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Coated OAL 124 ACME


NETim
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I've been loading 124 grain ACME's for my Glocks with very good results, acceptable accuracy and outstanding reliability.  OEM Gen4 17 barrels.

(I think they would chamber 40's if the stars were aligned just right.  Very forgiving.)  I loaded the 124's at a nominal 1.13".   Loading on a 650 with Dillon dies and mixed range brass. 

 

I've just started loading for an Apex barrel in an M&P.   I fully expected the necessity of reducing OAL for this barrel.   I settled on 1.10" after plunk testing dozens of finished rounds.  During the plunking, I'm finding a fairly wide variance in OAL, from 1.03" to 1.16".   (Not many but a few.)  Generally some of the longish ones, over 1.12, will drag during the plunk and spin but most don't.   

 

To further complicate matters, many of my original Glock recipe loads @ 1.13" pass  the plunk and spin.  But enough don't pass that it caused me to dial back the OAL.   

 

So, my question is, are others seeing this kind of variance in coated bullets?   I realize that cast/coated bullets are not the most precise  product in the world but I'm somewhat amazed at the deviation in length/coating thickness, profile, whatever that is causing this variance in OAL and plunk failure.

 

I'm not looking for benchrest precision just reliability.   Striker fired guns don't have much margin for error, especially when running whatever primers I am lucky enough to have on hand.  (TULA/CCI/WSP)

 

Thanks!

 

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3 hours ago, NETim said:

.....During the plunking, I'm finding a fairly wide variance in OAL, from 1.03" to 1.16"......

 

So, my question is, are others seeing this kind of variance in coated bullets? 

 

No.  Check your press. 

Something is wrong with this huge variance in OAL.

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I’m running 1.1” as well.  Mine seem to be be very consistent.   I had issues with my CZ Shadow 2, anything longer will not pass plunk test.   I found this out during a USPSA match.  I had a few issues at 1.130” with this gun.   My XDM, Glock 43x, and 986 worked fine.

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I'm not looking for benchrest precision just reliability.   Striker fired guns don't have much margin for error, especially when running whatever primers I am lucky enough to have on hand.  (TULA/CCI/WSP)
 
Thanks!
 


Wait a minute, you have Tula, CCI, and WSP primers on hand?

Lucky guy...


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Another factor with the plunk test is the loaded round case diameter.   Naturally, using mixed range brass more or less invites this issue.  Rounds that mike .380 at the case mouth are somewhat sticky in the Apex chamber.  Cases that mike .378 at GTG.  

 

I think I got spoiled by the generous chamber dimensions of the Glocks.  I'm thinking now the case diameter is a bigger factor than OAL.   

 

So, more rounds will be rejected into the practice pile if I do end running the M&P it appears.  

 

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I am having the same issue with 147g BBI bullets on a DIllon 750 with  Lee die set.  I don't believe its the bullet I think is has to do with the Lee seating die and using a flat nose bullet.   I posted about this in a couple of other threads looking for direction so please post what you end up finding.

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Just now, ML123 said:

I am having the same issue with 147g BBI bullets on a DIllon 750 with  Lee die set.  I don't believe its the bullet I think is has to do with the Lee seating die and using a flat nose bullet.   I posted about this in a couple of other threads looking for direction so please post what you end up finding.

I am thinking the RN bullet seating stem in the Dillon seating die may not match well with the bullet profile.  Just a guess.  I can measure a sample of bullets and I do see some variance in length.   Not a lot but some.   I seriously doubt the bullets all come from the same mold.  

 

My 650 is relatively young and is in good shape.   The dies are clean.  All I've ever loaded on this press has been coated bullets, so it stays pretty clean.  

 

Good luck!  

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1 hour ago, NETim said:

I am thinking the RN bullet seating stem in the Dillon seating die may not match well with the bullet profile.  Just a guess.  I can measure a sample of bullets and I do see some variance in length.   Not a lot but some.   I seriously doubt the bullets all come from the same mold.  

 

My 650 is relatively young and is in good shape.   The dies are clean.  All I've ever loaded on this press has been coated bullets, so it stays pretty clean.  

 

Good luck!  

I would have to suggest you strongly consider one of the Micrometer Seating Dies such as the Redding Pro Micrometer.  If you experience a very slight change in COAL for a particular bullet, simply adjust the Micrometer however many thousands of an inch needed!  Much easier that trying to accomplish with the standard threaded seating die.

 

Hope this helps:

https://forums.brianenos.com/topic/288207-lots-of-gauge-failures-with-redding-comp-seating-die-and-blue-bullets-147-rn/

 

🤔

 

 

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NETim,

I have posted about the very same problem, different guns but same problem. Big variation COAL and high reject rate with my EGW cartridge checker. I do not have a definitive answer, I do have some clues. The Redding Micro seater, which is wonderful on some bullet profiles, gut only some. I have had zero luck with this die and coated bullets. Variation in bullet diameter is a factor, the larger the diameter the closer the bullet is to the lands. I think part of the problem is also mold variation, how many molds are used to make a batch, probably 8, this a big chance for variation. I also think the coatings vary a lot, I can see it but have not devised a simple way to measure it, I am trying to use an R8 collet for tests. Revolvers eat all of this stuff and never even burp. At least one of my buddies guns, all pistols and 9mm, will find something to bitch about.

I don't know a way they can apply these coating with the methods in use and keep them accurate, some thicker, some thin, some thick on one side, I can see this but have not measured it yet. Set the COAL so you have a margin of safety and go for it. If someone knows for sure, please holler up. Thanks 

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9mm can be a finicky beast with oal and crimp. I never new how much until I got a Faxon G34 barrel. Nothing would fit I was going nuts. Anyway here’s what I did. Take a factory round measure the crimp. All the ones I measured were .375. Pull one. Set up your machine to have a long oal, but crimp to .375. You now know that crimp won’t be a factor. Start plunking your round and shortening till it plunks, and falls out. Subtract about .015 and that’s your oal for that bullet in that barrel. Now you can work on enlarging your crimp to around .378-.379 or if you chamber allows to .380. With a Glock gen3 barrel, I could load out to way past SAMMI specs, but with all the guns running minimum spec chambers, and everyone wanting to shoot coated bullets with wide profiles your going to have to load short. 

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1 hour ago, DryHeat said:

NETim,

I have posted about the very same problem, different guns but same problem. Big variation COAL and high reject rate with my EGW cartridge checker. I do not have a definitive answer, I do have some clues. The Redding Micro seater, which is wonderful on some bullet profiles, gut only some. I have had zero luck with this die and coated bullets. Variation in bullet diameter is a factor, the larger the diameter the closer the bullet is to the lands. I think part of the problem is also mold variation, how many molds are used to make a batch, probably 8, this a big chance for variation. I also think the coatings vary a lot, I can see it but have not devised a simple way to measure it, I am trying to use an R8 collet for tests. Revolvers eat all of this stuff and never even burp. At least one of my buddies guns, all pistols and 9mm, will find something to bitch about.

I don't know a way they can apply these coating with the methods in use and keep them accurate, some thicker, some thin, some thick on one side, I can see this but have not measured it yet. Set the COAL so you have a margin of safety and go for it. If someone knows for sure, please holler up. Thanks 

Thank you for the feedback.   I've only encountered this issue because of the tight chambered Apex barrel I have on my M&P.   I say "tight" because from what I gather from SAAMI chamber dimensions, case mouth diameter of a loaded 9mm round is spec'ed at 0.380".  My reloads that measure 0.380" with my Mitutoyo calipers don't want to spin when I plunk them in the Apex.  My Hundo gauge will only sometimes complain about these rounds and I thought it was tight!   My Dillon case gauge is happy with almost anything.  

 

I'm not getting many that fail in this manner though.   I haven't done any detective work to see if the problem is encountered with any headstamp more than others yet.   I have a hunch that will be a factor.   I have read on other forums that 9mm OAL issues are fairly common and quite often the finger is pointed at mixed brass.  

 

I am hoping that I can simply rely on the Hundo for QA at some point in time.  It's a great tool and a real timesaver. 

 

But I have backed off to 1.1" OAL as that seems to be a happy medium.   The promiscuous Glocks won't care regardless.  :)

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15 minutes ago, rooster said:

9mm can be a finicky beast with oal and crimp. I never new how much until I got a Faxon G34 barrel. Nothing would fit I was going nuts. Anyway here’s what I did. Take a factory round measure the crimp. All the ones I measured were .375. Pull one. Set up your machine to have a long oal, but crimp to .375. You now know that crimp won’t be a factor. Start plunking your round and shortening till it plunks, and falls out. Subtract about .015 and that’s your oal for that bullet in that barrel. Now you can work on enlarging your crimp to around .378-.379 or if you chamber allows to .380. With a Glock gen3 barrel, I could load out to way past SAMMI specs, but with all the guns running minimum spec chambers, and everyone wanting to shoot coated bullets with wide profiles your going to have to load short. 

Okay!  Thanks!   My Glock OEM barrels have spoiled me badly.   Now I have to refine my technique and tighten my specs if I want to run the Apex as issued.  I'll give your tip a shot.  

 

Thanks!!

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Measuring a VERY small sample of my "Failure to plunk" rounds (20 total), I find no one particular dimension as the cause for failure.  I measured OAL, case mouth dia., case length and max case diameter.   Nothing stood out.   

 

However, 7 of the failed cases were CBC.   4 were FC and rest were 2 or less.   The major brands like Win or RP were 2 and 1 respectively.  

 

Upon closer inspection all of the failed cases were bulged or had the "swayback" in the case behind the bullet.  

 

So it appears to me that CBC brass is more prone to this bulge thing.   Some cases just want to develop a bulge or irregularity during the loading process.   

 

I was barking up the wrong tree with the OAL thing it appears.   

 

 

 

 

 

 

 

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CBC is junk, toss it. You found the same thing I did. I had rounds that would not plunk, and when I measured some of the dimensions they were the same as rounds that did plunk. Only thing I could come up with is that if a round is fired in an unsupported chamber then at the 6 o’clock position there is bulge and that’s what might be causing the problem. 

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