crimping

[huntsd]

can someone school me on crimping. I have a lee factory crimp die. I have a 6.5cm load that shoots very well, but want to mess around with a crimp to see if that does anything. Is there a way to tell how much crimp is applied?

I crimped 3 rounds last night, I can see a "little" crimp on the neck. Not really sure what to do if I want more or less crimp besides slightly adjust die up or down. Is there a more scientific way to go about this?

 

[rifletuner]

can someone school me on crimping. I have a lee factory crimp die. I have a 6.5cm load that shoots very well, but want to mess around with a crimp to see if that does anything. Is there a way to tell how much crimp is applied?

I crimped 3 rounds last night, I can see a "little" crimp on the neck. Not really sure what to do if I want more or less crimp besides slightly adjust die up or down. Is there a more scientific way to go about this?

If the bullet has a cannelure, then you crimp on that. If the bullet has no cannelure, than the crimp will be less pronounced as the crimping tool is essentially pushing the case neck into the jacket of the bullet.

Having said all that, I only crimp heavy bullets in rifles that generate a lot of recoil - eg a dangerous game cartridges where the bullet is at risk of moving under recoil. For a cartridge such as a 6.5 Creed, I think crimping serves no purpose, and may be detrimental to accuracy.

 

[huntsd]

If the bullet has a cannelure, then you crimp on that. If the bullet has no cannelure, than the crimp will be less pronounced as the crimping tool is essentially pushing the case neck into the jacket of the bullet.

Having said all that, I only crimp heavy bullets in rifles that generate a lot of recoil - eg a dangerous game cartridges where the bullet is at risk of moving under recoil. For a cartridge such as a 6.5 Creed, I think crimping serves no purpose, and may be detrimental to accuracy.

thanks for the response. Yes these bullets have no cannelure.

I was under the impression crimping could be used to help "tune" a load.

 

[Truck24hr]

thanks for the response. Yes these bullets have no cannelure.

I was under the impression crimping could be used to help "tune" a load.

I use bushing dies, so no crimp at all. I've pulled bullets where the crimp in the bullet varied onneach one, but all were loaded on the same equipment, so..

Leads me to think crimps could cause accuracy issues. But, i only load precision rounds, so. Plinking ammo I just buy

 

[huntsd]

I am using hammer bullets and high quality brass/ primers ect.. the load shoots well as is, just seeing if i can milk a little more accuracy from it with the components I have

 

[Choupique]

With the lee FCD, the crimp is done via collet. You can really crimp the ever living hell out of rounds if you chose to, vs roll crimping where you'll destroy the case if you overdo it.

I use lee factory crimp dies for everything and crimp them pretty hard. I still have issues with bullet setback in stuff with lots of recoil.

 

[Wapiti1]

Crimping will likely not improve accuracy, or consistency and will probably be detrimental. It adds a variable that is dependent on case neck thickness, case length, bullet diameter and crimp groove diameter. Two you can control with extra steps, but two you can't do anything about.

I find crimping useful for two things: bullet security, and ignition consistency with magnum ball powders in revolvers. You do it to prevent setback or forward creep of bullets under recoil. For a revolver, the crimp helps build pressure in the case and start the burn if you will. With powders like H110 and heavy charges you can get incomplete ignition without a hard crimp. Even with mag primers. Compressed charges make it worse.

Just my take. I crimp my big bore ammo and my revolver/pistol ammo. Normal stuff I don't crimp and have never seen a need to.

Jeremy

 

[Castle Rock]

Crimping will likely not improve accuracy, or consistency and will probably be detrimental. It adds a variable that is dependent on case neck thickness, case length, bullet diameter and crimp groove diameter.

That is true of traditional seating dies that incorporate a roll crimp, but not so the Lee crimper.
I think using this crimper is an aid to accuracy in some instances, particularly when used in conjunction with the collet neck die

To the OP, set the die to touch the shellholder plus 1/4 turn, if the collet closes fully, back it off a touch, you don’t need a hell of a lot.
I think it does make a difference, particularly once the brass gets useda couple of times and mixed numbers of firings

 

[cstrah6]

Not to hijack the OP’s thread but would you suggest crimping on your gas guns (AR platform)

 

[coyotecreek]

Not to hijack the OP’s thread but would you suggest crimping on your gas guns (AR platform)

I was gonna ask this as well.

 

[jfk69]

Fwiw, I crimp everything with a Lee crimp die for my gas guns. I also crimp with a Lee crimp die for my Marlin 336 in .35 Rem. Those are the only cartridges I crimp for. I agree with the above that for a bolt gun, it introduces another unneeded variable into the accuracy equation.

 

[Compressedload]

I crimp for all self loaders. Also suggest checking AOL on chambered cartridges to check for setback. I don't care to use a cannelure and use the Lee FCD.

I crimp 375 H&H and larger mag loaded due to set back from recoil. You can mag load and check all rifles. Mag boxes with free space and a soft spring can cause issues. However I generally do not crimp for other rifles. If you are a PH carrying ammo around on a belt for a season there may be some sense in it as robust and reliable ammo trumps pinpoint accuracy in that case.

Crimp revolvers as mentioned for ignition and so as not to lock Up the cylinder! The Lee collet die is available in some of those cartridges.I used the Lee FCD with the carbide ring a lot. Hate them. Find that they swage handgun bullets below diameter. Rather gauge or chamber check ammo and toss or use out of spec for practice.

 

[wildernessrimfab]

I started loading hammer bullets recently (7PRC 155 Hammer Hunter) and they recommend crimping the valley in between the PDR bands. I experimented with 4 different crimp levels between 1/8 turn and 1/2 turn...1/8 was by far the best in terms of group size and velocity stats. I think crimping these bullets is a good idea because the PDR bands make very little contact with the neck of the brass.

COAL could change under recoil, also after a period of time with a compressed charge.

 

[Firth]

I've compared my crimped versus uncrimped reloads for accuracy a few times and uncrimped has won out each time. I think it's been three times, so not a lot, but more than none. As for the caveats, I used the same dies every time - Lee Pacesetter 223 dies - so that could introduce bias. I tried to be as consistent as possible with my crimping technique, but I haven't experimented with that much so that could be the issue. I was also just using range pick up lake city brass.

So, all that is to say I've seen people say it improves accuracy, but it hasn't been my limited experience. To me the bigger potential gain seems to be in reliability. I used to crimp everything I reloaded, but I don't shoot big stuff much, and I've never had a problem with reliability in my 223 rounds crimped or not, so I haven't crimped anything in quite a while.