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lampy · Veteran Member

The fun begins! My oldschool 1377 showed up yesterday. It will be the main donor for parts for this project. The pistol grip with its trigger group and the hammer and cocking knob will be used.

The barrel is from a Daisy 953 and was nearly as accurate as the LW 853 barrel I replaced it with. The pump tube will be made from a piece of 3/4" seamless brass tube. I will rob the pump linkage from my Frankengun project to get this build started. A new breech will be made and a 1399 stock will be added.

I have some options for the exhaust valve, my plan as of now is to use the front half of a 1400 valve (Top) on the back half of the 1377 valve (middle). That will make going with a flat top piston easier. I have a mystery valve (2100 ?) that I was thinking about using with its lower volume it would take fewer pumps to get the pressure up where I want it. Since the 1400 and 1377 valves are "stuffed" with the extra long check valve I don't think the volume is that much different between the two. I welcome opinions on which valve to use and why....

Robw · Veteran Member

Nice!

I have been thinking of doing a long barrel build of a similar
design incorporating a pump tube with a longer stroke and a
complete dump exhaust valve.

lampy · Veteran Member

This one will have a pump stroke of 8 inches, where the 1377 is about 4 inches. That should cut the number of pumps in half. With a flat top adjustable piston I'm hoping for 500 fps in 2 - 3 pumps. This rifle will be a basement paper puncher so I wont need more than 500 to 600 fps.
Of course I will have to see what it will do....

lampy · Veteran Member

The first session on the mill was a success....

The wall thickness on the brass tube is .004" thicker than the tube from the 1377 so the valve was a nice snug fit. I bolted the pistol grip on and tried out the hammer, everything functions fine. Very Happy

I see some room for improvement on the trigger group so I'll add that to the list.

lampy · Veteran Member

Another trip to the mill and I have the transfer port hole and breech mount hole drilled. The only things left are the slot for the cocking linkage and the hole for the pivot pin. The 953 barrel is about an inch short of reaching the end of the pump tube at its current length. I haven't decided if I will shorten the pump tube or shroud the barrel to get it past the end of the pump tube.

I was thinking I could just buy a steel breech kit to mount the barrel but that wouldn't be any fun so I'll make one out of aluminum.

Mentolio · Veteran Member

Watching this thread closely, can't wait to see how this evolves!

Robw · Veteran Member

Me too. It was the first one that I checked this morning.

lampy · Veteran Member

I should get some time this week to tinker on it. I'm working on the pump linkage next.

lampy · Veteran Member

I got some work done on the cocking linkage. I was going to use the linkage from Frankengun but figured this project would need it's own linkage so I might as well build it now.
I used some 1/4" thick hot rolled flat bar from my metal stash. I'm going with a "knife and fork" for the center link.

There are brass bushings for all three of the pins.

There is plenty more work to be done, I may sneak away for some more build time tomorrow.

lampy · Veteran Member

I was studying my parts stash and came up with a plan for the barrel. Originally I was going to cut the shoulder off of the 953 barrel, make a cutter to cut a new tapered leade and drill a transfer port.
My new plan was to cut the breech end off of a leftover 1377 barrel and bore it to fit the length and diameter of the 953 barrel shoulder. This would gain me a couple things, I wouldn't have to cut a new leade or drill a transfer port and I would keep the barrel length I need.

The breech end of the 1377 barrel parted off and bored to fit the 953 barrel.

The 953 barrel will start just past the transfer port.

Glued together with JB Weld.

It took some time to get the setup centered in the lathe but it was worth it, the lands and grooves of the 953 barrel appear to be well centered in the 1377 barrel.

lampy · Veteran Member

Single digit weather is slowing things down, I did manage to get a few things done on the lathe today before my fingers were to numb to work. I cleaned up JB Weld joint on the barrel and made some brass washers to tighten up the trigger and sear.

It is a bit hard to see in the pic, but there is a wave washer on the trigger pivot pin (to the left of the safety) This works but I didn't think it was the best way to keep things lined up. There is nothing to keep the sear centered it just flops around on its pin. I measured .028" gap.

I made 4 Brass washers/ shims .014" thick. It's not easy to part off brass that thin.

It took some fine tuning to get the thickness correct but I'm happy with the way things turned out.

The trigger is far from "match grade" but with a bit more work I'm hoping to get something I can work with.

Slavia · Moderator

Thanks for taking the trouble to post your work. I have a 1377 project in progress (stalled), and all this is useful. Keep the details coming!

That's an interesting solution for adapting the Daisy barrel to the Crosman breech. With all that surface area overlapping it should seal and be plenty strong.

My 1377 is a little newer, and the bolt cocks the hammer. That gives me some different options for the buttstock. With the cocking knob hanging out the back of the pump tube the 1399 stock would definitely be the way to go.

Robw · Veteran Member

I have both a 1322 (Stock so far) and a 1377 (since 1987) and both are very accurate to say the least.

lampy · Veteran Member

lampy · Veteran Member