H135 bore mapping and associated issues

[Toxylon]

Had a chance to chrono my H135, which now sports the custom rear guide gifted to me by Mikey. Seals, lubrication, mainspring etc. are exactly the same as before the guide switch, as I didn't extract the piston and didn't change any other part (and re-crowning doesn't affect velocities).

The gun shoots:

 Exact 25.4's at 215.1 m/s  / 706 fps, for 38.1 J  /  28 fpe

FTT 20.06's at 240.0 m/s  /  787 fps, for 37.4 J  /  27.5 fpe

Polymag 16's at 215.3 m/s  /  706 fps, for 39.0 J  /  28.7 fpe

Exact 16.54's at 270.7 m/s  /  888 fps, for 39.2 J  /  28.8 fpe



So, Exacts lost 22 fps  /  1.7 fpe, FTT's lost 20 fps  /  1.4 fpe, Polymags lost 23 fps  /  2 fpe, and the lead-free Exacts lost 29 fps  /  almost 2 fpe, over the exact same gun with the factory rear guide.

It's a little annoying in that the 135 is no longer a 40 J magnum, but objectively, this is no biggie.

The shot cycle with the new guide is more linear than before, but the difference in quality is not that great, after the gun had completed breaking in with the undersized OEM guide, which is suprising. There's still some twang, which is fully expected, as the used OEM spring was a little loose in the new guide, too.

Haven't had a chance to try the gun for accuracy yet. Expectations are low, of course, with the sieve-quality barrel.