Finally got a handle on loads for my AR!

[454Puma]

As most have seen I wasn't having a good time with my Colt Match Target as far as getting it to shoot where it should be for a target rifle! After curing the AR wobble(Loose fit between upper/lower)! I had to revisit all my loads to fine the ones that work!    With the added trigger time , addition of optic I am now proud to say it has given me some groups to be proud of!  Where I was getting 2" plus groups at 100 yards or worse with just about every load I'm now down to 1-1.5" or better on average!    Was really getting PO'd on the 69gr SEI Match bullets and was just about to give up on them until I tried IMR 4064 and also changed my trim length to 1.760" instead of the book 1.750" - mine is a NATO barrel so longer is better!  I just reloaded what should be the optimal load for both the 75gr HPBT and 69 gr HPBT SEI so I'll shoot them tomorrow and post the groups!

[84Jim]

mine is a NATO barrel

That's probably most of you problem right there!  The 5.56 throat is really deep which means the bullet has a lot of jump before it hits the rifling, especially with mag length.  You did a good job in finding loads that shoot 1-1.5 inches!  I had some measurements of the various chambering (.223, Wylde, and 5.56) OAL to touch the rifling with sierra 80 gr. MK's, but can't find them now    However, it's next to impossible to load most bullets to within say 0.020" of ther rifling in that chambering and it only gets worse as the throat erodes.  My question would be "Why would Colt desiginate a rifle as "Match Target" and put a 5.56 chamber in it?"

[454Puma]

84jim
  Yep I did the dummy bullet thing and to touch the rifling I'd have to load out to 2.40"  my max to use the magazine to load is 2.265"!! So I'm loading everything to 2.260"! I think I've nailed down the load for the 69 gr SEI HPBT today!   See the target below - still need to work on the 75gr Hornadays! I'm also sure the trim to length of 1.760" is helping as well!! My cases don't seem to grow as much doing this which in the long run should make them last longer! Well I assume since the barrel is marked 5.56 NATO it is a 5.56 chamber?