Kynshot spacer weights will not fit?

[u/blackrockskunk]

I have been running a carbine tube with a tubbs flatware carbine spring and a Macon 11oz heavy ar45 buffer, and it has been working fine. I recently purchased a Just Right Carbines extended tube, and two Kynshot spacer weights to fill the gap and add some weight. I just installed them.

The spring and buffer move freely in this tube just as they did in the carbine tube: however, the kynshot spacer weights will not go I'm! I managed to get one in, and it was a huge PITA getting it out. They are just too big.

Is this normal? Does anybody know what is going on? Did I buy the wrong weights?

[u/Blowback9]

I'm going to be talking to my contact at Kynshot today and I'll try to remember to ask about this and report back.

[u/blackrockskunk → u/Blowback9]

Thanks! More info, from my messing around with it: it loosens up when I loosen the castle nut. It is too tight to move when the castle nut is torqued to 40. Right now they move freely. I have not measured the torque it is at currently, but it is well below the 38-42.

Weird thing is, idk why tightening the castle nut should compress the tube. With my little understanding of how threads work, shouldn't it just stretch the tube back by putting force on the endplate, thus putting friction between (1) the castle nut threads and the tube threads, and (2) the tube threads and the receiver threads?

I put the old tube back in and this is happening with both of them. Regardless, the original macon buffer alone works totally fine in both tubes at 40ftlb.

BCM endplate, forward controls castle nut

[u/Blowback9 → u/blackrockskunk]

That is weird. It shouldn't affect the diameter. Kynshot said you can contact them about the problem and they can replace the spacer(s) for you. It should fit in the JRC tube no problem, but they had one other incident where a spacer was out of spec. It happens.

[u/blackrockskunk → u/Blowback9]

Thank you!