5.7x28 Sub Round

Recently worked up a decent subsonic 5.7x28 load for my AR-57 SBR (9" barrel) for use with my Gemtech SAR57 suppressor. Two powders worked pretty well, but case prep is a bear. Not an easy or quick round to reload. Used a single stage Hornady press I found on sale on Amazon. I do case cleaning one day (simple green/water soak and agitate for 10-15 min then water wash and dry), sizing and deprime second day, hand prime on third day and powder measure (with powder trickle by hand to get charges EXACT) and bullet seating on fourth day. Use Lee die set. I didn't crimp but Lee makes a crimper if you so need.

First:
Powder: True Blue 3.0 gr
Bullet: Hornady 55gr FMJ-BT
Case: once fired American Eagle
Primer: Winchester small pistol magnum
COAL: 1.575

Second:
Powder: Power Pistol 2.8 gr
Bullet: Hornady 55gr FMJ-BT
Case: once fired American Eagle
Primer: Winchester small pistol magnum
COAL: 1.575

The true blue is very fine grained compared to the round flakes of the power pistol. Both burn pretty clean and leave little residue with the TB being a little cleaner. These loads are just enough to cycle the heavy, heavy AR57 bolt (it's a simple blow back design) but remain subsonic through the 9" barrel. Be careful not to remove the case lacquer by tumbling them in case tumbler. However, I also apply a little dry lube spray to the rounds just before loading into the FN 50rd mags to help feeding. Seems to help a little.

As always: Use these loads @ your own risk.