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

.30 Cal Marauder

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Jzizzle:
This is something I have been wanting to build for a while.  I finally got all the parts in and began to assemble everything.

Parts list:

RAI Chassis
RAI Air Tube
RAI Drop Block
RAI Trigger Guard
Don Cothran Valve
Hill Valve
MDS Hammer
Peek Striker
OEM Trigger Assembly
Hill Spring Guide
Hill Tube Cap
Hill 22" Shroud
Hill Shroud Mount Kit
Hill Depinger
Hill Baffles (4)
Hill 12.5 lbs Hammer Spring
500CC CF Bottle and Regulator
Ar15 Houge Grip
AR Buffer Tube
AR Stock
Carm Magazines
30 cal 20" Barrel
30 cal Bolt Sleeve
Side Lever Breech
Donny FL Ronin
Wika Gauges

Original plan is to run the Cothran valve with .234 tp and barrel port, but I don't have the right adapter yet for the valve side.

First testing with the Hill Valve.  Hill port is at .2.  I drilled out the barrel to .2 and using PTFE .2 ID for TP.  Any larger will require tube and breech to be opened up as well as machining larger flats.

Reg set to 2500 psi.  Minimum hammer tension.

44.75gr slinging at 870-880 fps.  Any increase in hammer spring tension gives no increase.

This . 2 porting is definitely the restriction.

Next steps is to either wait for cothran adapter and swap the valves or machine the flat larger on the hill valve for a bigger port.  Either way I still need to machine the flat on the barrel too.


Overall, very satisfied with the rifle now that its all together. 

Jzizzle:
Looking good

Jzizzle:
Other side

Jzizzle:
I'm thinking to increase the ports thru out to either .218 (7/32)   or    .234 (15/64)  This should allow me to lower the reg setting and tune for ~930fps for JSB 44.75. 

FuzzyGrub:
Looks great!   8)

I see you have one of the new style Exclusive breechs.  :)

I noticed in your parts list the Hill Depinger.  Were you getting ping?  Typically, using a reg will eliminate ping, but haven't done any shooting yet with my BROD project, to know if that large of plenum can create ping or not.  Assuming it i installed up against the valve, I'd be concerned that it may also be a bottleneck

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