Grizzly 12.5" bbl dimensions - Why the XS Sights Big Dot T solves the POA/POI issue.

[grelmar]

Grizzly 12.5" bbl dimensions - Why the XS Sights Big Dot T solves the POA/POI issue.

So, Butcherbill dropped me a line asking for some dimensions on my 12.5" Grizzly that I've modded to (among other things) solve the "shoots high" issue these guns are known for with a bead sight. Other than "it works, moving on with life," I'd never put a lot of though into it. But being asked about it got me curious, so I pulled out the calipers and did up some measurements.

I figured what I came up with might be of interest to a few others, so here's what I found:

If you crunch the numbers, what you find is that the plain barrel XS Sights Big Dot T (Mfr Part: SG20033) raises the front sight to the point where the bottom of the dot is just below the sight plane of the top of the receiver, and the center of the dot is just above the sight plane of the top of the receiver.

Essentially, you want the front sight to line up as close to level with the top of the receiver as possible, so that when you sight across the top of the receiver to the bead (or dot), it makes the barrel as level as possible with your sight plane.

Hopefully this will help people with better metal fabbing skills than me, who can make up their own front sight arrangement.

Cheers.

 

[Butcherbill]

Thanks grelmar, you're awesome! That's really helpful, will be off to the races easily with this info.

 

[dogzilla]

That's one of the reasons Dlask has the big A$$ed blade on their barrels, and why the Remington shorter barrels while still a bead are on a pedestal. The shorter the barrel the higher the bead needs to be. The DA 8.5 shotguns were easily hitting a couple feet high at 50yds

 

[madashell]

Yup, figured this out by doing it sometime ago. It works.

 

[grelmar]

Yup, figured this out by doing it sometime ago. It works.

That's pretty much how i figured it out when I added the dot a few years ago. Someone mentioned "it works" so I figured give it a shot. Never measured anything at the time, just added the XS sight, found I was on target at 25 yards, never put any further thought into it.

When BB asked about it, though, I thought it would be interesting to actually get some dimensions. Getting out the calipers, sketching it out on a scrap of paper, then drawing it up on the computer, was kind of useful, for me anyway, so now I know which dimensions are important to look at if I need to do something similar on a different shotgun with slightly different dimensions.

 

[madashell]

Yes, your diagram is very useful, saved it. Thank you for taking the time measuring & drawing this up.

That's pretty much how i figured it out when I added the dot a few years ago. Someone mentioned "it works" so I figured give it a shot. Never measured anything at the time, just added the XS sight, found I was on target at 25 yards, never put any further thought into it.

When BB asked about it, though, I thought it would be interesting to actually get some dimensions. Getting out the calipers, sketching it out on a scrap of paper, then drawing it up on the computer, was kind of useful, for me anyway, so now I know which dimensions are important to look at if I need to do something similar on a different shotgun with slightly different dimensions.