300AAC in AR platform: Crimping?

[azrocks]

1) Accuracy is not my primary concern. The potential for bullet setback is.
2) I have both a Lee FCD and Dillon's carbide taper die
3) Have a variety of bullets (110g to 190g) I'll be loading eventually, but none of them have a cannelure (or they do have a cannelure, but it doesn't align w/ case mouth, so effectively the same).
4) Some bullets are boat-tail, for which I will not bell the case mouth. Others are flat-base for which I will (a tiny amount). Using Dillon .30 carbine powder funnel to give me this flexibility.

Question is what do you guys/gals do, and why? What would you recommend? What's been your experience regarding the potential for setback?

 

[mcb]

I have not flared any of my cases for any bullet type so far. I have loaded Barnes 110gr TAC-TX, Speer TNT 125gr, Berry's 220gr plate spire point, Maker REX 220gr. I am using the AK (7.62x39) powder funnel on my 650XL to load 300 BO I don't crimp much but especially using Berry's plated bullets as they don't like being plated too much. Same for the all copper bullets, they have a cannelure but its very shallow and so I crimp just enough to get to the bottom of it. Currently I am seating and crimping in one step using a Hornady die but I am probably going to buy a separate crimp die and use the Hornady seat/crimp die only for seating. So far neck tension alone has held everything pretty well. The only setback issue I have had with with the TNT bullets as they have a very short cylindrical part of the bullet and no cannelure.

 

[berettaprofessor]

I load 300 BO with Hornady 150 grain Match or SST, and crimp them with a Lee crimp die,for the very reason of preventing setback. I havent tried them without crimping so I don't know the real incidence of setback in 300BO with that load.

 

[cfullgraf]

I do not crimp my 300 Blackout, or any other semi-auto rifle for that matter. I make sure that I have enough neck tension.

While boat tail bullets are easier to seat, I still do not flare the cases mouths for cases that are getting flat base bullets. Virtually all jacketed flat base bullets have a small radius at the base. With proper setting of the bullet on the case and careful seating, the flat base bullets. Chamfering the inner edge of the case mouth helps a bit as well. It takes the corner of the case mouth off and prevents it from shaving copper while seating the bullet.

Crimping is no substitute for insufficient neck tension.

 

[Walkalong]

125 Gr SST with a light crimp into the cannelure. Feeds great, shoots great.