1377 build........" El Cheapo "

[MountainMan126]

I tried 4 different types of pellets , will shoot and group all well. Does seem to have the tightest groups with CPHP which is fine by me. Also tried Superdomes, Daisy HP, and Skenco ultra shock hp. As I see it, if the lady is willin' ta drink NightTrain, ain't no good reason to get her hooked on the fancy stuff.

[MountainMan126]

Tried out the valve today, not a big success or failure. I ported the inlet, flattened the nose where it seals to the cup, reshaped the inlet seal to be dished on the back, added a ball bearing to take up space. Then shortened the stock spring, ported the exit chamber and shorten the stem that comes out the back. Installed with new piston and no leaks. unfortunately also chronied at stock velocity, I tried as many different combinations of new and old parts, ported not ported, short spring , stock spring , with and without the bearing. The 2 best setups are the stock piston and valve , and the ported valve with with stock internals. I have had this apart and back together so many times today I don't have any idea. 

[MountainMan126]

It appears I did have a small leak, has been repaired. Now I have the original piston , valve front and seal. Different spring inside and ported back end , with shortened rear stem. Sounds good when pumping, dumps all the air at 10 pumps, it won't do that now with the stock hammer spring. So I guess the disco spring is needed after all. Spring inside the valve is the one from the trigger originally, with the porting I also flattened the inside where it seals at the back and in doing so lengthened the spring area.

Trigger spring sits better than the one I took out, almost clicks into place on the valve parts at either end.

537 with superdomes / 545 with cphp

[MountainMan126]

Questions for anyone regarding the high pressure low volume set up. Is this really effective ?

 I have tried several set-ups now , all of which leak after the stroke is complete, and only after 3-4 full strokes in . If I had to guess it leaked out the way it came in. Do you guys increase spring tension inside the valve to hold greater pressure ? Mine had about 15lbs by the bathroom scale. At ten pumps would hold after the leak and shoot about 485 fps.

 Yes, I cocked it to relieve any hammer pressure on the valve, no it is not coming out the barrel.

 My current set up is a stock piston pump cup assembly. into a stock valve front with original plastic seal. Spring from the original trigger [stiffer, fewer coils] uncut, into modfied back and tail. This should have more volume than stock, but lower pressure with each stroke. Still shoots close to the same as the stock valve with everything else the same, barrel etc. at 10 pumps. Do I have reason to believe pressure would yield it greatest benefit in a pistol that lacks the barrel length to make use of volume?

 Finally we get to the BIG question , if I pump this 5 more times for a total of 15, in theory I am compressing 50% more air into the same space , which on it's own should have a significant effect on pressure, FPS 545 at ten pumps, FPS 581 at 15 , does not leak either way. Clearly not a 50% increase in velocity,I was not expectin it either, so how much does this actually yield when sealed properly.

I know their are some who claim in the 700-800 range with a .22 cal., I have been realistic and been shooting for these numbers in 177? Is it worth tearing down the gun again to see if the current spring will have a good seal on the older setups? I don't know if I have room for it at full length either.

I know this is a lot all at once, sort of thinking this is like a voltage without amps isn't all that dangerous . I guess I am thinking flat top, but really a longer stroke for greater compressed volume is the way to get big gains here I think.

[MountainMan126]

Anyone at all?

Either way I have a new plan in the works to get where I want to be. This one will take a little more time than some of my others, but I will keep you updated as there is info available.

[4th Yote Recon Bn.]

Hi All:

Mountain Man I just got back in town 15 min ago and I noticed you need the weight for a stock 1377 so here it is.

Weight 32oz (9.91kg). sorry I haven't read all the posts since I left got to play catch up later.

4Th Yote

[MountainMan126]

Hey 4th, welcome back .Thanks for the weight, means I have added 6.8 oz so far, not bad all things considered. There is still a little more weight coming before it is all over.

[4th Yote Recon Bn.]

Hi All:

Mountain Man caught up on post you are doing some great work. I got a question for you Pg3 you say that you are still getting a loud crack when shooting ----- would two drill holes in the muzzle brake just in front of your barrel quiet it down. I think the air pressure just behind the pellet would vent before exiting the barrel Might help. Last question where did you get the derlin stock and how much is it.

 4Th Yote

[0351_Vet]

4th Yote Recon Bn.

Love that Name......

[MountainMan126]

Thanks 4th yote, I think the difference in noise may be from the front cut on the brake. It is straight across , not beveled at the edge like barrel when I re-crowned it. Holes drilled may help noise wise, but I also would think may have an impact on POI if not done properly.

Does anyone use or make different hammers or do we all just change springs?

Ethan

someone else put this up already but it is a good resource.

http://www.onlinemetals.com/merchant.cfm?id=203&step=2&top_cat=181

[4th Yote Recon Bn.]

Hi All:

 Vet thanks I like my name as well. Now back to business Mountain Man about your hammer would polishing and adding lightening cuts or adding drill holes help take off weight to make your hammer lighter ??


 4Th Yote

[MountainMan126]

Definately would be lighter, I don't know what material is used for these. Looks like some type of steel maybe. It would have to be fairly hard to smash that chrome pin in the valve without damaging the face of the hammer. Also I think if it were shorter, allowing for longer spring travel might be good too. Not so much a weight reduction, but a longer path and spring to be able to push it harder without maxing out the compression rate. Maybe easier with a longer power adjuster too.

[4th Yote Recon Bn.]

Hi All:

Mountain Man you could try a longer power adjuster it might help. I used a 3/8x1/2" set screw and I have it backed out to a full 1/4" with plenty of adjustment left.

4Th Yote

[MountainMan126]

I was thinking the adjuster itself and not just the screw, making the overall length of travel greater.

[4th Yote Recon Bn.]

Hi All:

  Mountain man Mellon air has them for $8.00 w/ no shipping fee you could try that to see if it works better.

 4Th Yote

[MountainMan126]

His stuff is good , That is what is on the one in my sig. down below. That rifle is shooting superdomes at 625 fps. It has his "18 barrel, valve, and flat top piston too.