Home Stretch Now!

[sholo]

I shimmed the hammer spring by dropping a plastic nut and a thin washer into the the spring pocket on the rear of the hammer.

I think I'd like to try backing off on the hammer spring pre-load a little. The need for an RVA is becoming increasingly apparent.

Before I got my RVA, I use to adjust preload by simply adding/removing small S/S washers on the cocking block spring guide. IIRC, they were 1/8" washers - perfect OD for hammer spring, but too small ID to fit on spring guide, so I would put 4 or 5 washers together, clamp them in a brake line flaring tool and drill them out to correct size all at once. A bit of sanding with 800 grit s-paper to smooth out the rough edges/burs and you're good to go!

Add a couple to guide, shoot over chrony, then add more if necessary. At a thickness of .060" per washer, you can tune velocity to pretty much whatever you want


HTH,
Todd

[Doc Sharptail]

Bought some "Carbon" drill bits. They cut like nobody's business in the rear tube cap. Also put my new "Vermont" taps to work- both holes are 10 x 32. Found a piece of blue plastic, and cut off a bit, and dropped it into the set screw hole. Seems to work...




Neither hole is straight. I intentionally tried to angle the adjuster screw with a center-ward slant The set screw is off kilter too. I did these by hand, and it shows. I still have to figure out a way to rebate the "inside" part of the tube cap. I'm thinkin time to break out the diamond cloth again...

Regards,

Doc Sharptail

[Doc Sharptail]

I tried putting the "RVA" into the gun last night. I'm beginning to understand that this won't be a simple endeavour.

It works, sort of, with the rear cocking pin out of the rifle. Not too sure I want to get into all those other associated mods~ eg: cock on closing, or cut a rear bolt notch, and pin/spring and detent the bolt handle.

Back to the hammer spring pre-load washers for the time being. Re-located the washer system to the spring guide shaft. What's on there now mikes to .1652". I ran out of steam, and did not get to shoot...

I'll try tonight, and see if I've cut back on the power a little.

Regards,

Doc Sharptail

[Doc Sharptail]

Chart wizard works. just have to find how to imagize it...

Regards,

Doc Sharptail

[Doc Sharptail]

The more I think about it, the more sense having a small regulated bottle on the gun makes. An "a-ha" moment for me, yes. I'm betting there's a few around here wondering when I would get to it

Is there a bottle around small enough for me to manage with the Hill pump?

For my current set-up, a reverse tank block is gonna be the most practical way...

There's no big rush on this yet- I'm having a great time with the 3K tube. But I fear it will become one of those hard to scratch itches...

I'm thinking it will end up being easier on the gun, especially for the reduced striker spring pre-load, and I'm pretty sure lowering pressure on the gun side will be advantageous some how...

Regards,

Doc Sharptail

[rsterne]

I would think SeanP could make you a Delrin stem no problem....

Bob

[sholo]

I'm betting there's a few around here wondering when I would get to it

LOL...it was only a matter of time, Doc!

A 13 ci bottle reg'd to 1500-1600 psi should work nicely for you. IIRC, it takes me around 255 strokes from my Hill pump to fill from 0 - 3000 psi (85 strokes per 1000 psi +/-). This was using a 30" S/S hose from Eric, but if you are using the shorter fill hose that came with the pump, you can knock a few strokes off that total.

Granted, my '78 is .177, but with a full 3000 psi shooting down to 1500 psi using a 13 ci bottle I am getting anywhere from 108 shots @ 16.7 FPE to 510 shots @ 3 FPE, depending where I set the RVA...

Bob has thee best looking/functional reverse tank block I've seen by far, but for us guys with no lathe (and in my case - the smart's to make such a block) this might be an option for you? http://www.canadianairguns.com/showt...-AR2078A-stock , although the 3K tube is longer than a stock one so it might make it more "nose-heavy" as a result.

Hope this helps somewhat, or at least give you some food for thought! Good luck scratching that itch!

Cheers,
Todd

P.S - Plus, if you running 1500-1600 psi as opposed to 2000 psi (or higher), your factory valve stem seal shouldn't give you any problems. I've had my gun pressurized at 1500 psi for about 1 year now with roughly 3000 shots through it with no problems at all.

[Doc Sharptail]

I'm currently @ 37-42 pumps on the 3K tube: 2400 on the pump gauge-22-2300 in the gun by my calculations.

Depending on how my back feels, and how tired I am, I sometimes take a 5-10 min. break around stroke #20. Not always, though. On a good day for me I can fill the gun non-stop.
By what I'm reading here, I'll probably need 3, maybe 4 rest breaks filling that 13 ci bottle from empty. It should get easier than that, after the initial fill. I don't shoot the gun right down when I'm shooting strings- I'm guessing I refill around the 1300 psi mark- which = around 12-17 pumps or so.

I suppose the only way to find out is to try. Mean-while, I have a bit of pellet work-up to do... haven't had this much fun since discovering the "finer" things.

Wonder what Freud would of made out of perusing this forum?

Regards,

Doc Sharptail

[Doc Sharptail]

Was shooting the gun down tonight, so I could get the breech off. Last shot before empty tube, something goes "toing". It was loud enough to have me thinking hammer spring. Gave the gun a shake and no rattles.

Went ahead and did the t.p. Put the gun back together, and pumped up to 850 psi. Another leak at the breech. Kept ripping bbl o-ring #1, and replacing it. I had been dipping into the wrong o-rings compartment - they were too big/loose, and rolled out of the groove too easily, and ripped themselves on that first edge going into the breech. Finally got the gun to no leaks at 600-850 psi. Back up to 2200 PSI, and I'm back at the lemming leap for strings. I bet it's that hammer spring- not surprising considering all the over/under compression I've been putting it through.

Enough for one night. I'll have at it again tomorrow night...

Regards,

Doc Sharptail

[Doc Sharptail]

Got the top end to where it doesn't leak. Gun now leaks from the valve stem on firing @ 1500 psi and below. I don't have any curve to my strings, either. Top of the string isn't bad- the first ten shots decline about 10 fps for each shot. Over-all velocity is down about 200 fps for the hammer spring pre-load I'm using.

I'm going to have to leave this, until I can get a couple of more replacement valves in. Apparently, 2200-2400 PSI is enough to make the stem seal flow/extrude...

Regards,

Doc Sharptail