Mate, truth is even the experts argue about it. Some reckon that the figures quoted for 7.62x51 NATO (The NATO bit is important) and .308 Win are iffy anyway (near identical) but are just measured in different ways. Yes the 5.56x45 chamber does have a longer leade but there are other chamberings, Rock River (Wylde Chamber) and Armalite, along with others.
One of the real UK issues used to be people sticking factory 155gn .308 loads through the old enfield actioned target rifles. A lot of these were designed for .303 with a single rear locking lug, and tight bored to deal with the 144/6/7 grain FMJ .306 bullets in issues L2A2 ammo, so they shot better but were weak to start with. The enfield action as was is weak, like it or not.
Stick a full spec .308 up one and you may well get a nasty surprise down the line. On the other hand my old M67 had a chunky 3 lug Mauser action in it and took abuse. I used it for FTr and it is still shooting 1MOA off the elbows.
The main idea was that the mil spec chamber would take and fire anything with the NSN mark on it to a required performance (the little circle with the cross in it). If it does not have that, it is not designated 7.62x51 or 5.56x45 NATO....officially. SS109 spec. The yanks have muddied the water with the M855A1 that has a steel core and copper jacket, goes like stink, would be banned at Bisley (as it does not break up) and is a barrel burner as it has to be blown along like stink. Then there is the Mk318 that is more lethal from a short barrel and better for penetration, looking like a match round but isnt, then you get the BH Mod262 match round with its 77gr bullet, that is being used in the field....and so it goes on.
Even our chambers get hot and can be a bit sticky so imagine the fun with an M16A2 or a Minimi. I am just about to have a .308/7.62x51 NATO rifle built. I have a 7.62x51 slot, but will be putting .308 Win and 7.62x51 through it (all handloads as it goes and possibly some surplus). I have a 7.62x51 slot so go figure. I am told it will be .308 Win proofed anyway.
Chambering in the military stuff is usually to allow for the same dimension ammo but possibly with slightly more generous tolerances for dust, oil and dust, oil, heat, water, friday afternoon on the ammo plant, captured local non spec ammo....moths...camels....bricks....yanks having good ideas.....all the usual shite that gets in chambers and shouldnt...and keep firing
Originally Posted by Parabuteo
Mate, truth is even the experts argue about it. Some reckon that the figures quoted for 7.62x51 NATO (The NATO bit is important) and .308 Win are iffy anyway (near identical) but are just measured in different ways. Yes the 5.56x45 chamber does have a longer leade but there are other chamberings, Rock River (Wylde Chamber) and Armalite, along with others.
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