Model 910 spring replacements

[4Patriot]

Hi, all,

I am planning to give USPSA shooting a try with my S&W Model 910, so I am contemplating some changes to the spring set.

In its present condition the SA trigger pull measures about 5.5 lbs on my trigger gauge. The DA trigger pull is off the chart on my gauge, but others have described it as 12-14 lbs. I don't know what is right, but it is hard to pull, a condition that will impede accurate shooting.

I am thinking about replacing the hammer spring and perhaps also the trigger return spring, which I believe will impact the DA and SA trigger pulls, respectively.

According to Wolf Springs, the hammer spring comes from the factory with a 20lb spring. They sell and I have ordered a three-pak which will include 1 each of a 16, 17, and 18 lb spring.

Also, I have ordered a three-pak of trigger return springs, at 2.5, 3.0, and 3.5 lbs, compared to the factory spring purported to be 4.0 lbs.

Of course, I want any changes I make to the gun to be safe. I'm thinking that even with the 16lb hammer spring the DA pull will still be plenty heavy. Going from a 20lb to a 16lb spring is a 25% reduction. If this translates linearly to reduced DA trigger pull I should be ok. I also figure Wolf wouldn't sell these springs for this gun if there were likely to be a problem. Am I mistaken? Any thoughts?

As for the trigger return spring, the whole set up is less well understood. I don't even know if there are going to be any effects on the SA trigger from the hammer spring replacement, let alone the trigger return replacement. I would appreciate any knowledgeable commentary on this topic.

Thanks in advance for your attention.

 

[handgunner356]

There isn't a lot that can be done with the TDA triggers. I've used the 17# hammer spring with good luck and it does help the DA pull. The trigger spring has little effect, you need the trigger to go back forward also. Your most likely class in USPSA would be Production which limits it to 10rds max scored Minor for all guns. Most all of the guys at our matches go ahead and shoot Limited/Minor just to load all 15rds. (It all pays the same). I wouldn't get to hung up on the DA pull, it only effects the first shot and if it a precision first shot you can always thumb back the hammer to start.

 

[BLUEDOT37]

Ditto what handgunner356 said on the hammer/mainspring. I've used Wolff Springs as low as 17# too on several guns without any issues. It'll have a small affect in the SA pull but more on the DAO pull, on most guns.

Since the mainspring also helps resist the slide from opening initially (hammer pressing against the slide), you might consider going up a few pounds on the recoil spring to keep things balanced.

.

 

[Fastbolt]

... I also figure Wolf wouldn't sell these springs for this gun if there were likely to be a problem. Am I mistaken? Any thoughts?

As for the trigger return spring, the whole set up is less well understood. I don't even know if there are going to be any effects on the SA trigger from the hammer spring replacement, let alone the trigger return replacement. ...

I've experimented with a couple reduced power hammer springs (S&W calls them mainsprings, FWIW). I noticed a little difference, but I eventually returned to using whatever stock springs came in the guns because I wasn't using them for sport, but for duty & off-duty. I never had a problem with them failing to ignite a round, but that was those springs, in those particular guns, using the ammo I was using at the time, in my hands.

Really dirty guns, or dropping a gun in water and contaminating the firing pin channel, and/or hard primers, are perhaps pretty good reasons to use the heavier stock springs for their intended purpose in pistols dedicated to defensive roles, in my humble opinion, at any rate.

The trigger return springs (S&W calls them drawbar plunger springs) have a warning listed in the Wolff website, "WARNING: Springs are for competition use only - NOT for duty use."

The reason is apparently simple. That spring is the only thing that tensions the drawbar so the tail of the drawbar can properly lift upward.

A critical function of the spring lifting the drawbar's tail is so both sets of the drawbar's tail notches lift high enough to properly engage both sets of corresponding hammer notches in order for DA to work.

An improperly tensioned or weakened (or damaged) "trigger return spring" can cause a condition known as "Skips Double Action" (or Skips-DA). That's where the drawbar tail may not fully engage both sets of hammer notches, and the hammer isn't pulled back far enough, and falls too soon, lacking the full force of the intended DA hammer fall. Light strike.

Naturally, another cause of Skips-DA can be worn or broken hammer and/or drawbar notches (or ones on parts that have been improperly "modified" ).

Armorers usually check this spring's tension - (IN AN UNLOADED GUN AND NO MAGAZINE IN THE GUN!), with the grips removed (to expose the sides of the drawbar). It's checked by gently pulling down on each side of the exposed drawbar (through the frame window cuts on each side), and briskly releasing it. It should lightly rise upward when the trigger isn't pulled (at rest fully forward, hammer & trigger uncocked). Then, when checked with the trigger pulled to the rear (and held to the rear), and the drawbar is again gently pulled downward and quickly released, the tail of it should snap upward a little more smartly, with a little more force (the spring is more compressed).

A reduced power "trigger return spring" is going to have less power to do all this to start with, and that also means less power to do its job when the gun gets dirty, fouled or otherwise contaminated, let alone as the lighter spring starts to weaken with use. (Hence the warning about not using them in duty guns?)

I tried one in a 6906 I used for a while. It's been a long time, but I think it may have been a 3.0 or 3.5lb spring. The 6906 worked normally for a while (a few months?), and then suddenly one day it started exhibiting Skips-DA, randomly giving me premature DA hammer fall during the DA trigger pull, and light strikes (no bang). I replaced the lighter spring with a stock one and the gun was once again working fine, and did for many more thousands of rounds before I changed guns (which I did now and again, because I could ). I decided to stay with the factory drawbar spring for my "working" defensive 3rd gen's.

Just some thoughts.

 

[DCW]

More, More Fastbolt!

". . . power hammer springs (S&W calls them mainsprings, FWIW) . . ."

". . . trigger return springs (S&W calls them drawbar plunger springs) . . . "

". . . before I changed guns (which I did now and again, because I could )."

Methinks in the name of "safety" a glossary/thesaurus posted somewhere on this forum is in order so as to provide a unifying set of notes with respect to making clear definitions and associated synonyms encountered throughout the industry.

The use of "could" ("can" in the past tense) in the third of your three extracts, Fastbolt, kinda disturbs inasmuch as it thus suggests those days may have passed for a man so eloquent and thoughtful in his contributions to this forum. One does not do as you have apparently done for life's bulk - and then pass that knowledge along to others - without a great love for doing it.

Lastly, one wonders (note the use of the preceding word, please) if a polishing of the drawbar's hammer notches (also noting the importance of following Fastbolt's referenced tests while in the process of polishing) could possibly alleviate the need of one or more springs. (If absent previously, one should be getting an idea of "why" custom work costs serious money, BTW.)

Thanks, Fastbolt!

Later.

 

[Fastbolt]

...

The use of "could" ("can" in the past tense) in the third of your three extracts, Fastbolt, kinda disturbs inasmuch as it thus suggests those days may have passed for a man so eloquent and thoughtful in his contributions to this forum. ...

You mean being able to carry different duty weapons?

For almost the last half of my career I was assigned to a plainclothes position. That allowed me to be issued both a full-size and a compact service pistol. In addition, my range instructor/armorer duties sometimes involved me being told to carry one or another different model or caliber, as different guns and calibers were put into service.

After the new production TSW's replaced the early 3rd gen's and some SW99's, there were a couple instances where I wanted to go from a full-size all-steel model to a compact/alloy model (easier on hip under a suit/sport coat all day/night), as well as a couple times when someone really wanted to carry some model or other of the newest TSW's, but we didn't have enough inventory at that moment in time. In those last couple of instances it turned out (of course) that I'd been issued the type of gun someone really wanted, so I arranged to let them be issued the gun I was carrying, and I either checked out whatever else was available in inventory, or arranged to be issued whatever they were carrying.

I ended up carrying 4 different TSW models, for one reason or another, until the decision was made to transition M&P's. Just about the time that happened, policy was changed to once again let people carry personally-owned guns (from an approved list of makes/calibers). I still have a duty weapon because I stayed on as a reserve when I retired, which let me do some consulting and also continue to serve as a trainer/armorer.

Then, of course, there are the collection of personally-owned guns, pistols and revolvers, I carried over the years as off-duty weapons, and continue to carry as retirement weapons.

I've been lucky.

I came close a couple of times to accepting a couple quiet tentative feelers/offers to go to work for one or another of the gun companies, but the timing wasn't right. I still haven't completely ruled something like that out, but I wouldn't want it to adversely affect my comfortable retirement (and being able to spend a lot of time with my grand children). Never say never, though.