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Starting charge for Glock Gen5 Barrel with Short Leade


Jimmydmai
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Hi all, I am new here and also new to loading 9mm (loaded tons of 223 & 308). 

 

As all have heard, glock Gen5 have shorter leade.   I am trying to do some load development for Xtreme 124gr FP and RMR 147gr FMJ Flat Nose and both OAL is shorter than publish data. I've done the plunk test with a fireform brass and 3 of each bullet and got the results:

 

124gr-

1) 1.077"

2) 1.080"

3) 1.079"

 

147gr-

1) 1.093"

2) 1.089"

3) 1.082"

 

I have Titegroup and since it's shorter oal, I don't know what to set my starting load at so I can begin  working up over a Chrono. So far, I've seen others OAL well over 1.100"+ and 3.0gr+ of TG. 

 

Should I back off 0.010 - 0.015" on the shortest results above of each round and use that as my OAL?  My biggest frustration is how do I determine my starting charge?  

 

Thank you. 

 

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Starting charge shouldn't really change because of the OAL. It would have to be something ridiculous for me to consider it a factor when determining a starting charge weight. I'm surprised the 124gr needs to be that short but I don't load Xtreme.

Edited by 4n2t0
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12 hours ago, 4n2t0 said:

Starting charge shouldn't really change because of the OAL. It would have to be something ridiculous for me to consider it a factor when determining a starting charge weight. I'm surprised the 124gr needs to be that short but I don't load Xtreme.

 

I thought pressure was going to increase if I seat those rounds shorter than normal but since this is my first time, I wanted to ask to make sure.  I didn't want to get a squib either.

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3 hours ago, Jimmydmai said:

 

I thought pressure was going to increase if I seat those rounds shorter than normal but since this is my first time, I wanted to ask to make sure.  I didn't want to get a squib either.

 

Better to ask now than to be sorry later.

 

You don't really have to worry about harmful pressure levels when changing the OAL as long as you start with published/known data (Not for the OAL information, that's useless, rather the charge weight spread). Rowdyb has provided you with an excellent data point. I can add that it took me 3.6gr of TG under a 147gr thick plated bullet  to make 130 PF in a 4.25" barrel.

Edited by 4n2t0
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I'm not using Xtreme bullets, but I am testing a new gen 5 17 and am surprised that the chamber is as short as it is.  I had to seat a BBI 125 .356 down to 1.115 before it would plunk and spin with no drag.  However, a Precision Delta 147 round nose at 1.135 spun freely.  The chrono told a strange story, though.  The 147 PD went +/-125 pf (3.2 grains Titegroup).  This load makes 130-132 all day in my Trojan and gen 3 G34.  Great, I thought, I have a slow barrel.  Yes the 34 and Trojan have longer barrels, but I didn't expect that much difference.  To my surprise, the BBI 125s (which I plan to use) shot better than I expected.  I loaded 3.7, 3.8, and 3.9, and expected to end up at 4.0 or 4.1.  The 3.8 consistently made the 1050-1060 I (131-132 pf) I wanted.  I would have rather seated these to at least 1.130, but am happy with the chrono results and will leave the OAL there.  

 

If you are worried about the shorter OAL, drop the charge another .1 or .2 more than you would if you were starting with your preferred OAL.  Like 4n2t0 said, you probably don't have much to worry about, but it can't hurt.  My velocity with my BBI load surprised me a little and I suspect it was due to the shorter OAL.  

Edited by deerslayer
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  • 3 weeks later...
On 6/10/2019 at 9:39 PM, rowdyb said:

I have 3 gen 5 glocks. And titegroup. And rmr 147 fp jacketed. 

 

Oal of 1.060" passed plunk test in my guns. 3.30 grains titegroup for 130pf out if my gen5 g34. 

This is great info!

 

I'm running both a gen 5 17 & 34 and just ordered some rmr 147gn fmj fp's. I'm hoping for something that mimics the Federal Syntech 150's.

 

Thanks again for the information. Looking forward to get these through the chrono too.

 

 

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