Hornady 300 Win Mag Case Gauge

UncleLoodis · May 26, 2020, 10:02 PM

Greetings all.

I decided that I am going to start loading 300 Win Mag, so I bought all the necessary items--dies, powder, primers, bullets, etc. I bought a Hornady case gauge (see photo). I noticed that it is different from my other case gauges in the fact that all of my other gauges have a notch at each end, which indicate if the case falls into acceptable length parameters. This new case gauge only has the notch at the base end of the gauge, not the mouth end. What am I missing here? Is 300 Win Mag different from other cartridges? Did Hornady forget to machine the mouth end of the gauge?

Thanks in advance for the replies.

Best regards,

Uncle Loodis

Shadow9mm · May 26, 2020, 10:22 PM

Quote:

Originally Posted by UncleLoodis

Greetings all.

I decided that I am going to start loading 300 Win Mag, so I bought all the necessary items--dies, powder, primers, bullets, etc. I bought a Hornady case gauge (see photo). I noticed that it is different from my other case gauges in the fact that all of my other gauges have a notch at each end, which indicate if the case falls into acceptable length parameters. This new case gauge only has the notch at the base end of the gauge, not the mouth end. What am I missing here? Is 300 Win Mag different from other cartridges? Did Hornady forget to machine the mouth end of the gauge?

Thanks in advance for the replies.

Best regards,

Uncle Loodis

that looks off to me... the case mouth should be right at the end of the gauge.

UncleLoodis · May 26, 2020, 10:24 PM

That's exactly what I thought. The case in the gauge is virgin brass, and looks about right, when compared to factory ammo. And the end of the case gauge looks...unfinished to me.

Bart B. · May 27, 2020, 07:52 AM

What does the instructions say? They are not yet available on Hornady's web site for me to read. Does the picture show the case mouth way back from the gauge front? Something ain't right.

What is the case head to mouth length? Should be about 2.61 inch. If the gauge is actually a 300 Weatherby Mag one, a 300 Winchester Magnum case mouth would be that far back from the gauge front as it's about 2 tenths inch shorter than the Weatherby that's about 2.81 inch long. How long is your gauge?

As the cases are belted and new ones don't headspace on their shoulder, the step on the base probably indicates the minimum and maximum headspace on the gauge base. The front is probably the maximum for case belt to case mouth. Doesn't matter if the case mouth is back several thousandths from the gauge front; even 1/16th inch is ok.

I don't think any case ready to fire has to have its headspace reference to mouth a fixed dimension. Mine have .010 inch or more spread with maximums several thousandths less than chamber length.

hammie · May 27, 2020, 09:00 AM

As usual, "Bart B." is right. Because the .300 win mag is belted, your gauge is only measuring the case body and case head space, not overall length. All case gauges are not the same. As you have observed, my Wilson bottle neck rimless rifle gauges, measure headspace, case body and overall length, while my straight walled, rimmed pistol gauges only measure overall length, not case body.

While it's nice to have a case gauge, I've not found them that necessary for belted cases, given my reloading technique. The belted case acts like a rimmed cartridge with a thick rim. I try to adjust my sizing die so that the reloaded cartridge continues to headspace on the newly fireformed shoulder... and not the belt.

I don't know about the hornady gauges, but the specifications for the hornady gauge said steel, not stainless steel. My Wilson gauges are steel and WILL rust, unless I spray them with Barricade or some other rust preventative, after use.

UncleLoodis · May 27, 2020, 11:28 AM

Gentlemen,

There were no instructions in the packaging...just a tagboard insert in a clear plastic case that says (on the outside) what the product is.

Cases are exactly 2.610"; I measured them with my calipers. Case mouth from end of gauge isn't only a 1/16"...it's .294" (also measured with calipers)

This morning I spoke with Matt at Hornady tech support. He said that their case gauges are simple go/no-go gauges. He said the base is notched for minimum and maximum SAMMI specs. Process should be to see if base of case meets minimum/maximum specs (if it fits somewhere in between high/low point on notch), and then to measure overall case length with calipers, and trim mouth end of case as needed to meet case length. I suppose I'll do as he suggests.

Thanks for the replies!

U.L.

Bart B. · May 27, 2020, 04:11 PM

Virtually all belted cases based on the original H&H headspace standard of .220" -.008" never change what they started with when new across a few dozen reloads. Nobody's ever changed ones dimension unless they remove brass from the case head.

Therefore, why does Hornady sell them?

stagpanther · May 27, 2020, 05:12 PM

Quote:

Therefore, why does Hornady sell them?

Maybe because of the unusually short neck length (relative to the projectile diameter)?

Bart B. · May 27, 2020, 05:27 PM

Therefore, why does Hornady sell them?

Quote:

Maybe because of the unusually short neck length (relative to the projectile diameter)?

I doubt it's related to neck length relative to anything.

I wonder where the guage shoulder is relative to the stepped base. .

UncleLoodis · May 27, 2020, 10:14 PM

Bart: Quote: "I wonder where the guage shoulder is relative to the stepped base"

If I understand the question--if I use my calipers to measure from the base of the gauge (in the notch) to where the taper begins inside the gauge, it's exactly 2.200". Or I could just say, 2.2".

stagpanther · May 27, 2020, 11:09 PM

Quote:

I doubt it's related to neck length relative to anything.

In 300 win mag cases that have been used repeatedly--especially in warmer loads, neck flow/elongation is a possible indicator of the case being "overworked," no?

Bart B. · May 28, 2020, 11:01 AM

Quote:

Originally Posted by UncleLoodis

Bart: Quote: "I wonder where the guage shoulder is relative to the stepped base"

If I understand the question--if I use my calipers to measure from the base of the gauge (in the notch) to where the taper begins inside the gauge, it's exactly 2.200". Or I could just say, 2.2".

Your measuring was good. Check out page 105 in the following:

https://saami.org/wp-content/uploads...sting-Copy.pdf

Bart B. · May 28, 2020, 11:07 AM

Quote:

Originally Posted by stagpanther

In 300 win mag cases that have been used repeatedly--especially in warmer loads, neck flow/elongation is a possible indicator of the case being "overworked," no?

All case necks shorten when fired.

They get longer when full length resized. Typically about .001" more every time if shoulder is set back about .002" after resizing. After growing about .010" trim them back.

All very normal and safe as long as case body at the pressure ring doesn't thin too much. I've got 15 to 20 reloads on belted magnum cases.

UncleLoodis · May 28, 2020, 10:07 PM

Bart, thank you for the tech info. I guess my measurement was only off by four thousandths, relatively close for a quick-n-dirty measurement.

I'll probably load some this weekend...just too much to do with work and my lady during the week. I like to reload when it's nice and quiet, no distractions.

As always, thanks to everyone for chiming in. Thefiringline is the best--because of its members!

U.L.

**Unclenick** · May 31, 2020, 06:10 PM

UncleLoodis,

That Hornady headspace gauge determines if your case head and belt will fit within the SAAMI chamber headspace intended to accommodate it and do so without going too far in.

The reason the neck measurement is not incorporated into that gauge is the measurement would not be as meaningfull as it is with rimless bottleneck cases. The length of a neck is measured from the shoulder, and without the case shoulder seating against a known registration point, the neck's length can't be determined by protrusion from the front end of the gauge. Only a cartridge that headspaces on the shoulder can have its neck and body length checked simultaneously in a single gauge. Both rimmed and belted cases would add their rim and head-to-belt length variation, respectively, into an attempt at that determination. For this reason, trimming of belted and rimmed bottleneck cases is best done with a trimmer that uses shoulder registration rather than COL. That way the amount of neck pushed into the chamber when the shoulder stretches or blows out forward is kept consistent.

UncleLoodis · May 31, 2020, 07:03 PM

Unclenick,

I guess I'm still confused. I thought that when the case goes into the gauge, what stops the case from going in further is that the shoulder of the case stops against the bevel portion of the inside of the case gauge. Of course this is different from my .357 mag case gauge, where the rim of the case stops the case from going in further. Are you saying the belt of the case is what is stopping the case from going further into the gauge? It almost sounds like it's the belt that determines headspace.

On another issue (this project is taking much more time than expected), Powder Valley sent me H4350 (I ordered IMR4350), and have been going through the thread regarding the differences between the two powders. I have done a great amount of business with them, and this is the first time I've ever gotten something I did not order. I'm not sure if I owe Powder Valley money or they owe me money.

I also bought a pound of H4831SC (from a local store) and although some forums are saying to use the same charge weight as H4831, others say it's different.

U.L.

Shadow9mm · May 31, 2020, 10:03 PM

300 is a belted case. it spaces off the belt at the base of the case rather than the shoulder.

UncleLoodis · May 31, 2020, 10:44 PM

Shadow9mm,

See there. I learn something new every day.

I have been reloading pistol for years and years, but am kind of green when it comes to rifle cartridges. I thought that the belt was just reinforcement. What you say clears things up quite a bit.

Thanks,

U.L.

May 27, 2020, 07:52 AM	#4
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	What does the instructions say? They are not yet available on Hornady's web site for me to read. Does the picture show the case mouth way back from the gauge front? Something ain't right. What is the case head to mouth length? Should be about 2.61 inch. If the gauge is actually a 300 Weatherby Mag one, a 300 Winchester Magnum case mouth would be that far back from the gauge front as it's about 2 tenths inch shorter than the Weatherby that's about 2.81 inch long. How long is your gauge? As the cases are belted and new ones don't headspace on their shoulder, the step on the base probably indicates the minimum and maximum headspace on the gauge base. The front is probably the maximum for case belt to case mouth. Doesn't matter if the case mouth is back several thousandths from the gauge front; even 1/16th inch is ok. I don't think any case ready to fire has to have its headspace reference to mouth a fixed dimension. Mine have .010 inch or more spread with maximums several thousandths less than chamber length. Last edited by Bart B.; May 27, 2020 at 09:27 AM.

May 31, 2020, 06:10 PM	#15
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	UncleLoodis, That Hornady headspace gauge determines if your case head and belt will fit within the SAAMI chamber headspace intended to accommodate it and do so without going too far in. The reason the neck measurement is not incorporated into that gauge is the measurement would not be as meaningfull as it is with rimless bottleneck cases. The length of a neck is measured from the shoulder, and without the case shoulder seating against a known registration point, the neck's length can't be determined by protrusion from the front end of the gauge. Only a cartridge that headspaces on the shoulder can have its neck and body length checked simultaneously in a single gauge. Both rimmed and belted cases would add their rim and head-to-belt length variation, respectively, into an attempt at that determination. For this reason, trimming of belted and rimmed bottleneck cases is best done with a trimmer that uses shoulder registration rather than COL. That way the amount of neck pushed into the chamber when the shoulder stretches or blows out forward is kept consistent. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

May 26, 2020, 10:24 PM	#3
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	That's exactly what I thought. The case in the gauge is virgin brass, and looks about right, when compared to factory ammo. And the end of the case gauge looks...unfinished to me.

May 27, 2020, 09:00 AM	#5
hammie Senior Member Join Date: March 18, 2009 Location: Temple, TX Posts: 959	As usual, "Bart B." is right. Because the .300 win mag is belted, your gauge is only measuring the case body and case head space, not overall length. All case gauges are not the same. As you have observed, my Wilson bottle neck rimless rifle gauges, measure headspace, case body and overall length, while my straight walled, rimmed pistol gauges only measure overall length, not case body. While it's nice to have a case gauge, I've not found them that necessary for belted cases, given my reloading technique. The belted case acts like a rimmed cartridge with a thick rim. I try to adjust my sizing die so that the reloaded cartridge continues to headspace on the newly fireformed shoulder... and not the belt. I don't know about the hornady gauges, but the specifications for the hornady gauge said steel, not stainless steel. My Wilson gauges are steel and WILL rust, unless I spray them with Barricade or some other rust preventative, after use.

May 27, 2020, 11:28 AM	#6
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	Gentlemen, There were no instructions in the packaging...just a tagboard insert in a clear plastic case that says (on the outside) what the product is. Cases are exactly 2.610"; I measured them with my calipers. Case mouth from end of gauge isn't only a 1/16"...it's .294" (also measured with calipers) This morning I spoke with Matt at Hornady tech support. He said that their case gauges are simple go/no-go gauges. He said the base is notched for minimum and maximum SAMMI specs. Process should be to see if base of case meets minimum/maximum specs (if it fits somewhere in between high/low point on notch), and then to measure overall case length with calipers, and trim mouth end of case as needed to meet case length. I suppose I'll do as he suggests. Thanks for the replies! U.L.

May 27, 2020, 04:11 PM	#7
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Virtually all belted cases based on the original H&H headspace standard of .220" -.008" never change what they started with when new across a few dozen reloads. Nobody's ever changed ones dimension unless they remove brass from the case head. Therefore, why does Hornady sell them?

May 27, 2020, 10:14 PM	#10
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	Bart: Quote: "I wonder where the guage shoulder is relative to the stepped base" If I understand the question--if I use my calipers to measure from the base of the gauge (in the notch) to where the taper begins inside the gauge, it's exactly 2.200". Or I could just say, 2.2".

May 28, 2020, 10:07 PM	#14
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	Bart, thank you for the tech info. I guess my measurement was only off by four thousandths, relatively close for a quick-n-dirty measurement. I'll probably load some this weekend...just too much to do with work and my lady during the week. I like to reload when it's nice and quiet, no distractions. As always, thanks to everyone for chiming in. Thefiringline is the best--because of its members! U.L.

May 31, 2020, 07:03 PM	#16
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	Unclenick, I guess I'm still confused. I thought that when the case goes into the gauge, what stops the case from going in further is that the shoulder of the case stops against the bevel portion of the inside of the case gauge. Of course this is different from my .357 mag case gauge, where the rim of the case stops the case from going in further. Are you saying the belt of the case is what is stopping the case from going further into the gauge? It almost sounds like it's the belt that determines headspace. On another issue (this project is taking much more time than expected), Powder Valley sent me H4350 (I ordered IMR4350), and have been going through the thread regarding the differences between the two powders. I have done a great amount of business with them, and this is the first time I've ever gotten something I did not order. I'm not sure if I owe Powder Valley money or they owe me money. I also bought a pound of H4831SC (from a local store) and although some forums are saying to use the same charge weight as H4831, others say it's different. U.L.

May 31, 2020, 10:03 PM	#17
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,974	300 is a belted case. it spaces off the belt at the base of the case rather than the shoulder.

May 31, 2020, 10:44 PM	#18
UncleLoodis Senior Member Join Date: June 28, 2011 Location: Oregon Posts: 160	Shadow9mm, See there. I learn something new every day. I have been reloading pistol for years and years, but am kind of green when it comes to rifle cartridges. I thought that the belt was just reinforcement. What you say clears things up quite a bit. Thanks, U.L.