On mine, I noticed the same thing. I first tried to dab a little wd40 inside the barrel but noticed that there was too much friction as I attempted to insert the to the correct depth so I ended up cutting the MPP back about 1 1/2 “ filed and sanded the edge and repeated the process.
Here are...
Nice Job on your build. I will send you some photos of mine as it comes together. I used a roman props mpp which but yours turned out really nice once you chromed it. Thanks for your help in selling my the rear greeblies.