Need QB36 Advice

[hdrider]

I got my Chrony today and did a test of 20 shots from the QB36 using Crossman Premier Lights.  I think the results pretty well tell the tale of a bad piston seal.  The first 3 shots were 525.3, 536.8, 468.7 after that everything was in the 300's.  The low was 302.6, High 536.8, Avg 370.3, Extreme Spread was 234.1, and Standard Deviation was 64.86.  From what I understand you want the Extreme Spread to be 30fps or less -- mine's 234!

I did the same 20 shot test on my almost new GAMO Big Cat and got Low 894.7, High 931.5, Avg 913.3, Extreme Spread 36.05, Standard Deviation 10.00 -- almost good results, but the spread of 36 indicates I may have some work to do on it also.

Also, I bought a Tech Force 97 "cleaning kit" from Compasseco -- it came with new seals and a new spring.  Unfortunately it came with a new leather seal instead of a synthetic one and it's literally hard as a rock.  Guess I'll need to soak it in Charlies Special Lube mixture to soften it up before installation  -- any advice on that would be appreciated.

[rr_shooter]

hd -

Was there anything else included in the kit besides the seals and spring (e.g. trigger parts)? The picture on the Compasseco site looks like a kit for a B3, instead of a TF-97/QB-36. False advertising to show synthetic seals and then send you a leather one.  Also, is there any difference between the stock spring and the one in the kit?

[hdrider]

The packing slip said Tech Force 97 cleaning kit, hoewver the actual "Shooters Choice" box was marked QF-2  and B2 whatever that means.  I received the kit very quickly (within a couple of days)

Besides the cleaning stuff the following parts are included:
Spring -- approx 18mm OD x 12mm ID x 267mm Long -- I haven't compared this to the existing spring yet
Trigger Part (1) -- looks like the part that catches the piston when cocked
Trigger Spring (1)
Leather Washers (3) -- approx 12mm OD x 6mm ID -- not sure what those are for yet
Synthetic seals (2) -- approx 12 mm OD x 7mm Long -- cylindrical outside with a conical hollow interior 10mm ID to 6mm ID
Leather Piston Seal consisting of a Leather Cup (1) with a synthetic interior plug (1) with a phillips head screw (1) through the center

I'm just about ready to pull the QB36-1 apart to see what these parts correspond to and if they are the correct size for this gun and what condition the existing parts are in.

[Graham]

My friend fixed his seal problems using this kit, pic in link.
http://i363.photobucket.com/albums/oo80/willis61/Air-Rifle-Cleaning-Kit.jpg

[hdrider]

The Pic "looks" like the same kit I have, but I can't tell from the photo what the part number is on the box.  Could you ask your friend what numbers were stamped on the side of the box?  Did he also have a QB36-1 or TF97?

Also, I just now disassembled the QB36-1 and checked the spring lengths.  The Spring in my gun is about 1.25 inches longer than the spring I received in the kit.  The Kit spring is 34 coils long while the stock spring is 39 coils long.  I don't know if the shorter spring is an "upgrade new design" or just a spring meant for a different gun.  The spring will fit fine, but just have less precompression (which may be good??).  Not sure right now whether I should reuse the stock spring (which has a slight bend in it from being in the gun I suppose) or stick the shorter spring in and see what happens.

[Graham]

It seems strange, but it is labeled as Industry Brand QF-2, which is what you have, si I can't understand why you should have a leather seal in yours. As for the mainspring, I can't tell you as he used a spring called the "Titan XS" mainspring. His rifle is a QB36-2.

ATB, Graham.

[rr_shooter]

hd -

That QF-2 cleaning kit is intended for the B3 and B4 models by Industry brand.    Here's a link to a similar kit at South Summit:  

http://southsummit.com/catalog/product_info.php?products_id=629

I haven't taken my TF apart yet, but from what I've seen and read, the trigger parts will not fit your rifle.  The breech seal will likely work, as will the piston seal, provided you can come up with a way to mount it.  Most B3 models have leather seals like the QB and TF, and need an aftermarket "button" to mount the synthetic seal; the B4 came from the factory with a synthetic type, so the swap is much easier.

Good luck with the rebuild. I'm looking forward to hearing how it turns out.

[hdrider]

The QF-2 kit I received from Compasseco (which they claim is for a TF-97) looks the same as that pictured on the South Summit website, although the description of what's included looks pretty cryptic.

I compared the parts in the kit to those I removed from my QB36-1 yesterday and confirmed that the trigger parts (Spring and Release Pawl) are identical.  The leather piston seal and breach seals are also a direct replacement for the existing leather piston seal and breach seal.  My existing leather seal was dry and pretty "carboned" up

Two things that still puzzle me about the kit are the shorter spring and the 3 leather washers that were included.  I think I'll install the shorter spring and see what happens (using the Chrony), but I still have no idea where the leather washers are supposed to go.  Does anyone have any idea where leather washers are used in a QB36-1 or TF97?

[rr_shooter]

hd -

Glad to hear the parts fit - I was obviously wrong about the contents of the kit.  I guess you can't always trust a picture in a catalog.  

Sorry, I can't help with the question on the leather washers - I've yet to tear into mine to offer any suggestions.  But, I'm sure there are others here that can lend some advice.

[rr_shooter]

hd -

I found the exploded diagram for the QB/TF, as well as the parts list, and have attached scans of both.  I don't see anything that could be a leather seal, as you received in the kit.  But then again, this list is not comprehensive - I also don't see a breech seal listed, but obviously the rifle has one.

Hope this helps.

[hdrider]

Thanks for the parts listing.  I noticed that there are several parts shown that aren't on my QB36-1 -- perhaps I've got an early model?  Mine is missing parts # 26, 27, 29, 32, and 33.  It looks like those parts are all related to safety locks that may have been added in a later design version.

I also took another look at the Piston Spring to figure out why the new spring was shorter (34 coils versus 39 coils that was in the gun).  The new spring is made out of slightly larger wire (.120" dia versus .117" dia) and has a slightly smaller coil ID -- looks like the new spring is shorter but stiffer so hopefully will provide the same/better results.

I should have it back together in a couple of days and then Chrony the results and check accuracy, and then post them here.

[hdrider]

I checked some on-line coil spring calculators and found that the .003" difference in wire size equates to about 40 pounds/inch difference in compression force.  So -- it looks like the newer, shorter spring supplied with the QF-2 cleaning kit from Compasseco is actually equal to or stronger than the original spring.  I'll know for sure once I get the gun back together and get a chance to Chrony it.

[rr_shooter]

Not sure about parts #26, 27, and 29, as I haven't yet disassembled the trigger.  Parts #32 and 33 are, as you stated, related to a safety mechanism that hooks into the cocking mechanism.  You have to depress the tab on part #33 to return the cocking arm to its locked position prior to firing.  

Look forward to seeing the chrony and accuracy results from the kit spring.