Upgrading, Modifying The QB78-How Far Can You Take It ?

Just wondering how far you can take the basic QB78 with upgrades and modifications ?

I guess I'm asking if I buy a QB78 would I be limited to what I can do with it compaired to another model of the same gun ? Can I add the bulk tank like the 78T and maybe someday convert it to PCP ? What exactly does the bulk end cap enable you to do with the 78 ?

Thanks Bill

[DanoInTx]

To give you the obvious question, the bulk fill end cap allows you to bulk fill your QB78....hehe, clear as mud right? Instead of adding powerlets(CO2 capsules), you can just fill the CO2 tube full of CO2 from a source such as a paintball tank.

How far can you go with a QB78....hehe, I've gone pretty far and I doubt I'm even close...here's my two, and my Crosman 2300:

Top one is a Mike Melick tuned AR2078 (match rifle variant of the QB78). Outside of the Mike Melick tuned action I have a barrel shroud by Roy Weid of Mountain Air, a beautiful curly maple stock by Steve Corcoran of Woods and Water Outdoors, and a 6X24X50AOE Chinese scope with one piece mount...this thing COOKS!

The bottom is a stock QB78, I tuned it following Charlies tuning guide and a few things out of my own hat, it has an Arts Shack muzzle brake, RJMachine barrel band and a shiney polished bolt handle (chucked it up in the drill press and spun it down with finer and finer paper then steel wool).

I love my AR2078, but really enjoyed the time I spent tuning my own QB78. I haven't gotten any real good chrony numbers on it yet(last time was in hot summer causing valve lock), but I'd guess it shoots in the low/mid 600FPS range...both of mine are in .22.

None of mine are bulk filled, but I'll probably move in that direction next summer when I can shoot them again(CO2 kinda lacks at 40F). I don't know much about the 78T variants, but suspect that there is a little something different to the air tube, someone else here probably knows that answer(probably length, and obviously the end cap).

I would have to say that there are tons of cool things about these guns, I wish I had 100 of them sometimes, definately can't beat the price. As far as being limited on mods....the only limiting factor on mods is what you can dream up...this is a very easy gun to work on if you have some mechanical ability. I don't think there are many mods out there that you can't do with most any of these models, except maybe run powerlets in the bulk filled "T" versions:)

HTH,

Dan

Dan, that is a beautiful rifle you have there.

I'm thinking about getting the standard QB78, but I was wondering if that would put any limitations on what I can do to it down the road. Maybe the T model would allow for more mods, I don't know. I don't want to buy one and find out later that I would have been better off if I had gotten a different model.

Thanks Bill

[IJL]

Hi Bill. Well I'm about to take my QB78 to the "next level". I've just ordered a .25 barrel to go on top of the existing PCP conversion.
We are limited to 12 fpe here in the UK but I expect that will give me a really good bunny gun and quiet too especially with one of those bulges on the end that are not mentioned here by name Add a good tune to smooth and lighten the action and it should be really something.(It's about time I had one for me!)
Being PCP I'll be happy to turn the wick up to the legal limit as gas costs will be minimal. I'll be posting a report when it is complete.


I also saw a post on another site where someone had fitted a very large calibre barell, about .38 as I remember, hmmmmmmm

I have some other ideas as well for the trigger and a magazine. (The mag was built but performed poorly so needs a re-think)

IMHO if you want a plinking / light hunting rifle then the type with the external bottle under the barell may be slightly cheaper in the long run. CO2 costs are less and I would expect a queue of people waiting to buy the CO2 end cap for their 78 if you go for a full PCP conversion.


How far can you take it? As I said before, I accidentally got 1017 fps from my PCP .22, about 38 fpe and it would probably have gone further with some valve work!. With a .25 conversion on top of the PCP, especially where you are with fewer legal restrictions on power, let's just say I'd love to be allowed to find out!

Ian

You stated you got over 1000 fps in .22 cal. with your QB78 converted to pcp. Can you tell me what you had to do in order to convert your's to pcp ?

Thanks Bill

[IJL]

It's basically a length of 2mm wall stainless tube with a fill valve at one end and a demand valve based on the QB type at the other. Cut the CO2 tube off, mill out the stock to take the wider PCP tube re assemble and start playing to get what you want from it. Got a machine shop here looking at a re designed version, hope it will be slightly shorter overall, slightly thinner so no stock milling but still the same volume, also easier filling. It will be nice if it works.
The tank is supposed to be good for 170 bar but with the valve and hammer springs I use 150 is fine. BTW the 1000+fps was an accident! It's sub 12fpe again now.

The bulk end cap enables you to fill the gun from a bulk CO2 source, much cheaper to run that way and maybe ups the fps a little.

Personally I have not yet seen a QB that could not be modified to PCP, but I'm sure someone has one!

Ian

Just wondering if you could post some pictures of what you did to your QB78 ? If you like you can email me at lib7273@msn.com or just post them here.

I'm really interested in these modifications to the QB78, should have a new one arriving this week.

Thanks Bill

I think we need to havesomeone do a write up on how to convert to pcp.. Even if I only got 20 shots from a fill i wouldnt care. 800+ fps in .22 would be well worth it.

Like maybe a list of what exactly would be needed to convert the guns. I think that would be pretty helpfull.

That sounds like a great idea to me.

It would be great to have instructions and pictures on the different ways to power the QB78. From co2 cartridges, bulk fill all the way up to PCP. I know it would be greal for people who know nothing about co2 guns in general. like me. It is very difficult for someone who knows nothing about them and their terminology to try to make heads or tails out of all the post on this forum. It is very hard to make a decision on what model QB to buy without knowing what modifications you can make to them later.

Bill

[IJL]

Ok, youv'e talked me into it, I'll put something together with pics over the next couple of days.

Ian

That will be a great help for me and all the other members who are thinking about getting a QB78 or for those who already have them and want to make the change over to some other power source.

I should be getting my new QB78 on Thursday, can't wait.

Thanks Bill

[IJL]

I'm sure you will enjoy it Bill, just run a few dry patches down the barell before you shoot it. Most of the new triggers feel gritty but less than an hours tinkering will fix that! Then just shoot it in a bit before you try to measure anything. The bolt will feel stiff to start with too, it will wear in or you can use the info on CDT's (Bob's) site to help smooth it out.

Over here I'm seeing the XS78 derivatives mostly coming through with the QB Deluxe butt pad, a nice easy upgrade I would recommend to any QB owner who can get hold of one. Archers do something very similar...................

I'm hoping to strip the PCP today and photograph it ready for the article I prommised you, just have to get the customers work done first.

Ian

[IJL]

Ignore this one

[IJL]

OK, well It's done. I did try and post it here as a PDF but it's a tad over the 100k limit  I've went a Word version to Gene in case he wants it in the library.

If you want your own copy drop me an email Air_rifle_tuner@yahoo.co.uk


Cheers


Ian

If you want you can maybe email it to me and I can host the file...