Question for the group on primer seating.

[meinbruder]

About a year or so back, I started getting the odd failure to fire from my reloads; four or five per hundred, a high enough number to be annoying. My first assumption was operator error on the seating depth; more attention to detail should be the cure. Visual inspection and tactile testing showed depth to be correct but the failures continued.

The typical failure is a click of the hammer drop on the cartridge, open the cylinder to see a shallow mark on the primer, back it up and it fires on the next hammer drop. Ahah! The seating depth is again the suspect, as the hammer drop finished seating on the first try. Or did it? I’ve tried mashing the primers down to the point of flattening them down and the failures continue; four or five per hundred.

Okay, how about the revolver? It had a trigger job by a former optimist so I took the grip off and turned in a screw to put a tad more pressure behind the hammer. It seemed a little dry so a couple of drops of oil in the right places might help. The next box fired just fine. By George I think I’ve Got It!! Open box number two and get a click in the third cylinder and then another in the sixth, great the failures are down to two per hundred. Well that’s a 100% improvement, right?

Primer metal hardness? I’ve read here on THR that CCI primers are the “hardest” and that’s what I normally use but the failures started with Winchester primers which are the “softest”, also according to what I’ve read here. Okay, one last idea.

I’ve been loading these cases for almost twenty years; the shooting budget has varied over time so they get loaded once or twice a year. The lot of them had been trimmed to length for uniformity so they’re about ten thousandths under size and the dies have been adjusted to suit them. I’ve always punched out the primers and cleaned the pockets, before loading the next cycle, with the little wire pocket cleaner and gotten a pile of soot with some noticeable brass specks in it. I just bought a motorized “gee-whiz” RCBS cleaning station and the brass flecks are even more noticeable. Have I deepened the primer pockets? ….enough to cause the failures? ….am I grasping a straw?

I load 9mm, .45acp, .30carbine, and recently started loading .357 again. The only caliber that is failing at this point is the 44mag. The pistols and carbine have floating firing pins, the primer pockets would have to get really deep to be a problem. The revolvers are a S&W28 and S&W29 which have a fixed pin on the hammer, pocket depth might very well be a factor. The M28 is a replacement for the one stolen fifteen years ago so the brass is “half” the age of the M29 brass, if that makes any sense. I’m curious to see if failures show up in it. I suppose I should buy some new .44 factory loads to see if they all fire without a problem.

I don’t mind replacing old brass but I know some of these cases by first name. Your thoughts and comments are more than welcome.
Mike


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[ReloaderFred]

First of all, all S&W revolvers should have the strain screw tightened all the way. The strain screw is what applies tension to the hammer spring. A lot of people unscrew the strain screw in an attempt to do a cheap action job. Bad plan. This is one of the most common causes of misfires in these revolvers.

Second, in order of hardness for primers, with the hardest first:

1. CCI
2. Winchester
3. Remington
4. Federal

This is based on firing over half a million rounds of reloaded ammunition since I started loading in 1963, and shooting about 800 different S&W revolvers. I used to be the rangemaster for a rather large Sheriff's Dept., and that was how many we had at the time and I fired them all at one time or another.

It sounds like you're doing the seating properly, so first I would check those strain screws on both revolvers. Then I would try another brand of primers. If the guns won't set off Federal primers, then the problem is with the guns. If they will, then the primers are too hard for how the guns are set up.

Hope this helps.

Fred

 

[JoeHatley]

+1 Turn your strain screw all the way in(keep it there), and use Federal primers.

Joe

 

[Mantis]

+2. I had the exact same problem with a S&W 44 mag a couple of months ago. I tightened the strain screw and the problem was solved.

 

[meinbruder]

Re--Question for the group on primer seating.

Gentlemen, thank you all for your suggestion. I pulled the grips off both pistols and the strain screws were about a half turn "out" from botom. I've set them both firmly and will shoot them this weekend. I'll post a note about the results.
Thank You
Mike


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[Steve C]

The trick in seating primers is to make sure they're seated to the bottom of the primer pocket good and solid with enough pressure to sensitize them propoerly. I've yet to see one seated too deep to go off but have seen plenty that don't go off if not fully seated to the bottom. that little note in the reloading manuals warning "not to crush the primer when seating" has done more to cause ignition failure than any thing else. Many new reloaders become so afraid of crushing a primer that they don't seat the primer fully. It takes a lot of pressure to crush a primer and its almost impossible to do with a hand priming tool' though it can be done with some effort when using the press to prime. A strong hit by the firing pin may make up for some sloppily seated primers but its still not the most reliable method to insure primer ignition.

On the old S&W revolvers the company used to set the hammer spring pressure and adjust (shorten) the length of the strain screw so that when screwed in all the way the hammer spring tension was set to a factory standard. My latest S&W a Model 657-4 .41mag Mountain Pistol had its strain screw set at the factory, though there was still several turns left to add tension to the main spring. With S&W revolvers made in the last 5 years I'd guess that they no longer "calibrate" the strain screw opting instead to set it at the factory to a specific gaged spring tension leaving any additional adjustment available un-modified. The advice to just turn it all the way in isn't as appropriate wth a recent S&W revolver as it is with earlier manufactured S&W's.

 

[meinbruder]

Gentlemen

I have mixed results to report from the day's shoot. After turning “in” the strain screws in both revolvers to the bottom, one still showed a failure to fire; the .357 M28. I loaded the .44mag ammunition with a double redundant push against the primer and it ran without issue. Fred, Thank You! Your input has been very helpful.

The M28 has a Hogue MonoGrip which will be seeing the dump in the very near future. It literally shook it’self loose in the first fifty rounds. The .44 had a couple of instances of the brass needing to be “Tapped Out” with a mallet. (?) Pressure signs were all normal with one case being a possible culprit. Once again old brass is the suspect.

Thank You All, so very much.
Mike


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