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Mark5043 · Silver Status Member

Someone recently asked me if you can use a newer model breech,on an older model 1377"The one with the rotating breech cover,and rear cocking knob".I'm assuming you can?I heard you have to use a newer model barrel though to make it work?......anything else involved in fitment?

AirGunEric · Site Admin

It will fit- but the transfer port sits a hair askew- i.e. about 1mm off dead centre. The transfer port still lines up and the seal still seals, but for whatever reasons is not a precise fit. I seem to recall that perhaps a newer hammer and hammer pin may also be required (?) to allow the bolt to pull the hammer back.

Mark5043 · Silver Status Member

Okay Eric,thanks..... Thumb Up!

1377x · Member

a newer style breech will fit on a rear cocking 1377
i have 2 rear cockers
1 with a crosman steel breech and phase 3 barrel
1 with a new style plastic breech and phase 3 barrel
both were a direct fit no modification needed
with the steel breech get the sbpk2240 on the crosman site it lists 1322 as a direct fit if your keeping it .177 then you will need a .177 bolt
and for the plastic breech it seems one from a 2240 will work and a breech bolt without a cocking pin
rear breech screw will need to be shorter if using a steel breech