Gauntlet Barrel Band

[WeaselCat]

I was discussing the Gauntlet POI shift with the owner of a local shop. I had a make-shift contraption that kind of worked but needed alteration since it was forcing the barrel upward. After some brainstorming and a little trial and error, I think he came up with a pretty good 3D printed design. Installation requires removal of the tank/regulator block and probably a little material removal from the web sections in the stock under the airtube. He posted pictures of the first prototype on his facebook page - ohio airguns llc. (the screws in the pic are crooked due to my hasty hand-drilling). He has now added screw holes to the printing program.

An update with pics will be posted once I get a chance to test it further. I'm currently waiting on parts to adjust the regulator before reassembly.

[Tygon]

I had a 3D version of my own made.  I had problems in the heat.  It would expand and force the barrel up.  This would cause my poi to shift 1” high at 25 yds.  Let the gun cool in the house and it would go right back to zero.
Took it off and put a stronger spring in the shroud and am careful to not handle the gun with the barrel an have not had issues.

[Springrrrr]

My dual solution seems to work well with no POI shifting any more.  The concept to to tighten the relationship between the barrel and the shroud so they are pulling or pushing against each other.  Adding shroud supports to the system helped too. I had the same situation as you with the change in temperature, not so much anymore.

https://www.gatewaytoairguns.org/GTA/index.php?topic=143151.msg1449919#msg1449919

https://www.gatewaytoairguns.org/GTA/index.php?topic=140487.msg1416107#msg1416107

[WeaselCat]

I'll have to do some hot/cold POI shift check when it's back together. Seems very sturdy. I'd rather have the same in aluminum but I think this will be OK.

[WeaselCat]

Sanded the visible surfaces with 150 grit and installed #8 black screws. The difference in barrel rigidity is night and day. Still haven't received everything to adjust the regulator so no performance review but I have confidence that it will be a major improvement.

One problem with the Gauntlet is the receiver flexing forward of the screw in the loading area. Lift up on the barrel and you will see a large gap open between the receiver and the air tube. This band (or any band) 100% eliminates that movement.

I did have to remove some of the thin web inside the stock to clear the new band. About 3mm around the perimeter and 20mm long. Certainly not enough to compromise function and it cannot be seen when assembled.

[CraigH]

Really nice work, Ken!     

[David Mccann]

nice clean look... nice

[WeaselCat]

Thanks for the compliments. Most of the credit, however, goes to the man with the printer. I just dressed it up and gave feedback for fine tuning the program.

As pictured, the screws are #8 sheet metal screws. I was concerned that the holes would strip given the nature of 3D printed parts. I tightened them down very snug with no issues so far. If needed I will counter bore the holes on the opposite side and use machine screws and nuts.

The pressure gauge for my reg tester did not show up today.  Third day in a row, USPS showed it at a different post office within 20 miles of my house.

[Ironman482]

I did something similar,  but I  machined a dovetail in the top of the vavle bloc, and mounded a scope ring with a bushing , works good for me ,I'll  try to laod pics

[Ironman482]

I like yours better more bearing surface

[WeaselCat]

She's back together and initial trials are promising. Shooting nice groups at 60 yards. Then I held it by the barrel and swung it like a pendulum, shook it back and forth, tweaked left/right.... No POI shift!!!
Still need to check hot/cold as previously mentioned.

FWIW: The reg was at 1100 psi from the factory with two .005 shims. Adding a .010 shim brought it up to 1200. Decided to try it there until I can get some chrony time.

[jarmstrong]

Give the man a GOLD STAR, you just fixed the Gauntlet biggest problem 
if the POI shifts every time you bump the barrel, it makes for an unreliable tool- 

[only1harry]

So is there anything on the market (that is bulletproof) for those that cannot make their own barrel band?

[WeaselCat]

Not ready to call this one bulletproof. Need to carry it over my shoulder like the Umarex ad.
The local shop printed a few more of these. He's just waiting for my evaluation before offering them for sale.

[jarmstrong]

"Need to carry it over my shoulder like the Umarex ad. "

Ads are misleading  they are meant to sell guns 
any gun will flex, it's just a matter of how much force it takes to do it
your fix is a good fix  , better than putting it on the bottle, IMHO

[Hajimoto]

Not ready to call this one bulletproof. Need to carry it over my shoulder like the Umarex ad.
The local shop printed a few more of these. He's just waiting for my evaluation before offering them for sale.

I actually busted out laughing when i read that! 

[WeaselCat]

One more round of testing done. There's good news and bad.

The Bad:
After parading around the yard all "Umarex Dude style", the POI shifted about 1" right at 60 yards. In all fairness, I was applying a lot of force on the barrel instead of just keeping a steady balance. Or ...maybe it was because I was wearing a 30 year old T shirt and flip-flops instead of full camo. I suspect that most of my airguns would perform the same.

The POI can be moved if deliberate force is applied. I didn't measure the force required but it is above what I would consider normal field use. An accidental drop would almost certainly be a problem.

The Good:
I don't handle my guns as explained above.

Resting the barrel against a wall, picking the gun up by the barrel when resting vertically. sweeping the barrel though small tree branches and other normal handling did not change POI.


I also put a few rounds over the chrony with the reg at 1200psi.
JSB 10.34  913 fps
JSB 8.44  972 fps

[Trigger_Finger]

Not ready to call this one bulletproof. Need to carry it over my shoulder like the Umarex ad.
The local shop printed a few more of these. He's just waiting for my evaluation before offering them for sale.

Ken, what filament  is the shop using?  Abs or PetG? If PLA it will shrink under the sun exposure.

[WeaselCat]

I'm not sure what material was used but will ask. 3D printing, in general, is not optimum for structural parts but making one from aluminum would be a little expensive. Next week I'll do more tests after leaving it in the sun and a hot car.

My son can use the Crown and I'll shoot the Gauntlet for field target on Sunday.

Couple groups at 50 yards with JSB 8.44:

[WeaselCat]

Zeroed the rifle yesterday, marked yardage on the sidewheel and put it in a case. Took it to a FT shoot today. Carried it with a sling all dy, layed it on the ground and handled it just like I was hunting. Arrived home and it was still dead-on.

The band is printed with PETG.