300 Norma Improved help needed

[jenstapio]

Hey roksliders, figured I would see what input you have.

I am working on my 300 norma improved custom that I have.

Shooting 230 bergers with N570 and ADG brass

While doing my load development I am finding that I am getting a tight bolt. "Bolt Click" The guy who built my gun said he usually finds a node on the rifles at 90-94 grains of N570 at 3080-3100fps. I found a good node at 92.4 at around 3095-3100 fps but I was getting a tight bolt. So a dropped down to find a lower node and I still had a tight bolt all the way down to 3044fps. I pulled the firing pin and bolt lug to ensure I was sizing brass enough and bolt closed on its own at the length I am resizing to, about .002 below fired length. So I'm not sure why I'm getting the tight bolt this low. The only thing I'm doing different than the guy who did the build is that he runs Laupua Brass and I'm running ADG. Could this be the problem? I tried looking for a carbon ring buildup in the chamber as well but didn't see anything obvious. If you guys have any input i'd really appreciate the help.

Thanks!

 

[travispe]

If it's unfired brass in an improved chamber you will likely need to decrease your load until the brass is fireformed.

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[Salmon River Solutions]

Ya like Travis said, if your fireforming… you should be at a reduced load. If your not fireforming, then I don’t know what’s up.

 

[jenstapio]

I’ve already fire formed brass at a normal 300 Norma load and am now working with fired and full length resized brass.

 

[rifletuner]

I’ve already fire formed brass at a normal 300 Norma load and am now working with fired and full length resized brass.

In that case, check the base of your case in fired brass against virgin brass with a micrometer. It may be that the F/L die is not sizing the base of the case enough. Also, are you seeing any other pressure signs such as ejector marks on the case head?

 

[jenstapio]

In that case, check the base of your case in fired brass against virgin brass with a micrometer. It may be that the F/L die is not sizing the base of the case enough. Also, are you seeing any other pressure signs such as ejector marks on the case head?

No other signs of pressure. I’ll measure some of the bases. How much should I be looking for at the base?

 

[rifletuner]

No other signs of pressure. I’ll measure some of the bases. How much should I be looking for at the base?

Ideally you want the die to size the fired case a couple of thousandths at the base. If the sizing die is not able to do this, then there is a mismatch between the die and the chamber.

I would be looking at the measurement of unfired cases, vs fired cases, then see what the sie is after FL sizing tough your die. A chamber that is tight and a FL die that is a bit lose can be a problem with standard chambers, but even more so when running wildcat cases such as improved versions.

Also, have you discussed this with the "guy who did the build"? Does he have a recommended die set that matches his chamber reamer?

 

[jenstapio]

Hey everyone I was able to get to the bottom of this.

The guy who made my custom used Lapua brass and I was running ADG. I ordered some Lapua brass and had no more issues with the tight bolt. I’m assuming the custom die that was made for the gun wasn’t sizing the ADG brass all the way down to the web.

Thanks for your help,

Jens

 

[wind gypsy]

Hey everyone I was able to get to the bottom of this.

The guy who made my custom used Lapua brass and I was running ADG. I ordered some Lapua brass and had no more issues with the tight bolt. I’m assuming the custom die that was made for the gun wasn’t sizing the ADG brass all the way down to the web.

Thanks for your help,

Jens

I had this same issue with a standard 300 Norma and it is a frequent issue with Normas and others.

Lapua brass is likely resistant to growing at the web which is where things are getting sticky in the chamber. Even if your die sizes it at the web you can still get clickers if it expands again easily when fired. In my case, norma brass would size down some at the web but it expanded again easily when fired and remained sticky on extraction.

This thread is the best explanation of this issue that i've found:

The PRC die "problem"

There are a number of people experiencing sizing issues with the PRC case. When designing a chamber, brass, and resize die there is no one size fits all. We want good hard case brass, but its harder to size. We dont want sloppy chambers either. I have experience with designing reamers with...

www.longrangehunting.com

 

[huntnful]

Hey everyone I was able to get to the bottom of this.

The guy who made my custom used Lapua brass and I was running ADG. I ordered some Lapua brass and had no more issues with the tight bolt. I’m assuming the custom die that was made for the gun wasn’t sizing the ADG brass all the way down to the web.

Thanks for your help,

Jens

Thank you for this. My builder also said to run Lapua because he knows his dies and reamer are made around lapua brass. I got a bunch of ADG, but sold it and went with Lapua just so I wouldn’t have any issues. Sounds like I avoided a potential headache.

Hells Canyon build your 300NMI?

 

[khuber84]

I've got the same clickers with my 300nmi but I have 8 firings on brass. I even upgraded dies from whidden to custom Hornady, to Micron hoping to get rid of it, nope. I'm only pushing 230s @ 2950 in mine. If the gunsmith doesn't have the chamber dimensions just right to the die dimensions, there will be issues.