New QB78 deluxe from ^&$@_=s FPS issues

[Death_By_Air]

I just ordered a new .22 QB78 deluxe through ^&$@_=s custom shop and I had them install their XP bolt upgrade and their XP valve replacement.

Well I gassed it up and set up my target at 12 yards to zero in a scope I wanted to put on. It seemed to shoot great and had great accuracy with several different pellets and felt like I got a good 35 40 hard shots.

Well then sadness set in as I threw it over my Chrony. With two fresh 12grams I shot 10 CP HP 14.3gr and FPS was 500-550 max. This was on a hot 86F day. Not only was it quite low, a spread of 50 FPS is a bit high in my opinion also. I went ahead and put 10 more CPHP waiting 60 seconds before each shot. Consistency improved a bit but FPS did not change too much. Ended up shooting the rest of the 12grams and FPS slowly putters out.

I put two more fresh 12s in and shot some lighter RWS 13grain. Fps hovered around 550-570. Still well under the stated FPS increase on @#$%^& site for having the bolt upgrade and valve installed. (They advertise ~670 ) I never heard of QB78 having any really break in period so maybe I got a dud? I guess I'm kicking myself for not getting the gold test (silver was free)and having them shoot it. I figured if they did the install on the parts what could really go wrong.

Has anyone had to send one back to them? I love the gun other than this FPS issue and really want to keep it in the stable! Not sure what all to check to try and remedy the problem and I don't really want to fool to much with it or start taking it apart if I have to return it for a new one or for them to trouble shoot it.

Thanks for help in advance!

[GumpIsrael]

If the shop you bought from ^&$@_=s, be aware that you have to return it in the packaging it was shipped in.
You might have a leaking o-ring in between the chamber and exhaust port. Or it could be that the factory seal is still in place, and if it is it's constricting the flow.
On the bright side though, these guns are super easy to work on and there are tutorials all over the place.
I bought all my mods through You-Know-Who's website and did them myself. I changed min from a regular QB78 in .22 cal to a .177 repeater that will go half way through 3/4" plywood at 10yrds (I don't have a chrony yet).

[Death_By_Air]

could be that the factory seal is still in place, and if it is it's constricting the flow.

One would hope not as I paid for the parts/service for them to replace that with their aftermarket kit lol. I do have all the packaging still.

After taking a look at it again last night, I notice the bolt cocks back super smooth but is very rough pushing back forward and almost feels like there is some resistance pushing back on it. Is this something out of the norm? I know the bolt will take some breaking in as its new but just wondering if it shouldnt be "that" much force on it once its cocked.
 

[Extreme]

    They cock on the forward motion. Also, the seal between the bbl and air tube get smashed Abe your co2 has too much resistance. Easy fix with after market seal. Should get in the mid 600's these are great little guns. Best of luck Brother Man

[Acapulco]

You may have experienced valve lock...with your temps.  I don't know how AA sets them up. Also, check/ replace the transfer port that could be your problem.

Forgot to add...remove the barrel there're 2 orings. One may have gotten chewed upon assembly.Dont worry ace has replacements rings.

[Death_By_Air]

You may have experienced valve lock...with your temps.  I don't know how AA sets them up. Also, check/ replace the transfer port that could be your problem. Forgot to add...remove the barrel there're 2 orings. One may have gotten chewed upon assembly.

Hmm...well I did go shoot it inside so this also happened at general room temps as well. I will take a look at the transfer port when I check the barrel orings you mentioned. Correct me if Im wrong, but the Arche.r XP bolt kit includes the replacement transfer port seal right? I just dont know why it would have the old one left in there.

[Death_By_Air]

Also I just remembered something when I first shot it. I swear it was shooting really hard when I put my very first rounds through it our of the box, a full 2 12grams. I didn't chrony it this first time as I just wanted to sight in my scope.
The sound of the "pop" was also much more pronounced as I recall. It hard to be shooting what it should be at FPS wise.

After I was done with it that first round, I sat on the couch and casually cycled the bolt (with a little extra muscle behind it) maybe 25-30 times trying to wear it in a little as the action was a little rough being brand new. 

I then put it away for the night and the next morning I brought it out and thats when I put it over the chrony and got those seemingly low numbers. Its like I could feel it wasn't shooting as hard as the night before. It just didn't have that same "pop" to it. Could I have done any harm cycling it the night before?

[Atomic Powered Gruds]

What if it just turns out there's a really leaky O-ring. I am no expert but if you where just cycling it and not letting the hammer slam down it should of been fine and please anyone correct me if I am wrong I need to know as well. Though I know a lot of people dry fire there QB79 to remove the bottle. So I really cant see whats wrong here besides what others have said. Valve lock or o-ring messed up down the line.

If somehow there was a burr in the breach where the O-ring on the bolt probe comes in that could explain it happening after being cycled causing it to eat in on it. You should be able to run a Q-tip around the inside of the breach where the bolt slides in and it not catch at all. If the Q-tip does not catch if I remember right you could try shooting it once with a tissue over the breech to see if any gas is being lost when firing. I have not done these things before but its stuff I remember reading  in the past on here at one time or another.

[Underwhelmed]

Personally, I don't trust that guy any farther than I can throw him after some seriously shady dealings I had with him in the past.

It wouldn't surprise me at all if you paid for an upgrade and didn't get what you paid for.

A Crosman 2240 transfer port fits the QB78 or 79 perfectly, or you can buy a section of ice maker line at your local hardware store and make your own custom Arc*er transfer port right in your own home.

I go to Airgun Depot for my QB-78 and 79 needs now.

[GumpIsrael]

Personally, I don't trust that guy any farther than I can throw him...

It wouldn't surprise me at all if you paid for an upgrade and didn't get what you paid for.

A Crosman 2240 transfer port fits the QB78 or 79 perfectly, or you can buy a section of ice maker line at your local hardware store and make your own custom Arc*er transfer port right in your own home.

I go to Airgun Depot for my QB-78 and 79 needs now.

+1. I agree. There is a reason I only buy parts from him (and only if the parts aren't readily available somewhere else), and I always double check to make sure I get what I paid for.

[Death_By_Air]

Personally, I don't trust that guy any farther than I can throw him...

It wouldn't surprise me at all if you paid for an upgrade and didn't get what you paid for.

A Crosman 2240 transfer port fits the QB78 or 79 perfectly, or you can buy a section of ice maker line at your local hardware store and make your own custom Arc*er transfer port right in your own home.

I go to Airgun Depot for my QB-78 and 79 needs now.

+1. I agree. There is a reason I only buy parts from him (and only if the parts aren't readily available somewhere else), and I always double check to make sure I get what I paid for.

Yeah Im starting to feel that way

I got the gun out tonight to throw a few rounds on target and try the tissue over breech suggestion the other member mentioned to see if any air escaped. The Tissue didnt budge in the slightest however the pellets now shoot out so slow that I can barely see them flying to hit my target thats only 12 yards away. Ugh its like its getting worse just sitting there lol!. Its been the same 2 12grams iv had sitting in there for about 2 days as I was looking to see if it was leaking. I just dumped a few more rounds thinking I was near the end of the co2 and went to twist off the end cap and the tube was still so pressurized I had to get pliers to even make it budge! So i know im not loosing air between the end cap and the valve...So there is some failure going on after the tube.

Should I even bother going through the return process? I have to pay shipping to send it back and and %20 restocking fee. THATS only if its new! The only way it says Its a "return" will be issued is if its "unused" Well how would I know it shoots like SHAT if I didnt use it?

Maybe Ill just cut my loses and keep the extra parts and order one from AiRE gun depot like the other guy said

[StevenG]

You won't need another. You can fix this one. There are lots of good threads on them here.

[Death_By_Air]

You won't need another. You can fix this one. There are lots of good threads on them here.

Yeah I guess I can try and take it down. Im just not sure what to look for as to where the problem is. The tube seems to be holding air so I assume its somewhere after the valve? This is just my first QB series so im pretty new at them.
 Though, Iv taken my 13xx and 22xx apart dozens of times so Im sure I cant be that bad at it lol.

[StevenG]

Transfer port seems to be the popular opinion. Not that long ago I had a member here talk me through taking apart an XS60C, over the phone, I bet if need be you can find the same level of help.

I figure there is a good reason that vendor's name can't be written here.

[Death_By_Air]

Transfer port seems to be the popular opinion. Not that long ago I had a member here talk me through taking apart an XS60C, over the phone, I bet if need be you can find the same level of help.

I figure there is a good reason that vendor's name can't be written here.

YEah I noticed that!

 Thanks for all your help man. AND everyone else's help!

I will strip it down tomorrow and take a look. Since the transfer port SHOULD be the larger aftermarket one that comes with their bolt kit, It shouldn't be the crushed stock one...at least I hope lol. But other than that is there anything I should specifically look for with the port that may be causing issues?  Maybe not seated properly? gunked with lube/no lube?

I did read/print out some of the take-down threads here on the QB78 and I feel confident I can take it apart. Now to find the problem!!

[Charles Outdoors]

Check youtube for how to video's.  It's really not complicated inside.  Basically the hammer weight driven by a spring hits a pin that breaks the seal and lets out a burst of air.  Sounds like you have the pressure, but either the hammer is not hitting the valve pin hard enough to open it or the valve pin is not moving free enough for it to open and let out a proper burst of air. Someone mentioned the transfer port. That is how the released burst of air gets to the barrel. If it was blocked or out of place it would keep the proper amount of air from getting to the barrel.

Once you get inside one of these you'll see there not hard to maintain.  Just be sure to always de-pressurize the co2 first when working on it.

If a name is filtered out here, you can bet there is a good reason.

[Atomic Powered Gruds]

I heard there was some knock off goods as well as a lot of stories like this one. I particularly remember one story of someone who bought a new rifle that when they removed the front sight there was signs of someone previously trying saw the tip off the barrel as well as rust being present on the internals.

lets hope its better then that.

[Gerard]

This could be silly, but I've heard that the QB rifles come stock with some sort of fiber washer ahead if the valve. I got my QB78D in already somewhat modded condition and the valve had been worked on, so no filter. But if there were such a fiber bit... could it be that the thing has slipped free and become jammed in the valve spring? If that happened I'd expect a serious drop in output volume. It would seem this is a possible explanation, since leaks don't seem to be an issue in this case.

[Atomic Powered Gruds]

I have a feeling once its been opened up the problem will be found in short order.

[GumpIsrael]

I have a feeling that the XP valve was never installed. In fact I bet your gun is completely stock. That fiber filter can disintegrate and clog the gun in a matter if shots.