Umarex Making a poormans AP16

[Genob]

Since Ataman AP16 is currently not available, my brother had me convert his Umarex Notos shorter, similar to an AP16. I cut the barrel down to 200mm, this allows for internal buffles to be used. I used 3 plastic cones from a marauder. It tunes it down but still a little loud for backyard use. I made a threaded end cap so he can add moderator if desired. The tank I only shorted 30mm and opened up inside of the end cap from 16mm to 22mm to gain back some volume. Shroud was also shortened along with the pic rail. AOL length is 350mm. It's doing 715 f/s with 14.3 CPHP. No loss in accuracy noticed at 32 yards.

 

[MikeVV]

Genob -

Nice work....BUT...
Did you do any testing of the air cylinder after machining ("opening up") the inside diameter ? Thinning the wall COULD...have disastrous results.

Mike

 

[Genob]

Genob -

Nice work....BUT...
Did you do any testing of the air cylinder after machining ("opening up") the inside diameter ? Thinning the wall COULD...have disastrous results.

Mike

Yes, had it hydro to 8K and passed.

 

[markhooper]

so you machined out the inside diameter of the tank? I'm getting ready to shorten mine too, same reason I wanted the attaman ap16 compact..
so there's a picture I have I'll try to find and attach where you can turn down the diameter of the regulator end housing quite a bit for more air..
also I hope to have time tomorrow to open the air tube and see how it is made.. wondering if it's just straight walled with the threads and o ring or if it is stepped.
I wanted to put the moderator insert in the shroud but it is too big.. if you don't mind could you send me a link for the baffles you got to fit inside the shroud?
do you have any pictures of the air tube disassembled on the inside? and what you machined out..
how did you do the front sight? did you mill out a notch in the picatinny rail and then epoxy the front sight in.. didn't look like enough room to make a new dovetail..
also do you notice any difference in noise between just the barrel with no shroud and now with the shroud.. if I understand correctly your barrel is shorter than the shroud and doesn't reach the end cap?
can you please remind me what size thread the air tube is?.
also what size is the thread on the inside of the shroud tube?
I'm wondering if it better to have the barrel shorter than the air tube so there's room for the air to cut down noise or is it not much different and just have the barrel the length of the shroud and air tube?
wishing I knew where to get just a little bit smaller moderator insert 3 d printed..because the factory one is 1" and won't fit in the shroud.. but if you have a source for baffles I'd like to know where to get them..
Mark

 

[markhooper]

found this picture where the other guy I was talking to, you can see where he turned down the regulator area for more air space..

 

[markhooper]

I've been making thread protectors and barrel extension for longgundallis today.. I have the steel one on the right finished and the brass one is also done..
the center 21 mm just needs facing and the barrel extension is turned, and internal threads and I just have to turn down the 11 mm for the male threads and finish.. hopefully tomorrow..
it was fun working with the lathe today.
Mark

 

[Genob]

found this picture where the other guy I was talking to, you can see where he turned down the regulator area for more air space..

View attachment 417196

You can bore out the end cap from 16mm to 20mm for added volume. If you decide to relocate the o-ring to the shoulder, you can open it more to 22 mm. I cut 10mm off the reg housing and open up inside wall 0.25mm around, then cut two threads that was not used when air block (#66) was bottomed out. The regulator only needs 2 to 3 threads as the pressure will push it towards the end cap.

 

[Genob]

so you machined out the inside diameter of the tank? I'm getting ready to shorten mine too, same reason I wanted the attaman ap16 compact..
so there's a picture I have I'll try to find and attach where you can turn down the diameter of the regulator end housing quite a bit for more air..
also I hope to have time tomorrow to open the air tube and see how it is made.. wondering if it's just straight walled with the threads and o ring or if it is stepped.
I wanted to put the moderator insert in the shroud but it is too big.. if you don't mind could you send me a link for the baffles you got to fit inside the shroud?
do you have any pictures of the air tube disassembled on the inside? and what you machined out..
how did you do the front sight? did you mill out a notch in the picatinny rail and then epoxy the front sight in.. didn't look like enough room to make a new dovetail..
also do you notice any difference in noise between just the barrel with no shroud and now with the shroud.. if I understand correctly your barrel is shorter than the shroud and doesn't reach the end cap?
can you please remind me what size thread the air tube is?.
also what size is the thread on the inside of the shroud tube?
I'm wondering if it better to have the barrel shorter than the air tube so there's room for the air to cut down noise or is it not much different and just have the barrel the length of the shroud and air tube?
wishing I knew where to get just a little bit smaller moderator insert 3 d printed..because the factory one is 1" and won't fit in the shroud.. but if you have a source for baffles I'd like to know where to get them..
Mark

View attachment 417195

I got the marauder baffle thru eBay, it comes in set of 7 with spring. I use carbon fiber tubing 22mm OD x 20mm ID also on ebay. Have to machine caps for the ends. I put 0.05mm interference fit.

 

[markhooper]

You can bore out the end cap from 16mm to 20mm for added volume. If you decide to relocate the o-ring to the shoulder, you can open it more to 22 mm. I cut 10mm off the reg housing and open up inside wall 0.25mm around, then cut two threads that was not used when air block (#66) was bottomed out. The regulator only needs 2 to 3 threads as the pressure will push it towards the end cap.

View attachment 417198

View attachment 417199

I see the 22.5 mm on the fill cap.. how deep did you go so it doesn't break off back where the o ring is? also, so with what you did on the regulator did it have a pelenium? did you shorten the pelenium. I didn't recognize the part corresponding to the picture I sent you, I guess I am a bit confused about how the regulator and end cap is..
what size threaders did you use? looks like you shorten the air tube, so one for that.. how about the regulator assembly?
do you have any other pictures of different views of the regulator?
Mark

 

[Genob]

I see the 22.5 mm on the fill cap.. how deep did you go so it doesn't break off back where the o ring is? also, so with what you did on the regulator did it have a pelenium? did you shorten the pelenium. I didn't recognize the part corresponding to the picture I sent you, I guess I am a bit confused about how the regulator and end cap is..
what size threaders did you use? looks like you shorten the air tube, so one for that.. how about the regulator assembly?
do you have any other pictures of different views of the regulator?
Mark

Yes it's 22.5mm, forgot to reset my DRO, lol. I went down to the base and did not face the bottom. I also use a 24mm x 2mm o-ring so the grove is only 2mm wide x 1.5 deep. Check with a depth gauge so you'll know where to cut the grove and have plenty of mat'l around it. The plenum I face off 10 mm, then cut new o-ring register for the reg. You can screw in part #66 to see how much you can face off the bottom of the plenum. Thinning the wall I don't thing give noticeable increase in plenum volume.

 

[markhooper]

Yes it's 22.5mm, forgot to reset my DRO, lol. I went down to the base and did not face the bottom. I also use a 24mm x 2mm o-ring so the grove is only 2mm wide x 1.5 deep. Check with a depth gauge so you'll know where to cut the grove and have plenty of mat'l around it. The plenum I face off 10 mm, then cut new o-ring register for the reg. You can screw in part #66 to see how much you can face off the bottom of the plenum. Thinning the wall I don't thing give noticeable increase in plenum volume.

so on the air tube, you didn't think it's wall did you? I'd be worried about future failure.. I need to just take the time and open the air tube and see if I'm up to the project.. thing is I don't and likely won't shoot it as a carbine.. and it got to be at least shorten to 16" because I can't freehand shoot it also can't afford the huben gk1 or anything similar.. I'm still kicking myself for not getting the attaman ap16 compact on clearance, but I was worried about parts and well the notos was the maximum my budget could do without skipping bills..
I suppose it would give me a little encouragement if I knew what the inside wall of the air tube is like.. is it just smooth and threads on the end or stepped?
I'm really waiting one actual pistol.. several cowboys powder guns in my collection but the notos is lonely because I don't like it as a pistol, and if I want to shoot rifle I want a long barrel..
so if you could tell me a little bit more about the air tube I might get the threading tap and get it done.. I guess I just don't like opening it up and then what, leave it open until the tap arrives or reassemble and wait.. kind of hard to keep my air charged with the end off
Mark

 

[Genob]

so on the air tube, you didn't think it's wall did you? I'd be worried about future failure.. I need to just take the time and open the air tube and see if I'm up to the project.. thing is I don't and likely won't shoot it as a carbine.. and it got to be at least shorten to 16" because I can't freehand shoot it also can't afford the huben gk1 or anything similar.. I'm still kicking myself for not getting the attaman ap16 compact on clearance, but I was worried about parts and well the notos was the maximum my budget could do without skipping bills..
I suppose it would give me a little encouragement if I knew what the inside wall of the air tube is like.. is it just smooth and threads on the end or stepped?
I'm really waiting one actual pistol.. several cowboys powder guns in my collection but the notos is lonely because I don't like it as a pistol, and if I want to shoot rifle I want a long barrel..
so if you could tell me a little bit more about the air tube I might get the threading tap and get it done.. I guess I just don't like opening it up and then what, leave it open until the tap arrives or reassemble and wait.. kind of hard to keep my air charged with the end off
Mark

The tubing is slightly undersize, it has to be opened up to 27 mm nominal to tap M28x1 pitch. If using the lathe chuck to hold the other end, install the end cap w/o o-ring just about to bottom out on tube. This way it won't deform when chuck is tighten. Also good to indicate the cut end to minimum TIR you can get.

 

[Genob]

found this picture where the other guy I was talking to, you can see where he turned down the regulator area for more air space..

View attachment 417196

I did similar on the regulator, made new housing for it . Base is 8.5mm thick (stock is 10mm) and short stem is 11mm dia. vs 14.5 stock.

 

[markhooper]

would you shorten a air tube for me?
also wondering, the grip is big and I have been looking at it wondering if I could make it at least a little bit smaller..
Mark

 

[Genob]

Oh what a fun day shooting both pistols, the Ataman AP16 and my just finished Not(os) AP16. I didn't realize how heavy the Ataman is compared to the Notos pistol.I can very easily shot it one handed being only 994 grams. Accuracy I give the Ataman a slight edge. I have them shooting both at 13 fpe. Trying out different grip to see which is more comfortable for off hand shooting.