2260 and 2560 HPAs Get LW Barrels

[rsterne]

Back in the summer I got a couple of Lothar Walther barrels for my regulated HPAs.... They are 12mm OD, choked, 23.8" long, with conventional rifling.... I turned them down to 7/16" OD at the breech end, machined in chambers, leades and ports, and threaded the muzzles 1/2-20 NF to accept Hatsan air strippers which tension the barrel and also mount a 3/4" OD shroud.... These replaced a Crosman .22 cal barrel which was OK but not stellar, and a .25 ACP liner from TJ's which is going to be used for another project where I don't want a choke.... These two rifles are my varmint guns, and share a lot of features.... Here is a photo of what they now look like....



Both rifles are regulated, using my own design of reversed tank block which mounts the tank under the 2260 air tube where it doubles as the forestock.... The tank blocks have a 3-slot Picatinny rail on the bottom and a barrel band, which I made larger to mount the shroud, on top.... They attach to the threads on the front of the 2260 tube.... The breeches are prototypes for a repeater breech I designed which never made it to production, and I have three of them, these two plus the one on my Grouse Gun.... They use MRod self-indexing magazines.... One of the features of this breech is a front mounting band which fits around the main tube and makes the assembly very rigid.... The guns have custom hammers with integral spring guides which double as a cocking indicator by protruding through the RVAs which I also made.... The stocks are walnut, made by Dennis Quackenbush, and intended for a QB but easily modified to fit the 2260.... I shortened and sanded them, and finished them with 7 coats of Watco Danish Oil, wet sanded with progressively finer grit, ending at 600 and then a coat of Dark Winwax.... Both rifles have Hawke 3-12 x 44 SF Varmint Side Focus Scopes with 1/2 MilDot reticles and extended sunshades....

After the new barrels were installed I checked the tune of both guns and set them up on the "knee" of the power curve, just below the plateau.... On both guns the plateau (ie maximum) velocity was 995-1000 fps, with the .22 cal using 18.1 gr. JSB Heavies and the .25 cal 25.4 gr. JSB Kings.... The tank on the .22 cal is a 13 CI, regulated at 1600 psi, and on the .25 cal I'm using a 17 CI tank regulated at 1900.... After tuning to the knee of the curve, the velocities were virtually identical, which is important because I want the two rifles to have the same trajectory so I can switch back and forth without having to relearn the holdover.... Both guns ended up with the ability to shoot 4 clips without the velocity dropping.... For the .22 cal that was 40 shots at 957 fps (36.8 FPE) and for the .25 cal it works out to 32 shots at 961 fps (52.1 FPE).... The .25 cal had only an 8 fps spread and the .22 cal had a 12 fps ES.... While running the strings through the Chrony I used only one target for each rifle, and here is the target for 40 shots with the .22 cal....



The small squares at 0.1", and the .25 cal shot virtually the same, just a slightly larger hole from the bigger pellets for a 32 shot string.... The efficiencies are also nearly identical, 1.05 FPE/CI for the .22 cal and 1.02 FPE/CI for the .25 cal.... If I dial the velocity down to ~900 fps, that increases to about 1.20 FPE/CI, but these are my varmint hunters, and I really don't need more than 4 magazines on a tank as I take a tank with me for topping up if I'm going out for a whole day anyway....

This is one of those projects that got postponed over the summer but had to be done before varmint season rolls around next spring.... All that remains is to sight them in and go hunting in May.... The ground squirrels, crows, magpies and marmots better look out next year !!!

Bob

[CarsonRatSniper]

I have LW choked barrels on both my 1322 (16") and my 2260 (full length).
Both were fit to my supplied breeches by Roy Weid (http://www.mountainaircustomairguns.com) from Georgia.
Roy also made custom bolts for each gun.

They are absolute TACK DRIVERS!!!

Yes - a properly prepped LW barrel in an airgun (especially regulated) using Diabolo style pellets will make you grin ear to ear.

Mine aren't finicky but do best with JSB's, Predator Poly Mags and Kodiaks.

Bob, I'm going to have to ty those 18.1 grain JSB's............I've only ordered/shot the 14.3's.

[Ribbonstone]

Nicely done!

Good barrel does make a difference, and although LW's have taken a few hits here, they can still turn out a very nice barrel.

Now tell me of air strippers.

[rsterne]

I've been putting Hatsan air strippers on all my recent builds.... I love the look, and they don't seem to hurt anything.... *LOL*.... I haven't had a chance to do any serious adjusting (the cone slides in and out to adjust the gap to the muzzle).... but some guys that have, have reported significant improvements in groups.... They fit standard 1/2-2 NF threads, so if you get tired of it, there are plenty of other options.... I machine a shoulder in the tapered section at the rear of the stripper to fit the ID of my shrouds, make the shroud the right length, and when you tighten the stripper up it tensions the barrel and puts the shroud in compression.... effectively stiffening the barrel.... Again, how can that hurt?....



Bob

[CarsonRatSniper]

I didn't know you could adjust the cone. That's pretty cool

The tension should be fantastic. That's what Volquartsen does for their rimfire barrels.

My 2260 barrel is in 'suspension' from the 7/8" carbon fiber shroud.
Its tight at the breech via 2 grub screws and a barrel band - then there's another barrel band at the forensic - then at the muzzle is the Delrin spacer ring for the shroud.

I like your tensioned setup.

[Ribbonstone]

Was wondering about the attachment.  Agree, they won't hurt, and between the air stripping and the added tension, is more likely to help.  For a "fiddler" would bring another set of variables to drive me crazy.