How heavy a crimp?

[Gibbs44]

Hey guys, I just loaded up some of my Lyman 429421 bullets cast from ww alloy. I noticed some leading from towards the cylinder end of the barrel. I only shot 5 by the way. They were loaded over 19 grains of 2400. I will slug my barrel now. I figured I'd shoot them to see how they would do before I slugged my barrel. I put a fairly heavy crimp on them, I guess. My question is could a heavy crimp squeeze the base down so that it does not completely seal the barrel and allow for some leading? My guess is that it could, but I don't know for sure. I'm still going to slug the barrel and probably end up trying to beagle my mould to open it up. I know most of this is covered here, but I don't know if I've ever seen anything about the crimp.

Appreciate the help,

Sully

[Le Loup Solitaire]

Crimping, particularly a roll crimp is necessary in revolvers; especially the 44MAG (reference Lyman 429421 above) to prevent the bullets in the cylinder from moving forward under recoil and tying up the cylinder. However the degree of crimp must not be carried too far for the working of the brass/case mouth cold works the brass and shortens the case life. The less the better...just enough to get the job done. it may take some experimenting/trial to determine how much crimp you need; the recoil factor plays a role in what you need. When ignition takes place the bullet moves forward with such force and so quickly that it removes the crimp without being altered. The crimp also is applied to a portion of the bullet well forward of the bullet base which is believed to "upset" and seal. Slugging the barrel is a good idea anyway to see what the numbers are and measuring what the "as cast" diameter of the bullets as well. Sizing to .001-.002 over barrel diameter is a standard practice. I shoot a couple of 44's using H&G #503 and a H&G full wadcutter and focus most on accuracy and grouping; all relevant things considered, but what is happening on the target is what really counts. LLS

[44man]

You only need "just enough", fold only to the bottom of the crimp groove, not into the lead.
Your boolits might be too soft so look at a fired case, there should be very little or no crimp showing left on the brass. It is best if the boolit can resist the brass, not sized when seating or sized trying to go through a crimp.

[Edubya]

Gibbs, I'm going to suggest that you "slug" your chambers. Identify each boolit and chamber with roman numerals and measure each one with a micrometer. If they all come out to say 0.4295 to 0.4290 then drop the smallest one into the breach and force it into the groves, remove and measure. this measurement should come down to approximately 0.4275. The cylinder is your last sizer and that should be larger than the breach opening.

Now, disassemble one of your boolits and mic it. You want to be sure that you are not sizing your boolit down to under the cylinder opening. If you are sizing it it to 0.4280 and your cylinders are 0.4290 then gas cutting is starting before it even enters the breach.

Go back and read what LLS said and all of this will start to make more sense.

EW

[Gibbs44]

Thanks for the info.

[David2011]

Gibbs,

I use the same mold for my .44, loaded with RCBS dies. I'm running the boolit at 1600 fps in a Contender so crimp it as hard as I can for consistent ignition. I set my crimp by adjusting the crimp die down until I could see that it was screwed down too far. This is easily identified by the mouth of the cartridge going from rolled to undersized and straight, above the roll. You can see this happening if you go as little as .01" too far and it's very obvious at .02-.03". It just looks funny. The area where the mouth is straight would swage the boolit undersize as it is above the area intended to crimp in the die and smaller than the proper diameter of the loaded brass. I backed off until the straight area above the roll crimp didn't happen any more and locked it down there. At that adjustment the boolits don't lead and I get better than 2" at 50 yards.

David