GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Nvreloader on April 28, 2019, 12:01:27 AM
-
Guys
I got tired of re zeroing my Gauntlet 22 cal, every time I wanted to snipe starlings, or touched it.
Here is some info/facts I found, after I tore it down and did some careful measuring etc.
Total overall bbl length = 23 5/8", 23 5/16" from the front edge of the bbl TP hole to muzzle,
the muzzle did not appear to have any crowning, and the chamber lead is a 90* step,
which will be tapered for easier chambering of the pellet, along with a good crown job,
and the air stripper was cracked, over have the dia of the "O" ring groove was broken off etc.
The breech end of the bbl is .4305 dia at the TP hole, .4310" dia on the middle band,
.4320" dia at the 2nd breech screw, bbl TP hole dia is .140",
the bbl is turned (stepped down for approx 3.550" long to .4305" dia, from the breech end.
Breech hole (bbl fits into) is stepped, inside dimensions, starting at the breech face is .443" for 1/2" deep,
then the remaining hole dia is .435-.437" to the mag slot, total distance of 1.900".
After removing the 3 bbl "O" rings, the bbl was slide into the breech and seated against a mag,
I had over .135" of play, top to bottom and the same for side to side measurements inside the bbl breech hole.
There is a threaded/"o" ring bbl bushing that holds the rear of the shroud, .855" long, .805" dia, bbl hole dia of .440",
this bushing is fitted inside the breech face in a .825" dia x .070" deep lip, with 1 set screw,
to lock the bushing, onto the bbl.
So, after finding generous dimensions of the bbl breech hole, .005+ " of slop/play,
(no wonder there is a drastic POI change), here is what I plan on doing.
Set the bbl up in the lathe, 20 rpm, clean the part of the bbl that fits into the breech,
mix up some brass infused epoxy, and give the bbl dimensions a good coating of epoxy,
let dry overnight, then carefully turn the bbl shank to a push fit for the breech diameters.
Re cut the bbl "O" rings and then fit the new rear bbl bushing to tighter spec's to fit the breech face,
after I find my metric thread gage, so I can order the correct tap/die set.
Please give me your thoughts or suggestions...............on my plan of attack.
Thanks,
Don
-
And some more info to add, for this gauntlet,
Pushed 5 pellets thru the bbl, very tight starting at the chamber/lead in, with 90* lip,
8" down the bore from the chamber, is another tight spot,
then at 22 3/4" there is a tight spot/area until the pellet exits the muzzle,
the crown is polished in and off set and not running true to the bore line.
I do believe that this bbl is choked, as the tightness is the same for the last 3/4" of the bbl. :o
I used some of the metal duct tape, 2 complete wraps, inserted the bbl, was a firm push,
checked the side to side and up/down play/slop and found that I had less than 1/32" at the muzzle end,
as compared to the .135" before.
The breech TP hole is .172" dia with a recessed lip .282" dia, .085" deep, to accept the black rubber hose seal,
the TP hole seal .192" in length, .273" O/S dia .170" I/S dia,
when the bbl is in it proper place, the TP hole are out of alignment by .025/.030", from dead square/true.
There is a black plastic plug pushed into the rear of the magazine slot, with a hole just big enough for the bolt nose to pass thru,
there is a recessed groove, under each bbl set screw, and there is a recessed cut right at the inside TP hole,
unscrew the set screw in the end of the bolt and the bolt can be remove, like the QB 79 bolt.
The plenum tube TP hole is .265" dia, the valve TP hole is .195" dia, and the exit holes are misaligned by .030"+,
the valve is held in via a single screw on the bottom of the plenum.
More later, have some starlings to thump.............. ;)
Tia,
Don
-
Great detailed info. Thanks!
-
Well she is back shooting straight again, ;)
Full test going on, nothing but the wet noodle hanging out there right now, waiting for the new shroud pipe etc,
5 shots (after zero) = 2 Hosp - 1 starling at 40 yds.
Tia,
Don
-
Don, is the brass infused epoxy different than the steel reinforced epoxy in strength?
I've thought about doing the same to the RS barrel, as it undersized in the breach. No lathe, so would have to carefully fit with draw filling. Nice selection of mill files here, from second to ultra find machine files.
Mike
-
Sounds like you're heading in the right direction
Don, you have the tools/ skills to make a barrel band like the .25 Gantlet has. It is very effective.
(http://i67.tinypic.com/2zxm994.jpg)
-
Guys
I got tired of re zeroing my Gauntlet 22 cal, every time I wanted to snipe starlings, or touched it.
Here is some info/facts I found, after I tore it down and did some careful measuring etc.
Total overall bbl length = 23 5/8", 23 5/16" from the front edge of the bbl TP hole to muzzle,
the muzzle did not appear to have any crowning, and the chamber lead is a 90* step,
which will be tapered for easier chambering of the pellet, along with a good crown job,
and the air stripper was cracked, over have the dia of the "O" ring groove was broken off etc.
The breech end of the bbl is .4305 dia at the TP hole, .4310" dia on the middle band,
.4320" dia at the 2nd breech screw, bbl TP hole dia is .140",
the bbl is turned (stepped down for approx 3.550" long to .4305" dia, from the breech end.
Breech hole (bbl fits into) is stepped, inside dimensions, starting at the breech face is .443" for 1/2" deep,
then the remaining hole dia is .435-.437" to the mag slot, total distance of 1.900".
After removing the 3 bbl "O" rings, the bbl was slide into the breech and seated against a mag,
I had over .135" of play, top to bottom and the same for side to side measurements inside the bbl breech hole.
There is a threaded/"o" ring bbl bushing that holds the rear of the shroud, .855" long, .805" dia, bbl hole dia of .440",
this bushing is fitted inside the breech face in a .825" dia x .070" deep lip, with 1 set screw,
to lock the bushing, onto the bbl.
So, after finding generous dimensions of the bbl breech hole, .005+ " of slop/play,
(no wonder there is a drastic POI change), here is what I plan on doing.
Set the bbl up in the lathe, 20 rpm, clean the part of the bbl that fits into the breech,
mix up some brass infused epoxy, and give the bbl dimensions a good coating of epoxy,
let dry overnight, then carefully turn the bbl shank to a push fit for the breech diameters.
Re cut the bbl "O" rings and then fit the new rear bbl bushing to tighter spec's to fit the breech face,
after I find my metric thread gage, so I can order the correct tap/die set.
Please give me your thoughts or suggestions...............on my plan of attack.
Thanks,
Don
I would try cutting some shim stock from some feeler gauges and wrap around the barrel outside of the outer o-ring.
-
Thanks Guys
Mike, thanks,
I think the the steel enforce epoxy is stronger, but I was out of that, and only had the brass left,
if that don't work, I lathe it off and I got some HD construction epoxy, (son uses it in his work,
takes several blows with a hammer before it cracks), some tough stuff.
I did some careful/accurate measuring and found that the bbl shank hole is tapered, after this test is done,
I'll indicate it in on the lathe and bore/ream it out enough to make a clean straight bbl shank hole,
then epoxy the bbl shank up in size or sleeve it, depending on the clearance left etc.
Mike D,
I haven't had the drop block tube off yet, so I am not sure where the air vent is drill thru at.
I am trying another option first, which should work, I hope, and is adjustable for placement etc.
Jonnie,
I want full length coverage/support of the bbl's shank length, and I'll bed that rear bbl bushing,
after turning a proper sized one, to fit within .001" diameter etc,
that way I'll reduce any tippage/rocking of the bbl shank, it is so sloppy and lose etc.
Tia,
Don
-
Well the casting wax came in and I did a cast the breech bbl channel area,
here is what I found,
Starting a muzzle end of the breech, .440" dia hole by .250" long,
then a groove .485" dia by .250" wide, (centered right under the bbl grub screw)
then a straight section .600" long by .440" dia,
and a repeat of the front groove under the back bbl grub screw,
a short .440" dia section by .500" long.
BBL dia is .430" by 3.625" long.
Can you think of a reason for the 2 grooves under each bbl grub screw? :o
I just got a new LW .630" dia 22 cal, un chocked, Poly bbl 23.85" long,
are you thinking, what I am thinking?
Thoughts or suggestions are welcome.
Tia,
Don