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October 17, 2017
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Many of the members of this forum (especially revolver aficionados) have probably read "Burning Powder" by Douglas B. Wesson. First published in 1938 (about the time his nephew Dan Wesson started working at S&W) it goes into great detail about the complexities of firearm accuracy. I've included an excerpt on revolver accuracy specifically that is very interesting reading. Link is at bottom of page.
I bring this up because of my experience today with a newly acquired DW 15-1 (the very last of the "pork chop" Dans before the introduction of the 15-2). My early model 15-2 has been a great shooter, but this 15-1 clearly has the advantage. Why? Same trigger, same hammer (and hammer throw), same cylinder, same cylinder gap, same ammo, yet somehow my groups with the 15-1 were smaller. The only discernible difference between the two revolvers was the mainspring tension. I suspect the 15-2 may have had a lighter spring kit installed somewhere in its history whereas the 15-1 has a much heavier (probably original) mainspring.
Doug Wesson details below how the mainspring tension can affect accuracy in a revolver. It's subtle, and for combat style shooting it means little; but when we're trying for that last bit of accuracy for long range shooting it is much more of a factor. It seems that many shooters are installing lighter spring kits in order to facilitate easier double action shooting which is all well and good for rapid fire scenarios, yet there seems to be a slight trade-off in pin point accuracy.
Of course there could be minute subtleties in design and build which could contribute to why my 15-1 outshoots my 15-2. Doug Wesson also addresses "selectivity", which offers no explanation for a particular revolvers preference for a certain brand of ammunition. Maybe my 15-1 simply "likes" the ammo I used today better than my 15-2.
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Dans Club
March 25, 2013
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I am not very knowledgeable on the subject or a very good shooter as I came late to firearms. However, I do know a bit about Dan Wessons, mostly thanks to the forum. 3ric is right about a mystery of why the porkchops may be more intrinsically accurate than the 15-2. I would like to suggest some possible reasons and maybe some defenses of 15-2s.
First, although the 15-1 has the longer hammer fall of the 15-2, the reputation for uncanny accuracy was already established by the 11,12,14,and 15 with the short hammer travel that actually is not because of the hammer but because of the differences in the trigger. The ledge that the trigger return spring rests on in a 15-1 is absent in the early models. That small difference is magnified by the time the 32cd of an inch difference reaches the arc of the hammer. The shorter hammer fall is a large factor in accuracy IMHO.
It has been written that Dan Wesson barrels are slightly choked the way Python barrels reportedly are. I do not know if that is true. It may be that in the beginning they were but I don't believe they are now. I suppose I need to buy a caliper and measure them myself. Does anyone have knowledge that would shine light on that mystery.
Lastely, I suggest that the degree of torque of the barrel nut may influence the accuracy. I always rely on snug but not overly tight.
February 22, 2017
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I came late to shooting as well, at least as far as shooting regularly and owning anything other than my Marlin 22 my dad gave me when I was a kid, so my knowledge is very limited. With that caveat, I've come to the conclusion that an over-tight barrel on a Dan affects accuracy as well, but I haven't really put it to any kind of test. In my personal experience, it seems that it is only evident as the barrel heats up, but that could be more from fatigue because of my back issues.
Jerry
10 Dans and counting...
October 17, 2017
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I completely agree that the Dan Wesson revolvers shoot their best when the barrel nut is just snug and not overtightened. I don't know if anyone else has experienced this or not, but I've found that as the shooting day progresses the cylinder/barrel gap can actually get smaller, and seems to happen if the barrel nut is overtightened. I've never experienced the gap getting larger. My theory on this is: DW barrels are right hand twist, and since the bullet wants to go straight as it slams into the rifling at the forcing cone the initial torquing is to the left before the rifling takes hold and drives it to the right. Since DW revolver barrels are nowhere near as tightly fitted into the frame compared to other revolver designs, this small amount of movement could be possible. Just a theory.
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Dans Club
March 25, 2013
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The barrel gap gets smaller because the small frame cylinder expands after several cylinder worth of rounds. Also, residue is deposited on the face of the cylinder. Always take a rag with you shooting and wipe the face of the cylinder after a number of rounds. The cylinder will bind on the proudest chamber. Some of the small frame cylinders are not exactly perpendicular. The recommended barrel gap of .006 is to prevent binding because of these factors. When novices force the shim in they are pushing the dedent ball in and the gap is smaller. The shim should slid in easily. I find that .004 works well if your cylinder is perpendicular, you wipe the face of the cylinder and don't push the dedent ball back. I started out with automotive feeler gauges instead of the factory shim but after a bit of cleaning and setting the gap you can just hold the gun up to a light and cycle the cylinder and check the chambers by eyeing the gap. Always take a tool with you when shooting.
October 17, 2017
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Good information as always, Ole Dog, but I don't think that is what is happening here. I too set my gap at .004 on the proudest chamber with a .006 shim slightly snug on the most open one. I rarely shoot more than 30 rounds (slow fire) in a session, so the gun doesn't really get that hot. I seldom have a chance to clean my gun immediately when I get home, so it's usually many hours afterward or even the next day. After thoroughly cleaning the revolver I have checked the gap and found that it had shrunk down to .002 on the proudest chamber. This first happened on my 15-2. I tried to loosen the barrel nut to make an adjustment but it wouldn't budge. After the next session the gap had shrunk to .001 (after cleaning). I had to do something, but the barrel nut was so tight I had to beat it out with a punch and a hammer. I purchased another barrel nut and never tightened it that much again. I make it just "wrist" tight and have not had a problem since.
So I guess the DW barrel system is meant to allow a tiny amount of movement during the barrel whip, but if the barrel is tightened down too hard that movement can only go one way; tighter.
October 17, 2017
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We seem to have gotten a bit off topic on this thread. I wouldn't resurrect it except for my experience today at the range shooting both of my Dans; a Model 15-1 and a Model 15-2. The 15-1 produced a five shot group that could be covered with a nickel; something the 15-2 simply could not duplicate. The point of this thread is that the amount of main spring tension on the hammer throw can have an effect on accuracy. Primers vary according to various ammunition manufacturers specifications, so that alone can account for a given revolver's preference for a certain brand of ammunition. However, Douglas Bertram Wesson was obsessed with obtaining the utmost accuracy from his revolvers, and proved that a weaker hammer strike can have an adverse effect on accuracy.
For casual offhand plinking this is of little consequence. It's only when we're trying to hit a target at extreme distances that the slight loss of accuracy becomes significant. The difference between a 1/2 in. and a 1 in. group at 10 yards becomes 10 in. and 20 in. at 200 yards; more than enough to account for a miss on a ram at an IHMSA match.
I will admit that my 15-2 with its lighter main spring is a more pleasant gun to shoot, and it groups well enough to keep me happy out to 50 yards. Beyond that distance I appreciate what the 15-1 with its heavier main spring is capable of.
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