Is crimping necessary?

[Muddly]

I'm going to start reloading for my Classic carbine ( 45 Colt) and was wondering if crimping is necessary as I dont have to worry about the bullet moving under recoil, as in handguns, or being pushed into the case , as with tubular magazines.I'd like to try different seating depths as my carbine will allow an OAL of 1.670 with XTP's. Does the powder chosen dictate the need for crimping( to get a better burn)? Or does the longer barrel make it a moot point? I'd like to get 1600 fps with both 250 and 300 grain bullets. Thanks for the help!

[Jason F]

I like to crimp all my rounds it is supposed to give them a more complete burn

[manatee1947]

over the years I have not usually crimped my loads, but recently I found that  crimping my 357's with fairly heavy loads of 2400 made a big difference. I still dont with revolver loads of unique or my 45/70 loads. I would say that if you get the performance you want without it, dont bother, but if other factors do not produce the results, it is definitely worth trying.

[bikerbeans]

A crimp with H110 in the 357 Maxi makes a big difference in velocity and accuracy.  Some of the slower rifle powders state that a firm crimp is required for consistent ignition.  I have found with the 45 cal rifles that if I seat the bullet into the rifling I can skip the crimp step but if you do seat into the rifling you need to start from scratch and slowly work up a new load. 
 
BB

[Squib]

I'm thinking that you should get close to the rifling but not on/in it.  that's a general rule, but especially true with handi's because it affects the lock-up a tiny bit if you "kiss" the lands & grooves.  as for crimp: yes, virtually anytime you can- without buckling a case.  as for how much, where on the bullet and with how much internal chamfer prior to seating, how much lube, etcetera... you gotta find out the hard way.  h110 is a pistol powder that will change wildly due to crimp and that last grain of powder in .357 at least.  remember that in revolvers if you don't crimp that bullet to get some strong pressure built up PRIOR to the bullet unseating, you are blowing some out the cylinger gap, gas cutting, wasting powder, and possibly slopping the bullet around into the forcing cone.  a handi is far different from a revolver BUT while the chamber and barrel are one, the latch does let the barrel move a bit, so the headspace can flex a bit during firing (like endshake on a revolver).  this CAN cause inconsistent contact on the rifling if you aren't seating close to start, worse if you're too close and stressing the lock-up prior to firing.  if the round is wiggling due to the latch being less than fully engaged (due to a round going into the rifling) then the primer can slide/shift slightly when hit.  that's not gonna make you or break you, but it could cause primer leak, another thing h110 is known for, because it is going to keep building up pressure long after the round gets started, and that longer peak is abusive on the back thrust.  I hope this rambling actually makes sense, sorry.  short version, I agree with bikerbeans mostly.

[Squib]

ps hornady xtp's are the bomb.  really, shoot water jugs and such with them versus other bullets and see the difference in the splash and corresponding energy dump (try cantelope too, hard to pop but good when they do, they do with quick stepping xtps)

[gcrank1]

I dont use heavy loads or those powders that usually are specified for a stout crimp, my cast bullets, fun shooting loads just dont seem to need it.
I usually dont even have to resize but still often put just enough flare on the case mouth to get the bullet base started, seat to depth and just nudge the mouth back to flush, or a tiny bit of crimp. That depends on how 'snug' snug the bullet fits the case neck. Im generally using bullets that are as large a dia. as will fit the fire-formed case neck and still chamber up and extract/eject without trouble. This go/no go can sometimes be as little as only .001", which is .0005" on a side, if thats the way you think about it.
My brass lasts about forever and I seem to hit what I shoot at if I follow the fundamentals, your mileage may vary, or you may be a better shot and more demanding than me.

[knight0334]

Crimping isn't necessary with Handi's, but you may find out that crimping provides for better consistency.  You will have less deviation in velocities when you crimp.  Even a slight roll crimp will suffice, and there really isn't a reason not to because that roll crimp is built into the seating die.

[rsl]

I don't crimp  45/70's in my BC but just enough tension to hold the bullet.. It seems I don't get a complete burn with 3031 but the recoil is most pleasant.. Good luck..

[bikerbeans]

I don't crimp  45/70's in my BC but just enough tension to hold the bullet.. It seems I don't get a complete burn with 3031 but the recoil is most pleasant.. Good luck..

rsl,
 
nobody gets a complete burn with I3031 but it still works well in the 45-70, 444M and a bunch of other cartridges.
 
BB

[Muddly]

Going to try some un-crimped loads. The throat on my carbine is long(ish) and with other calibers I've found that seating out closer to the rifling gives better accuracy. I'm hoping for the same with the 45 Colt but the cannelure on the bullet dictates OAL when crimping.If it costs alittle velocity its ok as even the minimum load of H110 is too fast for the 250XTP ( rated to 1600 fps). Of course i could use the 240gr MAG, but honestly I dont need that kind of power.

[yukondog]

I've tried both way's and get the best accuracy with crimped.

[gcrank1]

You can crimp into a grease groove too if it can take that much seat out.

[Squib]

my 45-70 is not nearly long chambered enough for me to put hornady 500gr interlocks anywhere near the crimping groove.  I have the bullets seated quite deep, maybe .010 deeper than I had to have to shut the gun without forcing it, and with all that neck tension on the bullet I STILL need to crimp it.  the crimp is light as I have no groove to dig into, but it makes all the difference in accuracy.  I've found that a tiny bit of roll crimp on .45 auto helps too (too much will affect headspace though). 

[quickdtoo]

I don't feel it's necessary, but I crimp with a Lee Factory Crimp die for every rifle chambering they make one for, and a few that they don't, for the reasons mentioned.

Tim

[gcrank1]

FWIW: If the brass case neck wall thickness is consistent, and so is the bullet size, with enough consistent neck tension to securely hold the bullet, with many powders it will group fine; the key here is good fit and that recurring 'c' word in reloading, consistency. Yes, some powders do respond to heavy crimps and/or tight bullet pull, neither especially good for cast bullets, so I dont use those powders. Note that a bunch of really fine, world class groups have been shot without any crimp or case neck tension at all, with lead bullets, in rifles chambered for 'breech seating' (an advanced technique not suitable for standard 'fixed ammo' chambers.
Over 100yrs ago match shooters were bemoaning the change by .22LR manufacturers to crimping the .22 ammo because their scores went down.
Try it both ways in your gun, what works for me isnt necessarily what you will be happy with, but you wont know until you test it with a real, proper test regime. For many it isnt just the question of getting another 10th inch off the average group size at 'whatever' range, but that the ammo sticks together in the field and when you extract an unfired cartridge the case c/w bullet comes out together.