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.

 

[peaches]

I only crimp if the bullet moves out of the case under recoil...ie 44 mag pistols.

 

[Ange86]

I crimp all my hunting loads with a Lee as a separate step. No crimp when seating. I feel like I get more consistent ignition based on ES, although I haven’t compared it head to head, purely based on the fact that I used to not crimp and my ES across multiple guns is lower. Whole reason I started crimping was a round I pulled out of my pocket and a projectile noticeably seated deep. I said Never again.

 

[Compressedload]

Ange86 you are certainly right that crimped ammo (if done right) is more "robust". Also Wilderness is correct that some banded designs may need crimp depending on the spacing (the old GSC was a good example where sometimes only two bands would contact the case neck and needed to be seated to a depth where neck tension was achieved - although GSC had their own recommendations).

So... as I said before I crimp only for 375 H&H and larger.... At one time we had a run of RP 375 H&H Mag brass here that was pretty crappy. Many of us struggled to get proper neck tension. You would seat bullets and many (more than 50%) could spin them around with your fingers and pull them out of, or push them deeper into the cases. Annealing helped a bit but didn't solve the issue and I did try resizing dies of various manufacturers. No, I didn't get undersize expander balls to try, or turn down the ones I had, which would almost certainly have addressed this, but seemed like a bad solution when the brass was the issue.

So here is the thing; the neck tension was no way the same across all of the ammo. I crimped them. The PMP softs I used for range use and lighter game were the worst, but the North Forks, particularly the mono FPS / CPS did the same and were quite often loose in the case. The NF are great bullets and I was the importer at one time for a good number of years until they closed and sold up in the USA. I use them to this day. So this is no comment on the bullets, but the crimped bullets stayed at the crimped overall length, but could usually spin in the case by hand. Nevertheless, the ammo produced shot single digit SD and less than MOA groups (no not twenty shots ;-)) in my New Haven Model 70 Classic SS.

I hunted very successfully with that very ammo and whilst not my first choice, wouldn't hesitate to do it again. I sometimes wonder about a lot of the precision and perfection that we chase. I have no idea how case necks release bullets, but I suspect they pop open and don't drag out of the case neck. That would explain why some of this may matter "less than it should".

One day I will load ammo with three, or four, different neck die bushings and test this out. I don't use bushing dies by choice, but do have a few sets. I also need to shoot crimped and uncrimped cartridges together....