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I've been reloading for the .357 using a variety of powders and bullet heads to find the best combination for accuracy, and one variable I've not investigated properly is the effect of crimping. I use a Lee reloading die, which gives the option of varying the strength of the crimp.

Some say crimped rounds damage bullets, affecting accuracy; others say uncrimped rounds may have bullets move inside the case due to recoil or from stacking in the tubular magazine.

Any experience of this? Does magazine feeding push bullets further into the case? Does the recoil affect the COL of loaded rounds?
 

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Not sure what other here will say, but I always crimp anything going in a tube magazine or revolver. Even with a crimp, I have had bullets get pushed back into a case occasionally.
ETA- most bullets I use in .357, .44, .45, 30 and 35 cal for lever guns all have crimping grooves in them.

ETA again. One thing you want to be sure of when crimping is to trim all your brass the same length. This will give a uniform crimp once you get you crimp die set correctly. By not trimming the brass you will end up with crimps that are all over the place and that inconsistency will show up downrange.
 

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I used to be anti-crimp for everything but pistol rounds. Now, I crimp everything. The epiphany came from watching extreme spreads shrink on my chronograph after I started shooting every round over the chronograph. I believe a consistent crimp will greatly aid in consistent ignition which will lead to better accuracy.
 

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Yes but I collet crimp rifle rounds....that's not really the same thing. Oh and to add....I only crimp lead in pistol calibers. I didn't specify since I only LOAD lead in pistol calibers other than a dozen defense rounds per year.
 

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I used to be anti-crimp for everything but pistol rounds. Now, I crimp everything. The epiphany came from watching extreme spreads shrink on my chronograph after I started shooting every round over the chronograph. I believe a consistent crimp will greatly aid in consistent ignition which will lead to better accuracy.
This has been my experience as well. Most reloaders don't use a chronograph so are unaware of how much the little details matter.
 

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me. I have tryed both in a single shot 45.70 so this is only one result. no difference. so I crimp anything that has a groove. I have seen un crimped rounds in a tube mag get pushed right inside the case. this happened to a friend the round did not chamber. lucky for him. it was an old 73 winnie.
 

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I'm from the crimp school. Every bullet that has a cannelure. Bullets without cannelures get the lightest touch at the case mouth,just like an Angel's kiss. Consistent crimp means more consistent shot-start pressure,more uniform internal ballistics,and less velocity spread.
Lee Factory Crimp Dies at this reloading bench.



Rob
 

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I crimp my 1894 loads 44 mag and 357 mag... the short straight or tapered sided cases will or can allow bullets to move easy. I have seen some cases sized outrageous amounts in reducing case size, the the bullet ream a huge bulge while seating.... and you can still wiggle the bullet with your finger !! so pistol straight walled pistol cases get crimped, and I prefer the lee collet style crimp. This loose bullet fit does little to give good ignition either, compared to a bottle neck cartridge you can lean heavy on a loaded round with no crimp.

For rifles I may crimp ar15 stuff if it's for plinking or mass loaded, I also crimp some hunting rounds... but the majority doesn't get crimped. On my BR gun it's all about trying to be i control of everything LOL money being the main most one, and I don't think I have ever crimped a 6ppc
 

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..so load 10 dummy rounds - shove them into the magazine - cycle the gun vigorously until emptly.

.. measure rounds.

..understand why the guys in the 19th century crimped their rounds.

..btw - the slow burning powders that develop the best velocities require heavy crimps - not my take, just the guys at speer, hornady and so on...
 
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