Rear cocking 1377 steel breech question.

[QB78Guy]

I have a rear cocking 1377 and I just ordered a small steel breech with the rear style breech screw.  Would my best bet be drilling and counter boring the breech for the front style screw? It seems to me that if I used the rear style screw and drilled and tapped the tube for it that the hammer would hit the screw.

Any input would be great.

[bgmcgee]

Either way you are giving ing to have to drill and tap a hole. The 13xx tubes don't have the rear hole and you will need to somehow notch the hammer so it doesn't hit the rear screw. You won't have to tap threads in tbe tube for the forward screw but like you say you'll have to drill and bore a new front screw location in the breech.

[QB78Guy]

Alright thats what I was thinking, I believe I'll go with drilling and counter boring a new hold in the breech.  Because it is rear cocking there is nothing that keeps the hammer from spinning so unfortunately I don't think I'll be able to use the rear screw. Thanks for the info bgmcgee.

[mudduck48]

And when you get done you will still have a rear cocker with a 5 to 6 1/2lb trigger pull. IMO, I would leave this classic alone and buy a new phase III to tear apart and mod. But, that is just me.

[beerhippy]

The original 1377 is not to mod friendly as I too am discovering.  Mine however has an excellent trigger pull.  Perhaps several thousands shots smoothed it out.  I re sealed it yesterday with the exception of the exhaust poppet which I dug the crud out of and will have to find an o ring for.  Once that is done it will stay in stock form.  Also need to remove a ring of rust that formed under the bolt's o ring where it seals on the barrel.  The barrel appears to be press fit into the breech so it will complicate that work.  Still it's fun to have my original pumper back in working order.

[mudduck48]

It sounds like you have a phase I with the steel breech and one piece wrap around grips. If so, that grip frame is the same one used on the 130 and 1300 pumpers. 

[beerhippy]

Yes, it's a phase one.  No forward breech screw.  Crosman does not even have the correct parts schematic of the phase 1 on their website ( look closely and you can see they show a breech screw ).  I want to order a TP seal but I'm not certain I would get the proper one. I'm curently using a type 3 seal.  Have to call them.  Only other issue is the valve holding air.  Have to try a lighter valve spring. Got a size 61 o ring for the exhaust poppet and it works fine.  It's shooting 7.5 grain pellets at 470 which seems a little low.

[mudduck48]

The TP seal is the same for all the 13xx guns. Sounds like you have it working right to me, 470fps is great. Did it pass the tissue test? Take a Kleanx and pump you gun up, put the tissue over the breech, pull trigger. If tissue does not move, then you got her sealed at the breech and the TP. Do this with an unloaded gun. Here is the parts list for Phase I and II.

https://support.crosman.com/hc/en-us/articles/203360694-1377-Owner-s-Manual-EVP-1977-1981-

[beerhippy]

There are a couple differences on that pdf file md - they show that little breech screw just  aft of the the port.  My phase 1 does not have that.  They don't show the little c clip on the end of the pivot pin.  Mine has one.  At some point one of the office gals must have given away the original parts schematic.  This was pre auto cad so if you lost the original drawing you were out of luck.

Nice to know the tp seal is the same.  I did the tissue test and it didn't rustle.

[1377x]

Idk but i modded my phase 2

[crossliner]

Idk but i modded my phase 2

Our guns look a bit identical..

[crossliner]

I was given this autocad drawing by Herr JmJ and I had it copied in ss..It's a one of a kind at least here in my country lol!

[ped]

nice pumpers  ed and senor
handy drawing for the plug all i do when i make one is copy a plastic one i have
ped

[crossliner]

nice pumpers  ed and senor
handy drawing for the plug all i do when i make one is copy a plastic one i have
ped

Thank you Herr Ped..I do not remember it very well but I think I paid something like $35-38 to have it cnc machined..Would come out much cheaper to have at least 10 made. Told the machine shop it was for a sprayer part because they do not accept any gun related machining even if it's just ag parts.

Mr. QB78 sorry for the thread hijack sir!

[QB78Guy]

Lol no problem. Great looking guns you guys posted!