New Barrel Velocities

[Schwag173]

I shot my brand-new 18" 1:8 Lothar-Walther barrel this morning along with my 16" 1:7.5 AA barrel. The latter has about 1000 rounds through it. With identical ammo, my chrony showed virtually identical velocities out of the 18" as with the 16," and 50-80fps faster out of the 16" with certain powders. My question: After it gets worn-in, will the 18" velocities creep upward and better the 16" a bit?:confused:

[stokesrj]

My experience, with a match quality barrel, they pretty much stay the same from first shot until the throat is so worn you no longer care. But I have seen identical barrels vary by 200 fps so it is entirely possible to have overlap between a 16" and an 18".
Bob

[LRRPF52]

When I was talking about barrel length and velocity change with Bill A., he said that the 16" and 18" produce nearly identical velocities for some odd reason. 20" and 24" are also very close to each other, but there is a drop from a 20" to a 16".

I've been very happy with the 16" Grendel velocities myself. My initial loads all followed the AA published data, and I averaged 18fps per inch of barrel length difference from the 24" velocity data, but the trend is not linear, so the curve starts to dive the more you reduce length, but the dive is still shallow.

[Drifter]

Among other things, the design of the barrel's rifling, tightness of the bore, size and position of gas port, and burn rate of powder are all factors that can affect velocity outside of barrel length alone.

[JASmith]

You can see the trends here: http://www.65grendel.com/forum/showthrea...d-Velocity

The software used to generate the curves was calibrated largely with the AA data so fidelity for the Grendel is pretty good.