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Weird 9mm Problem


gerritm

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For my granddaughter"s PCC & Glock 34 I changed from 115gr SNS casting poly coated to 115gr Everglades plated bullets due to leading in our PCC rifles & comps. It is a light load for 3-gun & steel matches. Same recipe, 3.1gr Titegroup @ 1.12 OAL. Double checked weights when I switched. Been super accurate and ran both guns with no problems.

 

Sunday in a falling steel match, kinda cool for Texas, mid to upper 40's, shooting the Glock 34 she finishes up the SNS rounds. Been running perfect. Loads up the first of the plated 115's. Will not run. Stove pipes almost every other round, finally drops the mag and has 1-mag of the SNS as back up finishes the stage.

 

Looks at me like what just happened? Had some other rounds for another gun with us and shot those the balance of the match. 124gr plated Everglades @ 3.4grs Titegroup.

 

It warmed up a little and end of the match tried them again and they did the same thing. Shot 1 or 2 and then stove pipes. 

 

So same powder, same amount, same weight of bullet, only difference is plated-no go, poly coated-works. Bullet diameters are coated .356, plated .355. Could this be the difference in pressure created?

 

gerritm

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If you’re running borderline powder charge, there’s a strong chance that two shooters with different calibers of recoils management will have 2 different outcomes. The one with better recoils management (or a carbine) will run reliably, but the one with slightly less will have feed or extraction issues.

The diameter likely plays part of this in your situation, and upping the powder charge 1-2 tenths will probably fix the problem.


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Bullet weight is not the only factor.  Coated lead obturates better than plated or jacketed, creates more pressure for the same mass of powder, and you get more velocity, and thus more recoil energy to cycle the action.  The remaining internal case volume after the bullet is seated also plays a factor.  The smaller the remaining case volume (and thus the smaller the initial size of the combustion chamber), the higher the pressure, and so you may well have less remaining case volume after the coated bullet is seated than after your plated bullet is seated, meaning more pressure for the coated lead.  And when all else is equal, the larger the diameter the bullet, the higher the pressure. 

Any 115gr bullet with 3.4gr of powder is a LIGHT load.  You're simply not producing enough recoil energy to cycle the action.  I'd go up to AT LEAST 4.0gr of TG with the plated, and probably more.  If it's too snappy for her, go up to a 124gr bullet.  OR go to 125gr coated, but go to BBI, which tends to be a closer to .357 than .356 in diameter, and that will likely mitigate the leading issue.  Leading is quite often a problem with bullet to barrel fit.  

 

 

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3 hours ago, gerritm said:

 3.1gr Titegroup @ 1.12 OAL.  SNS rounds run perfectly.  Plated 115's will not run.  

 

Agree with more TG, but while you're at it, I'd run The Plunk Test with the new bullets -

probably NOT a problem, but worth checking while you're at it    :)  

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Funny thing is the G34 operated just fine with the coated SNS and would FTE with the plated bullets under the same circumstances, weather, & variables. I know it is a light load and can go to a heavier bullet. My question more revolved around the bullet diameter making that big a difference and possibly temperature, being colder than normal. Mid to low 40's is cold here in TX.

 

Just kind of surprised me. Figured they would work. She was not happy.

 

Bullets plunked fine. I have run 124's &147's in this gun and her PCC. This is just what she likes. Want to be able to run same loads in both so no confusion. 

 

I will go up a few 10ths for the 115grs or bump up to the 124's I run. 

 

Thanks for the help.

gerritm

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Funny thing is the G34 operated just fine with the coated SNS and would FTE with the plated bullets under the same circumstances, weather, & variables. I know it is a light load and can go to a heavier bullet. My question more revolved around the bullet diameter making that big a difference and possibly temperature, being colder than normal. Mid to low 40's is cold here in TX.
 
Just kind of surprised me. Figured they would work. She was not happy.
 
Bullets plunked fine. I have run 124's &147's in this gun and her PCC. This is just what she likes. Want to be able to run same loads in both so no confusion. 
 
I will go up a few 10ths for the 115grs or bump up to the 124's I run. 
 
Thanks for the help.
gerritm

I also run titegroup and have found with wild swings in temp I also have similar issues. When it’s cold I get FTEs. From what I’ve read it is a temperature sensitive powder


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1 hour ago, Bullett said:


I also run titegroup and have found with wild swings in temp I also have similar issues. When it’s cold I get FTEs. From what I’ve read it is a temperature sensitive powder


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Thanks for the response, kind of what I was thinking.

 

Had an issue at the same match with my TG load in both my G34 open gun & Tanfo open gun. These are set up for falling steel & 3-gun. I know TG is a fast powder and not a lot of gas for the comp, but is what the guns both like. 3.4-3.5grs TG with a 124gr plated Everglades bullet, I have run this load for 1K or so rounds with no problems & Saturday had a couple of FTE stovepipes in my G34 so I switched to my Tanfo for Sunday falling steel match.

 

Coldest day was Saturday @ low 40's with 20 plus MPH North wind. Sunday it was a little warmer in the morning mid-upper 40's with no wind. Had the FTE stovepipes early, switched to some factory ammo & they worked. Warmed up to mid 50's switched back to the TG, 124's and they worked fine. So pretty sure it was temp.

 

First time I have had issues like this. Usually pretty warm/hot here. Going to bump both loads up a bit for the future, just thought this was interesting.

 

gerritm

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1 hour ago, gerritm said:

 

 Saturday @ low 40's.   Had the FTE stovepipes early, switched to some factory ammo & they worked. Warmed up to mid 50's switched back to the TG, 124's and they worked fine. So pretty sure it was temp.

 

 

Might also check your lubrication.

 

Might need a different lube, or more of it, when it gets cold   :) 

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Guns are lubed and cleaned especially hers. Her PCC/pistol is cleaned and lubed before every match and many times wiped down/lubed halfway thru matches cause TG is so dirty. I would never hear the end of it if guns MF cause of lack of maintenance between her dad & I.   Using a little BE Slide Glide light on the G34's rails and Mobil 1 0w-20.

 

Pretty sure not a lube problem. Ar's are lubed wet with Mobil 1. We have shot many matches before in the 40's and high 30's before. Not that unusual here in what little winter we have. Pretty sure it is powder temp and cutting it a little too close. Learned a lesson. Bump it up a bit. Will be wishing for the cool weather in a month or so.

 

gerritm 

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The charge is just way too light to handle the variables associated with shooting. You didn't account for the added friction of plated bullets. Powder charges should increase as you go up the "bullet ladder" (lead-->coated-->plated-->FMJ). As you can see from the data below you aren't even at a minimum lead load, let alone something appropriate for a plated bullet.

 

tite.thumb.png.d7ed631570d9d7b1c31bab29386f8391.png

 

 

Edited by 4n2t0
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Another thing to consider is that plated bullets tend to run slower than cast bullets when they are loaded with the same powder charge, possibly in the range of 50-60 fps.  That could cause cycling issues if you're running light loads. 

 

https://books.google.com/books?id=datxDAAAQBAJ&pg=PA234&lpg=PA234&dq=gun+digest+brad+miller&source=bl&ots=HNIngOtYpC&sig=WQCX-YWAqXinYRmwCJmpSwyk7n4&hl=en&sa=X&ved=0ahUKEwj4hZvsg67aAhWpnuAKHWKqAYkQ6AEIWDAL#v=onepage&q=gun digest brad miller&f=false

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All you need to do is bump the load up about 4 tenths to equal the same velocity as your coated rounds and you will never know the difference. Plated bullets are harder to drive down the bore than coated. Try it.........You'll like it.....

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36 minutes ago, bowenbuilt said:

All you need to do is bump the load up about 4 tenths to equal the same velocity as your coated rounds and you will never know the difference. Plated bullets are harder to drive down the bore than coated. Try it.........You'll like it.....

 

This.

 

Going for the razor’s edge in light loads means you’re occasionally going to get bent over by the reliability gremlins. Hard.

 

Bump it and deal with just a *little* bit more recoil, and your gun will actually run when it’s dirty on a cold day.

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On 4/9/2018 at 11:30 AM, gerritm said:

Funny thing is the G34 operated just fine with the coated SNS and would FTE with the plated bullets under the same circumstances, weather, & variables. \

 

Not funny/weird at all.  As I already said, coated bullets obturate better and reach higher pressures when all else is equal.  It's to be expected. That's already a super light load.  You made it lighter by moving to a plated bullet.  No mystery to it.  If it started working better at higher temperatures, that doesn't mean temp was the problem.  It means you were so close to the edge of unreliability that the slightest change in temp is enough to drop you below 100% function, which means you were too close to that edge to begin with.  Add a few tenths of a grain, and all will be well.

 

 

Edited by IDescribe
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Really don't need a lecture. My plated round I had shot well over 1K before this and her plated round at least 500.  They had been tested, glad you were the first. I test every load. Just never been tested in cold weather, this is Texas, doesn't happen very often this time of the year. That was the variable.

 

Shot both old loads from both guns yesterday in 80 degree weather and they shot fine, no failures and ejection was good.

 

Bumped up the load for both and tested yesterday, all good.

 

Thanks for the help,

 

gerritm 

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