SAI also says not to shoot reloaded ammo in the M1A. I find that is simply a CYA or lawyer made statement.
Springfield Armory is stuck between a rock and a hard place. Liability lawyers make these statements necessary. The M14 design has a free floating firing pin, which it got from the Garand. SAI is not going to change the design of the rifle. Any deviation from "GI Spec" is negatively commented on by a small, but vocal group of people. You can see this in the debates of cast versus forged, and SAI decided to keep 8620 steel, instead of using a better grade of steel, not to anger the "GI Spec" crowd.
So, they are not going to change the design, and they don't control the quality of people's reloads, nor do they control the sensitivity of primers used in commercial ammunition.
There are so many people out there who cut mainspring coils, don’t replace old ones, leave grease on the firing pin (in cold weather) and then blame ammunition companies for the subsequent misfires, that ammunition companies use very sensitive primers in their ammunition. Some, like Federal, are proud to tell you that their primers are the most sensitive on the market.
While all primers meet SAAMI specs, SAAMI is a voluntary industry organization. These specifications are written so that no one’s product fails.
As far as commercial ammunition, I would not use Federal in a M1a or a M1 Garand. I remember the first year Federal ammunition was issued at the Camp Perry Garand Match. A slamfire occurred standing. Everyone heard it. The shooter dropped the round in his chamber, dropped the bolt, and the Garand slamfired in battery. Federal primers in ammunition, factory or not, are too sensitive to use in these rifles.
Unfortunately, in 1999, Winchester changed the color of their primers to a brass finish, and made the primers more sensitive. As much as I liked the old Winchester primers, I don’t recommend them for M1a’s/Garands. So I don’t recommend Winchester ammo for these rifles either, even though I have read of only one slamfire with Winchester ammo.
It has been said before, always feed rounds from a SLED or a magazine. Never drop the bolt on a round in the chamber.
I did have a slam fire with a M1 Carbine once. That cost me a bolt and a stock, no injuries fortunately. I hope never to have that happen again.
Be interested to read more about this. Was it with GI ammunition, was it feeding from the magazine?