300blk Lee Die vs Hornady case Gauge

Melnic · Jun 15, 2020

OK,
So I had some failure to battery some loads and found my 300blk Lee die had not been set properly. Went back and resized about 300 cases. Per the advice of an MDS member, I got a case gauge. I in slapped a Hornady Case Gauge into my Amazon cart and headed out of town for a long weekend. Got it in and tried it and found a bunch of my reloads prior to resizing would not fit. This explained alot. However, I tried about 50 that were sized after resetting the die and found 10 that would not fit. Many of them fit snug. Factory rounds dropped in easily. I can't run the cases into the lee die any more than where its set so wondering if anyone else has seen this. I did take my empty cases and they do get into battery into my Barrel unlike some of the cases I did not resize from before.

outrider58 · Jun 15, 2020

What brand brass are you using? All the same manufacture?

Melnic · Jun 15, 2020

outrider58 said:
What brand brass are you using? All the same manufacture?

mixed bag of cases that I had resized.
Of the 10 rejects , 7 are LC (cut down I guess), 2 say SIG and 1 says RP

GuitarmanNick · Jun 15, 2020

Perhaps the cases need to be trimmed a little.

Before reloading, all of my brass gets run through the trimmer.

The Lee sizing die sizes the entire case when set up correctly. Perhaps the cases are hanging up on the rim if there are any imperfections. The only other times I have experienced rounds not dropping into the gauge as they should, there was a problem with the round like a split neck or a crooked bullet. Both of those are quite easy to spot so likely not your issue.

If you do find damaging marks on the case rims, you may want to examine the extractor in your rifle. Have had to remove some burrs in the past, mainly on surplus pistols to save my brass from destruction.

Melnic · Jun 15, 2020

I verified the case lengths are within spec.
I can even see the gap from the other side of the gauge.

outrider58 · Jun 15, 2020

Hmmm...
Not sure what the problem could be. Usually, when a round I have reloaded fails a case gauge, it is as GuitarmanNick eluded to, a damaged case rim. I can usually fix the problem with a small file.
But ten out of 50? That's either some bad luck or there's something else at play here. I'm scratching my head...

Melnic · Jun 15, 2020

I inspected another 100 or so and still getting about 10-20% failing the gauge.
I inserted them backwards and all of them, the rim will go in just fine. I'm just setting them aside for now.

mtlcafan79 · Jun 15, 2020

I have one of the Sheridan slotted case gauges for 300 blackout. https://sheridanengineering.com/product/300-blk-ammunition-gauge/

It makes it easy to see where the round is failing. It allows a visual check of possible issues with the bullet into the rifling (helpful for really long subsonic rounds), case mouth, case neck, or an overall sizing issue. I set my sizing dies using that as a guide and they chamber in everything. You can borrow it if all else fails.

Muleskinner · Jun 16, 2020

I had the same issue. My cases would fit perfectly in the case gauge but after I seated the bullet about 50% wouldn't. I bought a case expending die that opens up the neck to allow the bullet to seat without putting downward stress on the web of the case. The downward stress was actually compressing the case and causing a bulge in the web right about the extraction groove

outrider58 · Jun 16, 2020

mtlcafan79 said:
I have one of the Sheridan slotted case gauges for 300 blackout. https://sheridanengineering.com/product/300-blk-ammunition-gauge/

It makes it easy to see where the round is failing. It allows a visual check of possible issues with the bullet into the rifling (helpful for really long subsonic rounds), case mouth, case neck, or an overall sizing issue. I set my sizing dies using that as a guide and they chamber in everything. You can borrow it if all else fails.

Same here. I recommend them for gauging for all necked cartridges.

outrider58 · Jun 16, 2020

OP, are these coated bullets you are loading? If they are, are you sizing them? If you aren't, you probably should consider doing so. I assume you're flaring your cases in the loading process.

https://www.midwayusa.com/product/101019973

Melnic · Jun 16, 2020

outrider58 said:
OP, are these coated bullets you are loading? If they are, are you sizing them? If you aren't, you probably should consider doing so. I assume you're flaring your cases in the loading process.

https://www.midwayusa.com/product/101019973

I'm tossing the empty cases into the Hornady gauge right after sizing so I could check my sizing process. Yes, I have been working up Powder coated Cast 300BLK bullets and Yes, I'm using a gifted M die to flair the mouth.
Yes, I am running the bullets gas checked through a 309 Sizing die.
My Lee 311-160 PC gas checked bullets w/ H110 have been shooting well out of my 16" barrel. I saved a few that did not go into full battery and plopped those into my Hornady case gauge and those failed. I did not have many left so having the case gauge told me what was going wrong.

outrider58 said:
Same here. I recommend them for gauging for all necked cartridges.

Yea, I remember you recommending this. I just got lazy/cheap and Amazon'd the Hornady. If I had this gauge, the mystery would have been solved

At least I did not load up all 600 cases I had vibed, wet tumbled, trimmed sized and flared already. I'm about half way done with resizing and flaring them again. Adding the step of the case gauge after sizing.

Doco Overboard · Jun 16, 2020

Quick Question (s), Are you gauging your cases before or after you expand the mouth? Will a fired case from your rifle fit in the gauge? Will a resized case before being mouth expanded fit your chamber and then not conversely.

What is the difference between the length from between the datum of the cartridge shoulder and head of the case from both an unfired and then fired case fired from the chamber of your rifle?

This is where I think your problem could be stemming from.
Because the datum is an angle, the manufacturing tolerances from the gauge, to the actual chamber down to to the tolerances of the die are close but not close enough to ensure interchangeability between all the components and an errant case fired from another rifle formed to a different chamber.

Maybe the die is just slightly ground differently. Or, it could be a slight problem with the shell holder.
Stick a .001 metal shim under the shell holder on one or more sides to see how the problem cases react when the die is set up for cases that chamber with out a problem.

The shoulder on that cartridge is real short which could be problematic. its only .003 tall according to the drawing.The HS measurement is somewhere in the middle of that number on an angle. Thats a lot of conformity for mass produced gauges, dies and actual rifle chamber measurements.

Use a pistol case or something like a sleeve that just slips over the mouth of the cartridge but not over the shoulder, zero some decent calipers to see what your fired brass is doing.

Maybe something will pop up along the way to catch the problem or lead to a cause you can tell for sure.

outrider58 · Jun 16, 2020

Doco Overboard said:
Quick Question (s), Are you gauging your cases before or after you expand the mouth? Will a fired case from your rifle fit in the gauge? Will a resized case before being mouth expanded fit your chamber and then not conversely.

What is the difference between the length from between the datum of the cartridge shoulder and head of the case from both an unfired and then fired case fired from the chamber of your rifle?

This is where I think your problem could be stemming from.
Because the datum is an angle, the manufacturing tolerances from the gauge, to the actual chamber down to to the tolerances of the die are close but not close enough to ensure interchangeability between all the components and an errant case fired from another rifle formed to a different chamber.

Maybe the die is just slightly ground differently. Or, it could be a slight problem with the shell holder.
Stick a .001 metal shim under the shell holder on one or more sides to see how the problem cases react when the die is set up for cases that chamber with out a problem.

The shoulder on that cartridge is real short which could be problematic. its only .003 tall according to the drawing.The HS measurement is somewhere in the middle of that number on an angle. Thats a lot of conformity for mass produced gauges, dies and actual rifle chamber measurements.

Use a pistol case or something like a sleeve that just slips over the mouth of the cartridge but not over the shoulder, zero some decent calipers to see what your fired brass is doing.

Maybe something will pop up along the way to catch the problem or lead to a cause you can tell for sure.

Oh, this guy is good...

:thumbsup:

Melnic · Jun 16, 2020

Doco,

Are you gauging your cases before or after you expand the mouth?

I am using the Hornady Case Gauge after ONLY doing the full length sizing die. And before the flairing. With the flairing they ALL will fail and I have verified that.

Will a fired case from your rifle fit in the gauge?

I took 10 samples of fired cases from my Rainer 10.5" barrel and NONE will pass the case gauge which I expected.

Will a resized case before being mouth expanded fit your chamber and then not conversely.

About 80% do and about 10% don't

The datum between the fired and sized cases are so close, I can't measure the difference.
The diameter of the neck of the case is easy to measure between a fired and sized case though.

I put a 9mm case on the top and measured the difference between a fired and size case and it was about .005-.008 on average.
I put a .010" paper shim (will compress I guess to no less than .005") and resized a case that is failing the gauge and it still fails the gauge.

I took a sample of 15 of the failed cases (sized and NOT flared) and ran them into my AR and they all chambered.

SOME (about 1/3-1/2) of the cases I failed, could be pushed with my thumb into the chamber and then pass. When I tested them, if I dropped them in and if they did not drop in without pushing, I failed them.

I have noticed this, if I take a sized case and insert it BACKWARDS (rim first) in the case gauge, the cases that fail won't go as far as the ones that pass. I feel the interference in the gauge is in the area that the die can't size, the last .150-.250" does not seem to be touched by the die.

John from MD · Jun 16, 2020

Pull the bullet with a collet puller and see if the case fits in the gauge. If it does, your issue is with neck diameter. If it doesn't, blacken the neck and shoulder area with a match or butane lighter. Run it into the size die and see if the carbon is rubbed off the die AND the shoulder. If it isn't, you have a die that is out of spec. I have found a couple of these over the years. I just chuck it in the lathe and grind off a few thou and it usually does the trick. You can do the same thing on a grinding wheel as it is not that critical.

Melnic · Jun 16, 2020

John from MD said:
Pull the bullet with a collet puller and see if the case fits in the gauge. If it does, your issue is with neck diameter. If it doesn't, blacken the neck and shoulder area with a match or butane lighter. Run it into the size die and see if the carbon is rubbed off the die AND the shoulder. If it isn't, you have a die that is out of spec. I have found a couple of these over the years. I just chuck it in the lathe and grind off a few thou and it usually does the trick. You can do the same thing on a grinding wheel as it is not that critical.

Pull what bullet? the cases that are failing are failing right after sizing. No bullet yet.

outrider58 · Jun 17, 2020

At this point, I would strongly recommend you get one of these...

https://ballistictools.com/store/sheridan-engineering-300-blk-slotted-gauge

John from MD · Jun 17, 2020

Melnic said:
Pull what bullet? the cases that are failing are failing right after sizing. No bullet yet.

Sorry, missed that. Then your problem is a die that is not setting the the shoulder back enough. This can be intermittent depending on the brass thickness and brass hardness.

ironpony · Jun 17, 2020

Would Dykem be useful here?

300blk Lee Die vs Hornady case Gauge

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