Dear Ganderite

[Ganderite]

Hi there,

My name is Fred and I’ve been a member on CGN for about 4 years, in that time I’ve noticed that you seem to be one of the go to people for helping the younger less knowledgeable guys. I was wondering if you could answer or possibly shed some light on a few questions I have.

I built a 6mm Remington Ackley and I acquired a good amount of new Winchester Brass. The gun shoots very well but I can’t help but wonder if a better quality brass would help improve it a bit more. I know if one looks hard enough he can find Norma 7x57 and neck it down and may have to turn necks.

Recently I began playing with a straight 6mm Remington FL die and I watched a couple instructional vids and read a few articles and I managed to take down 30-06 brass down to 6mm rem and trim the necks. The issue I have found ( while not major yet ) is that there is a slight inside donut at the shoulder neck junction. Is there a way to avoid this? Would buying a proper forming kit with multiple bushings help?

Or do I need to jump into inside neck reaming? I’ve heard some people say to outside neck turn and to cut ever so lightly in tot he shoulder and that it may have to be touched up every now and then.

Any help would be much appreciated.

Fred


I have some Ackley experience. 6.5-08Ackley I ran it with Winchester brass until Lapua gave me 2000 pieces of Lapua.

Your first question asks if better brass would help. If you were starting from scratch, I would suggest buying Lapua brass, not Winchester. Not a big difference in cost. Big difference in quality and longevity.

If you have deburred the inside flash hole of your Winchester brass, I don't think you would see a big improvement in accuracy with Norma or Lapua. Run the Winchester till it is done.

The 6mm Rem is a necked down 7mm case. If you are sourcing new brass, I would look for 6mm Lapua, or failing that, 7mm Lapua. I doubt any neck turning is required, unless your rifle is cut with a tight neck.

The "dreaded donut" is to be avoided. It has been decades since I did any neck turning, so I will leave it to others to comment on that.

Ganderite

 

[elkhuntr]

Outside neck turn slightly into the shoulder (the idea is to remove brass around the donut area so that upon firing it will smoothen out. Look for about 80-90% surface cut on new brass. In any production process there is imperfections, you are just getting a higher standard with Lapua. You will see if there are thicker or thinner cases by averaging out the cut this way.

Inside neck turn if you cannot run the outside neck turn mandrel into the brass completely. You can buy inside neck reamers to achieve the same result as outside neck turning for removal of the donut.

Or....have your bullets seated out so they do not contact the donut. You can achieve this by having your smith lengthen the throat. Or match your bullets to suit the problem so that the donut is not contacting the bullet. Elky's 2c from what I've learned about the dreaded donut over the years.

 

[bigedp51]

I think your problem is you used a longer 30-06 case to make your 6mm AI and now have tapered necks. Meaning the necks are thicker at the shoulder neck junction and become thinner at the case mouth.

You need a ball micrometer and then check your neck thickness just above the shoulder and working upward to the case mouth.

Example, I have the Lake City military drawing for the 5.56 NATO case and it specifies the base of the case neck can be no more than .002 thicker than the mouth of the case neck.

When you convert a longer 30-06 to a shorter length case the neck will become thicker and need turned to a uniform thickness.

I do not think you have donuts, I think the newly formed 6mm AI necks are tapered and thicker close to the case shoulder.

And inside neck reaming can leave the inside of the case neck very rough and you are better off outside neck turning.

When neck turning factory cases it seems I always take more brass off near the case shoulder. And with your newly formed cases from 30-06 brass you will remove even more brass from the neck.

Many reloaders who case form use a expander die .001 larger in diameter than the turning mandril.

I use the Sinclair expander below and the mandrils are straight sided and not ball shaped. This helps keep the neck diameter more uniform when turning the necks.


Weekly Gear Update – Expander Mandrel Dies
http://www.65guys.com/weekly-gear-update-018-expander-mandrel-dies/