Resizing cases when loading for AR

[Alabama556]

I have been reloading for over 20 years for bolt action rifles but just started loading for my AR a few weeks ago when I finally built a 300 blackout. I have loaded for 300 whisper with no problems for a long time but it is for a custom Remington 700.

Typicality, I would set the sizing die to where it just bumped the shoulder for bolt guns.

My setup is noveske 11.5 300 blackout barrel with pistol length gas system. Brand new Colt m16 bolt. The lower is a factory colt 11.5 setup.

The brass I have is cut down from 5.56 cases and has never been fired. It will not fit in my noveske chamber when resized with my bolt action die.

The resized fired brass from my bolt gun won’t fit in my noveske. (bolt gun is a 300 whisper and was built before 300 blackout was commercially availible).

I set my resizing die all the way down and it resized almost the entire case. These fit and function but am I resizing the brass too much?

I have 2 sets of dies so I can easily set one for the bolt action and 1 for the AR.

Thank you.

 

[spife7980]

I don’t see any measurements. How could we possibly identify the issue if you don’t have measurements?

 

[Alabama556]

OAL with 208 grain amax is 2.250
Case length is 1.355

If I turn the resizing die all the way down, the cases will fit.

 

[918v]

We need more measurements. The case could be binding in the chamber at the neck, the shoulder, the body…

 

[spife7980]

OAL with 208 grain amax is 2.250
Case length is 1.355

If I turn the resizing die all the way down, the cases will fit.

So you have no measurements.
Take some real measurements.
Example:

 

[Doom]

The problem you describe is typical of brass shot in one gun then sized for another. Usually the base of the cartridge is the issue and is usually solved by turning the die down or using a small base die. The only problem with turning the die down is you may end up with excessive headspace.