You're welcome....
For some, it may be boring, but the concept of "Fit" seems to be really misunderstood. Some folks think since its a "scattergun" close is all its supposed to be...but that's not your optimum for hunting or for clay targets.
Its difficult to see, unless you have a lot of experience with shotguns, if a gun in a store fits you or not -- and Fit means it hits where you look. To check the "Fit"...go to a pattern board ..or somewhere that you can hang a 36" X 36" target...screw in a full choke ...and shoot at 20 - 25 yds...and check the point of impact ( put a 3" dot on target to shoot at )..mount gun, look at Dot ..and pull trigger. If your point of impact is high or low ..or left or right you might have a "Fit" issue. ( but shoot 3 shells ...to get an average ..in case you flinched or something ).
If you are consistently ...high or low/or whatever....then some adjustment to stock is necessary - if your gun allows it ( many don't ).
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In a gunstore...you can try to mount the gun, looking up at a spot on wall or something...but before you mount the gun, look at spot on wall ( says its a clock )...close your eyes, don't move your head, and then mount the gun...after gun is mounted, face on comb, etc - open your eyes...and see if you're still looking at clock or not. If your mount is inconsistent...it may be the problem / or the gun may not fit.
There is also a drill you can do at home ...to perfect your mount / empty gun...look accross room at a wall light switch. Close eyes, don't move head, then mount...and see what you're looking at ...if you are still looking at light switch you're good. Now do it 19 more times...about 3 times a week / you'll be shocked at how good your gun mount gets.
My opinion on gun mount...imagine a rectangle in front of your chest. Gun is near waist, in your hands...move the gun straight out in front of you along lower line of rectangle, then straight up to shoulder level ( not back, just straight up toward ceiling), then move straight back to shoulder along upper line of rectangle. Get your elbow angles correct during the mount, not too much pressure with your forward hand...fine tune it / and do it 20 times as well...
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Any gun with an angled comb ...means the position of your face on the comb..if you move up or back 1/2"...will change the elevation of the muzzle. So in the old days...we had guns that we shot really well ( because we had that fit just right )...with that particular shooting vest, that wool shirt, that coat.../ but then in early fall, with only a sweater on - we couldn't hit the broad side of a barn..( face was moving up or back on comb )...so we optimized our "clothing" to adjust the fit.
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Personally, I need a parallel comb gun...so comb is parallel to rib. That means once I adjust the comb to give me the point of impact correct ( move comb up, down, left or right )....then that gun's point of impact will not change if I'm shooting in a T shirt in 100 degree summer weather, or 30 degrees on a morning pheasant hunt, or whatever when my outer clothing changes.
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I had no clue about this stuff until I started hanging around Skeet shooters...and they started helping me understand and adjust my gun ...and it all improved when I went to a parallel comb gun ( Benelli Super Sport with optional comb pads and shims ..can be made parallel / my primary O/U's are Browning Citori XS Skeet models or XT Trap models - with adjustable parallel combs ). If I want to shoot a pump gun or something with an angled comb ...like a Browning BPS pump...then I put a comb pad that you can stick on to top of comb ...tape it on first with elec tape to get it set right ( again go to pattern board to check it )....and then permanently stick it on comb.
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Not all shotgun stocks are the same...even if they're all angled. The mfg's try to fit the average shooter supposedly ...but since I'm a little bigger than the average Buffalo ( at 6'5" and around 290 ..( maybe 300, as Fall gets here I need to put on some hibernation weight )...but what fits my teenage grandkids at 6 Ft and 125 lbs.../ won't work for me .../ and what fits me, may not work for you. You will probably find that some Mfg's combs fit you better than others..( less drop at heel / or more )...but you'll be surprised at how different they are - especially if you have some older guns in the family.
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The little things... a palm swell on the grip area of a shotgun ( if your gun has it, may or may not work ), a minor adjustment in length of pull can make a difference / weight can make a big difference.
Weight of a gun helps reduce recoil ( an extra lb in the gun probably reduces recoil about 20% ) ...so thats why some 20ga guns at 6 lbs beat the stuffing out of a guy ..vs an 8 lb 12ga.../ but with a light gun, like Benelli Super Sport at 7.2 lbs ( 12ga, and a 30" barrel / but they have a 28" barrel also that's even lighter )...because its so light, I tend to "slap" at targets vs making a smooth follow thru. So for a light gun ( 12ga under 8 lbs ) I want to go longer ( so I went with the 30" over the 28" on that gun ), because longer sight plane helps me smooth out the swing on follow thru. More weight ...like a 10 lb Citori XT Trap...helps my follow thru too on Trap targets / but the 10lb gun feels like a big ole sewer pipe if I try to shoot Skeet or Sporting Clays with it ..the weight is hard to overcome when I have quick crossing targets...so everyone has to find what works for them.
My buddy is 6 Ft and a lean 175 lbs.../ he thinks my 30" O/U's at 8.5 lbs are way too long for him / he shoots a 28" O/U at around 9 lbs.../ so again what works for me, won't work for him.
I have young adult grandaughters that are petite.. ( my wifes side of family not mine )...5' and 100 lbs...so a gun like the Benelli Super Sport 20ga, 28" barrel, comfort tech, at around 6 lbs is perfect for her. I don't shoot that 20ga Benelli much because its too light and too short - but mostly because its too short.
Another trick on some guns...go to golf store and get some lead tape made for golf clubs. They're usually in 4 oz packages ../ so if I have a 20ga that is around 7 lbs.../ I can put 8oz of lead tape under forend...and 8 oz of lead tape inside stock ..to give me an 8 lb gun. It then feels like my 12ga guns ...reduces recoil, feels better, swings better, etc..
So all that little stuff matters..../ and no matte what --- have fun with the process !!
None of these thoughts are originial to me....this stuff is discussed in any number of videos and books on Fit, selecting a gun, etc.../ my thoughts are just a summary of the stuff I've learned in 50+ yrs of shotgunning...