Yesterday's Weapons Forums

Thanks a bunch, Steve. I'll get something working here, soon.

Murderer? LMAO. I tell the grouse and walleye thank you very much for the sustenance you provide...

At any rate, center photo is the rear of the trigger group on the 20-78. That wedge shaped screw is the pull-weight adjustment. Tiny screw to the left is the over-travel stop screw. There's another tiny one above it that adjusts sear engagement. Awesome trigger, for it's degree of control, and clean let-off. It's a two-stage as well...

Regards,

Doc Sharptail

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"Ain't no Half-Way" -S.R.V.

"Oh Yeah!.....All Right!" -Paul Simon

My bad... our favorite grouse and walleye inviter home for dinner guy. SW

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Slava Ukraini!!

All in jest, Hogger! I knew it was all the way around.

Let's try this again, and see what's up in the world of High Pressure Air/Pre-Charged Pneumatics





Preview shows this is much better. Strange what can be accomplished with the windows help button

Regards,

Doc Sharptail

_________________
"Ain't no Half-Way" -S.R.V.

"Oh Yeah!.....All Right!" -Paul Simon

Evil twins!



Good things are happening, especially with the top rifle, and it's 3000 PSI tube. I'm getting 10 reliable shots in the mid 700's at 2000 PSI with an 18.1 grain pellet. My friends on the a/g forum tell me I'm about 200-400 PSI away from the efficiency curve- I should be able to get over 20 usable shots from a fill. Come to The Dark Side. We have velocity, and efficiency

I just had to do it. I ordered in the replacement 20-78 stock for the 78-D (bottom), like I was threatening to...

All this opens up another can of worms! (As if I needed it!) I want to do 2 more builds- another in .22, and one in .177 for shooting indoors...

But! I'm going to be ready this fall, oh yes. Come end of Sept., fire up the cast iron. There's gonna be sharptails and ruffies to eat...

Here's the power source:



Not a lot different in principle from what Louis & Clarke had on their trans-continental expedition. (some argue it was a bellows pump they carried, which I find hard to believe)

Regards,

Doc Sharptail

_________________
"Ain't no Half-Way" -S.R.V.

"Oh Yeah!.....All Right!" -Paul Simon

Nice looking air guns.

I used to rent from and help out with a scuba shop owner. He always pumped the cascade system to 3000# just to get 2250 in a tank.

Rad

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NRA Benefactor Member
AMA Life Member
Tri-State Gun Collectors Life Member

Yes, it's safer to step-down, than direct fill a large volume like a SCBA tank. I'm guessing your scuba shop friend has a water cooled system.

I think I should just barely be able to fill a 9~13 ci bottle with that pump. Any volume bigger than that is beyond the physical abilities of the pump...

Regards,

Doc Sharptail

_________________
"Ain't no Half-Way" -S.R.V.

"Oh Yeah!.....All Right!" -Paul Simon

With a few tweaks: cranking up the hammer spring pre-load a bit, and a modest increase in fill pressure:

18.1 gr JSB exact @ 980-1010 fps 2200 PSI.

Which is a bit on the fast side for stability at reasonable hunting distances.

Ideally, I'd like to see the 16 gr Predator loaf along at the mid to upper 8's.

There are a few flies in the ointment. The factory valve stem seal was not designed for those kind of pressures. Have some delrin replacement stems arriving soonish via the great white stork...

There is much trickery underfoot with the other rifle- low pressure pcp, easy as pie conversion on the way... most likely will be .177, throttled back at the transfer port for a quiet indoor plinker. Details as soon as it's up and running. Too many airgun projects on the go all at once.

Incidentally, the Predator pellets are performing exactly as I had hoped for:



That expanded up to about .30 cal. Looks like it's all finally going to work out...

Regards,

Doc Sharptail

_________________
"Ain't no Half-Way" -S.R.V.

"Oh Yeah!.....All Right!" -Paul Simon

i get the impression thats every bit the rifle one propelled by gunpowder would be and then some