Free float QB barrel?

[DanoInTx]

I'm sure this has been done/tried before, but I'm curious.

If I was to tap a second set screw hole just forward of the stock hole, then remove the barrel band completely, would this be stable enough to support the barrel?  Or maybe stable enough without the second set screw?  The fit feels pretty tight, but I know this has a little to do with the 3 barrel o-rings.  Thanx,

Dan

Free floating a barrel can bring a some poor shooting powder burning guns in line.  But that isnt a rule.  A gun that shifts in its bed will shoot poorly.  Many guns shoot better with some pressure or attachment partway up the barrel. Most guns' point of impact will shift when you reassemble the stock to the action.  Keeping everything snug is the key. Overtightening can damage a stock, so consistentcy is the rule.

[DanoInTx]

I'm actually mostly concerned with the QB-78's, and anyone that has tried to free float one.  I've never free floated anything, but this gun looks like it might be a good one to try it out on.  It has some fairly beefy breach attachment points that I think could hold up ok if I added another barrel setscrew.  I'm not planning to hunt with this, it will be a plinker/paper puncher, so the worries about it snapping off if I walk into a tree are kinda mute.  The other reason I'm trying to figure this out is because I've got a custom stock coming for it and if I don't need the barrel band I'll try to avoid getting it inletted for one.  It's 103F outside right now, but feels more like 100000F, so the idea of just trying it out is a bit difficult unless I feel like taking 3 shots, go back in the house, go take 3 more shots, go back in the house, take 3 more....you get the idea...I mean, I could melt!

Did notice the few shots I took in this heat actually slowed the pellet a bit, I'm thinking valve lock..anyone else?

Dan

[ribbonstone]

Been thinking on this myself.

The barrel and tube are both round...round on round isn't the most stable wy to stack things (whuld be nice t have a concave bottomed action.  Without the barrel band (whihc in itself can be a problem) all that weight and leverage would probably over stress the rear attachments...barrel falling to one side or the other of the round tube, giving two seperate groups.

Just my guess from looking things over, haven't done any modifications....but could take the band off and shoot it as it is to find out if my guess is on.

This isn't just an airgun problem...to free float a center fire or rim fire, have to build up the action's bedding....which we really can't do in this case.

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My thought is that if the barrel band was rock stable to the lower tube, and the barrel tight but still a slip-fit to the upper section of the band, it would have nearly the same effect as free floating (would allow the barrel to expand and contract as it goes through it's temperature changes). As issued, it clamps (kind of...smoe just done't seem to clamp all that well) both into a soilid uint.  Might be better if they could expand and contract seperatly.

[mikeiniowa]

I've worked on a few QB's now and have found that just removing the barrel band will help some rifles but not others, why? I don't know. Really no need for a second screw in the receiver, use a hardened 10/32 set screw and snug it down good. The newer OE set screws are harder than the old ones but will still round out with the cheap allen wrench supplied with the rifle, buy a good one and they seem to fit better and don't round out as easily. I have a .22 that didn't shoot very well at first, asked around and was told to remove the barrel band and try it, helped a whole bunch. On some rifles a small washer placed on the hold down stud will help settle a rifle down, must be do to the inletting of the stock not fitting quite right. On highly modified rifles the chill effect on the gas tube will make the barrel band and the barrel move quite a bit, on those types remove the barrel band for sure.

[ribbonstone]

Kind of convienced me it's worth a try....not right away, gun is shoot real well with teh band solidly fixed (and was shooting poorly with it as issued and unable to hold tightly0.

But the expansion thing has my attention...may just have to try fixing it solidy to the bottom tube but a slide fit to the barrel (tight slide...but still enough to allow for some tube expamsnion).


can always go back to the way its set up now neither of those work out.

remove it and see...also try epoxy bedding the tube.

[ribbonstone]

Did the work today.

Removed the band. Think the freezing with CO2 helped break the epoxy bond (have one of those Muzzle Loader ball removers that runs on CO2)..anyway, didn't ruin anything getting the band off.

Without the band, groups were worse...and I could shift zero with pretty gently pressure on the barrel. 7 test groups (5-shots each) averaged 25% larger, significantly the spread was more horizonatal...normal groups ae not only smaller, but tend to be round.  Floating might work for some rifles (I'd try it...is free and the band can always go back on) but it's not working for this one.

This time epoxied the band only on the lower tube surfaces. May not help expasnion; belive the upper part of the band would allow expansion and contraction but haven't tested for that.  With the barrel not epozied to the band, should be easier to dissassemble the rifle when that time comes.

[IJL]

Can anyone point a newbie to an article on bedding? I'd love to know about it

TIA

[DanoInTx]

I think I'll try it once it cools off.  I really still don't see how the barrel would move much even with the band removed, it is a very snug fit into the breach.  On the other hand I DO see where the heating/cooling of the air tube would throw it off if banded...although, in this heat mine really never cools, at least not for long.  I've yet to really shoot any groups with this thing, I just hate plastic and don't like it there...kinda cheesy to make a nice solid gun then put a chincy piece of plastic right on top of it..I know, cost.  Hehe, maybe I'll make a wood band to match my stock:)  Guess I could see what sort of aluminum we have running around in the recycle bin at work too...huhm.......

Dan