Reloading Issues

[aknott1994]

I put together some data for IMR 3031 to test, but my cases will not chamber after sizing. Every dimension matches but case length from an unfired piece of new hornady brass that will chamber. Could 5 thousandths case length prevent a case from chambering? They are right at 1.490 and the factory is 1.485.

[alwie]

I put together some data for IMR 3031 to test, but my cases will not chamber after sizing. Every dimension matches but case length from an unfired piece of new hornady brass that will chamber. Could 5 thousandths case length prevent a case from chambering? They are right at 1.490 and the factory is 1.485.

What is your headspace measuring?

[grayfox]

Your shoulder length, what is it? compared to a hornady case.
the datum point should be 1.183-1.190. Refer to the Saami drawing.
My guess is that shoulder is too long, needs to be set back a bit more.
Where did this case come from.

[CZ527 Guy]

Sounds like your resizing process resized the neck, though the case was not advanced far enough in to the die. As a result of not fully resizing the case. The shoulder datum was not pushed back at all or adiquitly. There are a few options to measure case head datum to verify shoulder datum being in specification or not.

Most likely cause of this potential issue is improper set up of the die in your press.

[aknott1994]

The datum line appears to be 1.185, they are once fired hornady cases fired from my gun. I have tried the die at multiple distances as well as bottomed out. There is no way to push the case further into the die

[aknott1994]

I ran a couple cases through my 6.5 Grendel die and then necked them back down with no change in results as well. I did find out that the Hornady 105 bthp touch the lands at 2.250 using the Hornady tool. Could it be the dies that I am using? It's an ATI Omni gas gun and I am using the Lee Pacesetter die set. I use these dies for other cartridges but heard 6 ARC can be picky

[grayfox]

As on the 65grendel forum, Lee dies have a bad rep. Haven't heard of the OTI gun before, but 1.185 seems to be still too long (for whatever reason), maybe have a short chamber or something.

Do you have a friend with 6 Arc, maybe they could do a couple resizings for you to compare.

There is some company that has shell case holders of varying depth so you can use one a tad thicker to get some more setback, I forget what they're called. they come in a set.

One last thing, and this is just off the wall, but measure the depth of the face of your bolt. should be 0.136". Off the wall b/c if it were way off then the hornady's factory stuff shouldn't seat and fire. But some chambers of Grendel were made to mate up with a 0.125" bolt depth (ala 7.62x39 bolt), so they are cut deeper in the barrel chamber too. 0.136" face depth and chamber is the original but one company named it "grendel type II" b/c they made the 0.125" face depth dies/bolts.

[CZ527 Guy]

I ran a couple cases through my 6.5 Grendel die and then necked them back down with no change in results as well. I did find out that the Hornady 105 bthp touch the lands at 2.250 using the Hornady tool. Could it be the dies that I am using? It's an ATI Omni gas gun and I am using the Lee Pacesetter die set. I use these dies for other cartridges but heard 6 ARC can be picky

Where are you located? Sounding more like yes, your dies may be the issue. If you would like to mail me a fired case & a resized case Id measure the shoulder datum point on both to verify difference. 

Am I reading to much into this? Were these factory rounds that were fired in your rifle, then resized? Meaning factory ammo chambers fine? Have you tried chambering a resized case only that has not been reloaded?

[Dino11]

If you are using Hornady 105 BTHP you need to seat them to a max OAL of 2.200. Your bullet is hitting the lands. Hornady had this problem with the first couple of batches of the 105's, they revised the spec for them.

[aknott1994]

I ran a couple cases through my 6.5 Grendel die and then necked them back down with no change in results as well. I did find out that the Hornady 105 bthp touch the lands at 2.250 using the Hornady tool. Could it be the dies that I am using? It's an ATI Omni gas gun and I am using the Lee Pacesetter die set. I use these dies for other cartridges but heard 6 ARC can be picky

Where are you located? Sounding more like yes, your dies may be the issue. If you would like to mail me a fired case & a resized case Id measure the shoulder datum point on both to verify difference. 

Am I reading to much into this? Were these factory rounds that were fired in your rifle, then resized? Meaning factory ammo chambers fine? Have you tried chambering a resized case only that has not been reloaded?

Yes, these were factory rounds that were fired in my rifle, none of the 10 cases I tried would chamber but unfired factory rounds and brass will. I am going to order the RCBS die set tomorrow or next Friday to test some different dies

[CZ527 Guy]

My personal least favorite 6mm Arc sizing die on the market would be the lee dies

Next least favorite would be RCBS


My favorite 6mm Arc die set would be Whidden https://www.whiddengunworks.com/product/...s-optional

If I were to measure your brass head space datum, the tool below is what I would use.

https://www.whiddengunworks.com/product/case-gauge-3/

As sizing die goes the Mighty armory die is top notch IMHO. https://www.mightyarmory.com/collections...apping-die

[aknott1994]

I bought some new gauges today and my dies are re-sizing back to exactly 1.190 to the datum line and factory brass is measuring 1.183-1.184. At 1.190 my cases fit in the case checker just fine. I'm guessing my chaber is a little short and I need new dies that will bump it back a little further. While I was out I also picked up some CFE223 so I may or may not abandon the IMR 3031 and use that in my 5.56

[CZ527 Guy]

Where is the datum measuring on your fired Brass?

I would guess your chamber is just fine,
Your dies on the other hand seem to be limiting you from adiquitly setting the shoulder back. This could be the dies or the shell holder, Though I expect the die is the issue at hand.

If we trust your measurements are accurate & honestly I am just a bit - skeptical not knowing the measuring tools or your comfort level using them, then your dies are resizing your brass at least .005" long. for an AR rifle IMHO. Zero clearance is unacceptable in any rifle IMHO. Personally in an AR I think Id be targeting about .004" to .005" clearance for your headspace.

So Id be hoping for .005 difference between your fired brass & the resized brass. of course you want the resized brass to be shorter.

https://6mmarc.com/showthread.php?tid=195

[CZ527 Guy]

In my honest opinion Lee should make this right. If not a guy could have a machinist remove .oo45" from the face of the die to allow the shoulder to be pushed back further. Not sure if the redding shell holder set would benefit your situation or not.

https://www.midwayusa.com/product/1012465352?pid=344665

[aknott1994]

Where is the datum measuring on your fired Brass?

I would guess your chamber is just fine,
Your dies on the other hand seem to be limiting you from adiquitly setting the shoulder back. This could be the dies or the shell holder, Though I expect the die is the issue at hand.

If we trust your measurements are accurate & honestly I am just a bit - skeptical not knowing the measuring tools or your comfort level using them, then your dies are resizing your brass at least .005" long. for an AR rifle IMHO. Zero clearance is unacceptable in any rifle IMHO. Personally in an AR I think Id be targeting about .004" to .005" clearance for your headspace.

So Id be hoping for .005 difference between your fired brass & the resized brass. of course you want the resized brass to be shorter.

https://6mmarc.com/showthread.php?tid=195

I am using the Hornady Headspace comparator tool and case gauge. I modified my shell holder a bit and can get the headspace/datum measurement down to 1.181 now. Anything longer than 1.184 at the datum line will not chamber but I have them all sized at 1.183 now. The necks are a bit long but I need to trim them all down anyways as most of them are 1.491-1.493. For testing seating depth I also use the lock n load modified case tool. I reload for 223, 6.5G, 300BLK. 45-70, 450BM, and 350 Legend as of right now. I've had the ARC for a little over a year and have been going through factory ammo and am just getting started with it as far as reloading

[CZ527 Guy]

So again, mind if I ask about the datum length of a fired cartridge?

[aknott1994]

So again, mind if I ask about the datum length of a fired cartridge?

I didn't measure any before the first attempt at sizing, I will measure a few after I fire some

[GRH]

Where is the datum measuring on your fired Brass?

I would guess your chamber is just fine,
Your dies on the other hand seem to be limiting you from adiquitly setting the shoulder back. This could be the dies or the shell holder, Though I expect the die is the issue at hand.

If we trust your measurements are accurate & honestly I am just a bit - skeptical not knowing the measuring tools or your comfort level using them, then your dies are resizing your brass at least .005" long. for an AR rifle IMHO. Zero clearance is unacceptable in any rifle IMHO. Personally in an AR I think Id be targeting about .004" to .005" clearance for your headspace.

So Id be hoping for .005 difference between your fired brass & the resized brass. of course you want the resized brass to be shorter.

https://6mmarc.com/showthread.php?tid=195

I am using the Hornady Headspace comparator tool and case gauge. I modified my shell holder a bit and can get the headspace/datum measurement down to 1.181 now. Anything longer than 1.184 at the datum line will not chamber but I have them all sized at 1.183 now. The necks are a bit long but I need to trim them all down anyways as most of them are 1.491-1.493. For testing seating depth I also use the lock n load modified case tool. I reload for 223, 6.5G, 300BLK. 45-70, 450BM, and 350 Legend as of right now. I've had the ARC for a little over a year and have been going through factory ammo and am just getting started with it as far as reloading

SAAMI 1.190  -.007 cartridge ogive (.350) so it sounds like your chamber is near the low tolerance limit.

As long as you can get the shoulder pushed back for that chamber, carry on... it's all part of the game.