QB79 Accuracy Problem

[Mebits]

Okey-dokey,

I've converted the QB79 to HPA. Like it a lot. The groups are good, too and getting better. Or, they were. I got a Umarex compensator and installed it.

First couple shots were 2" right and 3/8 apart. Whoops!

I removed and replaced teh compensator rotating it a bit. That put me right about back on target, but my groups have opened up. I'm getting flyers. I also note that while I WAS getting nearly one hole groups with the Super H-points, now I'm getting 1/2" or more groups at 45'. The domed which were worse are now better.

I shot about 70 shots through it and decided to quit as I was approaching 1100 psi, and feared that such might be affecting accuracy. I'll be down there again working on things, but there are a few questions...

Should I just keep rotating the compensator or do I need to bore it out? CAN I bore it out?

Should I do anything else to the compensator? Is it salvageable at all?

Tangentially, while I'm on the subject, should I be cleaning the barrel on this MM tuned gun? I've run about 200 shots through it, I think. If so, any preferred methods?

Thanks,
M

[bubba zanetti]

When I received my full tuned QB-79 from Mike I ran a patch down the barrel and could tell he had already done so. But nothing wrong with doing it again.

So the only change is the compensator? Nothing else?

BZ

[bubba zanetti]

I did the Goo Gone felt pellet method, but again the barrel was pretty darn clean.

BZ

[Mebits]

So the only change is the compensator? Nothing else?

Yeah. Yesterday, I took it off, groups back tight again. Put it back on with a twist, got better groups but still not tight.

I SUSPECT that I may have had some issues with air pressure on the last few shots. I'll know when I go back down. I also was messing a bit with the AO, and THAT could have introduced some parallax, too. I will keep it at the same regular adjustment this next go 'round.

M

[bubba zanetti]

Weird because my QB got a little tighter on groups when the TKO went on.

Can you send it back?

BZ

[wilsonj1018]

look for clipping for sure and look carefully as it will be hard to see.

[BrainsB4Beauty]

So this is regular off-the-shelf Wally World Goo Gone, or some firearm variant?

[bubba zanetti]

Just plain ol' Goo Gone.

BZ

[Mebits]

OK, we shot some more. The first few were all over the place, with both Super HP's and Domes with domes shooting better. So, we loosend the screws and turned the compensator 90'. Shot some more.

Better but...

Tried it another 90'. Much better. I wasn't sure how good it was, but I shot a couple targets. The Domes, which were looking good earlier fell back behind the HP's.

Here's the target. This is .22 at 45'. Note I took two test shots. The gun seemed to be shooting a bit left, but I stopped worrying about it and focused on keeping my field of view bright and clear hoping to minimize any parallax.

5 honest to goodness Bulls and 4 9's. I'm thinking the compensator is sorted. What do you think?

[canyonbiker]

Okey-dokey,

I've converted the QB79 to HPA. Like it a lot. The groups are good, too and getting better. Or, they were. I got a Umarex compensator and installed it.

First couple shots were 2" right and 3/8 apart. Whoops!

I removed and replaced teh compensator rotating it a bit. That put me right about back on target, but my groups have opened up. I'm getting flyers. I also note that while I WAS getting nearly one hole groups with the Super H-points, now I'm getting 1/2" or more groups at 45'. The domed which were worse are now better.

I shot about 70 shots through it and decided to quit as I was approaching 1100 psi, and feared that such might be affecting accuracy. I'll be down there again working on things, but there are a few questions...

Should I just keep rotating the compensator or do I need to bore it out? CAN I bore it out?

Should I do anything else to the compensator? Is it salvageable at all?

Tangentially, while I'm on the subject, should I be cleaning the barrel on this MM tuned gun? I've run about 200 shots through it, I think. If so, any preferred methods?

Thanks,
M

I too had a Umarex compensator  and I had trouble with it so I sent it back for a refund. I make my own compensators now.

[bubba zanetti]

Looks good to me 

BZ

[Mebits]

I too had a Umarex compensator  and I had trouble with it so I sent it back for a refund. I make my own compensators now.

Is that something you can elaborate on?

M

[Raizer]

Mine did something similar with a ldc fitted, but if wouldn't group that great even without it.
Thinking it was clipping I opened out the baffles in my ldc, fixed a couple of leaking seals that the gun had came with and in the end I found that my 79's .22 barrel is bigger than .224 and only the JSB express pellets would come close to grouping only since there skirts are so thin and soft they expand to the rifling.