I just read an article in Human Events warning against firing 5.56 ammo in rifles chambered for .223 Remington. Apparently the "danger" is the chamber leade in the two different rifles. In guns chambered for 5.56 the leade is greater, allowing for the supposed longer length of the 5.56 brass. If you fire a 5.56 cartridge in a .223 rifle, the bullet engages the rifling upon being chambered, causing higher pressures when it's fired.
Here's the problem I'm encountering. I came across a large batch of surplus 5.56 brass. I resized, decrimped the primer pocket and trimmed to .223 specs using a Lee case trimmer. I then reloaded the brass using the starting load of 23.4 grs of AA 2230 powder for a 55 gr FMJBT bullet. I fired about 100 rds and noticed very flattened primers.
I'm at a loss. I thought trimming would eliminate excessive length as a problem. Any ideas?
Also, I'm firing this ammo out of a standard Colt AR-15. Since Colt also manufactures the M-16, aren't all the parts essentially the same (except for the selective fire components)? It would seem a AR-15 could safely fire 5.56 as well as .223 Rem. Where did I go wrong? BTW, the article stated that both .223 and 5.56 brass has the same wall thickness, so that's not the problem.