Just to clarify,gota new battery for the Mahr digital caliper.Thomas M4's specs are also what Ive got on the Midway/DPMS Mcfrarland rings,.5030" on the money.Confirmed with a old Fowler dial caliper and also got .503".
Later I'll pull one of the bolts and see what a used Mcfarland measures just to be curious..
ETA
I pulled two of my LMT bolts with McFarland rings.One is .4970" and the other is .4985"....round counts on each is approaching 3,000.
That said the rings have worn in but still offer enough tension that they will pass a standard gas ring inspection.Certainly not loose.
As a note one of the LMT carriers has a rather loose bore compared to the others I have(particularly at the bolt tail),and it varies from carrier to carrier to a certain extent.
Of the carriers I have,the Armalite and DD have the tightest,smooth and most consistent bores of them all(per feel and eye ball),both in the gas ring chamber,bolt tail and bolt bearing band surface.
So yeah I can see there is a variation in the carrier bore diameters,and finish,in the samples I have on hand.
Last edited by Blankwaffe; 02-27-10 at 22:28.
Reason: ETA
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