Tuning Barrel Change Question

[Bogview]

I am adding another caliber to my Impact X and I have a question about how things line up back there on the rear block. When the barrel goes all the way in with the notch lined up, the end of barrel goes too far into the magazine area blocking smooth operation of the magazine in or out. I have to back the barrel off 2mm+- for smooth operation. Is this normal? Also, when the barrel is backed off for smooth operation it is showing a small amount of silver, unpainted barrel, exposed where the barrel goes into the block.

Below that, the original plenum also shows quite a bit more of unpainted surface where it goes into the rear block. Is this normal or is everything out of kilter back there. I've had the gun for a couple years now and never really thought about it until adding another barrel and thinking about upgrading to a Power Plenum.

 

[Saltlake58]

Just looked at my Impact. The back of the barrel should be flush with the front of magazine, so yes, you push it forward a couple millimeters. I can see about 2mm of silver in front of the block. Seems normal.

 

[heavy-impact]

Install the barrel with the magazine in place and the barrel making light contact against it.

 

[Bogview]

The thing that doesn't make sense is that the barrel is not all the way back seated in the notch on the rear block. So, when the gun is fired and the barrel recoils, the only thing holding it is the set screw without even a divot on the barrel.

 

[Saltlake58]

Give this a try:

https://www.youtube.com/watch?v=oWKO4c0jkpk

 

[Bogview]

I've seen this video and actually bought the Aztec scope based on that recommend. I don't like the scope, but that's another story. Matt's explanation on harmonics is spot on and could go even further with an explanation of powder burn rates and primers. His explanation of air volume and valve operation affecting harmonics is right, but I think the addition of the power plenum changes up what Matt was saying four years ago. Everything he said was correct but there's more information and evolution now.

About the machining of the barrel, barrel notch and barrel set pin, I need to measure this with a micrometer, but it cant be right that the barrel notch is seated on the pin and obstructs the magazine by allowing the barrel end to protrude into the magazine chamber.