Far be it from me to disagree with the "experts" here. Don't want to believe me then you might try reading page 196
of Speer's #14 Reloading manual. You'll find the same admonitions in Hornady and Sierra's manuals on using these type bullets in faster twist .223s. But then what do the boys who make the bullets know when we've the likes of the experts here.......

Larry Gibson

Gees Larry my Sierra manual #4 uses a 20" 1:7 Colt AR-15A2 HBAR as the test gun and gives loads from the 40 gn Hornet 3000fps to 3500fps up to the 80 gn SMK @ 2300-2600fps.

My Hornady #7 manual uses a Rem 700 with a 1:12 as the test gun for 40 gn - 60 gn, and then a Colt 1:9 with specific Service Rifle Loadings of 68gn (200-300 yd) and 75 gn (600 yd)BTHP's.

Hornady only warns against driving the #2240 50gn SPSX higher than 3500 fps as the SX stands for Super Explosive as it has a thin copper jacket. It says the #2245 50 gn SP is just fine for high velocities.

No 1:14 twist listed. This is 2011 not 1965. You are the only person I ever heard using 1:14 in a 223. Everyone else strictly warns against it as it severely limits the cartridge.

22-250, 220 Swift, 222 are fine with the old 1:14 twist.

Gees airgun1 read the RCBS manual and read a newer Hornady manual (test gun is a 12" twist and they specifically state not to use SX bullets in "rapid twist" Mini-14s and AR15A2s). The Sierra 40 gr bullet is not the "Blitz" Sierra bullet I refered to now is it. Read that manual again and also you might reread what bullets I said were not good in the faster twists. Yes there are some of the lighter weight .224 bullets made for the 22-250, 220 swift and such high end performers. At .223 velocities they do not perform that well on smaller varmints at the longer ranges both of which the OP asked about and stated were his uses for the rifle. I don't think he was interested in shooting 68 - 80 gr MKs in 1000 yard matches or pulling .22 RFM bullets to use either....... I also suggest you update your library, do some better research, especially as relating to the OPs question and requirements. You might even get a box of Blitzes or SXs, load them to 3150+ fps out of your fast twist AR and go try them. You might have some 1st hand knowledge that is useful then.

Larry Gibson