18" barrel bead height

M

mmatt

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I was just wondering if anyone had figured out how high a bead needs to be on an 18" barrel so that your slugs aren't lobbed into low orbit. :rolleyes:

I took my Mossy 500 out to the range to see how it shot with slugs and it is amazingly accurate with only the bead (got the holes to touch with some regularity out to 50 yards :cool: ) but it was shooting almost 6 inches high. :eek:

Now that I know this, I can simply aim lower to compensate, but I'd like to be able to just centre the bead and blast without having to think too much. (not usually too much time to think when there's an angry sow crashing toward you in the brush) :p

I ordered one of those snap-on HiViz sights as it appears to set the aiming point up a few extra millimetres, but I'm nut sure it that it'll be enough.

Waddya think?

:shotgun:
 
I have seen an article somewhere online about figuring out sight heights via math but in your case I'd be tempted to use a hot glue gun and put a little dab on the sight and see where it gets you.....shoot and adjust till you like the results then measure the height.
 
I would say that 6" high @ 50yds with only a bead is pretty good, considering how imprecise a bead is. You don't need much of an adjustment to change POI that much at 50yds, go slow with small changes using temporary pieces of whatever on the bead to change the height. Some of the milsurp guys will hot glue a piece of wire or round plastic along the top of the sight to build up the height.

Mark
 
I had the following posted in a sticky on Beretta Forums. Is this what you're looking for?

I'm sure you can taylor the formula to suit your needs to lower the POI.

Mac said:
If you prefer to file down your existing sights, the following may be of interest to you.

POI - POA

M = S x D ÷ ( R x 12 )

Where:

M = amount of movement or change in sight height needed (in INCHES)
D = distance needed to move the bullet's strike to hit point of aim
R = range to target (in FEET)
S = distance between front edge of rear sight and rear edge of front sight blade (sight radius in INCHES)

Example:

Your sight radius is 5.7 inches and you need to move the bullet's strike 3 inches lower at 25 yards (75 feet):

M = 5.7 x 3 ÷ ( 75 x 12 ) = .019

Thus you need to raise the front sight (or lower rear sight) by .019 inches.
Click to expand...
 
If your bead screws in just look for a bead like this by HiViz
ht tp://w ww.hivizsights.com/Shotgun-Spark-II-Front-Bead-Red-or-Green-P40C1.aspx
Or these can be had low or medium and may be perfect for you
ht tp://w ww.hivizsights.com/Shotgun-Spark-II-Front-Bead-Red-or-Green-P40C1.aspx
Kim
 
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