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Old 25th August 2016, 10:02 AM
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RobF RobF is offline
My Empire of Dirt
Join Date: Mar 2010
Member of: Southampton Buccaneers, Parkstone, South Dorset
Location: Poole, Dorset
Posts: 10,168

Nice to see some consensus...

Phil skimmed a seal yesterday and we developed the TTT. Two Tin Test. We found that was consistent over the chrono from 38 degrees down to 22.5 degrees. Same seal, just not so tight as original. Equates to about 600g deadweight to get it moving. We're not sure if less would be better... we didn't try it... at some point the losses will be due to the seal not sealing... but we now think the seal can seal too well and friction becomes the enemy. With the apparent swelling of a seal, the friction has more effect than the seal and the power drops.

We've got a couple of comp tubes which have had some treatment which have bore consistency better than 0.005mm down them. Which is better than some of the standard ones which have had variations of more than 0.2mm.

So the gun is back together, and locked down at 770 with Exacts.

The idea is that i'll just be shooting this when I see a temp change and noting any POI and speed changes. We're running it fairly dry, so there's no lube consumption to deal with.

Odd thing was after this, the batch that shot well shotgunned, and the one i rejected was much tighter. It was that dramatic that I thought i'd taken the wrong batch out to Portugal, but then I remembered putting in some fairly tight groups. Sat beside Calps one day for windage (because that seemed to move with the POI shift)

Shot Jon Budd's 22mm on day 3, which has super small sight picture movement (like a walther PCP) and was consistent all across the day. Only catch was it ran at 8.9ft-lb/689 so my windage estimation went a bit do-lally, and i had twice the clicks out to 55. So like shooting a .22 springer. But if Brian and Jon can get it up to 750 without affecting either then they'll be onto something.

Back to PCP for comps now. Honest!
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