I bought a Springfield Armory 'loaded' M1A in 1986 for shooting our club's 100yd reduced service rifle XTC HP matches; it came with a rather inexpensive 1907 leather sling that I had no clue how to properly rig. Shot that rifle until I'd shot the bbl out in1996, then set it aside and started using a Colt AR15 HBAR, then bought a CLE SR upper with Douglas SS match bbl, and IIRC, a Bushmaster lower that I put a CLE match trigger in.
Bought a good Turner quality leather 1907 from Champions Choice for use with the CLE upper - it was a much better sling than what the M1A came with. After I'd shot the Douglas bbl on the CLE upper out, I bought a new Krieger barreled upper from White Oak Precision, and sent the shot-out upper back to CLE for another Krieger, so I'd always have a fresh bbl on my main match rifle, and could practice with & shoot the oldest bbl in the 100yd matches, while using the freshest bbl'd upper in 200/300/600yd matches.
I'll never forget shooting the leg match at the New Mexico Regional HP matches at Whittington Center in 1997 - the wind was howling so hard that I thought they'd call the match, but nope - we kept right on shooting, even after the wind had broken a target frame. I was struggling to get my old sling rigged during prep time for slow fire prone at 600 when a Gunnery Sergeant who was there shooting with the 29 Palms Marine rifle team saw that I needed some help took pity on me. He was looking my sling over, trying to figure out why it didn't look right, and realized I had it all backwards/inside out, whatever, about as screwed up as it's possible to do. After he'd rigged it correctly and helped me get it adjusted, I laid down with that 1st CLE upper and shot a 186-?x in that wind. That's a lousy score in today's world, but was the best I'd shot at 600 at that time, and I wound up earning my first 6pt leg that day.
After I'd finally legged-out & earned my Distinguished Rifleman Badge, I contacted Leslie Tam in Hawaii, and had him make one of his fabulous 1907 slings out of premium harness leather, with actual old brass 1907 hooks, with copper rivets, and with my DRB # & initials stamped into the leather, along with the year it was made - 2002. Never seen nor heard of a finer leather 1907 sling, and was fortunate enough to meet & visit with Les at the Tulsa Show in 2003.