The Hornady Web site says this:
http://www.hornadyle.com/products/more_detail.php?id=72&sID=79&pID=1
This cartridge provides the police marksman a unique bullet that demonstrates rapid expansion, fragmentation and low retained weight. This bullet offers the least penetration in ballistic gelatin and lower felt recoil as compared to heavier TAP® loads. The 110 grain bullet demonstrates similar penetration to the 223 Rem. 75 gr. BTHP bullet, but with substantially more temporary and permanent cavity and fragmentation, proving itself an ideal choice for urban sniping.
NOTE: An excellent choice for the M14 and its variants.
The advice to stay within 150 to 168 grain bullets is a bit limiting. Early LC match was loaded with a 174 FMJBT at a velocity of 2550 fps. I have chronographed this ammo out of M1a's and that velocity is what the ammo gives . You can load 168's and have them around 2600 fps, 175's under 2600 fps, and keep your 150's at or below 2700 fps. With powders in the IMR 4895/AA2495/H4895 burn rate.
What you do not want to do is have a high gas port pressure. Heavy bullets increase port pressure (unless downloaded to spit wad speeds) and so will slow powders. High port pressures push the operating rod too fast, leading to torn rims, hard on extractor and will beat up the receiver heel. The bolt rebounds off the receiver heel, you don't want your receiver looking like the Garand receiver pictured below, do you?
I don't recommend bullets heavier than 175 grain, and I don't recommend speeds faster than 2600 with those bullets. I don't recommend any thing slower than IMR 4064. 4064 is a good powder in the M1a, just does not throw as well as IMR 4895/AA2495/H4895.
M1 Receiver cracked by Greek Ball
Going to lighter bullet weights is in fact easier on the rifle. As long as you use powders in the IMR 4895 burn rate and you are not using the 308 as a mini magnum. I have buds who shoot 125 grain bullets standing and sitting at 200 yards with their M1a's. I don't know what is a safe velocity with 125's, or 110's, but as long as the stuff functions the action, and does not rip rims off, and beat the heck out of your receiver (which is a lot of but's), it should be safe.