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All Springer/NP/PCP Air Gun Discussion General > Big Bore AirGun Gate

Starting a .308 ELR build

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Scotchmo:
Scott S, Cameron K and I had a good time at the Sacramento club long range match a couple weeks ago. Since then, I bought a Lee mold for a 300 Blackout. The as cast slugs are 1.36” long. I can fit up to 1.25” long in the latest build. I made a jig and milled .06” off each end of a bunch of the slugs for testing. The final length was 1.243”, and finished weight was 218gr. At 3500psi, I was getting 1018fps average for a little over 500fpe. That’s a milestone. I had some partial valve luck trying to go higher and got one stuck in the barrel. Took quite a bit to knock it out with the custom extra long cleaning rod. Accuracy at 100yds was not great (about 3moa), and neither was the BC. I suspect that those slugs are too much for the 1:10 twist barrel. I did a bunch more testing of the 151gr and 171gr BBT at 1020fps to 1060fps. Still getting no better than about 2moa average with this 73” barrel.

Took it apart when I got home and plan on starting on the piloted valve tomorrow.

rkr:
Shorter barrel gives better accuracy? I've had issues with long barrel and inadequate support, going for double CF tube around the liner and barrel band that very tightly attaches barrel to the air tube solved that. Any ways to stiffen your barrel more? Alternatively adding weight to the muzzle end could calm down the vibrations.

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