Umarex Notos Bottle Conversion Cautions:

I have completed just over a dozen Notos bottle conversions using an Amazon purchased drop-block and wish to bring some of the challenges to light and discuss the issues I have found with the parts and fit-up.

First off is thread pitch, thread angle and such:

The thread pitch of the air block on your Notos to the drop block is M16X1MM. The air block needs a bottoming tap, this means that the tap has to have a flat end, no point.

The tap has to cut clean threads, you need to use cutting fluid and do short cuts, clear the threads often.

Thread pitch of the block gauge and foster fill fitting are both M10X1MM tapered threads. Please dont use non-HPA hardware and ALWAYS hand-thread the fitting all the way to the bottom of the hole before wrenching on them. Both holes also require that the fitting contacts the white teflon/nylon washer before tightening. The angle and thread tip are also specific to HPA

Second is the drop-block:

Every drop-block is threaded a little differently from the factory. Be aware that your drop-block may not clock with the air-block or it may be a perfect fit! PLEASE try to hand fit your air-block to your drop-block first before you send it off to be converted.

Third is the regulator:

When purchasing a regulator, make sure you purchase one with the pressure you want for the speed you are looking for. My Notos was set to 2200 psi on the regulator, I purchased the same and I still get around 750 fps.

You have two options when it comes to the plunger where the reg attaches to the drop-block. The first is to make a pin that fits inside the drop-block that will depress the plunger inn the reg, allowing air to pass from the regulator to the gun. This is a safety device and "allows" the bottle to be removed from the drop-block without the bottle emptying catastrophically.

The second option is to simply remove the end of the regulator and pull out the plunger, reattach the end and attach it to the drop-block. The safety is missing but is it actually needed?

I do provide a service to convert your Notos but you can do the conversion yourself as well with some tools. Good luck and good shootin!
Hi Firewalker, Iv done
 
Hi Firewalker Iv done the bottle conversion on a pp750 (same as notos) and when I set the reg to 1900psi it holds fine but then take a shot and it'll drop to 1700 psi take another shot and it goes down to 1500psi and stays there for every shot thereafter. Doesn't matter how many times I crank the reg up to 1900psi it keeps reverting to 1500psi after a few shots! Do you think a reg rebuild is needed? Or could be an issue with exhaust valve stem and spring ? Have you seen this occurrence before on the drop blocks?
 
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Hi Firewalker Iv done the bottle conversion on a pp750 (same as notos) and when I set the reg to 1900psi it holds fine but then take a shot and it'll drop to 1700 psi take another shot and it goes down to 1500psi and stays there for every shot thereafter. Doesn't matter how many times I crank the reg up to 1900psi it keeps reverting to 1500psi after a few shots! Do you think a reg rebuild is needed? Or could be an issue with exhaust valve stem and spring ? Have you seen this occurrence before on the drop blocks?

Regulator rebuild time. It's slow to fill so I would start with the seat.
 
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I'm still shooting both of mine after a year with no issues. Love these guns.
Mines brand new, but out of the box the m18x1.5 bottle thread was bad and too big! Had to cut the starter thread off and then slowly work the bottle on back and forth , removing every so often to clean off debris until eventually it would thread right up.