Will a 16mm dia barrel fit a 13xx or 22xx?

[Adam77K]

Hi all, as above really.  What I mean is will it fit above the tube on a standard (Crosman, GMAC etc) steel breech without a riser or machining the whole barrel down? 

A quick search yielded the statistic that the std barrel is 7/16" which is 11.11mm.  This means there would need to be more than 2.44 mm clearance between std barrel and tube.  My gut feeling says it won't fit and will need a riser, but it could be close.

[Gippeto]

No, barrel will need to be machined to fit the receiver and either turn the rest of the barrel down to 1/2" (largest diameter that clears body tube) or add a riser to the breech.

Al

[Adam77K]

Thanks Al, useful info.
I knew the barrel would need machining down for the breech.  I'd seen a HW100 60cm barrel for sale at a reasonable price and was fancying a super-accurate pumper project (1389 on steroids) but having to add a riser or turn the whole barrel down makes it less economically viable.

Edited: mistyped barrel length; should be 60cm (2')

[eric]

like al said, but the botttom of the barrel could also be machined/contoured to fit over the pump tube. i had a 1320 with HB81 barrel in a rjmachine breech(short)like that --- edited to say --- you might consider a barrel band as well and that would need to be made custom as well if you ever decide to go that route

[K.O.]

I used a 9/16 barrel for a .25 13xx I figured out I should shim it .03. did it, but honestly think it would be fine with out them.  I think that's 14.5 mm or so. I am using a bored out 2289 barrel band it works but better would be better...

[Gippeto]

Why not give it a whirl and report back...supposition only gets a  fellow so far after all.

Al

[BDS]

+1 to Gippeto, it's just simple math, take the metric barrel dimension, divide by 25.40 and you have your std. decimal inch measurement. Cut her down for the breech and bore out a barrel-band and you are there

[eric]

just an idea to whet your whistle

[Adam77K]

Nice!

[DaveB50]

airgunbna makes a Riser Breech Kit for $28.
http://airgunbna.com/

Or, you can go this route. Low tech riser block.
http://www.network54.com/Forum/678247/thread/1320194790/Low+tech+riser+block

[eric]

Nice!

thanks ,the barrel was 14 inches and it was very heavy as a pistol and muzzle heavy as a small carbine. one more

[WyoMan]

Hi Adam,
Don't know if this will help...never had a 16mm barrel but I had to roll my own with some 12mm LW blanks
I'm not a big fan of riser breeches...pellet  further from the valve and the bolt to the striker the same
But here's how I did it, with 4 barrels so far...

Turning it down from .475 to .430 so using this "tool bit":


It's a mill file and general purpose file held apart by nuts and bolts wired on and equipped with an adjustable pressure device (number of loops control depth of cut): 


Making chips now...more like dust this is going to be slow:


Finish with that, its .430" which will leave me some room for a coating:


Chamfer the outside edges to fit in the bottom of breech:


Next is the forcing cone...using a double fine cut carbide tree burr cutter...what they call it anyway, in 3/8" x 3/4":


That only took about 1 minute...cuts fast, now check bolt fit inside the breech:


Mark the hole for the transfer port:


Centerpunch:


Drilling straight and centered with the gizmo guide thing...9/64" cobalt drill:

Same for countersink with a #8, 135 deg...drilled it a little more than 1/32" deeper than standard cuz I don't like the breech to rock on the TP sleeve:

Got it to line up with the bolt TP:


Next is the leade and deburring which I'll do at the same time with sandpaper rolled into tight rolls that are slightly larger than the bore. Force them in as you rotate and they will cut a nice taper (like fire lapping on steroids) and you get the polishing done too as you work from 400 grit to 600 grit.

Finished with 12 coats of lacquer...if I counted right 


hth...

[Adam77K]

Hi Adam,
Don't know if this will help...never had a 16mm barrel but I had to roll my own with some 12mm LW blanks
I'm not a big fan of riser breeches...pellet  further from the valve and the bolt to the striker the same


Finished with 12 coats of lacquer...if I counted right 


hth...

Oh my, that is beautiful mate! 

A little more skill and tools required than I have though.  Was it necessary to turn the barrel down even for a 12mm blank?

[WyoMan]

Thanks Adam, yes I had to cut about 0.040" o.d. of the 12mm to fit a standard receiver. I took 0.045" and added a few mils back on with the coating. If I had to do a 16mm, I would do it per Al's reco instead of turning the entire barrel down to 0.435 - 0.437".
There was a time when I didn't think I could do it either 

[KevinP]

WOW ..  !!! nice job  ...