smsguitarist Posted October 14, 2008 Report Share Posted October 14, 2008 Hey guys. I have recently purchased a QB78 Deluxe, running 10.73ftlbs out the box, need a tune and a bit of TLC but i can imagine being very good after that. I wandered if anyone knows anything about converting them to PCP as im very interested in that idea for a bit of fun really! I've heard some things like it can/can't be done is/isn't safe and im getting a bit confused. Any input about it would be good thanks! Anyone who's done it/used one ... even better Lewis Quote Link to comment Share on other sites More sharing options...
JK8 Posted October 15, 2008 Report Share Posted October 15, 2008 Hiya Bud, ..No you cant convert it as CO2 is a different system completely,Most CO2 powered Pistols/Rifles are powered by CO2 capsuls, Precharged weapons require a reservoir chamber that will contain the much higher pressures that precharged systems need. All CO2 and indeed Precharged weapons can be tuned? to push out more power than "Out of the box" But, with the draconian laws in place in Britain at the moment re, power levels, is it worth a trip to the slammer??. Quote Link to comment Share on other sites More sharing options...
smsguitarist Posted October 15, 2008 Author Report Share Posted October 15, 2008 Cheers for the reply. I'v seen rifles on t'internet with an extended air chamber when the CO2 chamber usually is... very odd. Also don't worry i know the law. No rifle i have exceeds 12ftlbs and never will until i get my FAC after UNI. Quote Link to comment Share on other sites More sharing options...
amateur Posted October 15, 2008 Report Share Posted October 15, 2008 Hi Lewis The SMK CO2 rifle with the bigger reservoir is the XS79 which has an 88g capsule instead of the 12g twin capsules used in the QB/XS78. If you look up Biffo's posts on here, he has converted his to bulk fill, but it is still CO2 as against compressed air in a PCP Ian Quote Link to comment Share on other sites More sharing options...
smsguitarist Posted October 15, 2008 Author Report Share Posted October 15, 2008 thanks amature, i am in current contact with Biffo and he has proved to be a most reliable source of information and a great guy! I'm interested in the bulk fills as well but it is still CO2 using temperature which is as loopy as a .25 trajectory! http://www.airgunforum.net/agf/index.php?showtopic=42129 http://www.qbtune.zoomshare.com/2.shtml/54...c393d.writeback Some things i've seen about PCP QB78's. Cheers Quote Link to comment Share on other sites More sharing options...
MM Posted October 16, 2008 Report Share Posted October 16, 2008 rather than spend all that cash on parts to tune it, would it not be easier to buy a PCP? seems like a big fix to a small problem. Quote Link to comment Share on other sites More sharing options...
rabbithunter2008 Posted October 16, 2008 Report Share Posted October 16, 2008 rather than spend all that cash on parts to tune it, would it not be easier to buy a PCP? seems like a big fix to a small problem. I think martin hit the nail on the head Just buy a pcp it's easier than all that Quote Link to comment Share on other sites More sharing options...
MM Posted October 16, 2008 Report Share Posted October 16, 2008 yup!, i can understand doing it if you had a machine shop, and knew what parts to turn out, but its a helluva lot of work for something that could blow your hand off. White lines mate........................... "DONT DO IT!" Quote Link to comment Share on other sites More sharing options...
amateur Posted October 16, 2008 Report Share Posted October 16, 2008 rather than spend all that cash on parts to tune it, would it not be easier to buy a PCP? seems like a big fix to a small problem. I think martin hit the nail on the head Just buy a pcp it's easier than all that New SMK XS79 available for less than £100 on the web http://www.outdoorsman.co.uk/index1.html Tuned by Ian Lamb up to 11.5 ft lbs £65 ( including delivery ) only £50 if you drop it off Total no more than £165 Anybody selling a secondhand PCP for that? Quote Link to comment Share on other sites More sharing options...
smsguitarist Posted October 16, 2008 Author Report Share Posted October 16, 2008 Its amature who's hit my nail bang on! :-P I'm a full time unemployed student at the moment so a PCP was pretty much out the question as i can't afford the gun and pump and the other things to go with it. So i've gone for the closest option to PCP where i can spend a little money over time to get it as good as it can be! This PCP conversion is only an interest at the moment but like you say its dangerous. For me the QB78 is a means of learning Quote Link to comment Share on other sites More sharing options...
wildoliver Posted October 16, 2008 Report Share Posted October 16, 2008 There is actually some quite bad advice on this thread. First off if your gun is running 10.73 leave it alone, it is running well for a QB and it unlikely you will improve it much, a more usual figure is 6ftlbs. I'd check again if I were you. Secondly it's personal choice but the 79 (with 88g cartridge) is unwieldy and badly balanced, stick a silencer on it and it becomes a right pig to shoot. You can bulk fill the qb78 and factory kits are available, there is even a factory gun (designed as a target rifle) with bulk fill capability, run off either a paintball tank or pub bottle, but do be careful and make sure you understand how to fill before doing so. Don't try to convert to air (pcp) the pressures required will probably be too high for the tube on the QB and it isn't really worth the messing around to make it safe, just bulkfill CO2 and enjoy it (although personally I preferred the 12g capsules as they are easy to change in the field). The best mods you could make to your gun given it's power output are a decent silencer (get a 1/2 UNF adaptor off ebay (s200) and a logun or weirauch silencer), a rowan magazine and depending on accuracy recrown the barrel (some are awful, it is almost always the crown). Quote Link to comment Share on other sites More sharing options...
MM Posted October 16, 2008 Report Share Posted October 16, 2008 thats righty! i was going to try and reason with you and show the bad points, but you seem hellbent on doing it. I hope for your sake, and others around you that nothing goes "BANG". Quote Link to comment Share on other sites More sharing options...
smsguitarist Posted October 16, 2008 Author Report Share Posted October 16, 2008 (edited) haha martinmoreton, im not looking at doing it at all at the moment. Just looking at idea's to put into action in the future. it's an interest in the idea and nothing more at the moment. The only thing that goes bang around here is bug's brains. Also the only thing im hellbent on is once inch groups! argh... the recrowning seems likely Edited October 16, 2008 by smsguitarist Quote Link to comment Share on other sites More sharing options...
amateur Posted October 16, 2008 Report Share Posted October 16, 2008 There is actually some quite bad advice on this thread. I didn't think that I was offering any advice - just pointing out that you can get a new CO2 gun tuned up to the legal limit for 1/3 the price of the secondhand PCPs offered on this site. I've not shot an XS79, so I can't comment on its capabilities. I do know that my XS78 is light, accurate, well-balanced, recoil-less and a damn sight quieter than the springers that cost more. Quote Link to comment Share on other sites More sharing options...
Biffo1262 Posted October 16, 2008 Report Share Posted October 16, 2008 (edited) The advice about not tuning it, is correct. Doing 10.73ft/lbs is about right (and btw very good out of the box) as it will loosen up and the power will rise. In addition to which next Summers warmer weather will bring the power to about the legal limit. You CAN run these guns on LOW pressure compressed air. That is, you can fit a Wevo bottle with a fill pressure of 3000/4500 psi with an 850psi regulator. This means that the gun will run on normal CO2 pressures BUT the porting and valve may need some attention as they are designed for CO2 which expands at a different ratio. The only concern with this setup, which is in fact quite common, is that should the regulator fail the guns reservoir will be subject to the pressure of HPA and WILL FAIL in your face. Until a burst disc of 1800psi is incorporated into the body of the standard gun it is not a modification I'm going to consider anytime soon. If you have any doubts that the gun won't run on LPA do as I did and charge it through a bulk fill nipple with a PCP pump to 1100psi. I got 6 full power shots out of it with no trouble so I know that should I run out of gas I have an alternative, albeit very limiting. Steve Edited October 16, 2008 by Biffo1262 Quote Link to comment Share on other sites More sharing options...
Biffo1262 Posted October 16, 2008 Report Share Posted October 16, 2008 rather than spend all that cash on parts to tune it, would it not be easier to buy a PCP? seems like a big fix to a small problem. Actually to a certain extent Martin is correct. I have spent far more cash on one of my 78's, it's ancilliary bulking gear and other custom mods than on the whole of my S400 combo which consists of S400 .22 Classic JSR 6-24x50 with ill ret, AO and mounts AA silencer (now replaced with 1/2" unf weihrauch) JSR Pro bipod Gun case The whole S400 outfit cost me £460 new in July 2007 (pre anti-tamper) whereas my complete CO2 outfit and with most modified gun probably runs well over that AND that doesn't include the amount of hours I've put into it. If it's a matter of pure cost then PCP is the way to go for when you get addicted to these CO2 guns you just cannot help yourself and you will constantly spend more money on it. You don't have to spend £1000 on a decent PCP. My S400 hits the same targets as my mates Steyr LG and by the same token my best XS78 also hit's the same targets (much to the annoyance of some ) . I've convinced my wife it's just a form of therapy which in fact has some basis in truth. Quote Link to comment Share on other sites More sharing options...
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