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PCP - HPA - C02 Gate => QB-7X Gate -W/Co2 & HPA => : March 03, 2007, 06:56:28 AM

: Accuracy of QB78 in .22.....
: March 03, 2007, 06:56:28 AM

Hi all,

I recently got a power-tuned QB78 in .22 and just can't get it to be accurate/consistent.

I installed an RJ Machine steel breech, which helped some, but the POI still shifts and one shot out of three will be a flier. Sometimes a string of three shots will be scattered, but centered. I've tried different types of pellets, but I can't get consistency with even the most accurate ones. The gun does get cold when I shoot, but I thought a metal breech was supposed to correct for that...

I can shoot other guns accurately (one-hole groups) at the same distance (home range, 8.5 yards). Any ideas what's going on here?

Thanks!

: Re: Accuracy of QB78 in .22.....
: March 03, 2007, 08:48:26 AM

I agree with mike on this one. I dont own a qb (yet) but I do have a co2 pistol. ANd notice if I shoot it very consecutave thatr the velocity dropps off quite a bit. But If I let the gun cool a minuet or so between clips it seems to hold a nice tight pattern.. hope that helps some.


Jason

: RE: Accuracy of QB78 in .22.....
: ribbonstone March 03, 2007, 11:28:53 AM

Are a few things to check.

1. The barrels come coated (inside) with some kind of preservative that really sticks to the bore...need to clean that out.
2. Muzzle crown can be rough.
3. Some have a little burr on the air transfer port (the hole that shoots air in at the breech)...will slice an occasional pellt skirt ande cause a flier.
4. that &#*#&  barrel band.
5. The fit of the metal to the stock...if you can rock it, feeling a little play, would pay to do a little bedding to keep it solid and level.


Now I don't know the RJ steel breech for the QB; haven't found anything seriously wrong with the issue steel breech (can stand some smoothing, but they seem serviceable and solid).

: MADE A MISTAKE. I MEANT BARREL BAND, NOT BREECH
: March 03, 2007, 11:56:06 AM

I installed an RJ Machine steel barrel band. The breech is the factory original.

: Thanks for the ideas.
: March 03, 2007, 12:24:08 PM

I took the gun apart earlier today and made sure the screws were snug and also replaced the transfer port piece connecting the tube to the barrel. I thoroughly cleaned the barrel last night after a lot of testing. The muzzle crown is OK, the fit of the metal to the stock is solid and the steel breech *should* prevent shifting of the POI.

I'll test the gun again tomorrow, waiting three mintues between each shot, and see how it does.

Thanks again for the help!

: Re: Accuracy of QB78 in .22.....
: wtc9 March 04, 2007, 01:28:03 AM

Besides the barrel band, if you're shooting with a scope, I would suspect your scope mounting.  I just had a day like this with a similar rifle.  Turned out my front scope ring was sitting on a screw head that impacted it.  Everything was tight, but apparently the screw head caused minute changes.  Once I moved the ring back a quarter inch, everything was perfect.

: Re: Accuracy of QB78 in .22.....
: Gene_SC March 04, 2007, 01:39:11 AM

Dat sounds like a scope problem, but heck what do I know...:)

Gene

: Re: Accuracy of QB78 in .22.....
: DanoInTx March 04, 2007, 03:46:52 AM

Gene_SC - 3/4/2007  8:39 AM

Dat sounds like a scope problem, but heck what do I know...:)

Gene

Gene you know alot more than you'll admit to I'm sure.....hehe!!!

Dan

: PROBLEM SOLVED
: March 15, 2007, 12:38:07 AM

Turns out it was the barrel. Got a new one and now it's shooting like a real sweetheart...

Thanks for the suggestions and ideas guys.