Limp Trigger

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lklawson
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Limp Trigger

Post by lklawson » June 8th, 2012, 9:05 am

OK, I experienced the dreaded Limp Trigger. I went out shooting, only had time to run two mags through, but had at least one limp trigger with each. I worked the trigger through a few times and it eventually "caught" and fired right but it really bugged me. I took the P64 out of my carry rotation.

I cleaned it well, inspected everything closely but didn't see any issues, and turned the screw on my Marschal grips back a rotation or so just to make sure nothing was dragging. I figured it might have been just that it was dirty in the chamber or there at the trigger disconnect.

Then I took it back out shooting next time I had a chance. I was still experiencing at least one limp trigger every two or three mags. Sometimes I could bump the slide and and it would be fine. Really started to upset me. I like this little gun and I can keep really tight groups with it (for me anyway - I wonder what I could have done with this pistol back when I didn't have to wear reading glasses just to see the front sight?).

So I started digging through the forums again. Then I found it. I recently started running Brown Bear ammo in it. I've run at least three different brands of ammo through it with no problem, then, when I started running Brown Bear, I just suddenly start having trigger disconnect issues? Riiiight...

I'm undecided if I'm going to try to dress the disconnect (as jaguy did), switch to a different brand for the P64, or just accept an occasional limp trigger (it's only range fodder, after all).

Just kinda a "heads up" on Brown Bear here. My CZ-82 eats it happily but, apparently, it gives my P64 indigestion.

Peace favor your sword,
Kirk
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Re: Limp Trigger

Post by Curly1 » June 8th, 2012, 10:18 am

Kirk,

I never shot any BB but if you place BB and SB next to each other is there any notable differnce between the 2?

If not then other than maybe being dirtier than SB one would think it would not make any difference.

Gary
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Re: Limp Trigger

Post by lklawson » June 8th, 2012, 10:46 am

I haven't measured it yet to compare to the others. No time this weekend. :)

I know that the Brown Bear certainly smells. Cleanup didn't seem particularly bad but there was more black carbon than on my PF9 which I also shot in the same session.

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Kirk
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Re: Limp Trigger

Post by lklawson » June 8th, 2012, 11:18 am

OK, I had a niggling little bug tickling at the back of my mind telling me that I've set calipers to Mak ammo before. A bit of searching and I found where I had already posted the results on the Hi Point Firearms forum.
I have on hand 5 different brands of Makarov ammo. Bear in mind that I only miked one round of each so there may be some variation, but likely not much.

Brown Bear 94gr. FMJ - OAL .98" 24.89mm
Sellier & Bellot 95gr. FMJ - OAL .97" 24.65mm
Hornady 95gr. JHP - OAL .948" 24.1mm
Master Cartridge 95gr. JHP - .96" 24.39mm
Wolf 95gr. FMJ - .974" 24.76mm
Wolf 109gr. "Truncated Cone" FMJ - .974" 24.76mm
So, the Brown Bear has the longest OAL but only by a bare fraction. I didn't measure the case length, only the OAL.

Peace favor your sword,
Kirk
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Re: Limp Trigger

Post by juniustaylor » June 8th, 2012, 11:24 am

There have been several cases of this really. I think the problem may be in the case length of the BB case. It's enough that when the case mouth headspaces in the chamber, it is still a hair longer and is causing the slide to push on the disconnector just enough to disconnect the trigger just a bit. There was one fairly recent in the last month or so. I was talking to the feller and that's the conclusion we came up with. He could slightly modify a bit of metal on the slide or just use different ammo. I'll try to find it.
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Re: Limp Trigger

Post by juniustaylor » June 8th, 2012, 11:31 am

It was this one - viewtopic.php?f=1&t=4733.

He was using SB. We PM'd back and forth and I'm not sure if he ever switched to another ammo. He had said he had shot over 400 rounds through it and never had a problem and we discovered he had never shot SB so this was the first time. Sounded like it would have been the problem. He didn't have any form of measuring device at the time but stated the case length looked a bit longer on the SB compared to whatever other kinds he had.
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Re: Limp Trigger

Post by lklawson » June 8th, 2012, 12:15 pm

If I get time in the near future, I'll try to put my calipers on the cases to find out.

The Mother-in-Law is visiting this weekend so I may not be able to do it for a few days.

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Re: Limp Trigger

Post by Curly1 » June 8th, 2012, 7:32 pm

lklawson wrote:The Mother-in-Law is visiting this weekend so I may not be able to do it for a few days.

Sounds like the perfect time. :)
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Re: Limp Trigger

Post by lklawson » June 11th, 2012, 7:47 pm

OK. MIL is gone. Have the night off from Judo. Kids are occupied. Time to drag out the ammo & calipers.

Here's what I found. First, the conclusion. Then, the methodology. Simply put, the Brown Bear 95 gr. steel cases that I measured were all over-length. Sometimes only ever-so-slightly, but nonetheless over-length. The specific measurement of 9x18 Makarov has the case length at 18.10mm. The Brown bear were frequently over that.

Methodology:
First I don't have a bullet puller and I didn't want to try to use once fired cases because that would deform them. So I ran the caliper up the edge until it dropped over the mouth then backed it back down. It lacks a wee bit of accuracy but not usually more than 0.01mm.

One important thing I noted was that no case was exactly the same length for the entire circumference. For most cases, there was about 0.01-0.04mm variation.

The brass cased rounds I measured were Sellier & Bellot 95 gr. FMJ, Hornady 95gr. JHP, and Master Cartridge 95gr. JHP.
  • Sellier & Bellot had the most variation with cases ranging from as little 17.9mm on the shorter side to as much as 18.1mm on the long side.
  • Hornady cases ranged from as little as 17.8mm on the short side to 18.00mm on the long side.
  • The Master Cartridge cases tended to be the shortest of all cases I measured, either steel or brass, with as little as 17.8mm on the short side and as much as 17.86mm on the long.
The steel cased rounds I measured were Brown Bear 94gr. FMJ, Wolf 95gr. FMJ, and Wolf 109gr. "Truncated Cone" FMJ.
  • Wolf 95gr. FMJ measured as little as 17.88mm on the short side to as much as 18.01mm on the long side.
  • Wolf 109 gr. "Truncated Cone" FMJ measured as little as 17.92mm on the short side to as much as 18.01mm on the long side.
  • Brown Bear 95 gr. FMJ measured as little as 18.02mm on the short side to as much as 18.17mm on the long side. Nearly every case measured had one side which measured greater than 18.14mm.
I have to say, 6 hundredths of a millimeter isn't much to be over-length, but I guess it can (sometimes) be enough if any of a number of circumstances come to pass. Possibilities include very exact tolerances on the chamber length, fouling in the chamber reducing over-all length, heat expansion changing the dimensions of the chamber, or some other possibility I having thought of. It's worth noting that I fired exactly the same lot of Brown Bear ammo, during the same range session, from my CZ-82 and it ate it without any hiccups.

I also suspect that some of the rounds load in with the "short end" of the case aligned so that it isn't enough to engage the disconnector.

I can see how bumping the back of the slide or shaving the disconnector by one tenth of a millimeter would fix this issue.

I have to admit that I'm really surprised that there was so much variance in the case lengths of the other ammo and particularly that the U.S. tended to be slightly under-length. But I guess it's was always within 1/10th mm of the specified 18.10 so it works.

Peace favor your sword,
Kirk
Last edited by lklawson on January 22nd, 2013, 12:34 pm, edited 2 times in total.
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Re: Limp Trigger

Post by Curly1 » June 11th, 2012, 8:53 pm

Do you have another 9x18 pistol to test the BB in?
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Re: Limp Trigger

Post by lklawson » June 11th, 2012, 9:16 pm

I have 3 others. :)

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Re: Limp Trigger

Post by RobsTV » June 12th, 2012, 7:08 am

Looks like you found the problem.

Just checked my 5 times fired 9x19 trimmed to 9x18 cases for comparison.
As fired 5 times and unsized were 17.81
After resizing die 17.98 to 18.02
Only posting to show the difference between fired and resized.

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Re: Limp Trigger

Post by lklawson » June 12th, 2012, 8:29 am

RobsTV wrote:Looks like you found the problem.

Just checked my 5 times fired 9x19 trimmed to 9x18 cases for comparison.
As fired 5 times and unsized were 17.81
After resizing die 17.98 to 18.02
Only posting to show the difference between fired and resized.
Thanks for the additional data point. It's starting to add up. :)

Peace favor your sword,
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Re: Limp Trigger

Post by lklawson » June 12th, 2012, 4:20 pm

OK, I was thinking of trying out the Brown Bear ammo in my other three Makarov caliber handguns: IJ70-18AH (hi cap Makarov), PA-63, and Norinco Type 59 (chinese made identical copy of the Mak.).

However, it occurs to me that they may not have a trigger disconnect to prevent out of battery firing. I've done a bit of searching and I know for a fact that the PA-63 has no out-of-battery disconnect. I don't think that the Makarov design does. I've run through the diagram and I don't see anything that looks like an out-of-battery disconnect. It also looks like the CZ-82 doesn't either (as I've "confirmed" from other user reports).

What do you say guys? If none of the Mak. cal. guns except the P64 has an out-of-battery disconnect then testing the Brown Bear ammo in them to see if it causes similar over-length issues is meaningless.

Peace favor your sword,
Kirk
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Re: Limp Trigger

Post by Curly1 » June 12th, 2012, 5:33 pm

At least you will know if it runs ok then you can use it in those pistols.
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