Sig Cross: Proof Research Prefits

[Rambling Yeti]

Bump

 

[glassing]

I ended up going with the Proof 18" Carbon barrel. I'll report back once I have it and put some rounds through it.

 

[Rambling Yeti]

Here's an interesting very small data set. I recently swapped my 16" factory barrel on my 6.5 CM cross out for a 20" Odin works pre-fit. and a brake. I swapped the barrels myself. I was expecting the 'standard' increase in muzzle velocity. My 16" barrel averaged 2560 fps with Hornady 143g ELD-X. I put a few rounds through the 20" barrel yesterday and the velocity only increased to 2599 fps - i.e. only a 39 fps increase in muzzle velocity. I feel fine about the barrel swap, followed along on the internet, gauged it, rifle performed as it should.
It's a small sample size with the new barrel. I asked the internet and AI tells me that it might be A) diminishing returns on the powder burn from the factory load in the longer barrel or B) new barrel needs to be broken in more and that friction is slowing the bullet and I can expect increased fps after a 'few hundred rounds' when the barrel 'gets smoother.'
I'd honestly expected the standard 25-50 fps increase with the longer barrel and I was pretty surprised when I didn't get it. I used the same chono, weather conditions were pretty close, etc...
Any thoughts or insights from the forum?
I'm located on Oahu and decent ranges are limited, I'm using a back woods range, ammo is relatively more expensive here. Based on these limited results I'm ready to swap back to the 16" barrel or put on an 18" barrel. Putting that long barrel on the cross, without a significant increase in fps, negates the positives of the cross being a compact and easy to carry rifle.