I sent my upper back to bushmaster to get an izzy flash suppressor put on.
When I rescoped the rifle I had to crank the windage to the left for a while to get zero.
This scope was on this rifle originally, and I have an ARMS throw lever base on it.
I figured it would be close to my last zero.

I also look at the rifle and it looks like the barrel is a hair to the right.
How can I tell if the barrel is straight?

Quoted: I sent my upper back to bushmaster to get an izzy flash suppressor put on.

Was the barrel threaded before, or was this one of the things they did to add the device?

When I rescoped the rifle I had to crank the windage to the left for a while to get zero. This scope was on this rifle originally, and I have an ARMS throw lever base on it. I figured it would be close to my last zero.

We need to know the amount of  MOA's degree’s you had to re-adjust the scope (read if the scope adjusts ¼”, then 4 clicks would be 1 MOA).  “A while” tells us nothing since it is not uncommon to have few degrees of POI change as items are added/removed to the end of the barrel will cause harmonics changes to it.

I also look at the rifle and it looks like the barrel is a hair to the right. How can I tell if the barrel is straight?

Pull the barrel and roll in down a flat surface, this will show you the straightness of the outside of the barrel, But what really matter is the inside bore and it continuity.  

The Question that I come up with is this,
Does the barrel group well with the new device (bearing in mind that a slight POI change is normal). If not, then are you getting bullet strikes down the inside of the device? And, does the barrel still zero out with the iron sights?

Thanks allot .

A buddy took it off for me and put it back on.
We went to the range and it dead on.
It even looks strait.



Any way Thanks for your help.