AR-Stoner 6.5 Grendel barrel short chambered.

[XcountryRider]

A lot of the projectiles listed in this thread need to be seated deeply regardless of the chamber they are in, because they have tangent ogives that will jam if you try to load them long. If you look at Volumes I & II of the 6.5 Grendel Reloading Handbooks, or check the manufacturers' load data, you will see that a lot of the shorter, lightweight pills need to be loaded short:

90gr Speer TNT 2.200" per AA
120gr Sierra Match King 2.220" per AA

Looking in Volume II, I find:

95gr V-MAX 2.200" from Western Powders, and 2.230" from Hodgdon's
100gr NBT 2.230" from Western Powders

Now the A-MAX should be able to be loaded quite a bit longer, at least to 2.250".
The 123gr SST ranges from 2.230" to 2.275" in Volume II.

The 129gr SST should be able to be loaded even longer, from 2.260" to 2.290". I can load it longer than the mags will allow, although there is enough variation in ogive shape lot-to-lot that we generally want to give ourselves some stand-off.

Don't expect much longer than 2.200" with the short pills with short radiused tangent ogives, like the 95gr V-MAX, 120gr SMK, etc.

That said, if factory Hornady or AA ammo isn't chambering, or is jamming into the throat/lands, you have a major problem.

Thanks for the reasonable and informative post.