Well as i have said before i love my 1077's, and i have done all i can reasonably to increase the power, but idealy i would like to bump up the power just a bit, maybe hit 700 plus fps, and i got to thinking...yeah i know its a new thing for me!! but when i got the pal parts to fit to my de tuned 1077 the only real difference between them, apart from the colour, was the size of the transfer port hole in the nose (the sprung bit that the co2 goes through to hit the pellet)the grey (restricted) one was just moulded smaller to choke off the co2, and the o ring was left off, i assume to allow gas to bleed past to further reduce power, so my thinking is if that hole was opened up a smidge more would power increase too? in theory the answer should be yes, like a gas engine the better/easier it breathes the more power etc, so this is a question for tose of you taht have the technical heads as mine is just filled with fug! has anyone tried to open up the transfer port (hole) if so what happened, it shouldnt use more gas as the valve chamber is left untouched, but it should allow that gas to get through the hole more quickly, pushing the pellet faster if ya see what i mean! so please feel free to blow holes in my thiking, as i don't want to try it and mess up he gun, although the parts are available so easily replaced, but any thoughts most appreciated, cheers CC

9 out of 10 voices in my head told me to do it!!

Hi CC, yes, I thought of the same thing. I drilled out my valve detent (transfer port) to the next drill bit size larger. It was a while ago, but IIRC, it brought the hole size to just under 4.5mm. The shots are more powerful.

I was out shooting today with my 1077. I was shredding pop cans at 30 yards with no problem. I could hit pop cans at 40 yards with a new CO2, but only with the first 2 magazine clips. I didn't try 50 yards today. Maybe next weekend.

There are two other methods I've read about to squeeze more power out of the 1077. One is to glue a lead fishing weight to the back of the hammer. The other is to put a weaker spring inside the valve. I may try the hammer weight next. But I really don't like doing valve work. I've taken my valve apart before, but that was just to flush it out for cleaning. To me, they're a pain to re-assemble.

Right, i may well hve a look at the size i got with the pal part, is that the one you drilled? or was that the grey one? i think i made abooboo, i put some pellgunoil in the valve wheni had it all apart, i heard somewhere they work better dry, so if thats true i may take it out and flush it through, as i got a 1077 for a buddy of mine the other day, and his was a detuned one, and although mine made it through the wind to the target without as much deviation, his seemed to hit harder, his split a can mine only deeply dented, maybe it was the pellets, i was using crosman hollow points he was on crosman pointed, , maybe it as just the way the gun sounded mine didnt sound as loud as his, but i was standing next to his, but behind mine when firing if you see what i mean, or maybe i am just a paranoid fool too hehe, so anyway if you drilled out the black one to just under 4.5mm i will have a go at that, let me know which one and if you know about the effect of pg oil in the valve, cheers CC

9 out of 10 voices in my head told me to do it!!

Hi CC. I drilled out the de-tuned (grey) valve detent. And yes, it's ok to have pellgunoil in the valve. It's actually good for it, it conditions the seals inside the valve.

With just drilling out the valve detent, mine seems to exhaust as much CO2 as I'd want. On a fresh CO2 powerlet, I can see a plume of CO2 from every shot of the first magazine cylinder.

Going back to yesterday's shooting. I was hitting pop cans at 30 then 40 yards. I have a feeling that if I try 50 yards, I may be lobbing pellets. I'll have to try it sometime.

What distance were you and your buddy shooting at? Have you tried to range your 1077 to see what's it's max distance hitting targets while keeping a flat trajectory (no lobbing)?

thats good news about the oil in the valve, if you drilled out your grey one to where the moulded choke meets the wall of hole then thats the same as black one, i also get the gas out the end of barrel for the first couple of mags so that sounds similar, the distance not measured very reliably was about 15 paces, so i gather thats about 40 to 45 feet the trajectory was kinda flat i held it over 1 division on my scope as i had zeroed it closer for rats n stuff, maybe it is better than i think, or i just got a bum cartridge or two, as the last time i used it i just couldnt get it on target by adjusting the scope, but could if i held it over a touch, so maybe my scope not adjusting up and down i will have to look at both those things, cheers CC

9 out of 10 voices in my head told me to do it!!

Hi CC.

I drilled out my grey valve detent (shhhh!) to the mould line to match the size of the hole of the black detent. I then took it a step further by drilling it out to the next larger size drill bit (can't remember the size).

I chronied my 1077 tonight. I did this before, but can't find my original data. I was getting speeds between 450 and 520 fps. I only used data from 1 CO2 powerlet. I think there's still room for improvement. I wish I had more time to tinker with my 1077.

One interesting velocity reading was 697 FPS! It was on the second magazine cylinder. I double tapped two blank shots to clear the valve's throat. I immediately followed up with a loaded shot. I know, that shot sounds like an anomally. BUT! The shot was distinctly louder. So I think there's room for improvement. I only had time to shoot one CO2 powerlet.

Thinking back to last weekend's shooting session. I think my practical shooting distance is 30 yards. I can only reach 40 yards at the beginning of a fresh CO2 powerlet. With the power output of my current set-up, I don't think 50 yards is attainable....at least, not until the next set of "tune-up".

BTW. I was using Crosman Premiere wadcutters. It's my main pellet.

Four_Eyes.

Dear All,

I am the proud UK owner of a Crosman 1077, which I have modded to increase power. It is not in the same league as my 12 ft lb Theoben Scirocco .22 but for short range vermin control it would work a treat. The mods I have done so far are:

Shorten the hammer spring by 2 coils to give a harder hammer strike (I havent increased the hammer weight yet). I also modded the trigger springs to reduce the trigger pull.

Fitted an adjustment bolt in the foresight assembly. This is to jack the barrel back as close to the magazine as possible, i.e takes all the play out of the barrel latch assembly. This ensures that a minimal amount of C02 leaks between the front of the rotary magazine & the barrel during each shot. The adjustment bolt is an M10 bolt with a 6.5mm hole drilled through the middle & cut to the correct length. I also obviously drilled & tapped the foresight to suit the M10 bolt. I got this idea from a previous thread where a fellow 1077 owner commented upon more powerful shots if the barrel latch tabs were held back.

Use Prometheus PPP1 pellets for C02 guns (made by Pax Guns in the UK). These .177 pellets weigh 6.9 Grains (Fast, Flat Trajectory) & are made of non toxic Tin. Tin has a much lower coefficient of friction than lead, thus the pellet has more in flight energy & loses less motive energy to barrel friction. Tin is also a lot harder than lead, so less energy is lost on impact due to deformation than lead (I suspect on higher powered guns the pellets would over penetrate live quarry).

I havent measured the velocity of the pellets, but at 20 yards they go through both sides of a Heinz Baked Bean tin. I can get approx 24-30 full powered shots with my rifle.

Regards

mattw975

Hi from another UK convert.

I chrono'd my new (2005 model) 1077 the other day and got some strange and disappointing results. I tried three 12g powerlets and the results were similar.

First few shots recorded around 640 fps with RWS Hobby pellets. Then the next 12 or so went around 440 fps before tapering off to 150 fps. Now the 12g powerlet in my QB79 .22 gives consistent results right up until the gas suddenly dies. There is no tapering off of power like I experienced with the 1077.

I got the 1077 for short range ratting and feral pigeon shooting and would be quite happy with 550 - 650 fps / 6 - 7ft/lb IF that power could be guaranteed for two mag's (24 pellets).

Does the modified / tuned 1077 retain consistency? And, are you running on 12g or 88g cylinders?

Cheers,

Clive

Hi there,glad to see another brit convert here, i use the small capules,although they can be quite finicky powerwise, keeping spare ones in a trouser pocket to keep em warm works on cold days, but only till the capsule cools down again, but i like the way the rifle looks and the 88 gram hanging off the bottom looks horrible, i am toying with a way of putting an 88gram in the buttstock, like the nightstalker, if i can work that out i will be happy bunny!

four eyes, thanks for the info, i will try a slightly larger drill, and after that see what the shorter heavier hammer spring thing does, i love prometheus pellets, i am proud to say i had one of the first boxes ever made, as i was given them by a friend who worked for survival weaponry and techniques magazine, and he had some for tests etc and he gave them to me, so i have used loads of them,

i think the 1077 even though i love it, even with all the mods is still a short range gun, at 30yards it is great but after that the performance drops off, and until someone comes up with a whole new valve to transplant into it, i think any improvements will only be marginal, so i think may stick to the short range where it really excells, and save ong shots for my Jackal or the new pal version something that i am gonna get one day, but the 1077 is still my first choice for a walk around the woods, light and quiet, and no fumbling for pellets, yeah ! i love it! cheers CC


9 out of 10 voices in my head told me to do it!!

I've read a lost of the threads about keeping CO2 capsules warm, etc. The thing is, that the self same CO2 capsules in my QB79 (effectively a Crosman 2260) and the issues you raise about keeping CO2 warm and the inconsistency don't affect thae QB79. Looking at the schematic diagrams of both guns the valves are internally different (I haven't physically measured them to see whether they can be exchanged) and the 2260 has a wide tube between the airsource and the valve that is missing from the 1077.

The way I see it; my unmodified 1077 CAN deliver 640 fps when the 12g capsule is new therefore if I could overcome the power fading issue I would be a happy bunny.

Before I start messing with my 1077 I would like to know whether the results using a 88g power source are consistent or does the fps just fade off over a longer period. Has anyone chrono'd their airsource powered guns? Similarly, has anyone chrono'd their guns that have had the valve opened out or had hammer work done?

I would be happy with 640 fps / 7 ft/lb power for what I intend to use the 1077 for IF the power of the gun does not fade away as the gas cylinder empties.