Strange problem M3 .30 Sniper

I bought a brand new FX Impact M3 .30 Sniper. I knew I was going to shoot some heavy slugs, so I ordered the Heavy liner, carbon sleeve and tensioner (and now I am waiting for a tungsten hammer). I installed the parts, got the slugs and went shooting. I started calibrating and setting up the rifle, and after finding the right tune, I noticed I can't make a normal group. The shots were going everywhere!
The slugs I got are 62 grain (4 grams).
After 40 shots, I noticed something strange - When I open the stock moderator of the FX, a lot of lead debris fall out. I started questioning the slugs. Tried measuring them, and at the base they were 7.63 (instead of 7.62). I don't know if this is normal.
A friend of mine is using the exact same setup, the exact same slugs, but there are no debris falling from his moderator, and his shots are a bit better than mine.
Should I change the slugs, or am I doing something wrong? These are my first experiences with an FX rifle.
 
It sounds like the moderator is clipping the slugs. I think Seeker is on the money and one or more of the baffles is out of line causing the problem.
You might start there and see if it changes anything. I've run into that problem before and a quick adjustment with a drill bit cured the problem.
Any interference at all in the LDC will cause the problem that you described. Be sure and post your findings.
 
I just had this issue with my Impact. Check your exit hole diameter of your shroud. My rifle was a factory 25 Cal that came with a 0.242" sized for a 22 Cal. FX uses 3 different sizes for some reason and I was shooting 30 Cal slugs through mine. The mod and shroud were full of lead shavings and chunks. There is an air stripper on the inside of the shroud that is all the same size, but then for some reason FX chokes it down depending on caliber.

Obviously check your mod diameter too, as that can also be an issue. There should be at least a 0.020-0.040" bigger exit diameter than your ammo.

Edit: Just realized you have a tensioner so maybe my situation wont help you, as I think those are all the same size. If shooting without a mod doesnt help, I would inspect the tensioner end adapter. Also carbon fiber tubes are not always cut with a perfect 90* shoulder. If your end adapter is not perfectly straight your mod axis can shift causing clipping.
 
A quick follow-up:
Not sure what was the cause, but the slugs were hitting the exit hole of the moderator. As @MongooseV8 said, may be the tensioner was not cut properly and was twisting the mod ever so slightly.
I removed it and now I am shooting with the stock shroud, making groups and there is no more lead junk in the moderator.
I will have to re-tune the rifle now, but that is the least of my worries.
Thanks a lot for the advices.
 
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