Barrel breach end dimensions for 1377

[Andrewjames]

Having difficulty with the breech end on my 2240 converted from a 1377 barrel + GMAC flow through bolt probe, I need to make the breach end right but cannot figure out the correct cutting angles..

Does any machinists out there know the figures by any chance? Might be a long shot I know. No pun intended..

A

[averageplinker]

Having difficulty with the breech end on my 2240 converted from a 1377 barrel + GMAC flow through bolt probe, I need to make the breach end right but cannot figure out the correct cutting angles..

Does any machinists out there know the figures by any chance? Might be a long shot I know. No pun intended..

A

What is the issue? In the past I have run a 2240 with a 1377 barrel without any issues. One with a crooked barn breech and another with a standard plastic breech.

I know this may seem insulting to ask but is the probe a.22" probe and is causing the issue not the breech?
Rich.

[T 20]

What is the issue? In the past I have run a 2240 with a 1377 barrel without any issues. One with a crooked barn breech and another with a standard plastic breech.

I know this may seem insulting to ask but is the probe a.22" probe and is causing the issue not the breech?
Rich.

I'm wondering if it could be due to their being 2 different 1377 barrels, Rich, the throats are different on early and late model guns ?


All the best Mick

[Andrewjames]

no the barrel was fine but it was bugging me that the barrel didnt sit against the breech as the pellet was seated, so i squared it off and then realised the breech was drilled and has a recess.. then to make matters worst the probe is now pushing the barrel more forward that the transfer port needs to be to be aligned with the tube.. its all a bit of a mess!

probe is for a 177 so all good!

[averageplinker]

Unfortunately I sold mine a while back otherwise I would measure it for you.

[--ped--]

I only have a drawing for the phase 1 and 2 barrels I'm afraid
I did make a chambering ream for .22 but for .177 I use the rack of eye and twist of gob approach

[Andrewjames]

I only have a drawing for the phase 1 and 2 barrels I'm afraid
I did make a chambering ream for .22 but for .177 I use the rack of eye and twist of gob approach

that sounds interesting, how do i perform that?

i need to up my tooling.. trying to get in a hole that tight.. its dam near impossible to get the debth i need.. the chamber is before a drilled section to as to allow the probe oring some room

[Andrewjames]

So no one does a dedicated 177 chamber reaming tool or would any 4.5mm reamer do the job?

[--ped--]

all I do is use a tapered ream to get basic shape then with a probe I have put a mark on to know how far it needs to go in to seal I just shape with a bit of emery paper
I imagine if you were to work from the old phase 1 drawing but changed the probe diameter from the larger 5/16" probe to the later 1/4" probe you could calculate the taper angle
if I need to do a .177 i'll fit an internal barrel o ring like the m-rod and other guns