.22 Gauntlet with Carbon Fiber Bottle

I picked up a 22 Gauntlet for one of my sons to prevent squirrels from eating all the aluminum fence ties at his house.

He doesn't have a pump so I fitted a 300cc carbon fiber bottle, a 1650 psi regulator and a Hajimoto tuning kit to give it a high shot count.

This is the largest diameter bottle (55mm) that can be fitted inside the forestock, otherwise you grind through the top screw holding the two halves together.

I used a sanding drum on a drill to make room for the bottle. The regulator has the ports reconfigured to match the stock openings.

The forestock fits tight on the bottle now and makes the whole stock feel solid like it's one piece. I tuned it to shoot 16gn JSB at 900 fps. I didn't check the shot count but it's about double a regular Gauntlet's because I fill the CF bottle to 4500psi vs 3000psi for the little aluminum bottle it came with. >High res pictures link<

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Squirrel damage to his fence... about 50 squirrels were put down in 1 month. No more problems now.

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Now THAT is some onboard air! 1 fill should be enough to eliminate the largest squirrel situation if that was all it was used for.

One question, " The regulator has the ports reconfigured to match the stock openings " what exactly do you mean and how did you do this?

Thanks,

John

He likes target shooting also so I fill it about every two weeks.
There are 4 regulator ports with 3 being bottle pressure and 1 being regulated pressure... fill, gauge, high pressure burst disc and regulated burst disc. The gauge and fill port were 90 degrees to each other so I swapped one with the high pressure burst disc to make it work with the openings in the forestock. There's a screw under the regulator holding the forestock halves together so you can't just drill a hole for the fill or gauge.
 
Question, did you do any modifications to the stock valve retention system in preparation for the 1650 PSI?

No sir, should I ?

The gun has had about 600 pellets through it so far with no problems.

I believe you should yes. I personally would add additional fasteners to the valve body on anything over 1400. The only thing holding that valve in place is 1 single M5x4 (Item #10) screw that goes into the valve body at 5-1. They have a locator block (Item #19) rearward of that which is what the hammer rams into but by the time the valve is stopped by that locator block the valve screw would have sheared.

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Just for additional information, the .25 Gauntlet valve body was revised to 3 fasteners (at 9 o'clock, 6 and 3) rather than the one fastener at 6 o'clock. These additional fasteners where included due to the increase in pressure from 1100 PSIG to 1900 PSIG.

I have serviced or tuned over 120 Umarex Gauntlets and I will tell you that I have seen wear marks on the back of the locator block (item #19) as it kissed the valved body from the hammer driving it forward. That said between the hammer bashing forward and the valve and the valve being pressed rearward towards the locator block, I have concerns about the fatigue of the fasteners.

Regards,

Hajimotos
 
Question, did you do any modifications to the stock valve retention system in preparation for the 1650 PSI?

No sir, should I ?

The gun has had about 600 pellets through it so far with no problems.

I believe you should yes.

Regards,

Hajimotos

I will make the changes. Thank you for your help.

James
 
Totally agree with Hajimoto on additional valve fastners-too much pressure for stock valve setup. Your dealing with potential missle in your face- be safe on these mods.

1400 PSI MAX on the regulator on the stock .22 cal Gauntlet to be safe.

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While I plan to upgrade the fasteners ASAP, I don't see much chance for personal injury if the single screw failed because the locator block is still trapped in the steel tube by four fasteners holding #6 the bottle drop down at the front and through bolted and pinned at the rear air tube plug which is also blocked by the stock. I believe that if the single screw holding the valve locator were to fail, the locator would remain trapped and the pressure would vent out the hole where the screw sheared and hammer pin slot, dumping all air as it passes through the regulator until the bottle is empty.

I am not arguing against safety, I'm just sharing my opinion on this particular issue and I appreciate everyone's concern.

Thanks

James
 
Please read my post again as I never wrote or inferred personal injury. What I am saying is the airgun will be damaged or broken when the screw fails.
My experience with these things is that failure will usually happen when you pack up all your gear for a day out in the field or range and "TINK!" your packing everything back up and heading home 😃