B 5-10

I have one of the little pumpers coming on Tuesday, just wondering if a QB-78 barrel could be made to fit with some machining, whats the OD of the stock barrel? I'll post more after I'm into this one and have it cleaned up and shooting.

Hi Mike,

The barrel on my XS-B5-10 mics out at about 14 mm, whereas the QB78 barrel is about 14.1 mm.  They are pretty close.  I don't know if much would have to be done.  You should know for certain by Tuesday evening.  I can tell you this--I used the same little homemade muzzle brake on the QB78 that I used on the XS-B5-10 without any modifications.

Bevo66

Well.......looks like it might work, a tenth of a mm isn't much.

Boy what a slimey mess, worse than a Fast Deer. Tore it down and cleaned it up, did everything but the valve, have to figure out how to get that apart. With 7 pumps it shoots about 650 any more and it won't dump the whole charge and is kinda slow. Trigger is tough but will smooth out with a little TLC and some thought as to how to do it. then on to the rest of the rifle to see what can be done. It is quiet to shoot.

Hi Mike,

I never removed the entire valve in mine, but you can use the little metal spanner to remove the rear of the valve to access the seal if it is leakingi.  That oil deteriorates the seal.  I put some Krytech on the pellet loading slot under the little plastic thingy after I cleaned up all of the oil.  The pellets slide in a lot easier.  It likes wadcutters and round nose type pellets like the Gamo Hunter.  I haven't tried any but I understand ointed pellets may jam the loading mechanism.  Smooth out the trigger by slightly rounding the front edge of the sleeve that threads on the cocking bolt.  The e-mail I sent you the other day tells how to do it.  Hopefully some other XS-B5-10ers will share their experiences with this little gun.

Bevo66

I opened the ports on the valve and the main block to .173 I'm now shooting in the rifle some and will be checking the velocity in a day or so, kinda work up a sweat in the heat pumping it up. It still dumps 7 pumps but with 8 or more you can get 2 shots with one pump up, 9 pumps and two shots both in the 500's, that doesn't make this a 1000fps rifle does it?

That sounds like Aggie math to me.  LOL.

Let us know what your velocities are after you work your magic on the B5-10.  With my B5-10, as delivered, I was getting just under 600 fps with 6 pumps when I chronied it a few weeks ago, so I have never pumped it any more than that.

Bevo66

I played around with the gun some last night, got a QB-78 barrel machined to fit today and got it back together after work. It will dump 6 pumps and shoot around 600. If I pump it up to 9 pumps then shoot an air ball and then load it the velocity for the next shot on that charge is in the 700 fps range(Beeman Lasers). The plastic window by the magazine broke so I'll have to make a cover plate next, did a quick tune on a B 3-1 also this evening, just to darn busy, should have a case of QB's tomorrow to do for the guys.

[Cvan]

Any more opinions on this gun yet? I'm thinking of putting my money down. Looks to be a good truck gun.