In case nobody else mentioned it, if you open the pump arm the pin will go in and out much easier. There are also a couple of companies that make replacement pins that ARE NOT roll pins and use retainers to hold them in place. That style pivot pin is also much better to set your piston length. If the piston is too long it promotes early wear on all the pump arm components.
I have a 1322 and I have recently purchased a new valve, bushing and an 18" barrel. I was looking for instructions for the valve installation. This video is exactly what I needed. Thank you.
Thanks for commenting. I was pleasantly surprised too although I think the poor initial figures were largely to blame on the old valve being past its best.
Open your transfer port to 3.2mm And put the trigger spring in your valve (sorter spring) It will release the air faster. I used a spring out of a hand wash dispenser for my trigger Just see what you have around the house nice and soft so you have a easy trigger pull
Thanks for commenting! I'm going to dial back the power mods until I have a long enough barrel for it to qualify as a rifle to make sure I stay on the right side of the law. I have a very free-flowing transfer port waiting in my parts box. I might experiment with a lighter spring in the stock valve that I removed. I already have an adjustable trigger spring which is set super light. One of my favourite mods. I'm going to make a video of how to fit it soon.
@@ThrHillSeeker Don't open up the transfer port too much you will lose power I tried 4mm tp and the power dropped Rule of thumb is the tp should be 80% of the barrel bore 3.2mm was bang on for me Remember you have a 177 Hi flow is for 22 177 needs max pressure 22 needs a lot of flow The barrel bore is 1mm bigger And the pellet weights twice as much Good luck these mods will never end It's like a can of worms Fun but expensive
@@jasonbuchanan7591 It's very easy to loose power with a larger transfer port. There is a fine line. Being in the states, I leave my transfer port stock and just use a 16 or 18in barrel in .22. I only pump to 10. If I need to pump it 20-30 times, I will just use a different gun...My 18in barrel setup works great on cottontail rabbits and squirrels out to 25 yards at 7 pumps. I don't know why 7 pumps, but it is most accurate and works. I chose the harder cphp 14.3 pellets and they provide the accuracy and needed penetration. I would not use softer lead pellets like the Jsb Hades in my setup. But it shows to go that whomever developed what FPE is required for certain game didn't use the correct pellet!!! Anyways the 13xx platform is a very fun platform to work with and has huge potential. It can be rough on the pocket book though. My next project is a 1320. Having Walter Lothar make a .20 cal barrel. That will give me the hitting power of a .22 and the better sectional density of a .177. So that will be fun.
Was on the fence regarding this modification then I saw. Getting the kit plus the top end and 2 stage trigger. Goal is a match worthy pistol. Thanks for the walkthru.
My maxed medalists has an 18in barrel with an enlarged air reservoir. With 30 pumps it will knock down a crow at 45mtrs. My latest build a co2 crosman pistol conversion. With an enlarged air reservoir adjustable hair trigger and trigger spring tension. I started with a 24in barrel and drilled it out for 2.5 in at 7.5mm. then cross drilled the 2.5in for a shroud silencer. This is super quiet and powerful. My next build, a crosman lower and Chinese parts for a PCP rifle with the same 24in shroud barrel. I love playing with crosman's. None better for the price.
I unfortunately purchased the 1377c which is for the Canadian market so that it doesnt exceed 495fps which i was a little upset with so i did the same Gmac mod, i studied a couple of "how to" videos on youtube. I heard "somebody" pumping theirs 25 times and although it didnt rise dramatically from 10 pumps, it still increased in power. I also bought the Gmac barrel band/1/2 inch unf adapter and fit an airarms silencer so that it tames the bark quite alot. I sold it on for £125 to get a. 177 Hatsan Supercharger which is a great gun as well. I then started to miss it so i then snapped up a 1322 which are quite hard to get these days, and deccided i would turn it into a survival carbine. i put a 3-9x40 illuminated recticle scope and a cree ultrafire flashlight on top of the scope. I put moderator on with a carbon fibre wrap, i then ordered the 2289 backpacker large pumparm which looks badass and saves you trapping your skin. I bought the extended stock and fitted a quick release button. I purchased a neoprene velcro cheek rest that wraps around the stock and secreted a survival kit inside 2 zip up pellet holders. One of them holds 200 different rounds of 22 pellets inside, and the other is my survival kit consisting of fishing hooks, line and weights, a firestarter, waterproof matches and foil blanket, a minature folding knife, some feathered kindling, plasters, and 12 feet of paracord which fit inside the hollowed part but held snuggly inside with the velcro neoprene cheekrest. Very unlikely that it would ever be used as a survival carbine as you cant exactly take it camping in Britain, but it does look supercool though. I would send pictures if i could. All the best from Lancashire.
The easiest and cheapest way to increase velocity is to change the barrel. I know you said you want to keep the 10.25" (216mm) barrel but changing it to the 18" (457mm) makes a huge difference and a barrel cost US $45.00 and 20 minutes of your time. By changing the barrel I increased velocity from 585 to 665 fps. My next mod is changing the hammer spring and flat top piston with the hopes of increasing velocity to over 700 fps. I checked velocity with a borrowed chronograph shooting 7.9 grain Crosman hollow point pellets.
The problem with changing a barrel in the UK is that they're quite hard to get hold of and are subject to the same strict laws regarding shipping as whole airguns. I might still do it at some point though. Good luck with your hammer spring mod, make sure to replace the hammer pin with something made from a harder steel. The stock ones the to bend and break with heavier springs.
@@ThrHillSeeker GMAC will send them to your nearest RFD it's not much hassle just costs usually between 15-25 quid depending on the shop you get it sent to on "handling fees" lol
Nice video! I encourage you to get an inexpensive set of roll pin punches to avoid flaring the side of the pin while driving it out. It looked like you were using a tapered punch. Thanks for the post. It was very informative.
The black seal goes into the tube with the short side of the transfer port down do so with a trace of oil and the long side goes into the barrel which is located in the breech.
Hi, I bought my 1377 25+ years ago. Didn't know nothing about 1377c being Canadian . lol So I looked at the box it came in ( yes still have the box)and it said 1377c, so didn't there was a difference . now I'm looking at doing some upgrades lol . I'm in the U.S.
my CDN. 🇨🇦 spec. piston , transfer port has a bleed hole that vents above the plunger hole . I’ve found #2 x 56 NC ideal size thread tap for a screw to plug said bleed . Thanks for your excellent guidance !
Nice info, for those of us working in metric then you can tap the hole using an M2.5 tap and then fit a small 2.5mm screw with loctite. Or drill it out to 2.5mm and tap it to 3mm and fit a 3mm screw with loctite. All info I got from a great informative forum thread "New Crosman 1377 are under power- here's how to fix them".
I haven't done a valve to mine but went with a longer barrel and all the other mods. I easily take dove and pidgin at close range - 25 - 30 foot elevation by 20 foot length +/-, .22 cal. It doesn't reach 45 + feet in elevation, I see the pellet hit an elevation and just arches down drastically from that point. It runs out of velocity before it runs out of lethality for the birds. I wouldn't try rabbit with it. I have a p-rod or discovery that would work for that. I like my pumper. I'm thinking of doing the valve and like your video. I went with a threaded two piece retaining pin instead of the roll pin at the pivot.
you can change the bolt probe to a .22 probe and add a .22 barrel, quick upgrade and you can swap it rite back to stock. you will need to slightly drill out the barrel band as the barrel is slightly wider.....2 seconds does it with a Dremel.
If you dont want to spend much on your low power Canadian 1377/1322 then you can block the bleed hole on your valve. Its just a matter of tapping the 2mm hole with a 2.5mm thread and plugging it with a tiny 2mmx2.5mm screw and some loctite. Just done mine this week, im getting 5 foot pounds on ten pumps, and 5.7 foot pounds on 14 pumps. I could probably get a little bit more with a bigger transfer port. I would like to make 5.7 ft lbs at 10 pumps ideally.
Great review. What I have picked up online. Is if the gun is manufactured as a pistol.. Even with a rifle stock and barrel it's still classed as a pistol by the police.. Apparently they try all different pellets.
@@ThrHillSeeker yeah I should of been more clear. I realise your gun is well legal from your chrono reading. Hope your good this morning love your channel.
Hi Jamie, graphs and tables are not at all boring! Very useful video, thank you. I've been looking at the 1377 as an SHTF bag addition but was put off when I learned that the UK version was underpowered. Seeing 5.9 on your chart reignited my interest and the upgrade will be an interesting project. GMAC seem to have gone into liquidation. Where would you get your parts from now please. More thanks, James.
Great vid, but how much more power did you actually get as with the old piston you was losing air out of the back. So debating if this upgrade would be any good to me.
Thanks for commenting! I realised the old bolt was jumping before I did the power tests with the stock piston so I held it down to get as good a seal as possible when I did the "before" power tests. As such I'd say the power increase is still pretty significant. I hope this helps.
SECONDTWONONE, I understand what you're saying, if this was a fairly worn pistol when he took the readings before the modification it's similar to comparing the increase in power of a car with 200,000 miles on it to the same car with a fresh engine with high compression pistons. If you compared the new high compression engine to the same car with a new low compression engine the figures would likely be totally different. In this case I understand the theory behind the different pistons, you aren't compressing as much air in the pump chamber, instead forcing that compressed air through the check valve into the storage cylinder so you'll have an increase, just not as much as when you start with a worn out piston. And I'm not assuming his was worn to a degree that would have a measurable impact anyway.
I have a 1322 and was wondering whether the piston diameter was the same in the 1377 as in mine. If the bore were larger, could the barrels be swapped for a probable increase in velocity without the shorter (I have been dubiously informed), life expectancy of the piston swap?
Don't know why the don't use a hydraulic seal I stead of an o ring witch is round and only pushes a certain amount of pressure on the contrary the hydraulic seal is a unidirectional sea with a sharp conical shape that in extreme pressure it expands and seals even tighter I'm planing on machining mi own but with upgrades. nice video cheers for Florida USA
Thanks for commenting! Glad you enjoyed the video. A friend of mine is borrowing my chrony for one of their projects at the moment but I'll run some more power tests once I get it back.
If you don't extend the barrel with or without the stock it's still a pistol so be careful with those power figures, your 10 pump is just barely legal (with that specific pellet weight, so different pellets may well be over already) so any more than 10 pumps you will be in firearm territory in the UK, it needs at least a 12 inch barrel and to be something around I believe 24 inches complete length minimum to be classified as a rifle in UK law, I can't remember exactly but you may want to read up on it yourself just to be safe.
Thanks for the advice. I'll do some more reading and start looking for a longer barrel. I might also swap back to the stock transfer port for the time being.
@@ThrHillSeeker the transfer port would be the best way to restrict the power (may retain air depending on number of pumps) the problem with modded multi pumps is if the police get hold of it and send it to ballistics there's nothing stopping them pumping it 50 times, adding the heaviest pellet known to man and saying it's capable of an illegal figure and it's a hefty charge and may even introduce new restrictions. Unless the gun is incapable of going over 6 or 12 ft lbs depending on the barrel length they may well see it as a firearm. It's a huge grey area really
@@MDM1992 That's true, although the same could be said for some stock multipumps and some pcps. Thanks for all the advice. I'll limit it with the transfer port for now until I get hold of a longer barrel.
@@ThrHillSeeker I always use the 14.5 inch barrel and fix the stock then you double your limit, but with these guns they can quite easily go up to 16-17 ft lbs so it's still best to chrony and restrict them mechanically, if its retaining air in the valve at 11.5 ft lbs then no matter how many times it's pumped it's legal, just needs to be fine tuned to that point.
Did they neuter yalls air pistols. Our crosman 1377s in america average 5 -6 ft lbs of energy. Yours got that after modifying it. Makes me wonder what they did to neuter it down. Unless your chrony is wrong.
The standard valve in a UK 1377 has a hole drilled in the transfer port end of the valve. When you fire, a large percentage of the air just dumps into the pump tube. Thread this to 3mm and loctite a grub screw in ...instant double power
Thanks for your comments! I'll make a video with higher numbers of pumps once I get my chrony back (a friend is borrowing it for a project right now). I'm pretty happy with the short barrel for now as I still sometimes shoot it as a pistol. I also prefer .177 as I only really shoot paper targets (all of my guns are .177). Interesting to know that gmac do installations, I'll bear that in mind!
@@ThrHillSeeker I wouldn't recommend taking or posting that video for legal reasons. Video proof of a modification to create an illegal "firearm" by UK standards might end up in court and fuck all of us over from buying mods online and maybe even lower our already low powered limits of 6 and 12 none of us want any more restrictions as there is too many already, please be careful.
I have a crosman 1322 pistol..all original excpet for 14.5 inch barrel .Is it possible to get this pistol to shoot around 600 FPS { with 12.9 Gr lead pellets} with only 12 pumps or less , by only doing a transfer port mod and a air valve mod ? I assume that taking material out of the air valve, will not meet my goal, because that would result in having to pump the pistol more then 12 times ?
At 29:05 did you account for the different weight of the pellets for the muzzle energy? Thanks! Edit: also, 3'4fpe isn't low to begin with, in a Crosman 1377? I thought advertised was more like 6fpe or so. I know on joules, it was advertised at 8'56J, at least for the 1322 but they have the same advertised energy as far as I can remember
In the UK we almost always can only find the Canadian 1377c or 1322c. These models have a different valve with a factory added bleed hole and smaller transfer port size compared to the USA models, to keep them below the Canadian 500fps law. But luckily plugging up the bleed hole and buying a bigger transfer port is fairly easy to bring them up to 6ft pound. I believe that in the UK, aslong as we add a shoulder stock and a bigger barrel then we can legally take these things up to 12ft pounds. More than that would require a Firearms Certificate. Yes I know our laws are stupid, but it could be worse if you look at Canada, Germany, Ireland or China!.
@@99ron30 well, I bought this one in Spain and just chronied it once but gave me the full 8'5J I still wonder if such a small transfer port allows for a lower pump on the following shots. It could be more important that one would think, because any remaining air could be getting higher an higher pressures and damage the gun Any clue about that?
New barrels are kind of hard to get hold of in the UK. I could get one but even the cheapest ones would cost more than all of the money I've spent on the project so far.
Can you tell me how to remove the small hex nut that’s under bolt if it’s damaged? I stripped it and now it’s stuck but I’d love to replace it with something like you used…
Thanks for commenting! When I got the gun it still had the plastic breech and the previous owner had rounded the hex nut. I had to cut into the breech and the hex nut with a Dremel. This allowed me to unscrew it using a flat headed screwdriver. I hope this helps.
@@ALL-AMERICANA Ah, in that case all I can really suggest is drilling it out with a very thin metal drill bit but there's a risk of stripping the tread on the breach and the main cylinder in the process.
@@ALL-AMERICANA I don't know if it already solved your problem, but the same thing happened to me so I glued with superglue the key that best fit the damaged thread to be able to turn the screw, so after I removed it I made a slot to be able to use it with a screwdriver
Damn, I should have gone to this setup. I when with alliance hobby in NA and my performance has actually dropped vs stock. 9 pumps = 260fps. So frustrating since I spent the $$ on it.
i take it you do know that you can take these up to 15 ft pounds and now with the stock fitted its a rifle by law and can go up to 12ft lbs.. . many people have the 1322 and 1377 to over 11 ft lbs... it depends on the amount of pumps.... your spread is mainly because the chamber is not fully empty between shots because you need a more powerfull spring for the hammer due to the flat top valve holds more air.. now being as you have the new flat top valve chamber it holds more air and needs to have more pumps to get the psi in the chanmber to be the same as original.... a gune in good condition that needs 10 pumps on a new flat top valve might need 12 pumps for same psi.. velocity is down to how fast the air can be released intothe barrel ( high airflow port). or you can open the flat to ppiston and put a weaker spring in there, ( not advisable ).
Thanks for commenting! For it to be a rifle it needs at least a 12 inch barrel and to be 24 inches over all. As such I've put the stock transfer port back in to keep the power down. If I get a longer barrel in future, I plan to put the wider transfer port and power spring back in but I'm pretty happy with it for now. As it is the flat top is hardly retaining any air after 10 pumps. I don't get a lot of time to shoot any more so I'm unlikely to do much more to it for the time being.
guys, I hate to break it to you but flat top is purely cosmetic, it does nothing to improve performance, you know what does? the valve! drill larger output port hole, cut off half the thread off the male end, get longer softer valve spring and shorter harder hammer spring, drill a hole in the end cap of the tube and utilize a screw to act as hammer spring tension adjuster, I did that and with the stock setup using the original short barrel im getting 700+ fps with a LEAD pellet with just 11 pumps!, I have flat tops as well but they alone did not cut it, switched back to stock hardware and just turned my attention to the valve alone, also don't do this if your valve has been factory detuned (I'm looking at you UK, Canada, Australia..)
Ciao! Finalmente un GRANDE VIDEO fatto per me! Purtroppo non parlo inglese e non so tradurre!! Tanto meno non sono neanche tecnologico! Faresti un attenzione per me mandarmelo in italiano? Se si ti mando anche il mio numero cellulare! Grazie, anche se non avrai tempo per me!
