Barrel Length Query

[NugginFutz]

I recently shot some proof loads in both my 18" BHW and 22" BHW. I shot the 123 AMAx through both, with CFE223 and IMR8208XBR. The 31.5 gr of CFE drove the 123 through the 18" barrel at 2509 fps, whereas the 22" barrel achieved 2647 fps. With 28.0 gr of 8208, the results were 2409 fps for the 18" and 2524 fps for the 22" barrel.

Code:

Temp Powder Charge 18" 22" Diff 81 'F CFE 223 31.5 2509 2647 138 81 'F IMR 8208 XBR 28.0 2409.2 2524.4 115.2

With the CFE 223, I had a little more headroom, but ES was degrading. As with the CFE, I had some additional headroom with the 8208, but OCW workups showed no reason to go any higher.

Long and short of it is that Apples:Apples, the 4" of difference the two barrels gave me an average increase of 126 fps. Extrapolating, another 2" for the 24" barrel, it could offer an additional 60 fps, for a net of ~185 fps.

Also, it looks as if the CFE benefited from the additional length more than the 8208 did. I suspect that this had something to do with the 8208 burning faster than the CFE, but I have no other data to support this hypothesis.

So, should your shooting abilities exceed the reach of your current 18" setup, it looks to me like an additional 4-6" of barrel can up your MV between 115 - 207 fps (using the above loads as a baseline).