Originally Posted by Scharfschuetzer

As noted above, your AR will tell you what it likes after shooting groups starting on the low end an working up to a max load with your components.

Is your barrel free floating or is it secured at the end of the handguard as most 16" ARs are? Any discussion of barrel harmonics will need to start with this.

What is your rifling twist? a 1 in 14" is actually the best for your 53 grain SMKs, although a 1 in 12" twist is very good with this bullet also. I've shot a lot of prairie dogs with the SMK 52 and 53grain MK bullets out of a 1 in 14" and 1 in 12" twist rifles. Faster twists can be as accurate, but generally over stabilize these light bullets and accentuate any concentricity issues a bullet might have, thus opening groups up a bit.

Your actual chamber's throat (lead) may also have something to do with the accuracy you obtain with the light SMKs. The GI chamber's throat v. a .223 chamber's throat v. a Wilde chamber with its compromise throat. A long bullet jump can degrade accuracy a bit, but can lower chamber pressure.

All the above can impact accuracy, both positively or negatively. So what's the answer? Just work up your loads till you find one that meets your accuracy and velocity goals.

Let us know what your results are.