1377 finished!!

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killercrow · #1 Post by **killercrow** » Thu Nov 24, 2005 4:38 pm

well, i think im finished...

we'll see though!

finally got out to test velocity with the new piston and new bolt (that doesnt leak anymore... my barrel was creeping foreward on me! causing leaks after a couple shots. i fixed that with a set screw thru the top of the breech into the barrel.)

here it is. 7.4 grain rws hollow points. i dont like crosman pellets

5 pumps- 525fps
10- 695
15- 765
20- 807
25- 835
30- 840
at 30 pumps i have reached max valve capacity. i can pump it up more but i still have air left over. maybe i'll bore out the valve some more

my goal is 900 fps. think i can do it???

#2 Post by **webstien** » Thu Nov 24, 2005 6:45 pm

wow man, what other mods did you do? Was the piston the biggest FPS increaser? Did you make the piston or use a 2200?

RM422 · #3 Post by **RM422** » Thu Nov 24, 2005 6:51 pm

I think you could make 900fps. My 1377 must be doing over 800fps for sure. When I get a chrony I will tell you exactly how fast it shoots.

killercrow · #4 Post by **killercrow** » Thu Nov 24, 2005 7:28 pm

webstien... well i think the piston helped a lot. it pumps higher pressures due to the 2 o-rings, if i can figure out a way to enhance the outer valve seal, i should get even more power

. yeah, i made the piston out of brass. at the same time though i installed a rediculously light valve spring, and that might have helped too. you can get then at canadian tire. same size as the stock spring, just longer and real light. i didnt even cut it.

RM422, i got these plastic/steel prometheus pellets, and i probably am doing around 900 fps with them. forgot about them, then i realized "hey! why dont i chrony these?" but it was just a little too dark

but they dont really count

i want to try for 900 fps with at least an 8 grain pellet. i think the trick is just in getting more pressure into the valve.
but for sure, let me know what yer gun is shootin when you can! id like to know! you can be my competition

j/k!

RM422 · #5 Post by **RM422** » Thu Nov 24, 2005 8:17 pm

Try boring out the valve more. And put in the strongest hammer spring you can find. You should get some real good power then. I will gladly be your competiton. When I get a chrony then the real fun will begin. lol.

killercrow · #6 Post by **killercrow** » Thu Nov 24, 2005 9:29 pm

yeah man, sounds good! competition is a healthy thing!

yeah i was told to do the stronger hammer sring over on the crosman forum. also suggested adding weight to the hammer. since im retaining air i guess thats still potential wasted power. gonna be sweet when its done! it'll never be finished... i guess this thread's title is a lie

when im done i'll probably have enough parts to build another stock pistol

but it's all gonna hafta wait... im going away from home for work. i leave tomorrow morning, and wont be back for 3 weeks. but when i get back i'll be gettin my stuff fully outfitted

papaburger · #7 Post by **papaburger** » Fri Nov 25, 2005 1:18 am

Killercrow :

very powerful mod and excellent result !! I am tempted to mod my 2289 now. I have just ordered a crosman steel breech.

Do you have to drill a hole on the breech to put the set screw for the barrel ? How long is the barrel ?

killercrow · #8 Post by **killercrow** » Fri Nov 25, 2005 2:07 am

well, i had to put the set screw in cuz the backpacker barrel band is basically garbage. wouldnt hold the barrel in place no matter what. the set screw keeps it from creeping foreward, but theres still side to side movement at the front...

i think the steel breech comes complete with set screws, doesnt it?

and yeah man! mod that thing up!!

great fun!