Re: Tight bore vs. regular bore
Guys, There are a lot of variables and just taking what you see form one or two or even three barrels is not conclusive data.
From what I see.
There is no real difference in barrel life between a tight bore or standard bore.
You should see a little more velocity with a tighter bore than a standard bore with the same load. But this is not a guarantee because of other variables.
What chamber reamer was used with what dimensions.
Talking about bore size is vague. When talking bore size you are really talking about 3 different areas. The bore itself (tops of the lands), groove size and groove width.
Also number of grooves has no real bearing on barrel life or velocity etc....I just haven't seen it. I've shot 2 groove, 3, 4, 5, 5R and 6 groove in calibers ranging up to .338.
A chamber with different throat dimensions etc....can make a difference also.
You could buy at one time 20 barrels from one barrel maker and out of those 20 two or three of them could run a little faster or slower than the rest and they could've been made as identical as possible from one to the next. A difference of even a 100fps I say is just the individuality of the barrel.
To get good data you would have to take say 10 barrels of a nearly identical bore sizes and the same number of grooves ( and the same groove width) and take another 10 barrels with the same number of grooves and groove width and make those 10 with a looser or tighter bore dimensions and run a test in controlled conditions and take the average of each 10 to see what the difference is. Now take 10 more with a different groove size etc....
The last two barrels I compared one was a 4 groove and one was a 5R. Both in 6mm Rem. chamber (with a slightly shorter throat than standard but the case dimensions where standard). Bore sizes where both tight at .236 and the groove size was .243. One barrel on average was 30fps slower than the other one. Again that small of a difference is not really conducive to say anything.
Later, Frank
Bartlein Barrels
