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Measuring mainspring strength

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Navy Six:
I intend to conduct a series of tests on Colt style percussion pistols in regards to mainspring strength and its affect on percussion cap performance. I would like to accurately measure and compare a variety of mainsprings. I do have a trigger pull gauge and considered measuring that as I swapped out different mainsprings on the same gun. Is there a better way of doing this? I don't want my results to be based on "well, this spring feels heavier than that one". Any thoughts would be appreciated.

Coffinmaker:

 :) Navy Six  ;)

Well Ok, a couple of thoughts.  First thought, Trigger pull only measures trigger pull.  A poorly fit trigger can have a heavier "pull" than a well fit trigger, regardless of Main Spring.

One would have to build a jig to hold ALL subject Main Springs in a like position, then connect them to a gauge that measures the amount of "pull" required to move the action end a measured amount of deflection.  Then one would have to measure the effect of "stacking" (increased pull) over the full deflection of the spring.  Once documented, one would have to insure there was absolutely NO drag in the moving parts of the subject test action.

The results, as applied to the reaction of Percussion Caps, would then be skewed by the differentiation of material used by the manufacturers of differing cap brands.  Also skewed by the differing types/amounts of explosive material and thickness of sealant, also skewed by specific lot numbers of the various manufacturers.

The same variations would also be observed in various Main Springs, by manufacturer, based on lot numbers (unknown) and varying dates of manufacture.

Considering ALL the variables and complications, I think the objective "Gee, That one feels different" is as definitive as it's going to get.  along with measuring the specific Brisbane of the various caps.  Also, the test subjects would all have to be tested on exactly the same set of nipples.  Yule also need to arrange for a High Speed High Frame Rate camera and a skilled operator with a concurrent trigger mechanism.

Have Fun!!

Navy Six:
Thanks Coffinmaker. I received a response from Mike Brackett about how he does it(uses trigger pull gauge after hammer is brought to half cock. Hook gauge behind hammer face. When hammer moves record numbers).
My testing is to satisfy me as to why, some of my Colt style percussion guns will still occasionally suck caps despite:
arbor length correction
Slix Shot nipples
polished hammer face and safety notch
polished internals
One or two of my problem guns have responded to a heavier mainspring which cut down the problem significantly. I have no intention of installing a "cap rake". I feel the real problem is the darn caps. The thin construction material of caps combined with hotter caps along with generally lighter factory mainsprings has created this "perfect storm" of cap sucking, at least in my opinion. Having the opportunity to examine several original Colts, both SAA and percussion, I've noted a much heavier mainspring in all of them. Even though I am actively involved in SASS and enjoy a smooth, light action as much as the next person, if I have to go to a somewhat heavier mainspring in my percussion pistols in order to avoid problems, so be it. Besides, all this testing gives me an excuse to shoot more!

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45 Dragoon:
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45 Dragoon:
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