I’m pretty sure I have talked about this in the past. The Seirra flat base 53 gr. Hollow point MatchKing is an often over looked bullet for use in the AR15. especially rifles with 5.56MM NATO chambers. It used to be well known all around that the bullet when used in the AR was often times hard to beat out to 300 yards.
Back in the 90s, it was used as the 300 yard/meter bullet for loads used in service rifle. Barrett Martin and Derrick Tillman wrote about it quite a bit in the pages of Precision Shooting and mention in their excellent book https://www.amazon.com/Complete-Guide-AR-15-Accuracy/dp/0967094852.
The flat base , shorter bullet does well in the semi auto with the military chamber. It is not as easily disturbed as some of the longer match bullets. I will save excatly how and why it works so well in a mil-spec chamber in a few days. I want to go into greater detail for this and I want some illustrations to help explain why it is. Now that isn’t to say the longer match bullets don’t shoot well in a NATO chamber, because they do. But if you want some real precision at 300 and in, the 53gr FBHP will almost always deliver in your gun as long as its decent quality.
I loaded up the last 30 I had and shot a couple of ten rounds groups at 100 yards off the bench with a Colt 20 inch A2 to demonstrate today. And I suffered mightily in the heat for this. Believe me.
I shot the right hand group first. and then the left was second. You can see the heat and it’s affect on me in the group. 98 degrees with what felt like 200 percent humdity. I admit I was glad that I ran out of hand loads. Notice I was going to shoot three groups but nuts to that. I’m ugly and stupid and no one likes me, but I’m not insane.
That was from a rack grade A2 upper. I did use the lower off my MK 12 with the SSA Match Trigger and a Leupold 10X on a Leupold carry handle mount that I removed and put up before I remembered I forgot to take pictures of it. For load development on fixed carry handles I use an optic. You just can’t get the kind of groups with iron sights you need to really wring out all the accuracy a load may have.
Above is the page for the 53 and 52 grain bullets in a Sierra loading manual. I am not going to tell you my personal load because some oaf wil blow a gun up and blame me sure as day follows night if I do.
Yes I could have used the match barrel on the MK 12 A 6940 M4, Colt Accuracized Rifle or a vamint Model 70 to show this load. The point is to show you what kind of performance you can get out of a non-free floated rack grade milspec NATO 556 chambered barrel with the 53gr flat base. If you hand load and didn’t know about this bullet give it a try.