View Full Version : Patterned My Under Barrel

July 24, 2012, 06:46 PM
I patterned the lower barrel of my o/u with a modified Briley Extended Choke. It appears to shoot neither right nor left, but to the POI appears to be about 4" higher than the POA at 16 yards and sighting it with a perfect figure 8. Is this high for an XS Skeet with a high rib?


July 24, 2012, 06:59 PM
How does this compare to the top barrel?

July 24, 2012, 07:48 PM
First of all ....you're not "patterning" ....you're determining Point of Impact....to see where it hits vs where you look.

When you check the POI ....you put a say 3" dot on the pattern board...and screw in a mod of Full choke...so you can see where the center of the pattern hits.... this Point of Aim concept makes no sense....what is the Point of Aim vs Point of Impact at the pattern board.....does the gun hit where you look or not....

does it hit the same as the top barrel....

July 24, 2012, 08:39 PM
Okay. I used the patterning board to see where my lower barrel's Point of Impact, with a modified choke, was in relation to my Point of Aim. I did not check the POI of the top barrel.

I replaced that poor quality picture with a better one after I figured out how to upload it to photobucket. Are you telling me what I did is of littlel purpose without knowing where the upper barrel shoots?

July 24, 2012, 09:10 PM
Today I just horsed around on the patterning board. Tomorrow I am shooting, but will use the patterning board to check where the POI of both barrels in relation to the POA.

I will also some shots to emulate firing on the line. Three at the board with the lower barrel and then three at antother piece of paper with the top.

Dave McC
July 25, 2012, 09:07 AM
Good idea. For patterning, I oft rest the gun on a solid object. For establishing POA/POI, I shoot as if the aim point is a bird flying straight away.

Often the top barrel of a O/U will shoot flatter than the bottom one. Not a glitch, the paradigm is both clays and birds will climb at first and level out. Second barrel works better shooting flat most of the time.

Do not get overly bent out of shape if the POIs are a little off each other. Beretta supposedly thinks within 8" is acceptable. More crucial is POA/POI convergence.


340 Weatherby
July 25, 2012, 11:42 AM
Klawman, the problem here is a lack of comparable Data. You need to acquire about five more shotguns so we can collect more relative data to do a comparative analysis. As you know, I'm not a trap shooter, but I think patterning the gun at sixteen yards is too close as that is not where your breaking the bird. Just bring your checkbook, 300 and I can help solve these problems. It is what we do.

July 25, 2012, 11:57 AM
Your purpose in checking Point of Impact ....vs where you look ...is to decide if the gun fits you in its current configuration or not....and if not / then you need to adjust the comb or maybe the recoil pad.

8" high is quite a bit ....but I also wouldn't bench the gun, I'd shoot it offhand ...standing at 20 yds or whatever ....and I'd put in a Full choke ...and I'd shoot 3 shells at the same spot. Sometimes you might flinch a little ...or slap the trigger or something...so 3 shells will tell you, if you're consistent or not.

Obviously when you are checking the POI for one barrel ...you have to dismount and reload ...for the other 2 shells...so if there is too much variation in the POI some of this may be a bad mount as well...you have to kind of work thru all this stuff.

and yes, I'd check one barrel with 3 shells.....then check the other barrel...ideally, you want them both shooting to the same POI. As you know I have 5 Citori XS Skeet models ...( in 4 gagues ) ...and both barrels on each gun shoot to exactly the same point of impact. Browning does not, at least on that model, intentionally regulate one barrel to hit a little higher than the other ( but they do, on some of their sporting models for some reason / like the old 525 series ) ...which I've never understood.

Some deviation in POI is probably acceptable ....after all it is a shotgun ...ideally shooting a dense 30" pattern at the kill range...but I'd want both barrels to have virtually the same POI.

If the POI is left or right ...then you need some adjustment for cast ...either on or off...( move comb left or right )...move comb up or down to move point of impact up or down. I don't know the formula gun fitters use ...but a change as little as 1/8" adjustment in your comb height ...will make a pretty big difference at 21 yds.

July 25, 2012, 12:05 PM
checking point of impact doesn't have to be done at the "kill" range. I'd recommend about 20 yds ...so its easy to see the 3" dot you put on the pattern board. Going back to 35 yds ...just makes the dot too hard to see.

Patterning is different...as you know....so if you're pattening your gun ...say with a Modified choke for 16 yd Trap singles.../ you want to shoot that Modified choke at about 30 yds...( which is the kill range on a 16 yd Trap bird ...you stand at 16 yds ...bird goes downrange to about 30 yds as you kill it )... at the same 3" dot.../ draw a 30" circle around the Point of Impact ...and see how many pellets you have inside that 30" circle....or probably more importantly, how many flyers do you have outside the 30" circle ....and do you have any holes in the pattern big enough for a target to fly thru unscathed.

I "pattern" my reloads once in a while....and I compare them to "factory" shells....and the patterns do vary a little with different mixes of components....and with how many times the hull has been reloaded ( a little / not much but a little ). I might also pattern a 1oz shell at 1200 fps, a few at 1150 fps, some at 1225 fps....to see if there is a difference as well.

It tells me ( because I know the Point of Impact is set right on my gun ) for a 50% / 50% pattern on my skeet - sporting clays guns ( my XS Skeet models ) ...with the POI right on to where I look .....so if I see a lot of flyers in my patterns....then maybe my reloads are a little suspect...maybe my shot is softer than I'd like ( giving me some mis-shaped pellets ) that become flyers..../ maybe my velocity on the shell is too fast...blowing holes in my patterns ....

and sometimes more analysis ...is paralysis.....

don't drive yourself nuts with this stuff.........but get your Point of Impact fixed first.

July 25, 2012, 05:32 PM
Back from a horrible day of trap. I am just patterning (even if determining poi is considered not truly to be patterning) to get an idea where the gun shoots in relation to where it points. I was so hot (temperature wise and after shooting so poorly) that I wan't going to hang around to check the Upper's POI.

July 25, 2012, 05:51 PM
so let me get this right ......because you're shooting at a patterning board...you're going to call it patterning...no matter what you're doing ...??:p

Ok, it might be a " duck " ....but we'll still call it a chicken .....:D ...just for you .......

( You're not patterning a gun ....you're checking Point of Impact...geez )../ good think we like you around here my friend .......( too hot out to check point of impact on both barrels ...you wimp ! )....

July 25, 2012, 06:13 PM
Truth is I also wanted to pick up something akin to a large roll of Kraft paper, but white instead of brown, and some cardboard to lay between it and the steel to prevent ricochets form tearing the paper apart. I want a good clean "pattern" to send to someone that is going to analyze it with a PC program. No way am I counting 350 pellet holes.

July 26, 2012, 06:53 PM
I wouldn't count 350 pellets either...all you want is to look for big holes...

but you can analyze it if you want ....

but you better shoot at least 12 shells ... on separate sheets ...so he/she can calculate the variance..../ decide what the average is. Be careful you're not driving yourself crazy with this stuff....vs really focusing on your mount, hold points, follow-thru,etc...

July 26, 2012, 08:21 PM
I doubt that the problem is the gun, but I am just checking the POI because the Non-Patterning Process is itself of some interest (but not interesting enough to count 350 holes). Besides, the young ladies at the range, without a clue what I am doing, think from the fact that I am doing it that I must know something.

July 26, 2012, 08:28 PM

July 27, 2012, 12:45 PM
Ok, now we at least know why you're doing it ....

July 27, 2012, 01:38 PM
Ok, now we at least know why you're doing it ....

If I only I could be doing it. Not that it matters, but here is a photo of how I set up. Next time I am using whiter paper, placing some cardboard beneath it, and moving the table up so that I am shooting at 13 yards.


Sorry to disappoint by not having a shot of the back of my bald spot in the pic.

July 27, 2012, 02:22 PM
I am disappointed...

13yds is a little too close in my opinion....but I wouldn't sit / or put the gun on a rest either...it might alter the way you're mounting the gun. The concpet of Point of Impact...is to see if the gun fits you / and hits where you look .../ then you can go on to patterning it...

but sure, taping paper to the pattern board works.../ or at least it should work..

July 27, 2012, 07:06 PM
BigJim, The purpose is not to determine if the gun fits me, but simply to see determine where the barrels impact in relation to their point of aim. I also am not wild about shooting at a steel plate from as close as 13 Yards due to ricochet risk. Another reason to cover the plate with cardboard.

I may move back a little to reduce that risk. In that pic I am set up at 16 yards. The reason for choosing 13 is the results trasfer more easily to 16 yards singles (every single inch off of the POA at 13 yards equals three at about 40. I could set up at 20 and simply use a multiple of 2 instead of 3 to approximate the same thing.)

The advocate of the method doesn't use a steel plate/grease board but shoots through a hanging piece of paper so as to get clean holes with no richochet risk or distortion.

If this was a club I belonged to, I would build something to hang paper but it is a public range and the idiots will shoot it to pieces witing days. Meanwhile, I got a roll of white "banner paper" at Staples to do some more non patterning.

Dave McC
July 29, 2012, 05:11 PM
The Brits, among others,established POI at 16 yards. Supposedly, moving the stock 1/16" at that distance equaled an inch of movement on target. Easy formula vs cut and try.

July 29, 2012, 06:03 PM
The other day I tried something and the results indicate that I badly need some dedicated shooting glasses. Until I get some, I doubt that any data obtained by POI testing or patterning is reliable. I am also wondering if there is any point in wasting ammo and target money until I get some glasses.