SPR Loads....Crimp or no?

[nksmfamjp]

Should I use my Lee Factory crimp....collet type...for best accuracy?

Looking for SPR accuracy ....sub 1 MOA at 100 yds.

Build is WOA barrel, Geissele hi speed, 2-8x quality optic....

[jaholder]

Most precision loads don't require a crimp, bullet deformation may degrade accuracy.

With that said, I've got a Mk262 clone using TAC that I got better groups from my 16" carbine by crimping the Sierra 77's with the Lee FCD. My other AR's had no difference in accuracy between the crimped and uncrimped bullets, so I crimp.

I also crimp (with the FCD) my 55 grain Sierra HPBT but the Nosler 55 grain BT's get none.

[bp7178]

Sub MOA is sub MOA regardless of distance.

I applied a light taper crimp, but not to the point where it would deform the bullet. IMO, good neck tension is more important.

[gunnerblue]

I believe that neck tension is more important than crimping in a precision load. I control tension by using Redding Type-S sizing dies which use interchangeable bushings. Typically for an auto loader I will go for about 0.003” worth of tension. This is subtracted from the outside diameter of the neck of a loaded cartridge. I haven’t used the Lee product but a lot of people seem to like them.

[markm]

Buy the die and try it out. There's no correct answer since it depends on dozens of variables in your specific set up. I crimp everything.223. In my set up, I lose gobbs of accuracy without the crimp. I tested it once, and it was dramatic.

[Vegas]

markm, what is the amount you crimp?

Thanks.

[Vegas]

Thanks. You had asked me in another thread a while back about whether I crimped. Think I am going to get motivated to order a LFCD and give it a try.

[markm]

Thanks. You had asked me in another thread a while back about whether I crimped. Think I am going to get motivated to order a LFCD and give it a try.

I think the reason it helps me is that I don't anneal. So the FCD gives some neck consistency improvement.

Sinister, another experienced loader here, does almost the opposite process that I use and gets great results. He anneals with no crimp if I remember correctly. So the FCD alone is only part of the total process.

[Vegas]

I think the reason it helps me is that I don't anneal. So the FCD gives some neck consistency improvement.

Sinister, another experienced loader here, does almost the opposite process that I use and gets great results. He anneals with no crimp if I remember correctly. So the FCD alone is only part of the total process.

I don't anneal 223 brass, only my 308 and 7mm brass for bolt guns. So basically crimping in lieu of annealing gives that consistency to neck tension. Makes sense.

Thanks.

[markm]

So basically crimping in lieu of annealing gives that consistency to neck tension. Makes sense.

Thanks.

That's my guess. I tested the same loads with the crimp as the only variable, and the non crimped ammo wouldn't even hold MOA.