Crimp or not to Crimp ?

I have loaded most of the rounds that you list - say 80% of them - have not crimped a centre fire bottle neck rifle round in that list since the 1970's?? No clue about whether they were more or less accurate as a result of that - what I ended up with was fine for what I needed... I never owned a chronograph until into the 1990's so no clue about velocity differences either - just was not something that I concerned myself about... I had a 45-70 double barrel - with cast bullets and cannelure jacket bullets I did crimp - but just because I had read to do so - nothing that I proved to myself as needed or not.
 
I recently started loading for 32 Special, which is the first cartridge I've loaded that fed through a tube mag. First I tried not using a crimp, and the SD and ES numbers weren't impressive.

Then I decided to try crimping into the cannelure on the bullets (170 gr Speer) and the SD and ES numbers dropped by at least 50 %.
The only explanation I could come up with is that the crimped loads gave more consistent pressure, therefore more consistent velocity. Your mileage may vary.
 
I’ve crimped for rifles that recoiled enough to move the bullet deeper into the case, but haven’t tried with others crimped vs uncrimped.
 
I have crimped a few. 300 win and up. For recoil reasons. But then I went to Ruger No1s and haven't since. I tried crimping some 308. As I was using ball powder and had no Magnum primers as our powder guru has suggested. Couldn't tell the difference in ignition. But accuracy wasn't as good.
 
I've tested crimping most of the bottle neck cartridges I load for. The only times I've really noticed an increase in accuracy from crimping was when shooting reduced loads, the lighter the load the more crimping seemed to help accuracy, and before I started annealing I'd have brass that was work hardened and neck tension was inconsistent (too cheap to discard) so crimping seemed to be a big help to tighten up the groups, but in most situations with consistent neck tension I've found crimping to either slightly decrease accuracy or not make much difference.
I do crimp most hunting loads with Lee factory crimp dies, just got in the habit after years of loading for a 30-30 lever with a stiff magazine spring, now I have a compulsion even with bolt actions to crimp most cartridges I'm hunting with weather they need it or not just makes me feel more confident the bullets wont get pushed in somehow.
I can't speak to velocity differences as my crony had an incident a while back & never got replaced.
 
I put a crimp on all my pistol and revolver ammo. I would crimp any lever action ammo. I crimp .223 ammo that I use in semi auto rifles and I oad by the bucket....

I use the LEE factory crimp on lots of precision and hunting ammo now. I never used to but I often do now. According to my Labradar and groups it seems to work. But to be honest, no animal would die or not die depending on a crimp. Nor would a small gong be hit or not hit. So....:)
 
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I guess I'm of the minority here. I crimp on a case-by-case basis for each cartridge/rifle combo but due to me mostly reloading .223 I crimp more often than not.

I use a Lee FCD for .223, it's used in a semi-auto and when I tested it did seem to deliver more consistent results over uncrimped in my particular firearm. I had a few bullets set back into the case when cycling before I started crimping, but whether a crimp would have prevented that or not (rather than checking neck tension) is up for debate. I primarily do it because I run a 4-hole press with auto-index so my press is set up to resize/deprime -> charge -> seat -> crimp. It only takes me about an extra 1.5 seconds per round to do a light crimp, otherwise I just have an empty spot on my press I have to cycle through which can sometimes interrupt my rhythm, when you account for that the time investment required for crimping in my case is very minimal.

If I were using a single stage I probably wouldn't crimp unless I was loading ammo I was expecting to encounter rough handling/storage before being used. If there isn't a cannelure on my bullet I test with vs without and would not bother if the results are indistinguishable. If I were using a bolt-action I would probably still do it (depending on testing results), once again because I just find it easier to use all 4 stages on my press rather than have an empty one.

I also recall reading (can't remember where) that a crimp (specifically the Lee FCD) can help with old military/surplus rifles with long or worn out chamber throats, but I have not put that to the test myself.

In the end it comes up to individual preference. I wouldn't fault anyone for deciding to crimp or not to crimp. Excluding revolvers, lever-actions and very high-recoil cartridges it's not essential (at least to my knowledge, I am still a new reloader so feel free to correct me if there is another case I am forgetting about).
 
6 to one 1/2 dozen to another!!

Your best accuracy w/ jacketed projectiles will result w/out a crimp.

Size the inside &/or outside of the necks accordingly.

Annealing will prolong case necks & improve ballistics...internally & externally!

I crimp pistol ammo & my cast rifle ammo for better ignition.

My .22Hornet to 50BMG ammo is NEVER crimped.
 
From LEE :
Lee Factory Crimp Die crimps your bullets in place the same as factory ammo. A collet gently, but firmly squeezes the very end of the case into the crimping groove, exactly the same as factory ammo. A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move.
 
remington jim - is a curiosity for me - I think the Lee Factory Crimp Die is a different thing than what some of us think is "crimped" - I certainly was thinking the "normal" roll crimp, like into a crimping groove on a cast bullet. None the less, I do not do either, although I have bought a Lee FCD for 9.3x62 with the idea of cutting it down for 9.3x57 - I flair the cases to seat a cast bullet, and the rifle's chamber is just that tiny bit tight that I can feel that bent out flair on the first trip in - no groove or cannelure on those bullets, so I thought to try to "flatten it out", before hand... The Lee FCD seemed to be the answer, although not made for the 9.3x57
 
remington jim said:
From LEE :
Lee Factory Crimp Die crimps your bullets in place the same as factory ammo. A collet gently, but firmly squeezes the very end of the case into the crimping groove, exactly the same as factory ammo. A firm crimp improves accuracy because pressure must build to a higher level before the bullet begins to move.
Click to expand...

If crimping really improved accuracy, all benchrest shooters would crimp. Crimps are beneficial for handgun ammunition, tubular magazines, and very heavy recoiling cartridges, and if your neck tension is not adequate, and you choose a band aid, instead of resolving the actual issue.
 
I only crimp (with Lee factory crimp die) my .223 loads when I reload in batches. These are my plinking, fun rounds... I do not crimp any of my rifle rounds if I'm going for accuracy...
 
I only crimp for semi auto and lever action to help ensure bullets don't get pushed deeper into the case. I did a small test with some 223 a few years back for fun and crimped cartridges were less accurate than uncrimped by .25-.5 MOA less. It wasn't a scientific test though just a fun little experiment.
 
stubblejumper said:
If crimping really improved accuracy, all benchrest shooters would crimp. Crimps are beneficial for handgun ammunition, tubular magazines, and very heavy recoiling cartridges, and if your neck tension is not adequate, and you choose a band aid, instead of resolving the actual issue.
Click to expand...

A crimp can/will eliminate unburnt powder in lower pressure reduced power loads...just adds a slight "hold back to the slug" for the burn duration in large capacity cartridge's. I have proven this out many times with a 45-70 & 38-55
 
If the Bullet has a canelure, I crimp. Altogether more work (Casings need all to be the same length) but then I know for sure the Bullet stays in the Case neck exactly where it was meant to be.
Nothing worse then needing to chamber a Shell and your Gun malfunctions because the Bullet got pushed into the Casing or on a heavy Revolver a Bullet "walked out" off its casing preventing the Cylinder from turning.

Cheers
 
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