Tuning Modded 1377

[MI_Yeti]

This 1377 is my first crosman lego gun. I have been working on this off an on for a couple years. I never got the power I wanted out of it in .177. It barley hit 600 fps with 7.9gr. So fairly I recently swapped it to .22 with a 12" barrel and extended probe bolt from mellon air. Doing ok now but might still be on the slow side. Still has all oem porting other than the hard 90 degree in the valve being smoothed out so opening that up might help. The mod list is long if any one wants it I can try to remember everything.

I still need to find a decent metal barrel band with a front sight that dose not cost $70, and I'd like to try out a super sear in it. It's quiet, and lighter than it looks thanks to the aluminum breech and carbon fiber moderator. Crosman projects are rarely ever done. I'll post updates to this thread when I tinker with it.

A few shot strings. All shots using 14.3gr CPHP

6 pumps
5 shots
average 438.2 fps
Standard deviation 1.78 fps
6.09 fpe (about what it made on 10 pumps in .177)

12 pumps
5 shots
Average 564 fps
standard deviation 4 fps
10.10 fpe

15 pumps
one shot
596 fps
11.28 fpe

 

[Long_Gun_Dallas]

Looking good! I know how it goes, lol. Always something to upgrade. I'm still having shifting POI, so did drop the change for the $60 front barrel band. I think my addtional band would have likely fixed the issue, but the top set screw hole is stripped out.



You're getting way better numbers than mine. I need to get a factory valve and factory porting. Mine is all hogged out and would do 15fpe max, but took something crazy like 30 pumps to get there. 14.5" and 520fps at 15 pumps using same pellets. Though the tight choke, being a LW barrel, will cut some speed.

If you're going to dump any money into the trigger at all, just call up Crossman, and order a p-rod trigger group. $40 or so for the whole grip, and all components. Can't recall if it was more like $35 or $45?? You will need to fill in the gap in the hammer or hold the trigger down when you cock the gun (not recommended) But the p-rod trigger is a drop sear setup, and is 2-stage. I think mine breaks crisp at 10oz or so.

The P-rod group also has an over-travel set screw which is nice as well. Not that you couldn't add one. Just nice it's there already. (my pcp 1322 is the one with the p-rod trigger)

 

[Raden1942]

I spent like 400 bucks on mine. Flat top piston etc.... I love that gun but the accuracy isn't what I would consider to be good. I might need a lw barrel. 

 

[Long_Gun_Dallas]

You'll have other accuracy issues. The breech is flimsy, and so is the front barrel band. Maybe if you can get the gun to settle in... It might stay put-ish.... or, honestly... I think the best option is to use the sight mounts that clamp directly to the barrel. They don't look great, but It's a good workaround for needing to buy a nice breech (Gmac) and a nice barrel band (maverick)



Thant said.... I do have 4 Crossman barrels that are not LW that fit this gun and they ALL have poor accuracy.... The LW, on the other hand, if you can get it to stay put on the gun, will shoot some crazy good groups when you feed it what it likes.

Oh I might should mention, I've been trying to buy a LW barrel from crossman for close to a year. To avoid feeding the price gougers. They JUST got some in stock. This 1322 of mine has been down for a good yr or so until yesterday

 

[MI_Yeti]

Thank you, looks like you guys have build some nice 1322s. I guess mines not a 1377 anymore since it's been converted to .22. I've not had any issues with wandering zero or accuracy, but I have not shot it past 10 yards. The barrel band is very poor so I know I will probably have issues sooner or later. I'll get a metal barrel band for it at some point.

I like the hard case full of moderators.

 

[Longfellow]

I have a flat topped 1377 and a flat topped, homemade, .22 Backpacker. I use the old model 760 pump handles instead of the OEM pump handle. I'd love to get a couple of the 2289 fatty pump handles for them.

Both have the same parts, Alchemy Airwerks, plug & play flat top piston and flat top valve. Crosman 1701 adjustable sear spring, Disco hammer spring, Boss Buddy transfer port.

I'm fixing to add a 12 inch barrel from Charles Mellon and a LDC from Geo Schoonmaker to the 1377. Make it more backyard friendly.

The Backpacker has a 14.6 inch barrel and a Geo LDC. My Backpacker is probably my favorite air rifle. I have others that are more powerful; maybe even one or two that are more accurate.

Both are scoped. An NC 2.5X30 is on the 1377 and a Tasco2-7X32AO is on the Backpacker.

My Backpacker and 1377 both are capable of 0.5 inch groups at 20 yards when I do my part. It's easy to get 1 inch groups from the Backpacker at 25 yards.

There may be a mod or two I've neglected to post.

 

[Blankshot17]

I have a 1322, when I replaced the plastic breech with steel I used permatex high performance thread sealant. Applied a thin band of sealant around the barrel about a 1/4 inch shy of the breech end and install and buttoned all together. I let it cure and result is no play in barrel to breech I don't know if it helped but pretty sure it didn't hinder. Also did light dremel polishing on trigger sear group, an extended stainless steel pellet probe installed, and trigger shoe. Found a spring at work that mimics the stock trigger spring and used an old spent .22lr casing with it. It seems to create more feel in trigger pull, in my opinion. With Crosman 14.3 I get with 10 pumps a smidge over 500 fps and with 5 pumps I get 396fps. With a red dot offhand 5 shots at 10 meter I can do under a quarter sized groups. Almost thinking about trying a scope on it and I recently installed the plastic rifle butt stock, this thing is so fun to tinker with. For the price, the trigger shoe is a no brainer, as the surprise in making the function of the pistol more agreeable. Planning on a few more things that are more cosmetic and functionality than performance. One other thing, I did do a crown job on it, as the factory crown was just horrid. Used a dremel and then a brass screw with compound in a high speed drill. This, I believe, improved the accuracy greatly over the course of development. Just my two cents, YMMV

 

[Stefanjan]

Blankshot17 great advise on the re-crown. I have my first 1377 on it's way (supposed to be delivered today! but realistically it was still 15 states away from me last night so very low hope there). I'm keeping mine bone stock for now (lol well except the steel breech I ordered for it, and a red Dot, or possible a small scope). I mostly shoot indoors at 10 meters, and already have a pesting pistol in my .22 Diana Bandit. Once summer gets here, I will be shooting this on my outdoor range and will probably start looking for more out of this gun.