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Old 11-05-2012, 02:28 PM   #1 (permalink)
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greystone's Avatar
Join Date: Dec 2009
Location: Tucson, AZ

Absurd Halfblock Inconsistencies

I am having issues with a halfblock I built, trying to get it to shoot consistent velocity. I can get it to shoot consistently around ~320 fps, and consistently around ~240 fps, but no where in between. When it shoots around ~320, I'm getting enough blowback to break all the balls in the feedneck. Using a Jcurt bolt.

I have sweetspotted the regulator, have adjusted it higher and lower. Tried running a stock valve and stock slotted hammer. Tried a heavy slotted hammer, it became more consistent, but started randomly venting the valve every few shots.

Using a freshly rebuild Torpedo that works fine on another fullbody pump cocker. I've swapped valve and spring setups from another working fullbody pump, with no avail. Tried blue valve, green main. Tried stock valve, green main.

Anyone have any setup combinations that work for them? I have a plethora of valves and springs available - have almost every variation of stock WGP valve, in addition to Tornado, Shocktech, DYE, ANS black and others.

The internal combo and regulator was extremely consistent before it was halfblocked.

I've tried underboring the barrel with fresh, matched paint - as low as .676 - still horrible inconsistency.

Driving me nuts. I have 5 other pumps that I have built from scratch, but this one is getting the best of me.

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