I have always used the traditional roll crimp on revolver rounds. However, a couple of recent events have me thinking of taper crimping for revolver rounds. Here is what leads up to this question...
A fellow on another website made a statement that started me thinking. He said he taper crimps all his .357 Magnum rounds instead of the more common roll crimp because the taper crimp applies even pressure concentrically around the entire bullet base within the case. In his experience this provides a much stronger and consistent crimp that resist bullet creeping much better than a roll crimp. He said to prove the taper crimp is better, take two rounds with identical bullets and a decent crimp pressure for both, one roll crimped, one taper crimped, and put them in an inertia hammer type bullet puller and whack away. The roll crimped one will come unplugged much easier than the taper crimp. That started me thinking...
The next event was that just because, I bought a new set of RCBS Carbide Dies for the .357 Magnum/.38 Special. I have two other sets for the same cartridges, but they are getting a little rough and I just wanted the new set. To my surprise, this die set came with a taper crimp die for the revolver round instead of the more common roll crimp. Interesting...
As I began to mull this over I started thinking about how hard it can be to really know the amount of crimp you are putting on a bullet with a roll crimp. That is a thing that experience and feel develops after loading and shooting quite a bit. It isn't too hard to over crimp a roll crimp. When that is done, you actually lessen the grip on the bullet. That little bulge from over roll crimping is the case buckling away from the bullet and loosing tension. Of course, that can also cause the round to not chamber in the cylinder. Both are problematic. Additionally that cannot be a good situation for uniformly consistent velocities and accurate ammunition.
Then there is the matter of repeatability with roll crimps. Once you've found an accurate consistent load, if you reset your die at some point and then come back later to load another batch of those first rounds, how do you accurately get the same amount of roll crimp? Other than guessing and by feel, how can you accurately measure the amount of roll crimp for consistently reproducing that special load you developed?
A taper crimp actually does apply pressure around the entire bullet base evenly. So in this case it isn't just a lip of brass in the cannelure or crimp groove that is holding the bullet. Isn't this pressure surrounding and gripping the entire bullet base a stronger union than the roll crimp? This should also provide a more consistent bullet pull and allow propellant gases a more even burn. Wouldn't this be better ballistic? More accurate?
And finally, isn't it easier to repeat a taper crimp by measuring the case in the same place near the case mouth. As an example, I taper crimp my .45ACP rounds for my 1911 semi-auto handguns to a consistent .470." I can repeat this amount of crimp from brass lot to lot, various bullets, or in the case of special loads I can duplicate this over and over time after time. Why would this not work for a revolver round as well? Find a suitable amount of crimp, measure that, make a note, and you can always replicate the crimp on future batches of that particular loading.
Am I making sense, can you follow my train of thought? Or, am I derailed?
A fellow on another website made a statement that started me thinking. He said he taper crimps all his .357 Magnum rounds instead of the more common roll crimp because the taper crimp applies even pressure concentrically around the entire bullet base within the case. In his experience this provides a much stronger and consistent crimp that resist bullet creeping much better than a roll crimp. He said to prove the taper crimp is better, take two rounds with identical bullets and a decent crimp pressure for both, one roll crimped, one taper crimped, and put them in an inertia hammer type bullet puller and whack away. The roll crimped one will come unplugged much easier than the taper crimp. That started me thinking...
The next event was that just because, I bought a new set of RCBS Carbide Dies for the .357 Magnum/.38 Special. I have two other sets for the same cartridges, but they are getting a little rough and I just wanted the new set. To my surprise, this die set came with a taper crimp die for the revolver round instead of the more common roll crimp. Interesting...
As I began to mull this over I started thinking about how hard it can be to really know the amount of crimp you are putting on a bullet with a roll crimp. That is a thing that experience and feel develops after loading and shooting quite a bit. It isn't too hard to over crimp a roll crimp. When that is done, you actually lessen the grip on the bullet. That little bulge from over roll crimping is the case buckling away from the bullet and loosing tension. Of course, that can also cause the round to not chamber in the cylinder. Both are problematic. Additionally that cannot be a good situation for uniformly consistent velocities and accurate ammunition.
Then there is the matter of repeatability with roll crimps. Once you've found an accurate consistent load, if you reset your die at some point and then come back later to load another batch of those first rounds, how do you accurately get the same amount of roll crimp? Other than guessing and by feel, how can you accurately measure the amount of roll crimp for consistently reproducing that special load you developed?
A taper crimp actually does apply pressure around the entire bullet base evenly. So in this case it isn't just a lip of brass in the cannelure or crimp groove that is holding the bullet. Isn't this pressure surrounding and gripping the entire bullet base a stronger union than the roll crimp? This should also provide a more consistent bullet pull and allow propellant gases a more even burn. Wouldn't this be better ballistic? More accurate?
And finally, isn't it easier to repeat a taper crimp by measuring the case in the same place near the case mouth. As an example, I taper crimp my .45ACP rounds for my 1911 semi-auto handguns to a consistent .470." I can repeat this amount of crimp from brass lot to lot, various bullets, or in the case of special loads I can duplicate this over and over time after time. Why would this not work for a revolver round as well? Find a suitable amount of crimp, measure that, make a note, and you can always replicate the crimp on future batches of that particular loading.
Am I making sense, can you follow my train of thought? Or, am I derailed?
