Mike. Dont over think it. The dies fingers squeeze the case mouth into contact. With a firm crimp you can even see a slight indentation in the brass. There is a slight deformation of the bullet jacket but not enough to affect accuracy at normal ranges. Trust me it works. No grove required although using a cannelured bullet is probably optimal.
Crimping and neck tension
- Thread starter Dmagna
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I read an article similar to this one back in ~2016. This link may or may not be that article.
I thought the neck tension on my 223 bullets for my AR-15 might be low. After having read that article, I thought I'd try crimping some of my 223 shells with the Lee Factory Crimp (LFC) die. I took ammo that had already been loaded for my AR, which I had already shot for group size (precision). I then crimped some of those shells in the LFC die.
Photo of group size shooting shells that were not crimped:
Photo of group shooting identical shells which were crimped with the LFC die.
I don't claim to know how crimping produced the substantially reduced group size. But crimping obviously did something to improve precision. The orange squares were cut closely to the same size. I continued testing additional loads, and generally, each time I crimped with the LFC die, my precision improved.
I am familiar with the historical practice of most reloaders - rifle ammo generally is not crimped. Only reason I crimped at all was due to the article I'd read, and because the semi-auto AR-15 I was firing the shells in. I thought I might need more neck tension to keep bullets from moving in the case neck when they were getting slammed from the mag into the chamber. My neck tension seemed on the light side.
After my experimentation, I showed the article I had read to a friend of mine who owned about 100 different rifles. His hobby and passion was reloading and shooting and hunting. I showed him some photos of my groups with and without crimping. He said he wanted to test the LFC die on his loaded ammunition. About 9 months later I questioned him about his overall experience crimping his hand loaded ammo. He said he almost always experienced improved precision, to the point he'd purchased LFC dies for basically all of his cartridges. Said he never experienced any big degradation to precision after crimping. Almost always some improvement.
I don't crimp all ammo used in my LRH rifles. In fact, I mostly don't crimp. One reason..., most of my LRH cartridges are wildcatted and LFC dies aren't available for them. Another reason..., I invest much more time in load development for my LRH rifles than I do with my AR-15. The AR-15 is for plinking more than hunting. After a load has been developed for my LRH rifles, it requires more time and components to re-test those loads after crimping. Or even more time consuming, starting load development over again with all bullets crimped.
It could be that carefully developed ammo that provides consistently good precision may not shoot any better with bullets crimped. I haven't tested that it that much in my LRH rifles. But without any doubt, crimping with a LFC die does do something to affect load precision. And in my experiences with the 223 ammo, I usually experienced better precision.
Take it or leave it. Maybe test some of the shells you've already developed for LRH. Apply a LFC die crimp. See what gives.
I thought the neck tension on my 223 bullets for my AR-15 might be low. After having read that article, I thought I'd try crimping some of my 223 shells with the Lee Factory Crimp (LFC) die. I took ammo that had already been loaded for my AR, which I had already shot for group size (precision). I then crimped some of those shells in the LFC die.
Photo of group size shooting shells that were not crimped:
Photo of group shooting identical shells which were crimped with the LFC die.
I don't claim to know how crimping produced the substantially reduced group size. But crimping obviously did something to improve precision. The orange squares were cut closely to the same size. I continued testing additional loads, and generally, each time I crimped with the LFC die, my precision improved.
I am familiar with the historical practice of most reloaders - rifle ammo generally is not crimped. Only reason I crimped at all was due to the article I'd read, and because the semi-auto AR-15 I was firing the shells in. I thought I might need more neck tension to keep bullets from moving in the case neck when they were getting slammed from the mag into the chamber. My neck tension seemed on the light side.
After my experimentation, I showed the article I had read to a friend of mine who owned about 100 different rifles. His hobby and passion was reloading and shooting and hunting. I showed him some photos of my groups with and without crimping. He said he wanted to test the LFC die on his loaded ammunition. About 9 months later I questioned him about his overall experience crimping his hand loaded ammo. He said he almost always experienced improved precision, to the point he'd purchased LFC dies for basically all of his cartridges. Said he never experienced any big degradation to precision after crimping. Almost always some improvement.
I don't crimp all ammo used in my LRH rifles. In fact, I mostly don't crimp. One reason..., most of my LRH cartridges are wildcatted and LFC dies aren't available for them. Another reason..., I invest much more time in load development for my LRH rifles than I do with my AR-15. The AR-15 is for plinking more than hunting. After a load has been developed for my LRH rifles, it requires more time and components to re-test those loads after crimping. Or even more time consuming, starting load development over again with all bullets crimped.
It could be that carefully developed ammo that provides consistently good precision may not shoot any better with bullets crimped. I haven't tested that it that much in my LRH rifles. But without any doubt, crimping with a LFC die does do something to affect load precision. And in my experiences with the 223 ammo, I usually experienced better precision.
Take it or leave it. Maybe test some of the shells you've already developed for LRH. Apply a LFC die crimp. See what gives.
Varmint Hunter
Well-Known Member
It's quite possible that your un-crimped ammo had the bullets shifting in the case as they were slammed up the feed ramp. Crimping should alleviate that problem. It's standard practice to crimp all ammo for autoloading rifles just for that reason.
IMO that most .223 bolt gun shooters do not crimp simply because there is no benefit to it. I load .223 for two bolt rifles. Both shoot VERY well without any crimp. Crimping can solve some problems but where those problems don't exist, it's hard to see the justification to crimp.
Just my 2 cents, and I own many crimp dies and have done a fair amount of experimenting with them. If they work - USE THEM.
I rarely crimp in the cannelure.I get my cbto and put a light crimp there and if it's in a cannelure then ok but most times it is not.
I don't compete but am happy with my groups.
I don't compete but am happy with my groups.
Hugnot
Well-Known Member
I got a Lee .264 WM factory crimp die for my 6.5-06 & it works real good. I was able to shoot 1-inch groups at 200. My load was 6.5 123 ELDM with 52.5 gr. of T8000, Fed 215 primers, reformed/trimmed .270 Win PPU & Fed brass. The brass is real cheap & I pay $27-$37 per 100 including shipping. T8000 is sort of like H4831.
Beautiful Rifle
I appreciated phorwath's comment as that is the only way to find out if it works for you!
I took shot 5 shots to properly foul the barrel and 20 Lapua brass and my favorite load and loaded 10 without crimping and 10 with crimping and let my rifle tell me which it liked.I crimp.Enough about my rifle.
Your rifles are different from mine and may act differently so check for yourselves and act accordingly.
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Copied from the article "Why I Crimp" by other well known members on this site. I take no credit for it, simply reposting for informational purposes only. I have a very well developed and super accurate load for my 300 WM using 180 AB. I tried crimping those rounds according to the Lee instructions and did not follow this setup and it neither improved or hurt my accuracy in those loads, however I followed these procedures with different Hammer bullets and it did improve accuracy just like what is stated in this article. In my experience it helps, sometimes a lot. Starting at 1/8 turn and increasing the crimp by 1/8 turns fine tunes the crimp in a trackable manner. I now at least try crimping on the calibers that I have LFCD for.
Thank you sir. I built two that are pretty much twins, the 22-250 in the photo in my post and a 260 Remington. Both have Shilen barrels, and both shoot very well.
