comparator and copper bullets

[aggro]

Dropped down from 123 amax to 100 copper and having misfires with same OAL. Guessing my length to OGIVE is different and keeping bolt from completely locking up. Which one can anyone recommend?

[Oryx]

Given today's primer shortage have you swapped any primers for your usual primer?

I would first check and make sure the brass is sized properly. This is more typical of bolt closure issue and a good place to start. Tons of threads about people that are not getting proper shoulder set back in the resizing operation.

A different bullet and shape will possibly require a different seating depth. Not familiar with "100 Copper" so hard to say what the profile is like on that one.
Are you loading for a bolt gun or Autoloader? Either way you should be able to tell if you are getting full bolt lock up. You will likely feel it on a bolt action on close and you would be into the lands pretty hard if that were the case. You could always extract and inspect and then adjust. On an autoloader you can visually see if the bolt is not fully closed. If you suspect it's not closing all the way you can check in your chamber to see if it's seated properly.

OAL is definitely not a one size fits all thing. BTW - Have you checked the bullet manufacturer recommended OAL fro the cartridge?

[Oso Polaris]

Each type of bullet has a different design (shape/profile and location of ogee) even when comparing two different types of bullets with the same weight. As you move between bullets of different weights the profile will definitely change with lighter bullets being shorter and heavier bullets being longer, which will shift the ogee backwards or forwards. In addition, the composition of the bullet will also effect the shape. Copper is lighter than Lead, and when you move to an All Copper bullet the profile can really be different. Blah Blah Blah.

What type of Rifle - Bolt Rifle or AR15??? You should be able to tell if the bolt is fully closing. Bolt gun - did handle cam over completely and was there any resistance. AR15 - does the bolt look like it is all the way forward when looking at the ejector port... did you use the forward assist to double check/advance the bolt?

Assuming that (1) your bolt was fully closes and that (2) your powder and primers are not the issue....
The most likely cause of your Misfires are light primer strikes. This would be result of there being to much head space... the loaded cartridge is shorter that your rifle's chamber. If you are using factory new brass then your rifle may have a long chamber than spec. If you are resizing these cases then you are bumping the shoulder back too much. Take some measurements of fired cases (from your rifle) versus the brass after you resize it. You don't want to move the shoulder more than a few thousands (0.002"-0.003")

If the cartridge is too short (base of cartridge to the shoulder) then either the firing pin doesn't make contact with the primer or if it does there isn't enough resistance to ignite the primer (cartridge simply gets pushed deeper into the chamber). Assuming that you are doing the exact same case prep (resizing cases the exact same) for the the 123gr Amax reloads and the 100gr Copper reloads, the difference of why the Amax reload would fire and the 100 Copper would not all comes down to the bullet ogee making contact with barrel. The longer Ogee on the Amax made contact with the lands and provided enough resistance locking the cartridge in place (jam fit) so that the firing pin could hit the primer hard enough to ignite. The Ogee on the Copper bullets is further back and isn't sufficient to hold the cartridge in place (no jam it). With the exception of rimmed cartridges or belted magnum cases, the vast majority of cartridges (rifle and pistol) index off of the case shoulder. The shoulder helps position/support the cartridge inside the firearm's chamber providing resistance for when the firing pin strikes the primer. Jam fit is fine for fire-forming brass, but you shouldn't needed to do this for Grendel Brass. Check you measurements and resizing die setup.

Edit: While I was writing my response Oryx posted his with 1/3 the words. Well stated.

[A5BLASTER]

Dropped down from 123 amax to 100 copper and having misfires with same OAL. Guessing my length to OGIVE is different and keeping bolt from completely locking up. Which one can anyone recommend?

Stop right now, dont load anything else until you get your hands on the hornady OAL tools and know exactly where that bullet is in relation to the rifling/throat in your chamber.

[VASCAR2]

You can experience failure to fire if the cartridge fails to go completely into battery with an AR-15. Having the bullet seated to long can keep the bolt from completely going into battery. Another issue pertinent to the 6.5 Grendel is insufficient firing pin protrusion which can cause failure. Excessive firing pin protrusion can cause pierced primers and damaged bolt face. The length of the 6.5 Grendel bolt can vary in length as well as the firing pins. It is not recommended to mix firing pins in the AR-15, especially the 6.5 Grendel.

[Oryx]

Each type of bullet has a different design (shape/profile and location of ogee) even when comparing two different types of bullets with the same weight. As you move between bullets of different weights the profile will definitely change with lighter bullets being shorter and heavier bullets being longer, which will shift the ogee backwards or forwards. In addition, the composition of the bullet will also effect the shape. Copper is lighter than Lead, and when you move to an All Copper bullet the profile can really be different. Blah Blah Blah.

What type of Rifle - Bolt Rifle or AR15??? You should be able to tell if the bolt is fully closing. Bolt gun - did handle cam over completely and was there any resistance. AR15 - does the bolt look like it is all the way forward when looking at the ejector port... did you use the forward assist to double check/advance the bolt?

Assuming that (1) your bolt was fully closes and that (2) your powder and primers are not the issue....
The most likely cause of your Misfires are light primer strikes. This would be result of there being to much head space... the loaded cartridge is shorter that your rifle's chamber. If you are using factory new brass then your rifle may have a long chamber than spec. If you are resizing these cases then you are bumping the shoulder back too much. Take some measurements of fired cases (from your rifle) versus the brass after you resize it. You don't want to move the shoulder more than a few thousands (0.002"-0.003")

If the cartridge is too short (base of cartridge to the shoulder) then either the firing pin doesn't make contact with the primer or if it does there isn't enough resistance to ignite the primer (cartridge simply gets pushed deeper into the chamber). Assuming that you are doing the exact same case prep (resizing cases the exact same) for the the 123gr Amax reloads and the 100gr Copper reloads, the difference of why the Amax reload would fire and the 100 Copper would not all comes down to the bullet ogee making contact with barrel. The longer Ogee on the Amax made contact with the lands and provided enough resistance locking the cartridge in place (jam fit) so that the firing pin could hit the primer hard enough to ignite. The Ogee on the Copper bullets is further back and isn't sufficient to hold the cartridge in place (no jam it). With the exception of rimmed cartridges or belted magnum cases, the vast majority of cartridges (rifle and pistol) index off of the case shoulder. The shoulder helps position/support the cartridge inside the firearm's chamber providing resistance for when the firing pin strikes the primer. Jam fit is fine for fire-forming brass, but you shouldn't needed to do this for Grendel Brass. Check you measurements and resizing die setup.

Edit: While I was writing my response Oryx posted his with 1/3 the words. Well stated.

LOL - I was Just reading your post and thinking ... man... I thought I said something similar ... Laughed when I got to the bottom of your post. Great minds think alike.

[Oryx]

The length of the 6.5 Grendel can vary in length as well as the firing pins. It is not recommended to mix firing pins in the AR-15, especially the 6.5 Grendel.

Can you expand on what you mean by the 6.5 Grendel can vary in length? I also haven't heard of the firing pins being specific to the Grendel for the AR platform.... Is this due to some of the type II bolts having a deeper cut face? Never thought about that, but also never heard anything else about specific firing pins ... I would have thought you would see a very high rate of failure on something that common. Definitely interested in learning more.

[VASCAR2]

[Oryx]