New Crosman 1377 are under power - here's how to fix them.

[Adam77K]

Thanks for sharing that.Wish I had the skills to do a bit of engineering such as this I would struggle with lego .

These pistols are so easy to work on you wouldnt believe! Reading this thread has made me want to start fiddling with my 1377 again. There's something about making a silk purse out of a sow's ear.

[TonyL]

These pistols are so easy to work on you wouldnt believe! Reading this thread has made me want to start fiddling with my 1377 again. There's something about making a silk purse out of a sow's ear.

100% agree.
Very, very easy to work on.
Some might be wary of working on a beautiful, expensive gun, but these are cheap and dead easy to work on, so nothing to be scared over.

And the accuracy is STUNNING for such a cheap thing. Again, you'd expect an expensive, top-end gun to perform brilliantly, but to get such stunning performance out of something so cheap and underrated is a lovely bonus.

[Biker_Bob]

Definately, even the trigger (which is the worst bit out of the box) can be easily fixed for no money by squashing the sear spring down in a vice and 5 minutes polishing the sear with 1000 grit wet and dry.
Everybody seems to be in a rush to replace the plastic breach - no need at all unless you're intending to fit a scope, the standard breach is perfectly fine.

[TonyL]

Yep,
I fitted the steel breech mainly because I was going to turn it into a mini-carbine with scope.

Will be in touch soon re meet up.

[barry32]

Ive not been a vistor of the pistol section for a while but im glad I did now intresting read. I have a old 1377c the ones that came in the box instead of the plastic I think its around 4.7ft1bs with heavy pellets. I am at some point going to add a steel breach flat top piston and one of them brass scew cut front sight jobbies to it but the bank balance dont seem to be working out at the minute its always in the minus. Good bit of info thanks all

[Biker_Bob]

I've received a bunch of the GMac brass transfer ports.
They're 1.6mm bore, which is smaller than even the Canadian spec restricted ports.
The 3mm port I've got in is perhaps a little much, the power is up in the high 5's
So I'm going to go to 2.5mm as a starting point and see what happens.
The GMac ports are brass so are easy to drill out. I'll just use my drill press, rather than the lathe.
I'll post when I've got test results.

[airgunpete]

Underpowered or not I just use mine for punching holes in paper and knocking field targets down, I'm very happy with it.

[TonyL]

Will keep a lookout for your findings, Bob.
And I will be in touch at some point re meet up, bit busy with loads of things at the mo'.

[Biker_Bob]

I ended up with the new tuneable transfer port drilled to 2.5mm.
That gives 4.5 ftlbs, I'm going to leave it there. 3.0mm is too big and I don't have a 2.7mm drill bit!

[Benelli B76]

Matty, Canadian limit of 500 fps will be 25 ft lb with .30 calibre barrel and the 45 grn Falcon pellets off fleabay.Good for bunnies.

Baz

[TonyL]

Thread revival to tie in with the current enquiry from Zeroexpo1.

[Biker_Bob]

Thread revival part III

I've just done another newly bought 1377.
Bleed hole plugged and no other mods, it's doing 5 ftlbs on 12 pumps with 8.3gn pellets.
It's doing 5.9 fltbs on 14 pumps with 7gn RWS Hobby - that's a problem. I may make a smaller TP for this one.

I wonder how much variability there is between individual guns? I've got three more here which if I do them I'll report back on the range of powers produced.

[Antoni]

No-one has mentioned adjusting the dead volume of the pump.

I got one these pistols in the 70s after covetting my mate's one - I only had a crappy break-barrel at the time. I simply used the piston position adjustment to change the dead volume at the end of the pump stroke. The trigger was never very nice and it was certainly less nice after the adjustment. My point is, that indicates that an "adjustment' had indeed been made.

[Biker_Bob]

No-one has mentioned adjusting the dead volume of the pump.

I got one these pistols in the 70s after covetting my mate's one - I only had a crappy break-barrel at the time. I simply used the piston position adjustment to change the dead volume at the end of the pump stroke. The trigger was never very nice and it was certainly less nice after the adjustment. My point is, that indicates that an "adjustment' had indeed been made.

No adjustment option on the new pistols. The pump is a moulded plastic part.
This is why the "flat top piston" mod is popular. But as I mentioned above, mine is getting perilously close with the standard pump - don't need any more.