Home Forums Hunting & Shooting AR and Tactical Rifles AR-15 bolt / bolt face sizes

I know the 223 and the 300 Blackout use the same bolt size.

I know the 6.5 Grendel and the 50 Beowulf use the same bolt size.

I know the 6.8 SPC and the 30 Rem AR use the same bolt size.

What bolt size does the 458 SOCOM and the 450 Bushmaster use, and is it the same as one of the above?

The original AR-15 rifles in .450 Bushmaster utilized a standard .223 bolt, which was modified by increasing the bolt face diameter to a nominal .473 inch, with the low pressure cartridge.

IIRC, the 458 SOCOM still uses the same size bolt face as the 450 Bushmaster.

So the bolt face for either is different from the other 3?

I would like to buy a mid size caliber for my AR for deer hunting or medium size game. I like the Grendel over the 6.8 SPC because it has better hitting power downrange and is supposed to be a little more accurate.

I would also like to buy a big bore and sine I already reload for the 45-70 was thinking about the 450 or 458, and not go the 50 Beowulf route.

I was also trying to cut costs by using the same bolt for the two larger cartridges if possible.

Interesting. I think the 6.5 and 50 use a .450 something bolt face and the 6.8 and 30 AR use a 429? bolt face I think.

So if both use the same the 458 Socom would be the better route because it uses actual 45-70 sized bullets with no swabing. The 450 requires a slightly smaller bullet diameter.

Wonder what kind of power you could get out of a necked down 458 to say 30 caliber? More case capacity

I know Olympic makes an upper using the 25 WSSM.

With 2 million AR's being sold a year, (as of 2011 statistics and over 8 million total guns sold that year), other adaptable calibers will eventually be sold to push them for hunting. That helps shut up the liberal media.

Yes, the 450/458 are 5.56 bolts opened up to a .308 bolt face with thin walls. From what I understand from reading, the length of the action for 5.56 guns, prevents using a larger .308 AR bolt.

The 6.8 bolt is similiar in the opening of the bolt face, but a bit thicker wall and higher pressures.

IIRC, the Beawulf uses the 7.62 x 39 bolt.

Oly is also making a .22-250 AR as well. I think we are about to see a surge of high power cartridges as the next wave of ARs.

actually all bolts are 223 bolts, basically, just opened up to fit head size.

Saami search will give you head size on each case head.

What would be the correct size for a .308? are the faces just opened on a lathe to a measured ID? does anyone possibly know this dimension that i could machine?
thanks

.473 +/-

The .308 Winchester and like cases use a completely different sized bolt than an AR-15.