200 straight rounds of Norma Mag

[Mike D Texas]

Oh yeah. They lose speeds as the throat erodes further and further away. But that’s normally from less pressure. I’ve never seen a speed loss, accompanied by higher pressures.

I started a load in my 28 nosler at 83gr. N570. When the barrel was shot out at 800 rounds I needed 87gr. N570 to produce the same speed. Same jug of powder.

Well I say speed loss because I had to back my loads down to higher pressure. I originally thought it was a carbon ring but I scrubbed the chamber throat area down to bare metal and it didn’t change significantly.


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[huntnful]

Well I say speed loss because I had to back my loads down to higher pressure. I originally thought it was a carbon ring but I scrubbed the chamber throat area down to bare metal and it didn’t change significantly.


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Oh weird. I’m not sure about that one. I’ve never seen that personally. Normally lose speed as the barrel wears out. Have to either seat bullets longer or add powder to chase it (or both)

 

[Mike D Texas]

I agree it’s weird. I did some reading and found mixed opinions on it. What I do know is that a proven load for hundreds of rounds suddenly started showing pressure signs and I had to back down a full 2 grains to keep it from happening.


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[Quicksilver]

My 300 Norma is slowing down, but I haven’t had to chase the velocity with more powder yet. It has tapered off 20-25fps but still seems to be happy.

 

[huntnful]

I agree it’s weird. I did some reading and found mixed opinions on it. What I do know is that a proven load for hundreds of rounds suddenly started showing pressure signs and I had to back down a full 2 grains to keep it from happening.


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That’s definitely weird. Not sure what would cause that honestly.

My 300 Norma is slowing down, but I haven’t had to chase the velocity with more powder yet. It has tapered off 20-25fps but still seems to be happy.

Yeah you definitely don’t HAVE to chase it. My accuracy’s never really dropped off because of it. Just an extra click or 2 on the turret haha

 

[huntnful]

For anyone that thinks I only like magnums lol.



The big magnums are cool, but seriously only necessary for LONG range. But they kill shit really well up close too anyways as a bonus hahaha.

 

[nidahobrushswimmer]

My tinnitus flared up just seeing this lol

 

[Quicksilver]

I’ve started building smaller rifles for majority of my hunting. My Norma only comes along in certain hunting locations now…although the 2 times I didn’t take it this season I could have used it haha. Go figure…

 

[huntnful]

I’ve started building smaller rifles for majority of my hunting. My Norma only comes along in certain hunting locations now…although the 2 times I didn’t take it this season I could have used it haha. Go figure…

Hahaha I really do like the smaller calibers/cartridges. Having a 6 PRC and 22 CM built right now actually. But I want to be able to take any opportunity I can in the field, and I just don’t shoot the big magnums bad enough to bring a smaller gun. If I’d kill it with a 6mm, I’d kill it with a 300 NMI. But not always the other way around.

 

[solarshooter]

Litz states that the main symptom of a barrel getting "shot out" is an increase in BC SD due to eroded lands failing to promptly/smoothly engrave the bullet. Instead, the bullet initially slips on on the worn rifling, causing damage/scraping/tearing to the surface of the bullet in an inconsistent way, which affects the BC in an inconsistent way and therefore will cause increased dispersion at range. Therefore you will notice a "shot out" barrel when dispersion begins to increase at longer ranges, but that barrel can still be used at shorter range where BC SD is less important. MV migration can also occur. A few questions:

Were these groups shot at 100yds?
Did you track MV during the string?
There is definitely a string or cluster of shots above the main group, did you notice when these occurred in the string?

Love the torture test by the way and thanks for sharing!

 

[huntnful]

Litz states that the main symptom of a barrel getting "shot out" is an increase in BC SD due to eroded lands failing to promptly/smoothly engrave the bullet. Instead, the bullet initially slips on on the worn rifling, causing damage/scraping/tearing to the surface of the bullet in an inconsistent way, which affects the BC in an inconsistent way and therefore will cause increased dispersion at range. Therefore you will notice a "shot out" barrel when dispersion begins to increase at longer ranges, but that barrel can still be used at shorter range where BC SD is less important. MV migration can also occur. A few questions:

Were these groups shot at 100yds?
Did you track MV during the string?
There is definitely a string or cluster of shots above the main group, did you notice when these occurred in the string?

Love the torture test by the way and thanks for sharing!

I only measured velocity with the first like 10
Shots, and never did check it at the end.

Anything you see in that 195 round group is totally random. Sometimes I didn’t even have the gun shouldered but maybe halfway lol. I was just loading it, putting it on orange and pulling the trigger as carelessly as you could safely do it.

 

[The Fish Box]

Let’s see a picture of the throat

 

[huntnful]

Let’s see a picture of the throat

Damg, I forgot to clean it before I pulled the barrel off, so you can’t see it near as well now

Right in front of the chamber


I should have cleaned it and don’t a full scope. But I’m not savvy with the video recording and uploading and stuff

 

[TxLite]

What barrel and who chambered it?

Looks like it held up great for all the abuse

 

[huntnful]

What barrel and who chambered it?

Looks like it held up great for all the abuse

It’s a 4 groove brux #6 1-9 twist chambered by @barehandlineman at High Voltage Armory. He does all my work and is first class.

 

[mddat]

Hahaha I really do like the smaller calibers/cartridges. Having a 6 PRC and 22 CM built right now actually. But I want to be able to take any opportunity I can in the field, and I just don’t shoot the big magnums bad enough to bring a smaller gun. If I’d kill it with a 6mm, I’d kill it with a 300 NMI. But not always the other way around.

Just out of curiosity, what actions are you building the new 6 PRC and 22 CM on?

 

[huntnful]

Just out of curiosity, what actions are you building the new 6 PRC and 22 CM on?

It’s on a defiance Exodus. Gunsmiths own actions machined by defiance. The new 7-300 will be on one as well. First impressions are extremely good.



This was the first 3 shots down the barrel of the new 6 PRC