light strikes

[ck1]

Tried a different Wolff reduced power striker spring with my borrowed Glockworx lightened striker: zero light strikes through 300rds of my ammo du jour (Federal Champion ala wallymart). No lightstrikes, albeit delivered a mushy pull with a weak reset, sticking with the stock striker spring here but looks like it's a combo that can indeed be reliable if one wishes to try running it to get their trigger pull-weight down.

[Duane Thomas]

While I'll agree there is a slight affect when we are talking about high pressure rifle cartridges, I'm skeptical that there is any primer indentation "fire forming" for normal pistol pressure cartridges. If you have some data, or a pressure model to suport your statement, please provide it.

Perform the following test:

Take a primer and kill it by impregnating it with oil. Load it into a cartridge. Dry fire on the cartridge. Yes, I'm talking a handgun cartridge. Compare the resultant firing pin strike - which be shockingly shallow and ill-defined - to what happens when you fire the same primer type as part of a live round in the same gun which will be deep and well-defined. If this is true - and I assure you it will be - then why would that be the case? It's because much - most, actually - of the depth and well-defined character we see in the typical impression in a fired primer is not caused by the impact of the firing pin per se. This is simple observed reality.

I do have to say, though, you've got me curious. The post to which I originally replied said:

I compared the indentation made by the striker on both the CCI and Win. primers under a magnifying glass. It's really hard to tell the difference but I think that the Win. primer has a deeper indentation than the CCI, meaning that the CCI primer cup is harder that the Win.

I made the case that you can't tell the difference between the hardness of primer cups [in this instance CCI and Winchester standard small pistol] by looking at the impressions on fired primers because pressure inside the casings is going to fire form the primers equally in either case. How about I perform the following test:

I will take one each CCI small pistol primer, one each Winchester small pistol primer (admittedly I'm going to have to track down some of the older silver colored Winchester primers so the gold color of current production Winchester primers doesn't instantly identify it), and I think I may throw into the mix the Federal Small Pistol Magnums that I use in my own match ammo. I will load one round of ammo with each primer, each consisting of my match load, a Rainier 147-gr. TRN over 3.5-gr. N320. I will fire them, one right after the other, in my Glock 19 running a Wolff 4-pound firing pin spring, during the same range session - in the same location, with the same ambient temperature, to factor out environmental considerations. I will fire all three rounds over a chronograph to factor out a possible difference in chamber pressures as any sort of contributing factor.

To make the cartridge casings easily, immediately identifiable I will load the CCI primer into a Speer casing (if I can't find a casing marked "CCI"), the Winchester primer into a Winchester casing, the Federal primer into a Federal casing. Alternately, if you think it's important to factor out different brand casings as a potential factor I can load them into same-brand casings and find some other way to keep them sorted. (If you think it's worthwhile I can do 20 rounds apiece and average the velocities instead of just one - which, thinking about it, is an idea I like better.) Then I will use a macro camera to take photos of all three types of fired primers. Assuming we go the CCI-Speer/Winchester/Federal casings route, I will then crop out of the resulting images anything but the primers and post the pictures here to see if you can pick out which primer is the CCI, which is the Winchester, and which is the Federal by appearance of the primer strike alone - or really see any difference at all. It may take me a week or so to get this done. If I am wrong, I will certainly be the first to admit it. Would that strike you as a worthwhile experiment?

[Thomas H]

Would that strike you as a worthwhile experiment?

I agree with you on how the primer will change form when fired---nonetheless, *I'd* like to see this, just for the sake of my curiosity. By all means, please take up your time doing this!

[MarkCO]

That would certainly be interesting, and a good piece of data to have. I am not sure 20 is a big deal, but keeping the brass all the same would be a good idea.

[Duane Thomas]

Okay, just give me some time. And like I said, if I'm wrong I'll certainly be the first to admit it.

[eric nielsen]

That will be an interesting and worthwhile experiment. Many times the most useful experiments find not what the designer expects but something totally unforeseen.

Just a guess but you might find the repeatability of primer impressions to be very disappointing or even scary-bad. In my previous jobs getting consistent crush depth and getting consistent inertial behavior were very difficult and for the striker-fired pistol designs you combine both of those hairy problems.

My opinion, Mr. Glock's original design that has tiny cheap semi-circles of plastic held by striker spring coils that are VERY inconsistent for inside-diameter, holding a critical interface [controlling both the path and the friction on the striker travel] is very shaky engineering at best. The one sure way to get good performance in that small but critical area is to use much more than enough spring.

[Duane Thomas]

Even if we ignore for a moment that the gun, in overwhelming probability, wouldn't go into battery during cycling with such a heavy firing pin spring (unless we also compensated with such a heavy recoil spring the gun also probably wouldn't cycle, natch), how would using much more than enough firing pin spring possibly give more consistent firing pin strikes? Just asking, I'm curious. And when you say "much more than enough spring" do you mean much heavier, longer, what? Again just curious what your theory is here.

[eric nielsen]

The light spring is 4 pounds. Sometimes it's enough, even on a CCI. The standard spring is 5.25 or 5.5 lbs. It's usually enough on any primer, exception being the Hirtenberger 9x19 machine-gun ammo, of which I still have about 800 rounds. The Heavy spring is something like 6 pounds. It's pretty good on CCI and about 80% on Hirtenberger.

So 5.5 or 6 would each be much more than 4. Maybe 5.5 is enough, maybe not. As you say, the slide-closing limitation is a big deal and prevents trying a 10 or 20 pound spring. Of course I like dry-firing the 4lb the best but in a match I can't tell it apart from a Standard.

Edit to say "better" would be separating out some of the Glock striker functions and spring functions, by way of comparison the JMB design in the 1911 firing pin tunnel is pretty nice. There's no way to approach that in a Glock but if a machinist was motivated he could put out spring cups and striker springs that are much tighter tolerance than what Glock makes. The last few coils need to be improved, made consistent I.D. and more resistant to stretch.

From what I've seen the Light springs are also the worst at holding the spring cups together. When they separate, you have more friction that needs to be overcome and yet there's your reduced, 4lbs of force. In search of a nice-feeling trigger you have many people combining light striker springs, bad spring cup alignment, too much over-travel removed and now another friction source which is the FP safety plunger not getting completely out of the way. Which begs for more spring force. And so on.

Edited December 14, 2010 by eric nielsen

[Duane Thomas]

Interesting. Thanks for sharing your thoughts.

[eric nielsen]

Sorry. Kept editing in a vicious circle, much like the problem I was describing.

[Bill Nesbitt]

I made the case that you can't tell the difference between the hardness of primer cups [in this instance CCI and Winchester standard small pistol] by looking at the impressions on fired primers because pressure inside the casings is going to fire form the primers equally in either case.

The picture doesn't show it as well as I would have liked. These are minor rounds fired in a newer 38 Super S&W revolver with the convex firing pin bushing. The Win brass is Federal primers and the R-P brass is R-P primers. The Federal primers are dished in while the R-P primers look like any other fired primer. Federal primers will "fireform" more than other primers.

[Duane Thomas]

That IS interesting. How about posting Winchester versus CCI so I don't have to?

[Bill Nesbitt]

I'm not sure Win or CCI will go off in my light action revolver.

I could easily get the firing pin imprint of rounds that didn't go off without using oil and stuff like that.

I would have to switch my 550 over to 38 super. I might do it but I don't know when.

[Duane Thomas]

Sigh! Well there goes my attempt to fob off that job.