AR2079A HPA project...

[AirGunEric]

Got a .22 cal Lothar-Walther barrel machined up (not by me) and installed it on an out-of-the-box AR2079A (with a couple snags- needed the breech end machined down a bit more- seems the Chinese have quite a large tolerance range on breeches). Used a .22 extended probe bolt, and then attached a 13ci HPA tank to it, regulated at 1300psi so as not to cause any issues with the stock parts (valve or tube). Topped it off with a Simmons 3-9x32 AO scope (economical, $89.99, but I may change the rings- don't like two screw caps much- but they come in the box with the scope).

Started out shooting a consistent 670fps using 14.3gr pellets for about 50 shots, then over the next 100 shots the range started to widen from 665fps to 690fps- but averaging around 685. Not so bad so far. Barrel has not settled in yet with about 250 pellets through it, but is tightening up. Seems to prefer Crosman 14.3gr FT .22 domes and the H&N Hunter Extreme (Philips-head ones) did fairly well, but were hitting 6" lower due to the weight (19gr)- didn't like the Spitzkugel so much, the Baracuda Power (copper coated) also drifted too much- but as I found with the Condor they really want alot of power behind them. The Benjamin Destroyers (part of the sample pack) were, as expected, all over the place. Funny enough, the non-lead H&N Baracuda Green worked quite well. All this is telling me is that at about 15fpe, it prefers lighter pellets.

So, with some use I think the barrel will get alot more consistent- which might open up the range of usable pellets- but I didn't really try that many different pellets yet anyways.

Leaving the LW barrel out- it seems like a pretty good combo- retail on it would be $441 for the rifle, extended bolt, HPA tank and scope, and the factory barrels have proven to be alot better the last year than they had been previously.

All in all, I'm pretty happy with it, but need more shooting time to get that barrel settled in completely.

AR2079A_chrony.jpgAR2079A_1.jpgAR2079A_2.jpgAR2079A_3.jpg

[sholo]

Nice setup you got there

[Gippeto]

Agreed! Nice rifle.

Any groups to share? :)

Al

[rsterne]

Your performance is just about what I had at the same pressure before any major mods to the valve.... I had drilled out the flow-through probe, removed the filters, and fitted a poly transfer port and drilled out the barrel port to 5/32".... The piercing pin was still in place.... I did find that the velocity was slightly higher at 1000-1200 psi than it was at 1300, however, but that was on a QB78 with the larger volume tube and might not apply on the 79 series.... The higher pressure may be necessary to compensate for the smaller volume....

Sounds like a very nice combo, and by keeping the pressure to 1300 psi you should be able to run a 1.8K burst disc on the output side of the regulator with no drama....

Bob

[SeanMP]

How much extra did you take off the tenon?

[AirGunEric]

About 0.020-0.025" or so across the diameter- the o-rings are there to take up excess space- and the unit as received got to the first o-ring before I gave up with the wood block and mallet and decided continuing would be really stupid if I ever wanted to remove the barrel again. Even cut down, the o-rings that passed the mount screw location wanted to expand into it and tear- so they had to be 'finessed' into it.

[SeanMP]

I'm guessing you meant 0.002 to 0.0025
2 thou as opposed to 20 thou

[AirGunEric]

No- I meant 20-25 thousandths- the steel was jamming in the breech- forget about the o-rings.

[SeanMP]

...That ain't good.

OE tenons have all measured .498-.500 for me

Breeches have measured around .510

If you had to take off 20 thou that means their own barrels wouldn't fit some of their sockets

[AirGunEric]

Could be- mind-you I didn't measure it- but it was, absolutely, over 10 thousandths- I had a bit of a run by not using the best possible tool in the lathe and used a file (with lathe turning) to smooth it out- it alone took off more than 2 thousandths as a result.