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Discussion Starter · #1 ·
I recently dissected and patterned these low-cost factory shotshell loads to assess their component consistency, quality, and pattern performance from a full choke at 40 yards.

Powder and shot data were obtained by cutting open five shells from the same box as the shells to be patterned and counting and weighing the components.

Patterning was done with a 12-gauge Browning Citori having 28-inch Invector-plus barrels and using a Briley flush full choke measuring .036-inch constriction from a bore gauge. The 40-yard (muzzle to target) pattern data is the result of hits registered in a 30-inch post-shot scribed circle from ten separate pattern shots.

12 GA 2 ¾" FEDERAL FIELD & TARGET LOAD
1 1/8 oz #7 ½ lead (486 pellets) @ 1200 fps

PELLETS/SHELL (1 1/8 ounce = 492.2 gr)
In-shell pellet count / weight (grains)
491 / 516.8 gr
488 / 512.9 gr
487 / 512.3 gr
486 / 511.2 gr
480 / 511.7 gr
Mean 486.4 / 512.98 gr

PELLET SIZE (25 pellets, 5/shell, #7 ½ = .095" dia.)
.113", .100", .097", .097", .096", .094", .093", .093", .092", .092", .092", .092", .091", .090", .090", .090", .090", .089", .089", .087", .086", .085", .085", .085", .083"
Mean pellet diameter .09164"

POWDER/SHELL
18.1 gr
18.1 gr
17.9 gr
17.8 gr
17.7 gr
Mean 17.92 gr (small flake powder)

40 YARD PATTERNS (Full choke / .036" constriction)
30" pattern totals (%)
380, 366, 363, 350, 344, 343, 340, 323, 319, 319
Mean / 344.7 (70.86%)
SD / 19.698

12 GA 2 ¾" FEDERAL TOP GUN LOAD
1 1/8 oz #7 ½ lead (405 pellets) @ 1200 fps

PELLETS/SHELL (1 1/8 ounce = 492.2 gr)
In-shell pellet count / weight (grains)
382 / 492.6 gr
389 / 494.9 gr
394/ 471.2 gr
403 / 480.6 gr
459 / 502.9 gr
Mean 405.4 / 488.44 gr

PELLET SIZE (25 pellets, 5/shell, #7 ½ = .095" dia.)
.104", .100", .100", .099", .099", .096", .095", .095", .095", .095", .095", .093", .093", .092", .091", .091", .091", .090", .088", .087", .086", .083", .082", .081", .081"
Mean pellet diameter .09208"

POWDER/SHELL
17.6 gr
17.5 gr
17.4 gr
17.3 gr
17.0 gr
Mean 17.36 gr (small flake powder)

40 YARD PATTERNS (Full choke / .036" constriction)
30" pattern totals (%)
295, 291, 289, 288, 286, 272, 271, 268, 265, 233
Mean / 275.8 (68.03%)
SD / 17.532
 

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Not liking the range in powder weights, this means that Federal isn't doing any capability studies on thrown charge weights. With that range I suspect the standard deviation is rather large, which leads directly to a rather large 6 sigma spread, possibly as much as 1.5 grains. What you may want to do is check the charge weight of 30 charges and post the standard deviation for that.

BTW, in my experience a small flake powder such as ST7625 will produce a SD of 0.074 from a volume powder measure and a 6 sigma spread of 0.444 grains. For large flake such as Unique or Longshot the SD is 0.17 grains with a 6 sigma spread of 1.02 grains. BTW for a MEC 600 or Sizemaster if you leave the powder bushing parked under the powder bottle as you cycle the press you can expect to basically triple the Standard Deviation. It's why I've notched that lockout bolted to the charge bar so that I can offset the powder bushing from under the powder bottle. Doing this makes for much more consistent ammo.
 

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scooter123 indicates: "What you may want to do is check the charge weight of 30 charges and post the standard deviation for that."

Speaking only for myself, cutting open 10 shells and doing all the pellet counting and powder weighing that Joe Hunter did; is far more effort than I want to expend.

IMO, the sample size seems more than adequate enough to derive useful results.
 

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oyeme said:
scooter123 indicates: "What you may want to do is check the charge weight of 30 charges and post the standard deviation for that."

Speaking only for myself, cutting open 10 shells and doing all the pellet counting and powder weighing that Joe Hunter did; is far more effort than I want to expend.

IMO, the sample size seems more than adequate enough to derive useful results.
Yep. This entire exercise was way more work that I would find useful to provide any formation.............

We all know ammunition is mass produced and has veriations in numbers and weights - all within tolerences.
 

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Discussion Starter · #5 ·
scooter -- Thanks for your comments, but I think I'll pass on cutting open 30 more rounds to get a SD and Six Sigma. The shells are too hard to come by right now!

Thanks to oyeme and Road Rat for their comments, too.

Shotguns are pretty low-tech firearms, so some variation is to be expected, but I enjoy knowing what's in the ammo I'm shooting and how it performs in my gun/chokes.

Good luck!
 

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Six Sigma...been down that horror show of defining the product specification. For all we know the product spec for Top Gun is 1 FTF in 10k shells.
 

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From a Six Sigma perspective when I used to do work for Remington as a Black Belt and manufacturer of wads. It was a pretty open spec as some of the shotgun shells a pretty good size variation did not change the ballistics. The most important part of the shell was the only one that was being consistently engineered and fine tuned which was the wad. Slight variations in the wad could have major runability and also ballistic issues.
 

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As a side note, I had to dig into my stash of 12 ga field and target that I bought several months ago. I was experiencing a failure to fire about 1 per box fired from a 725. It may be somewhat a firing pin issue but did not experience it with other manufacturers or reloads. The primers occasionally seemed seated deeper than others.
 
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