6BR Barrel with .050 more freebore

[JBattles]

I started shooting 6BR on an MPA chambered barrel a couple years ago and it shoots Hornady 108s great with .035 jump. I just got an AI AT-XC and put a Mile High Factory WinTac 6BR barrel on it. When I measured the AI barrel, it has .050 more freebore to the lands that the MPA barrel. I haven't seen this with other calibers when getting different barrels, they are all pretty close, but .050 seems like a big difference. I used the standard OAL tool to find the lands on both barrels with the same bullet.

Anyone run into this before - these are both very high quality barrels and smiths? Is there a 6BR variant that is shorter and longer? I am planning to load for the 2 rifles differently and run the AI rounds longer to make up the difference.

Hornady 108 ELDM
MPA - 2.350 OAL to Lands
AI - 2.400 OAL to Lands

 

[Mike Casselton]

I've seen 6-BR barrels from 0 freebore all the way to .200.
It just depends on what reamer was used, and the purpose of the barrel.

Personally, if I'm never going to shoot short, light bullets, I'll take as much freebore as I can get in the BR.

They feed better and you can add a bit more powder to help with velocity. Just don't go crazy trying to get speed out of it.

I have a barrel with 5290 rounds on it. To reach the lands, the 112 Barnes won't fit in my MDT BR mag.
The 105s will though.
It does feed extremely well in the 5 round plastic Magpul mag.



From a rickety-assed wooden bench, it'll still do this, so I'm gonna keep using it until it completely dies off.

I should probably try it from a concrete bench or prone to see what it is still capable of.