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All Springer/NP/PCP Air Gun Discussion General > "Bob and Lloyds Workshop"

.458 big bore mule test bed project (video added)

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lloyd-ss:
This is the start of a thread about my big bore mule test bed.  It's been around for a long time, in a lot of configurations, and done a lot of things.  I just put a  .458 barrel on it, but its had everything from .25 to .510 on it . The hope is to optimize that barrel and bullets for this gun.  It's a process i have never really been through, and it will take a while.
This first entry will just have some basic info.

The barrel, which is actually a chrome moly barrel liner from Mike Sayers,  is .458 groove dia, .450 land dia, 5 grooves, .065 land width, .220 groove width,    1 in 18 twist, 36" long. It's O.D. is 5/8", and it is sleeved and tensioned in a 1" O.D x 3/4" I.D. aluminum tube.

To begin establishing some sort of baseline, I took a number of low pressure, low power shots across the chrony to get a feel for where the gun was at.  That data will be forth coming.

I then took 4 low powered shots with 143 gn .457 dia round balls at a cardboard box set at 38 yards. All the round balls measured .457 on the average, but were terribly egg-shaped from .453 dia to .460.  I'm sure that did not help accuracy.  The target is a cheesy setup because I didn't think it was going to be a keeper.  The shots were all done at 1200 psi, the dwell time was set fairly low to hold the velocity to about  650 fps.   The 4 shot group measured 1.50" C to C, so there is lots of room for improvement, but not terrible for a first time out.

More to come.
Lloyd

38 yd target. Lots of room for improvement.


Backside of the same target to get a better idea of the group.


The mule with the 36" .458 barrel. She's all business, and had a rough life.
6X A.O. Leapers Bug Buster.  279cc tank


The brains

Guam Airgun Shooter:
Nice work, gratz. Whats next? larger air res? higher operating pressures? keep them coming.

rsterne:
I will be following the thread with interest.... Lloyd has recently prodded me into considering a .458 barrel for my Hayabusa project eventually....

Bob

dk1677:
Looking good Lloyd!

melloroadman:
Lloyd so I have a clear understanding and can follow this correctly . Can you give some more info on the rifle . From what you have said I believe the psi can be set electronically . And the dwell on the valve as well . Is the dwell time totally capable of not being affected by the weight or friction increase or decrease of the bullet ? Is it capable of measuring the consumed amount of air per shot as well?Also is there any control over the port size or is it fixed ? Marvin

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