P45 Failure to Fire Light Primer Strike

[gman]

Thanks for the info on the striker's pin out of the breech face by 0.035 compared to mine of 0.025. I did a little smithing and now have a presentation of 0.035 and did some fire testing today. Results- -

1) Will it fire various factory rounds that were 10% fail to fire (FTF), last week. All my FTF's appear as light primer strike, dead trigger (letting up trigger no reset click, no trigger reset until slide back and to fire positon). No rifle marks on the bullet, so bullet isn't too long.

2) Will it fire my typical reloads that it would not fire at all last week. WOLF primer, 205 RNFP (round nose flat point lead), 5.6 grains W231, all reloads are checked thru chamber checking gage. I use a Lee Factory taper sizer crimper.

3) Will it fire my typical reloads but with soft Federal 150 primers, that I use for revolver work.

RESULTS:
3) Wow, a real improvement, started with the 3) Reloads with Federal 150's, 30 rounds no FTF, no jambs real pretty never had been able to fire reloads.

1) I took a limited number of factory rounds, no FTF, with 20 rounds. Wolf steel case and WWB. Happy ness. Although gun would run these with infrequent FTF. No verification due to limited test sample.

2) My typical reloads- Wolf hard primers, fired 18 rounds, then started to get repeated FTF, like three in a row?? Breech is fully closed etc. same old light strike and dead trigger after FTF (see above). Pulled slide off, tried to see if the trigger bar is getting hung up, it didn't seem to be stuck. Worked the ears and trigger bar tab manually it looked like it was working releasing the reset etc. I'm not absolutely sure I comprehend this trigger bar reset sequence, etc.

After this manipulation, it ran with only couple FTF in test 2) and again no FTF in 3).

I think I still have a trigger bar sticking going on, because once I get a FTF, FTF becomes very frequent where it was running fine previously.

Obviously, having increased the striker protrusion by 0.010 to make it 0.035 really made an improvement and the federal 150 primers have showed no FTF.

Help- - -Trigger bar sequence, timing checks, ideas
Thanks to all

[gb6491]

I'm not absolutely sure I comprehend this trigger bar reset sequence, etc.

This might be of some help:
http://www.kahr.com/kahr-unique-design.asp
If you view the page with Firefox and have add on Image Zoom
installed, you can zoom the animation for better viewing.
Regards,
Greg

[gman]

How is the trigger bar and cocking cams connected. If the trigger bar sticks down occassionly does this cause the pre-cocking to not occur? Would this be cause for the failure to fire from light primer strikes

Thanks for the link to the operating diagram

[gb6491]

How is the trigger bar and cocking cams connected. If the trigger bar sticks down occassionly does this cause the pre-cocking to not occur? Would this be cause for the failure to fire from light primer strikes

Thanks for the link to the operating diagram

gman,
You can get an idea how the parts interface, if you'll look at the parts diagram on this page:http://www.gunreports.com/special_re...mbly184-1.html

Here's how I see the system operating
Starting with a ready to fire pistol:
At this point the striker (under some spring pressure) is mated to a lobe/ear on the cocking cam (I'll call this ear the cocking lobe)
The trigger bar is mated to a surface below the center axis of the cocking cam by a perpendicular tab on its lower rear end. The trigger bar is spring loaded upward to keep this tab in contact with the surface of the cocking cam.
Pulling the trigger causes the trigger bar to move forward. The tab on the trigger bar starts pushing the cocking cam around its axis; as the cam rotates, the cocking lobe forces the striker rearward. As the forward motion of the trigger bar continues, the cam continues to rotate forcing the striker further rearward, but also rotating another lobe on the cocking cam into position. This lobe pushes the striker block up clearing the striker’s path in the slide. Shortly after this, the cam has reached a point where the cocking lob disengages from the striker. The striker springs forward firing the pistol.
Now, as the slide moves to the rear, it moves the cutout for the upper surface of the trigger bar (visible at the top rear of the pistol) out of position and the slide pushes the trigger bar down and out of engagement with the cocking cam.
The cocking cam is spring loaded and will return to its original position at this point.
Now, as the slide travels forward, the striker will again engage the cocking lobe (resetting the striker). When the cutout in the slide comes back into position above it, the trigger bar will try to rise into its spring loaded position. If the trigger is still held back at this point, the tab on the trigger bar will be forward and below its starting position on the cocking cam. Allowing the trigger to go forward causes the trigger bar to move rearward and up, engaging its original position on the cocking cam. The gun is now completely reset and ready to go again.


Hope this helps and if, I'm incorrect in my description, someone will correct me.
Regards,
Greg

[jfrey]

Here's my .02 worth on it. Jocko and Bawanna can correct me if my thinking is out of whack here. It seems that with various bullet problems in kahr barrels, they may be short throated. I don't have any way to measure this exactly but if bullets aren't seated DEEP we all seem to notice slides hanging up and sometimes going into battery but get FTF issues. The Federal primers are known to be soft and apparently cure other problems we may not notice in our ammo. Upon looking into a Kahr barrel and then a standard 1911 barrel, one notices a definate difference in the way the rifling looks. Such is also the case with a Glock barrel. As Jocko pointed out on another post by me, a few thousandths will make a big difference when it comes to seating depth. Along with this, it is also necessary to look at bullet configuration. A flat nose bullet has different dimensions than a ball (round nose) bullet. This may seem elementary to those who reload a lot but a paralell sided bullet will hang up when a tapered sided bullet will work in a Kahr barrel.

Other things may be at play here as well but we have to go through it all to solve some of these annoying problems.

The wealth of knowledge and patience here amazes me all the time.

jfrey

[jocko]

gb6491. very well done

jfrey. I would have to agree with you that maybe for some reason kahrs are kinda tight throated. I when I had my kahr custom worked over at Cylinder and Slide, they throated the barrel in the process. So I am not qualified to ever say I had rounds stuck in my barrel. . Reloaders have to be more careful for what may seem like a tad bit longer, will just not fit in some guns PERIOD. Not the guns fault either. Nice post ..

so damn much information on this forum, maybe kahr techs should be reading some of it--????I do really like what Bawanna stated a few days ago about one testing out his carry ammo for sure by inserting in the barrel and if it falls back out, it is gooto go afar as not over seating goes. New ammo can give issues.

[gkstemple]

Great desctiption of the firing cycle.

I'm going out on a limb and suggest that there are two kinds of "dead trigger" FTF's

1. No primer strike -- striker is in precock position, but trigger bar is not in reset position

2. Light primer strike -- striker did not go to (or hold in) precock and observed strike may be from inertia -- not sure why that would be a "sometimes" event, perhaps clearances or parts tolerences at the outter limits of spec? Different loads "vibrating" the parts differently?

[gman]

Striker protusion past breech face-

Very good descriptions of sequence of parts thanks-
I'll be firing a combat match tomorrow,trying out my change in striker protrusion from the breech face from 0.025 to 0.035 to accomodate a typical taper crimp on lead bullet; I believe this slight bullet crimp and a chambering of 0.910 on my P45, plays into poor light off of reloads. Bullets are not striking long in chamber in to rifling or barrel not going to battery. So will report tomorrow.

[gman]

Happy DANCE!! My P45 will now run my reloads after increasing the striker distance past the breech and using Fed 150 primers. 80 rounds of combat stages no FTF.

[jocko]

Happy DANCE!! My P45 will now run my reloads after increasing the striker distance past the breech and using Fed 150 primers. 80 rounds of combat stages no FTF.

did u get a new striker from kahr and for some reason it is longer than the one that wa sin your gun, or do you think u had a bad striker or a partial tip broken off or waht.