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Acceptable OAL variance


GIO

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Hi All,

 

I am loading 147g Bayou on top of 3.2 TG, mixed range Brass, using a Dillon 550. This ammo will be used in a G17.

 

I was shooting for a OAL of 1.125 and I am ending up with loads that measure between 1.121 - 1.127 with most being between 1.122 - 1.126. I also use a Dillon case gauge and I keep the barrel handy for a "plunk" test. The rounds that push the 1.127 and anything above that don't seem to fully seat in the Barrel.

 

Questions - is this range normal? I have my bench bolted to the wall, all Dies tight, etc. Also, does this OAL seem right for a G17?

 

Thank you in advance!

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I wouldn't be super worried about a 0.004 variance with a cast bullet. Even my precision rifle rounds vary 0.002-0.003 in. If they varied 0.020 I would worry about it. If the nominal length allows for the 1.127 inch to touch the lands and fail the plunk test. I might back the nominal length  3-4 thou. 

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I too wouldn't worry about .004 but as suggested if 1.127 isn't passing (and I'm surprised because Glocks are very generous) than move the target down to 1.12.

 

I don't load that bullet but maybe someone else who does can comment on the shape/ogive because 1.127 seems short for a Glock.

Edited by 4n2t0
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Thank you. Yes, I thought the same regarding the depth seeming short but it seems to be the case with my G17. If I give the round a push to make it seat I have to pry it out.

Must be the shape of the bullet. Any G17 owners loading BB 147's please chime in. 

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4 hours ago, GIO said:

Thank you. Yes, I thought the same regarding the depth seeming short but it seems to be the case with my G17. If I give the round a push to make it seat I have to pry it out.

Must be the shape of the bullet. Any G17 owners loading BB 147's please chime in. 

 

Make sure you have sufficient crimp, as stated above. There should be absolutely zero outward flareto the mouth of the case remaining. Remove all trace of belling but crimp as little as possible: you can swage a lead or coated bullet to a smaller diameter with excessive crimp.

 

I pull a bullet and look for the smallest hint of a ring on it where the case mouth sat. Just barely visible and pretty much impossible to feel in the coating with your fingernail.

 

Then conduct a plunk and spin test will long ammo, and back it down until your dummies will just barely drop into the chamber and spin freely. If you’re right at that’s the 1.125-1.127” neighborhood? Ensure that your longest ammo is 1.120” and you should be good to go.

 

When discussing coated bullets, 147s tend to have wide, rounded shoulders and these catch in the rifling at a shorter OAL than some other bullets. It all depends on the profile of the round. The pointy 125gr offerings from Black Bullets will feed in a Glock well past 1.150” for example.

Edited by MemphisMechanic
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13 hours ago, GIO said:

If I give the round a push to make it seat I have to pry it out.

 

Take a black permanent marker and paint the bullet ogive and the top part of the case.  Do the plunk test with your barrel/chamber, and push down slightly while rotating the round.  Pull it out.  If you see the marker rubbed off the bullet ogive, then you need to load it shorter.  Drop the OAL by a couple thou and try again.  Repeat until the round spins freely with no scratches on the painted areas. 

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14 hours ago, 4n2t0 said:

I too wouldn't worry about .004 but as suggested if 1.127 isn't passing (and I'm surprised because Glocks are very generous) than move the target down to 1.12.

 

I don't load that bullet but maybe someone else who does can comment on the shape/ogive because 1.127 seems short for a Glock.

I load that bullet/TG with single headstamp brass. That amount of variation should not be a problem. Like 4n said,  that OAL seems quite short for a Glock. Glock can usually reach way out there and still chamber fine. I have had them at 1.142 without a problem in a Glock 17 barrel or even in a KKM barrel. Like others have said, crimp could be the culprit.

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4 minutes ago, rowdyb said:

I accept anything in the thousands place. So if I want an oal of 1.125" then for me anything from 1.120 to 1.129 is just fine.  Anything greater than 0.009 from my mean value i care about.

 

This.

 

And listen to LGH about the sharpie and plunk & spin. I should have gone into more detail - that’s the best way to check.

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Regarding the Crimp. I can just catch the edge of the case when I run my fingernail down the bullet. Should the crimp be flush (embedded) into the bullet/coating? 

Edited by GIO
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I load to 1.135".  My max OAL that'll run in my mags is 1.145".  However if during my random QA check I find a 1.140", I'll run it through seat and crimp again to get it to 1.135".  So I guess my tolerance is +0.005"

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1 hour ago, GIO said:

Regarding the Crimp. I can just catch the edge of the case when I run my fingernail down the bullet. Should the crimp be flush (embedded) into the bullet/coating? 

 

The crimp should not embed itself into the projectile. In 9mm it shouldn't even be called a crimp, lol, all you're doing is de-belling the case mouth. Generally speaking you'll want a measurement somewhere between .375 (heavy) - .379 (light) depending on what a pulled projectile looks like. You should see no more than a faint line when inspecting the pulled projectiles.

 

Way too much on the right, good on the left:

 

blazer_brass_factory_bullet_crimp_left_reloaded_crimp_right_200.jpg

 

Note: Coated and plated projectiles are more susceptible to the adverse affects of over-crimping when compared to FMJ or thick plated projectiles. Regardless, shoot for minimal crimp with 9mm.

Edited by 4n2t0
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1 hour ago, GIO said:

Regarding the Crimp. I can just catch the edge of the case when I run my fingernail down the bullet. Should the crimp be flush (embedded) into the bullet/coating? 

 

Think of it as a “flare removal die” and not crimping. You’re trying to return the case walls to being dead straight, not flared outward even slightly, and not crushed inward.

 

Edited by MemphisMechanic
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Gotcha! Ok, I pulled a few bullets and did a bunch of measuring.  The only common denominator i can find is any round that does not fully drop into my Dillon case gauge also won't fully drop and spin in the barrel. I found one 1.127 that cleared the gauge and the Barrel but for the most part any round under 1.122 is ok. looks like I have a crimp issue as well. see below.

I really appreciate the help guys.

IMG_0555.JPG

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I once had a problem with a few thousand purchased projectiles not being able to fit a short barrel due to the Ogive.

The mfr. sent me an article after I showed them the attached picture where the left bullet was the recommended OAL and the right one was what fit in the barrel.

This is a full 1/10th of an inch shorter and works just fine - although it started my quest for testing OAL's.

https://www.google.com/amp/amp.dailycaller.com/2013/03/05/battered-bullets-does-bullet-setback-matter/

These guys smashed bullets further into a case than any sane person would with no adverse effects - it eased my mind tremendously.5a132bfbb44f6_20170305_165403(Medium).thumb.jpg.11fb36263d156f9e535b5af5a0bb17ff.jpg

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Ok. I adjusted the crimp and pulled the bullets as i adjusted until it barely left a ring on the coating. Presto!! Seems like it was a crimp issue and not really OAL. Not sure if the excessive crimp was bulging the case or what exactly but I am hitting a steady 1.25-1.27 and 99% of the rounds are passing the Gauge and Clunk-Spin test.

I really appreciate the help and I had a great Bday (today) hiding in my reloading shed working on this.. Headed to the range for a little fun to wrap it up. Thanks again!

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1 hour ago, GIO said:

Ok. I adjusted the crimp and pulled the bullets as i adjusted until it barely left a ring on the coating. Presto!! Seems like it was a crimp issue and not really OAL. Not sure if the excessive crimp was bulging the case or what exactly but I am hitting a steady 1.25-1.27 and 99% of the rounds are passing the Gauge and Clunk-Spin test.

I really appreciate the help and I had a great Bday (today) hiding in my reloading shed working on this.. Headed to the range for a little fun to wrap it up. Thanks again!

 

I'm glad to hear you figured it out.

 

Cheers!

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16 hours ago, GIO said:

Seems like it was a crimp issue

Crimping issues are pretty common with reloading. I believe Lee says overcrimping is the most common, at least with handgun. It might take a while, but learning to accurately and reproducibly measure the crimp saves a lot of grief. Under a magnifying glass, I put half the thickness of the calipers on the mouth. Seem to work.

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I had similar issues when loading the same bullet. Getting the crimp right was a big part of it as most have said. I cant find my oal for that specific round but i want to say it was around 1.130. Loaded it for a glock22 with 9 conversion barrel. I also found that the lyman m expanding die helped a lot with consistency of seating those bullets as well. Using the lee expander i wouldnt be able to press the bullets as straight down as i wanted. With the 147 that youre using it was enough to cause the ogive to kiss the lands and not go to full battery especially at the longer range of your oal. It could also fail the chamber check as well. Switching to the m die pretty much eliminated that issue. I now use the lyman m for all my expansion needs. They are pretty much the same design as the daa powderfunnels (i recently switched to these since i got a bullet feeder and lost a stage) Excellent product that i would highly recommend.

Edited by CamboSoup22
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