The Big Shot Likes Open Chokes (BSLOC) Rule

 

Waterfowling is replete with delightful paradoxes.  For example, we hunters pride ourselves in braving the cold and wet in pursuit of our sport, tacking up photos of early 20^th century market hunters in their soggy woolens and waxed cotton; but we spend hundreds of dollars on Gore-Tex, Thinsulate, and blind heaters (and thank God too—I certainly have no intention of staving off hypothermia and/or influenza with greasy buckskins and a bottle of whiskey).  Another paradox is the oft stated rule of thumb that larger sizes of steel shot, especially letter-sized, will produce more open patterns with tighter chokes and tighter patterns with more open chokes. 

I have no idea what the origin of the Big Shot Likes Open Chokes (BSLOC) Rule is.  Scanning back across the literature I have on hand, it is always stated as a given.  For example, BPI’s Status Of Steel VI from 1991 proclaims, “The appropriate tightness of a choke is also related to the particular size of pellets being used.  Larger pellets require a more open choke.” (pg.23)  And that’s it—no further explanation of WHY that may be, to say nothing of proof that it actually is the case.

I don’t know if I was born this way, or if it’s the result of reading books like A Transatlantic Tunnel, Hurrah! but I’m drawn to the cutting edge of yesteryear, the obscure, and technological dead ends.  My guitar has P90 pickups, I take great pride in the fact that our family used a videodisc player up through 2000, and I’d give up a lot of things for a C96.  So when I walked into the hardware store and saw two boxes of Remington Nitro Steel 12 ga 3.5" #TT’s, I had no choice.  When time came to pattern them, I followed the Received Wisdom and screwed in an Improved Cylinder. and paced off 50 yards.  I knew with only 69 pellets in the shell, the pattern was going to be sparce, but good grief.

IC @ 50 yards

36/69 = 52.2%

So I tried a Light Modified...

LM @ 50 yards

37/69 = 53.6%

...then a Modified.

Mod @ 50 yards

52/69 = 75.4%

At last I had something I could work with.  I went out and crippled this goose. 

Was this upset of the BSLOC Rule a fluke?  Well if you can’t shoot geese, you might as well shot paper.  The test for this is pretty straightforward: I shot a lot of goose loads.  I used a selection of letter-sized steel shot in case my 870 had an odd relationship with a particular size.  Most of the loads are handloads, but I threw in a couple factory shells as well (mostly because I had them on hand).  And no, I don’t have any intention of using a 550 g load of #F on geese; I loaded that one up specifically for this test. 

Chokes used:

Patternmaster Black Cloud Extended Full (.687”)
Carlson’s Sporting Clays Extended Improved Modified (.704”)
Hastings Steel Shot Extended Full (.706”) (actually an IM (maybe?))
Remington Flush Modified “A” (.710”)
Carlson’s Sporting Clays Extended Light Modified (.714”)
Remington Flush Improved Cylinder (.718”)
Hastings Flush Cylinder (.723”) (actually a Skeet (again, maybe))
Carlson’s Flush Cylinder (.730”)

Load A:

12 ga 3” Fed .090 replacement
f.209a
32 g A.Steel
MultiMetal 2.75” + felt x 1
550 g #F steel (50 pellets)

Load B: (factory load)

12 ga 3” Fiocchi Speed Steel
1.125 oz #BBB steel (70 pellets) @ 1475 fps

Load C:

12 ga 2.75” Fed. .090 replacement
f.209a
32 g A.Steel
CSD118
473 g #B steel (air rifle shot) (91 pellets)

Patterned at 40 yards with a Remington 870 Express:

Choke	Load A	Load B	Load C
Patternmaster Full	30/50 = 60.0%	56/70 = 80.0%	55/91 = 60.4%
Carlson’s IM	43/50 = 86.0%	53/70 = 75.7%	74/91 = 81.3%
Hasting’s Full	40/50 = 80.0%	53/70 = 75.7%	63/91 = 69.2%
Remington Mod	42/50 = 84.0%	52/70 = 74.3%	66/91 = 72.5%
Carlson’s LM	43/50 = 86.0%	52/70 = 74.3%
Remington IC	38/50 = 76.0%	48/70 = 68.6%	63/91 = 69.2%
Hasting’s Cylinder	32/50 = 64.0%	40/70 = 57.1%	47/91 = 51.6%
Calson’s Cylinder	26/50 = 52.0%	32/70 = 45.7%	33/91 = 36.3%

 

Load D:

12 ga 3.5” Winchester
w.209
35 g. A.Steel
TPS 3.5”
649 g. #F steel (59 pellets)

Load E: (factory load)

12 ga 3.5” Remington Nitro Steel
#TT steel, 69 pellets (1.5625 oz) @ MAX dr. eq.

Load F:

12 ga 3” Fed .090” base one-piece
w.209
35 g. A.Steel
LBC43
1.25 oz #BBB steel (75 pellets)

Patterned at 50 yards with a Remington 870 Express SuperMag: 

Choke	Load D	Load E	Load F
Patternmaster Full			60/75 = 80.0%
Carlson’s IM	34/59 = 57.6%	51/69 = 73.9%	52/75 = 69.3%
Hasting’s Full	40/59 = 67.8%	48/69 = 69.6%
Remington Mod		52/69 = 75.0%
Carlson’s LM	36/59 = 61.0%	37/69 = 53.6%	56/75 = 74.7%
Remington IC		36/69 = 52.2%
Hasting’s Cyl	22/59 = 37.3%		21/75 = 28%

 

Now, almost all shell and choke combinations only got shot once.  Yes of course, averages of five would have been standard patterning procedure and could have given a different percentage for each combo.  The load B pattern I got with the Hasting’s Cyl. choke may have been sparser, and the one with the Carlson’s IM may have been denser then a five shot average of either; but is it likely that that would have happened with ALL six loads?  In other words, even with the small sample size for the individual combos, when all the numbers in the table are taken together, trends do appear.  Think of it as a pattern of patterns. 

 Across all six loads, in no case does the either cylinder, (true Cyl and Skt), or IC outperform Modified or IM chokes.  Larger sample sizes might change the performances ranking of the LM to Full chokes—look at the numbers on Load B to see what I mean—but I highly doubt that put them below the Cyl and Skt tubes.  The IC appears to be the next stairstep up, but I’m not as confident on which direction it would move with a larger sample.  

But you might object, was it fair to compare flush chokes with extended steel shot chokes?  Sure, the more open chokes I have are flush mounted, but so is the Modified, which performed very well.  And though two of the extended chokes are designed (or at least marketed) specifically for steel shot, the other two, though safe with steel shot, are designed (or, again, marketed) for lead shot.   

Of course, birds aren’t killed by percentages.  A pattern may have a high number of pellets, but they may be all clumped leaving large areas of the pattern paper un-holed.  On the other hand, a pattern may have only the minimum number of pellets but have them evenly spaced across the target. 

 To illustrate the point, here are three patterns that have basicly the same percentage.  All are Fiocchi Speed Steel 1.125 oz #BBB

Rem. Mod @ 40 yards

52/70 = 74.3%

Hasting's Full @ 40 yards

53/70 = 75.7%

Carlson's IM @ 40 yards

53/70 = 75.7%

 

And while some folks use “tight” as interchangeable with “good,” some proponents of the BSLOC Rule do specify that open chokes produce more EVEN patterns with large shot.  

 After dismissing the patterns that fell woefully short of the 50 pellet minimum recommended for geese—which is to say, all but one pattern looser then Light Mod--I used two methods to evaluate evenness of patterns.

 First was a simple visual evaluation.  I was looking for an even spread, as well as noting the load/choke combo that appeared likely to be useable past the patterning distance based on the density of its core.

Second, I drew a 15” circle in the center of the 30” pattern to define the core.  Then I divided the outer ring of the pattern into quarters.  This created five roughly equal pattern zones. 

 I counted the pellets in each zone, and where two or more pellets could be covered by a 12 ga hull rim, I counted them as one hit.  These clumps obviously didn’t improve the evenness of the pattern; however, clumps in the core do imply a better long-range performance. 

I picked the most even pattern based on how similar the number of hits in the ring zones were and on how much clumping it had, and the best long-range load based on how dense the core was. 

The results of this dividing into zones fiddling turned out to coincide with the simple visual evaluation.  It was an interesting waste of time.

	A, numbers	A, visual	B, numbers	B, visual	C, numbers	C, visual
Patternmaster			Best LR	Best LR
Carlson’s IM					Best LR	Best LR
Hasting’s Full	Most even*	Most even*
Rem. Mod			Most even	Most even	Most even
Carlson’s LM	Best LR*	Best LR*
Remington IC						Best SR**

 

	D, numbers	D, visual	E, numbers	E, visual	F, numbers	F, visual
Patternmaster
Carlson’s IM			Best LR		Best LR
Hasting’s Full	Best?*			Most even***
Rem. Mod			Most even
Carlson’s LM		Most even*			Most even

 

*Neither #F load produced any patterns that met the 50 pellet minimum.  This isn’t surprising given the low in-shell pellet count.  But I evaluated them anyhow.  It’s remarkable how bad all of the Load D patterns were—there was no best.

**This load wasn’t the best looking one.  Though it had very little clumping, its core wasn’t much denser then the ring and probably would have been too thin in much more than five yards, forming a donut.  However, given that 40 yards is about all you can expect from #B penetration-wise, I made note of it as the best short-range pattern for this load. 

***This #TT load falls just short of the 50 pellet minimum, but is the most even with just one clump.

 

Comparing the evenings of the patterns to the raw percentages leads to some tweaking of which pattern is best but doesn’t reveal any upsets.  Again, neither of the Cylinders or the IC pattern better than the tighter chokes with any load. 

 Obviously, none of this proves that there isn’t a load of large steel shot that will pattern better with an open choke.  In fact, we can assume that some do—or did--because how else would the BSLOC Rule have started?  But the fact that I couldn’t come up with one makes me confident in saying this bit of Received Wisdom can be safely jettisoned.