crimps
 

From the Accurate reloaders Guide - Crimping: This is certainly one of the most important aspects of the shotshell reloading process. The influence of crimp on the ballistics is often ignored, and assumed to be of lesser importance than primers and wad make/design. The fact is that the effect of Crimp-strength can totally overshadow the influence of the other components and parameters. This is controlled by the following: Crimp depth, condition of case, wad length and condition.
Some reloaders want to extend case life and they tend to crimp as shallow as possible. However this pratice can be problematic if a "soft" combination is used it can lead to underperformance or in extreme cases "bloopers".
They go on to say the difference between a shotshell and a rifle is the rifle cartridge gets its resistance and Maximun Peak Pressure from the bullet being engraved from the rifleing where as the shotshell gets its from the crimp. There for, the shotshell Maximun Peak Pressure is reached long before the base of the shot/wad assembly has left the case. From what I've read in other articles, reloading data is with a .060 deep crimp. A .020 depth would have about 2000psi less pressure.
Just thought I'd give you guys something to think about. Maybe that's why I had trouble with nitro powders in Brass hulls and glueing in the over shot wad - too much volume for the powder and no resistance for load. Paul

paul i totally agreewith what uve just said...ihave been loading a lot of the plastic and paper hulls using no crimps at all...i noticed that when you seat the wads with pressure that they will rise slightly back up...thus with no crimp to put a little pressure back on the wads you will have a few bloopers....i use the no crimp method to lenthen case life....but on my hunting shells i crimp all of them.....boy you sure hit the nail on the head..... thanks charlie

I wondered about crimps. I had originally considered Magtech drawn brass with RCBS 12 gauge dies. The RCBS dies apply a nice little crimp to hold the over-shot wad in place, much like brass factory loads in the early 20th century. Unfortunately, the RCBS dies come in 12 gauge only. 4D makes a large array of brass case shotshell dies, though.

precision reloaders also have several differant crimpers for the roll crimp....they work very well i have one in the 8 ga that does a good job....need a reverse type drill or drill press to make it work right...... charlie

Mark, I never crimped a brass shotshell. I would think it wouldn't last very long - that's why everyone glues in the overshot wad - the brass shell would last forever. I had at one time 14 boxes of Magtechs and loaded black powder. It just got to be too much of a pain in the a** to clean them. Sold every thing to a cowboy shooter. I run the shotgun venue at our club and we shoot three times a week. My wife and I go through about 24 to 30 boxes of shells a week. The Remington hulls in 12ga will reload 10 to 20 times before I throw them out. And the cheap " Gun Club" ones are laying everywhere. For that reason I like a nice deep crimp. I believe when useing the roll crimp you'll have less pressure than a star crimp. That could be helpfull if you're trying to keep pressure down. Just about all my guns are damascus barreled so I'm always watchfull of reload pressures. Paul

Paul, I bought a very nice BGI roll crimper and a worn out 10 gauge crimper was thrown in the deal. I tried the 10 gauge unit on a few old hulls and it really does a swell job. I plan on using it when my 10 gauge gets put together. I agree with crimping brass hulls. I would imagine that their lifespan is greatly reduced. If I go with brass, I plan on RMC and a suitable adhesive for over the shot wads. Cheers!

The quickest overshot card adhesive that has immediate set up is the hot glue gun. Waterglass is expensive, takes a day or so to set up, has a short life and is difficult to remove from the brass.

To deep of a crimp on plastic hulls will cause excessive pressure.

Harry

harry ive also noticed thedifferances in preassure when you crimp to deep and some times i get a shell thats bent a little bit from me pulling on the handle to hard...have learned not to pull on the handle so hard....some hull do not need as much preasure on the handle....have you noticed this before or is it just me......charlie

I have the most problems with 10 gauge shells bending or denting in a little. 3" 410's have been a source of agrivation as well.

Harry

Food for thought ?

http://www.clayshootingusa.com/html/...d%20Crimps.pdf