A tip of the hat to Anonymous who suggested I visit the Michigan Trap Association event in Mason.
I was able to score some 20 gauge hulls. They are Winchester A-A hulls which typically have very long life with regard to number of reloads. Their shortcoming is that they have limited volume which makes them less desirable to the velocity lovers.
What does more velocity get the shotgun shooter?
In my estimation, not as much as one would hope.
The first order of business is to hit the target. If the target is moving then the shooter must "lead" the target so the target will occupying the same volume of space at the same time the column of shot is attempting to pass through it.
A sensitivity analysis where the shooter errors by 5mph with regard to the targets speed results in a 5.5 inch variance at 20 yards for #7-1/2 shot launched at 1135 feet-per-second and a 4.8" variance for the same distance and shot launched at 1330fps. So the gain from 200fps in muzzle velocity is a reduction of 0.7 inches in error due to velocity estimation.
At 40 yards (beyond what most mortals should attempt with #7-1/2 shot) those variances grow to 12.8" and 11.4" respectively. The reduction in error has grown to 1.4" which is hardly earth-shaking.
Differences in the amount of lead needed for errors in range estimation are even smaller.
What about impact velocities?
Velocity of #7-1/2 pellets at 20 yards when launched at 1135, 1200 and 1330fps are 830fps, 875fps and 930fps. That 200fps difference at the muzzle shrank to a 100fps advantage at 20 yards. At 40 yards the difference shrank to 65fps.
All data used in this analysis is from Lymans Shotgunning book.
Is there a downside?
Well, in my case it means that I will have to swap out the 128 bushing in my Lee Load-All 2 and install a 116. I will also have to relabel the unit to indicate the powder dropped for-the-duration.
What about using a more aggressive powder? A smaller wad to increase powder volume?
ReplyDeleteIf you look at the published loading data, there are at least three wad/powder combination that hits 1350fps with a Winchester A-A hull (Longshot/PC-20 and Longshot/Windjammer and Alliant Pro Reach/Orange Duster).
DeleteThe question becomes "Does the incremental value of +150fps justify the incremental complexity of an additional powder and wad on the reloading bench?"
Shotguns are inherently low-pressure firearms and approaching the limits of their performance envelop (while respecting SAAMI standards) is fussy. Taking a couple steps back and producing reloads that demonstrate "commodity ammo velocities" gives the reloader a very wide and very forgiving window with regard to powders, wads, primers and hulls.
Is the value of the juice worth the cost of the squeeze?
Even with modern plastic wads hotter loads will sometimes turn your shot string into a donut shape, or blow it appart altogether. Mid speed loads seem to hold a better pattern.
ReplyDelete+1 Above
ReplyDeleteMy trap gun throws a better , more dense pattern with 1oz loads than 1.5 oz loading with the same powder (Red Dot). The choke is trap full in a 32 inch barrel.
Regardless of the number of bb's the bottom line is, you still gotta hit em.
ReplyDelete+1 on Anon/Gerry
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In my experience, lower velocity gets denser patterns. YMMV.
ReplyDelete