1399 carbine stock fit problem

[Mort Canard]

I have recently added a 1399 carbine stock to my 1377 pistol.  It has the grip screws on either side and I have them as tight as I would think prudent.  I am still getting a little bit of rocking action of the stock against the 1377 when I am pumping it up.  Is there a way of tightening up the fit of the stock and the frame so that it does not move while I pump up the gun? 

[JMJinNC]

I put a third screw on the grip bottom. It is very solid.





Others shim the grip to tighten the joint.

JMJ

[Mort Canard]

Looks like a good solution! I have tried using duck tape to add a little thickness to the edge of the frame but it doesn't seem to work that well.

Looks like you are using the same size screw as the regular grip screws.   Very clean modification!   

[breakfastchef]

I put a third screw on the grip bottom. It is very solid.

X2

Excellent solution and rock solid!

[Davio]

Crosman actually makes part # 1389A070 for this, but I have been using a small square of the felt half of some Industrial self-adhesive velcro at that location.  It tightens it up, is permanent, and does not interfere with the quick change ability (or an extra screw to remove or see).

I use the same valcro on the under side of the pump arm for quieting it considerably.

[Mort Canard]

Crosman actually makes part # 1389A070 for this, but I have been using a small square of the felt half of some Industrial self-adhesive velcro at that location.  It tightens it up, is permanent, and does not interfere with the quick change ability (or an extra screw to remove or see).

I use the same valcro on the under side of the pump arm for quieting it considerably.

Ok, that sounds interesting.  Where do you put the velcro felt?  On the pistol frame or inside the carbine stock? 

Likewise, where do you attach the velcro, on the pump tube or inside the channel on the pump arm?

[Davio]

Ok, that sounds interesting.  Where do you put the velcro felt?  On the pistol frame or inside the carbine stock?  INSIDE THE CARBINE STOCK, OF COURSE.  ON THE FRAME IT WOULD BE IN THE WAY OF A GRIP SWAP.

Likewise, where do you attach the velcro, on the pump tube or inside the channel on the pump arm? ONE STRIP ON THE TUBE AND ANOTHER CURLED AROUND THE CROSSMEMBER.  JUST SEE WHAT TOUCHES AND GO WITH YOUR INSTINCTS.

Not a fan of random screwage... 

[JMJinNC]

Looks like a good solution!

Looks like you are using the same size screw as the regular grip screws.   Very clean modification!   

It's exactly the same screw as the two on the sides of the grip, so when I tear the gun down I don't have to keep track of which screw goes where. The large cross drilled hole is for clearance of the screw on the other side of the bottom flange.

A pretty easy modification if to have a drill, drill bit set , and the right tap. Took me maybe 5 minutes.

Btw. I have the felt on the inside of the pump handle to damp that dreaded "pump slap".

JMJ

[Mort Canard]

Decisions, decisions!     Will have to think about both solutions.  I don't think I am going to change grips back and forth.  I do have all the drill bits and taps.   OTOH I also have some stick on velcro to try that solution.   Thanks to both of you and thanks JMJinNC for posting the pix of your mod. 

I'm going to have to think about this one. 

[mudduck48]

You know what I think? These screws go into the same hole, cut 2 threads off the stock screws and then the screws will not bottom out on each other.

[Mort Canard]

You know what I think? These screws go into the same hole, cut 2 threads off the stock screws and then the screws will not bottom out on each other.

I had noticed that my old pistol grips never tightened up.

I am learning that there are a lot of quirks to the Crosman air pistols.  ...and even more quirks to the full range of mods that people do to them. 

[JMJinNC]

Fwiw, the mod procedure I used was:
1. Cross drill the large clearance hole
2. Measure from the exposed pinky "nub" to the center of your clearance hole
3. Install the shoulder stock.
4. Measure across and down perpendicular from measurement in step 2. This is the tricky part, but having a large cross drilled clearance hole will here. You can also lay the grip frame on top of the stock to see where you need to start your hole.
5. Drill your pilot hole (screw minor diameter) all the way through the stock and the grip frame into the clearance hole. I drilled straight in perpendicular to the bottom surface, right on the parting line, center line of the stock.
6. Remove stock.
7. Tap hole in grip frame.
8. Drill out hole in stock to clear screw threads (screw major diameter plus some tolerance).
9. If using flat head screws as I did, countersink the stock hole.

Using slightly shorter screws is also a great idea.

Note: you can also drill the cross drilled hole afterwards, but when you drill the screw minor diameter hole , it may get a bit wonky when the drill hits the thin section on the other side of the flange.

I hope this helps. JMJ

[targettgii]

That is an excellent picture of you Mort.

[Mort Canard]

Yep! That's about the way I figured the procedure went.  I am a steel fabricator by trade and used to doing layouts at quite a range of complexities. 

Thanks J.

[BillK]

I use a piece of rubber band either taped or glued to the stock just below where the quick change pin is located.  RUbber band is the one used on Broccoli heads at the grocery.
Doesn't sound like much. I know, but it does work.


This shows the blue rubber band with elect. tape over it lifted up from the stock.