wads in use then, blowing into the shot column as it left the barrel. It was also evident that the weight of the shot just pushed the over-shot wad away. As speciaclized shotshells began to come into fashion, it was found that more hull capacity was needed. The obvious was to go to rolled crimps. This combined with hulls like Federal and Fiocchi, plus new things like the styro wads I began to write about, and new designed heavy duty wads, have brought about an entire new concept on long range high center core shotshells. Another surprise came when we chrno'ed the loads. The rolled crimp quickly proved a reduction in Extreme Spread. One thing to remember....if you decide to load specialized shotshells with rolled crimp, you are better off with unskived hulls. Ballistic Products list whether the hull for sale is skived or unskived. They also have excellent roll crimp heads for drill press, etc. Best Regards, James

Rick618
Shotgun Expert
Posts: 331
(3/29/03 11:00:22 am)
Reply ?
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the blown patterns were caused by the heavy waxed filler wads in use then, blowing into the shot column as it left the barrel

How does this occur? If the wad is behind the pellets and everything starts at the same speed how does it get blown into the column?

What applications do the the rolled crimps do better than standard crimps? With turkey shells I see the added benefit of extra payload and generally you aren't loading for quantity so the "extra" time needed to roll crimp isnt an issue. This might be something the folks at Nitro should check into, as I have seen several of their loads with a pooched or partially opened crimp.

I do see an issue with waterfowlers as the cards would need to be sealed, does this increase pressure or effect patterns?

Lex Talio
Frequent SW Visitor
Posts: 17
(3/29/03 10:08:24 pm)
Reply Re: ?
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Righto!.....There was difference in opinions even in the ballistic lad as just what was happening. Remember now this was before the change over the lighter molded or wool/felt wads. It appeared that as the shot and wad left the barrel, the wad (lighter than the shot) popped with more velocity?????? You could see it expanding the rear of the shot column a few inches out from the barrel. Patterns from these shots showed a weak center. The strange thing was it showed up more in IC barrels than FC barrels??????? Was the tigher choke retarding the waxed wad???WW went to a lightweight molded wad and others a wool/felt mix....that stopped the problem.
There is no real advantage over the folded crimp in loaded shells until the need for more hull capacity happens. Plus ...the rolled crimps have to be done by hand. I change the crimp in 2 3/4" above 1 1/4 oz and in the 3" above
1 1/2 oz when using a powder like Blue Dot (my favorite).
The point I am trying to push is...don't worry about a rolled crimp in these high density loads. As for pressure...we saw little difference, except the rolled crimp gave a little less EV's. One other advantage of the rolled crinp is there is no buffer leaking that will mess up the inside of the mag tube.
Another advantage in 2 3/4" 20 ga......using the Fiocchi hull, Blue Dot, and a shot cup from a yellow AA wad... one can load up to 1 1/4 oz if one uses a rolled crimp.
Best Regards, James




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