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

[4th Yote Recon Bn.]

Mountain man:

Good pix of the adjuster but now I have another question. Having just got back from the hardware store I got the 3/8x16x1/2 set screws. They have a taper to them already so this means you ground off more on the set screw to match the opening of the spring. Why wouldn't it be easier to put a small flat washer in front of the set screw and make adjustments that way and not worry about deforming the end of the spring.Would this increase power a bit more,being able to compress the spring more with out spring damage

4Th Yote

[MountainMan126]

The taper mine has I thought was sufficient, and did no additional grinding or shaping of the point. Just got done installing the new bolt. I think it shows a modest increase in FPS, but numbers are still fluctuating. My guess is the ammo will be differnent once I run through a bunch of different types of lead and find the one it likes best.

Best with new bolt was 518

[MountainMan126]

518 FPS was a fluke, I don't think I pumped it an extra time or anything . However I have been getting much more consistant numbers. Getting it down to an aver. of about 495 with +/- 3 FPS either way. Next is goiing to be the valve and piston install, I am hoping for major improvement with these parts. I will not have time to do this until tonight or tomorrow, as I must go to work at some point.

[MountainMan126]

Plan change , when I ordered the disco hammer spring for my first build, I bought second in case. If that one wore out at some point or I did a second build and wanted the same option. Well I found where I put it this morning, so that will be the next thing. About 2 bucks direct from crosman , plus for $4 in ship/hand and whatever else you put on the order. I will swap that when I get home and have to re-chrony in the morning . I need daylight for that , and am not set up do any of that sort of testing indoors.

[MountainMan126]

The disco spring is the one on the bottom , nice easy change with the adjuster. Just pull the screw , drop old spring out the back , add new one reinstall the screw and done.

[Muppit]

mountain id you used a longer screw in the adjuster i would put more load on the spring, we used to do this with our paintball guns and the refs at the field found out would not lut us use them and we had to take the longer screws out. ....

[MountainMan126]

mountain id you used a longer screw in the adjuster i would put more load on the spring, we used to do this with our paintball guns and the refs at the field found out would not lut us use them and we had to take the longer screws out. ....

Having a longer screw will only have more hanging out the back, not give you any more adjustment from what I can tell. I have done chrony testing with this screw in all positions with the stock spring with no legit. change. I don't think the stock spring is strong enough against the air pressure in the valve at 10 pumps.

Tonights work is a smoother , lighter trigger. Original spring is in the pic on the right. I used the front tapered section from a click top bic pen , cut both ends with razor, turned the brass thumb screw with smooth top [8/32 thread] through the middle and trimmed flush with a dremel tool. I cut a lighter weight spring down to fit , a little fine tuning and it is done. Tested several times , feels nicer, and maybe a little more than 1/2 the original weight, but I don't have an accurate way of measuring.

[MountainMan126]

Chrony testing with disco spring reveals no significant change in velocity. I think next maybe the barrel, and then the valve and piston. New trigger work is sweeeeeeet!!!!!

[4th Yote Recon Bn.]

Hi All:

 Mountain Man again nice work. Its a shame that the disco spring didn't increase anything.I to did some trigger work on my 1377 and went about it a little different. First went to local hardware store and got a #90 spring then cut 5/16"off the end then inserted a spent 22 cal. case inside the spring and put it back together. This made for a smoother trigger. I Then drilled a #29 hole in the trigger guard and tapped a 8-32 set screw to make a trigger stop -works great with no backlash from the trigger.

 4Th Yote

[MountainMan126]

Very cool 4th yote, do you think the 22 being flat on top is an advantage? In comparison to mine which is rounded. Today I drilled out the barrel band and added a 16" at home recrowned barrel [face could be polished more]. I will clean and test fire tomorrow. I ran out of time having to take some time to skin a beautiful black squirrel I took this morning. Fleshing when I get home and into tanning solution.
Anyway here are the barrel pics, hole is drilled to what I think is a perfect fit. So snug I didn't use any adhesive. Drilled from the backside into a maple block with a colt fluted bradpoint 7/16 drill bit.

[4th Yote Recon Bn.]

Hi All:

Mountain Man I don't know if there is any avantage between your and my set up.I went with the 22 case just because its flat and has more contact surface,its cheap to replace. Nice job on your barrel that is my next step on my mod list but got to wait till MellonAir has them in stock. I figure a nice 14.5" barrel w/muzzle brake should get me a least another 8 FPS.

 4Th Yote

[MountainMan126]

Hey 4th yote, many thanks on the trigger stop mod. I did mine tonight as you suggested, drilled the hole [gettin' by with a 1/8 bit, do not own a #29] and tapped 8-32 . Installed a stainless set screw, a dab of blue locktite, a little fine tuning to get it set to stop the trigger movement right after the shot breaks. No more over-travel after the shot, and I thought the trigger was good before, what a difference. I will let it cure over night and shoot tomorrow.

[MountainMan126]

All right , got up , got the chrony, gun and ammo. New test results are as follows with the barrel. Previous was about 495 FPS, all other factors the same except the barrel, finally gettin' somewhere!!!

10 pumps
CPHP 7.9gn

Average=548.5 FPS
Standard deviation=2.0
FPE=5.27

Noise out put is greatly reduced with longer barrel. I also believe I may see greater effects from the power adjuster since now I have the barrel length to use any extra air released from tightening the hammer spring adjustment.

[4th Yote Recon Bn.]

Hi All:

Mountain Man glad you liked the trigger stop mod. Now I have to go on a little tanget about the power valve. First you weren't looking to increase FPS or FPE right. What I thing you are trying to do and tell me if I'm wrong is to put enough pressure on the hammer to remove any gap between the hammer face and the valve stem face.This I think will dump the compressed air faster.Now trying to adjust the original spring didn't get any results,so you tried using a disco spring and still no promising results. Let me now throw a wrench into the works here. What if you could find a spring with the same length,have more tension,and be able to slide over the existing spring. Would this double spring combo be able to acheive the results you were looking for?? let me know if I'm half baked or not.

4Th Yote

[MountainMan126]

My use of the power adjuster is not so much to gain FPS/FPE , but to set it to pre-load the hammer spring with the minimum amount of tension and still dump all the air in the valve. Therefore eliminating any un-needed spring compression while in storage.

As far as double springs, I think it may bind and be less effecient than one stronger spring.

[Muppit]

mountain man i would put as much pressure on the spring ad you can without the adjuster crushing the spring this will give you the most force in the hammer and then run it across the crony backing the screw back out until you notice a drop in velocity.if your not preloading the spring enough you will not dump any More air in the valve possably leaving air in the valve. what you want is for the spring to allow as much air to leave the valve as possible. a heavier spring is not always the answer as it could keep the valve slightly open, i am not familiar with the 1377 but it uses the same principals as my pb gun

[MountainMan126]

Not a huge mod, but a big difference. Ambidexterous grips are for people who appreciate having options and not having any one particular really good option. A little time spent with a shaping file and sandpaper , and I have eliminated the left hand thumb shelf. Way more comfy, no money spent.

Muppit , I agree to get max power from the adjuster I should crank it in as far it will go. My goal is longer more consistant spring life, storing at max usuable compression should reduce the over-all spring length over time and should eventually result in a weaker hit. JMHO

Ethan

[Muppit]

i agree, i misunderstood your goal i thpught you were searching for more power aout of the build ,which you are but you also want dependability.

[4th Yote Recon Bn.]

Hi All:

Well I got my power adjuster adjusted.I ran the set screw in all the way until the bolt wouldn't cock, then I started backing it off until the valve dumps all the air and be able to cock the bolt. I'm not able to hear the bolt click  as it is being pulled backwards but does work. I also used a heavier spring #44 cut to original spring size - it didn't work to stiff so I'm using original spring. One feature that I liked was using the 3/8x1/2" set screw I can adjust power valve using only my fingers - good bye allen wrench. All for now.

4Th Yote

[MountainMan126]

Good deal 4th yote, I cock the gun , and then run the screw all the way in until snug. Then back out 3/4 of a turn and call that max power. Cocks at this point first time every time. Then over the chrony and shoot 3 times and back out a half turn. This is where the allen wrench comes in handy, I use the end facing me like a clock hand to get accurate half and full turn adjustments. Repeat until there is a noticable change and turn back in 1/4- 1/2 turn to account for any loss of tension when the spring takes to it's new position. This is what I consider to be ideal in the sense , you haven't loss FPS from the max position and are no more than a half turn more than the minimum required to hit peak fps. Depending on the spring weight and length will depend on how far you can go with backing it out with no change.

I can not back this up with published materials, just thinking out loud on what I think makes sense.

Ethan