Should I be worried about my neck clearance?

[GW Hunter]

I've been using Nosler brass for my .280AI. That fired brass neck measures at .314". I purchased some Peterson brass a while back and just got to messing with it. I can't believe how much thicker it is. After running the brass through my expander die (.282") to round the necks they measure at .311". After seating a bullet in a dummy round, the neck measures at .314". The SAMMI maximum cartridge dimension drawing shows the maximum neck dimension at .315". Should I be concerned about anything with these numbers? The cartridge chambers fine in the rifle. It just seems a little close...

 

[JMW67]

will a bullet drop back in the mouth of a fired case before resizing

 

[GW Hunter]

Yes. I guess I should have stated that I am concerned about clearance for bullet release.

 

[JMW67]

If the bullet will drop back in the fired case you should be fine

 

[GW Hunter]

I get what you are saying but I haven't shot the brass yet. I don't want to find out the hard way...

 

[entoptics]

IMO, ≤ 0.001" clearance is a bit tight. I think it would be safe to load up a minimum load, and fire one to see if you get the same measurements.

If so, I think you'll need to invest in turning tools, if you don't already have them.

On the bright side, those fat Peterson necks mean you'll be able to perfectly set your clearance just how you like it, by turning them. You'll have superbly concentric necks, with just the right amount of clearance.

 

[25WSM]

Do you know what your actual neck diameter is? A chamber cast of the neck will tell you for sure.
Shep

 

[GW Hunter]

I've been trying to avoid the neck turning thing but I'm afraid you might be correct entoptics.

I do not know the actual neck diameter and wouldn't be opposed to getting one done if I knew a gunsmith I would feel comfortable with. Anyone know one in the Sacramento, Ca. area?

 

[GW Hunter]

The SAMMI dimension of .315" I referenced is what SAMMI calls out as maximum neck for a 280ai cartridge, not chamber. This makes me think I may be ok. Am I misinterpreting the drawing? Their minimum chamber drawing isn't as clear with the minimum chamber neck dimension...

 

[25WSM]

Cerro safe and a little ladle to melt it in are cheap and it's a very easy process. I cast the neck on most rifles I didn't chamber myself. It's reusable too.
Shep

 

[25WSM]

Sammi chamber spec shows .3176 at the back of neck and .3156 at the mouth. If your chamber is this exactly I would turn your necks. .0016 is a little tight.
Shep

 

[243winxb]

Should I be concerned about anything with these numbers?

At .314" loaded round neck diameter, you should be ok. But you may want to mic each loaded rounds neck diameter. Check the manufactures quality control.

The SAAMI chamber looks like it has a taper. Near the neck shoulder junction .3176" At the chamber mouth .3156" (all diameters plus .002") Should be ok clearance?

But is it a custom barrel or modified factory barrel? May make a difference in chambers.

Your call, your pulling the trigger.

 

[Pizzaman1]

I've been using Nosler brass for my .280AI. That fired brass neck measures at .314". I purchased some Peterson brass a while back and just got to messing with it. I can't believe how much thicker it is. After running the brass through my expander die (.282") to round the necks they measure at .311". After seating a bullet in a dummy round, the neck measures at .314". The SAMMI maximum cartridge dimension drawing shows the maximum neck dimension at .315". Should I be concerned about anything with these numbers? The cartridge chambers fine in the rifle. It just seems a little close...

I chatted with Ben Preston from Peterson the other day, and I asked him if my cases(6.5 CM) needed FLS or Neck sized- his response was load and shoot. I can't imagine yours would be any different.

 

[vancewalker007]

I've been using Nosler brass for my .280AI. That fired brass neck measures at .314". I purchased some Peterson brass a while back and just got to messing with it. I can't believe how much thicker it is. After running the brass through my expander die (.282") to round the necks they measure at .311". After seating a bullet in a dummy round, the neck measures at .314". The SAMMI maximum cartridge dimension drawing shows the maximum neck dimension at .315". Should I be concerned about anything with these numbers? The cartridge chambers fine in the rifle. It just seems a little close...

I think you might have case and chamber measures confused. Every 7mm cartridge I've ever messed with the fired cases usually blow out to .317-.319 range. If the numbers were that close Peterson's would be in law suite city. But, on another note changing brass horses in the middle of the river is going to effect any loads you developed using the Nosler brass. Be careful, thicker brass usually means higher pressures.