Proper placement of mid-barrel shotgun bead?

317wc

January 06, 2015 08:22

I am converting an H&R Pardner into a "Whippet" style gun. It fits minumum barrel length & AOL requirements. Its 12 ga. 3" inch chamber. I am thinking of installing a mid-barrel bead since I have a new spare laying around. But I'm wondering if its worth it. I probably won't shot this very often because of the recoil but a mid-bead would help accuracy. I was planning on placing it about 4-6" behind the front bead.

Any tips and also, how close to the chamber is too close? Out of curiosity, I would think at least 2 and maybe 3 chamber lengths would be the limit.



I'm stringing a floss loop from the front bead on it now to he hammer to find bead placements before I cut.


Edit: There is no rib, the chamber area is thicker and the barrel is about a straight counter from the chamber area out.

The mid-barrel bead is shorter and would appear as a blurry figure 8 sort of sight picture.

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  MG1890

  January 06, 2015 08:27

  I doubt that it has a rib on the barrel; I usually put midbeads about 13 or 14 inches out from the receiver, directly over a rib post.
  
  Won't the unribbed barrel contour cause your proposed midbead to appear lower than the front bead, when drawing a line from the breech diameter to front bead?

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  charliemeyer007

  January 06, 2015 08:38

  I put a mid bead in the rib of the 20" barrel of my pistol gripped 870 Express. I use it as a rear sight when shooting Lyman cast sabot slugs. It is small enough to see the front bead behind it in normal shooting position.
  
  I'd consider makoing a base to install it in and a matching ramp for the front.

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  tsr1965

  January 06, 2015 16:31

  As has been suggested, the mid rib bead, is meant just for that...a rib. Unless your H&R has a rib on it, then the project would be pretty futile, and most likely cost a bunch more than expected.
  
  You might also consider that punching a hole in your barrel, could lead to a pressure rupture, if the pressures have not dropped off enough to the length at which you place the bead.
  
  Best
  
  EDIT 1
  
  Yes I do see a couple of reasons.
  
  quote:With a chamber pressure of about 11.5K PSI it is not very high pressure.
  
  I agree that is true, but these are not rifle barrels we are talking about. Shotgun barrels are thinner than rifle barrels, and the relationship is exponential between thickness and strength.
  
  Furthermore, you are going to be degrading that thickness even more, by as much or more than 50%, by drilling and tapping a blind hole. Just because you fill the hole with something, does not mean the grain structure that strengthens the steel has not been disturbed.
  
  Lastly, since it is not my face that is going to be testing this, do what you wish.
  
  Best

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  317wc

  January 07, 2015 07:24

  There is no rib on it and it occurs to me that I have probably never seen a a plain (no rib) barrel with more than the front bead, but why is this? Is there any reason pertaining to safety that I can't do this?
  
  Edit: With a chamber pressure of about 11.5K PSI it is not very high pressure. This bead would be about 4-6 behind front bead. Any reason why I should not attempt this?
  
  PS: I realize the beads will not line up, they will appear as a blurry figure 8, which to me is not a problem. Shooting a shotgun I am looking at my target and the gun is in the peripheral of my vision. The dual bead is to be able to bring the gun to bear faster with more accuracy.

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  MG1890

  January 07, 2015 07:38

  Barrel contour and higher pressures at barrel midpoint are the 2 big reasons.

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  beantownshootah

  January 07, 2015 10:45

  To actually answer the question, no, I don't think a hole drilled in a shotgun barrel 14" past the chamber would cause a burst barrel. . .but I've never tried it to know, and honestly, I wouldn't want to try.
  
  You'd certainly need to make sure no metal was projecting INTO the barrel. . .that would be "bad". How were you planning on attaching this thing?
  
  Can't you just silver solder a bead onto the outside of the barrel without drilling any holes? This is supposed to be a rib-bead, right? So how about installing a rib first, then putting a bead on that?
  
  Personally, I'm sort of confused about this whole thing.
  
  Bluntly I don't understand what rear beads "do" anyway. Aren't you supposed to "point" shotguns? If you've got a "whippet" style cut-down gun, presumably that's for close range use. . .how much "sights" would you really need on something like that? IMO front bead only should be "plenty". If you can hit a moving 4" clay disk from 25+ yards away with just a front bead, I'd think you can probably hit a human sized target at 7 yards with "just" one, right?
  
  If you really want something to act as a rear sight, then how about installing an actual rear sight?
  
  Edit, responding to below.
  Gotcha.
  
  To be clear, I don't think installing a second bead will be unsafe, I just think its a bunch of bother for something that won't really make the gun any better.
  
  Have you ever seen ANY combat/defense shotgun with a mid-bead on it? Me neither.
  
  If you really want to use this gun for defense, how about just taking it to the range and testing it out with just a front bead? I suspect you'll do great. The fact is, traditional front bead only is STILL the standard for most combat shotguns, and people do perfectly good work with that setup. Some people like a ghost ring or rifle-type rear sight for shooting slugs at distance, but for a cut down type gun that you probably aren't using past bedroom distance, I don't think that's going to add anything, either.
  
  Do you see a mid-bead on Bonnie's whippet? [;)]
  

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  MG1890

  January 07, 2015 11:41

  I think this is pretty straightforward, and your mind is made up. Do it. There is not much to lose.
  
  Accuracy from a minimum length H&R Pardner 12 gauge????[:D]
  
  I'd put a truglo on the front as big as I could get for late night hallway clearing.

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  317wc

  January 07, 2015 13:40

  Barrel thickness at the bead is .100, probably slightly less since my micrometer does not account for barrel curvature. The current bead is drilled and tapped and the replacements would be also. The depth of the current and replacement bead is about .090.
  
  I will have to think on it. Thanks for the tips

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