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Old January 2, 2008, 11:28 PM   #1
jrothWA
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Besides shooting, how determine...

proper spacer for use in M500?
With 24" choked tube barrel, shooting skeet, I seem to have to hold low for breaking birds, if using th fixed choke "MOD" 28" it appear that no low hold in needed.
If I put the receiver and bead (of the 28") against wall and note the distance the stock comb is away, then put the 24" on, should I duplicate that distance???
Thanks.
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Old January 2, 2008, 11:39 PM   #2
Smitty in CT
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Changing the barrel shouldn't drastically change your POI (Point of Impact).

If you find that you have to hold low you can add a drop spacer to the stock (add more drop) that will cause the POI to go down.

This is really something that should be done with a pattern board, though.

You might want to try one of the laser bore-sighters, I don't know if they make one large enough for a shotgun but that would give you an idea of where it should hit....
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Old January 3, 2008, 02:02 AM   #3
hogdogs
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Ya'll are way beyond my league! I just pull and shoot. If I miss I compensate. One day I will be a "technical" shooter I have junior's 12 gauge maverick walmart special, his NEF 20 single and my mossy 500 20 18 1/2 incher
I just go for broke and if I miss it is double or nothin'
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Old January 3, 2008, 02:36 AM   #4
kirbythegunsmith
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What you have here is your own discovery of something I realized many years ago when a shooter brought in his shotgun and was complaining that he couldn't hit anything with the new barrel.
Testing proved that the barrel had a very high impact for him, about 11" high at 19 yards, so any bird that he pointed at was safe!
The chokes are consistently installed improperly with alignment that is haphazard, sloppy, and sometimes, even unsafe.
I do not make this pronouncement lightly, but have proof and pictures, along with explanations, all included in articles on my website.

Article 3 has pictures of crooked choke holes and a damaged/dangerous situation.
Article 1 has illustrations to explain these concepts, as well.
Article 2 and the home page both have a comprehensive explanation and multi-faceted illustration pertaining to shotgun barrel physical design, alterations, and limitations.

The evidence is incontrovertible. Anyone that claims otherwise hasn't examined the evidence. See for yourself.

The shim arrangement of aligning the gun to the shooter is great for making adaptable guns, but should not be considered the solution to a crooked choke, anymore than resetting a steering wheel is a substitute for a proper front-end alignment. The steering wheel may be re-positioned to be in line, but the front end is still out of kilter.

Of course, that is cheaper, but not correct. You can use shims to adjust an off-center impact, but the crooked choke hole remains to affect the pattern quality.
When your shot strikes harder against one side of the choke, and then has to also change direction, the shot abuse against one side is more severe than the other side, and distorted pellets don't stay in the pattern as well as the lesser distorted pellets, so pattern quality must suffer. The only point of contention is the level of severity.

Some may consider personal experience to be the best teacher, but learning from other's experiences and mistakes can shorten the learning curve.

20 years in my own shop plus years of technical schooling (and more) have exposed me to many problem situations, so take advantage of this opportunity to become more aware of potential safety issues.
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Old January 3, 2008, 03:16 AM   #5
hogdogs
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Kirby makes valid points! I think the choke on juniors Mav 88 is pretty square as we both do okay with hand slung clay birds. It is the only gun here with removable chokes. I can see where a poorly made choke or bad thread job on the barrel would be a poor shooter...
Brent
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Old January 3, 2008, 01:18 PM   #6
BigJimP
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Point of impact on a shotgun can vary from barrel to barrel on a gun - and the only way to really tell is to go to a pattern board - fire at a dot - and see what your point of impact is. Make sure you fire 4 or 5 shells to make sure the point of impact is consistent - if its not consistent, your mounting of the gun probably needs work.

You can change wedges, combs, put pads on comb, change recoil pads etc to alter the point of impact on a shotgun. On shotugns - your eye is the rear sight - and the point is to make sure the shotgun impacts where you are looking. Shotguns do not come in one size fits all - they need to be adjusted to fit you.

There is also some variance in chokes - 2 Mod chokes may throw different densities of patterns - but the point of impact/or center of the pattern should not change when you change the choke - if it does go to the pattern board again and work on it some more. You can't tell what the point of impact is in the sky at a skeet target ( people say they see the shot cloud, but its mostly bs ..). The idea of a choke is to put a 30" pattern, with density, on the target at the kill range ( so that usually means a skeet choke out to about 25 yards, an IC choke 25-30 yards, a Mod choke at 30 - 35 yards (like 16 yard trap) - and IM 35 - 40 yds / a Full choke beyond 40 yards is a guideline.
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