I bought several mcfarland rings when they first started advertising them on the old board several years ago, have never had any problems with them, except for, when I tried them on a Baer bolt a few years ago. All it took was about 20 to 30 rounds to start short stroking in my daughters' Bushmaster shorty.
I had called & talked to Les a couple of times before he fessed up to admitting plenty other folks were having the same problems, mainly F/A guys out west somewhere.
I couldn't get a straight answer about where the tolerance problems were, so I left it at that. I keep all of my GI bolts wrapped in slinkys & the Les Bears' in their 3 ring suits.
No problems since, I can't wait to see how well they work in the SEBR rifles, if they show up [red]THIS YEAR[/red]!!
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The only hope you have is to accept the fact that you are already dead. And the sooner you accept that, the sooner you will be able to function as a soldier is supposed to function, without mercy, without compassion, without remorse.