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:
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Photo of group shooting identical shells which were crimped with the LFC die.
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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.