What size mandrel when making a Hornady Modified case

[LVLAaron]

Will be making a custom modified case for a hornady comparator. 6mm bullet. What size mandrel is generally accepted as the right size to open up the neck so the bullet moves freely?

2 thou over? 3?

 

[hogpatrol]

I used fired brass and just size the body with a bushing die with the bushing removed.

 

[bcarico]

What Hog said. If you need a little more bullet clearance chuck a bronze brush in a drill and give the inside of the neck a good reaming.

 

[LVLAaron]

Makes sense. I'm waiting on a rifle to be chambered and sounds like I'm a step ahead of myself. Thanks for the tips guys!

 

[Dusty Stevens]

Just use your cases youre about to load. Get the best reading possible using your case, bullet, and bolt

 

[Roeder]

One tiny thing to add: When you resize the fired case, avoid pushing the shoulder back. The idea is to get the most accurate measurement that will translate to your loaded round.

 

[LVLAaron]

One tiny thing to add: When you resize the fired case, avoid pushing the shoulder back. The idea is to get the most accurate measurement that will translate to your loaded round.

Yep. Makes sense.

 

[jkohler]

I’d do as dusty said. Go watch Alex wheelers video on the tube and don’t monkey with the modified case.

 

[tobnpr]

I needed a 6.5 Grendel in a hurry and pushed bullets into the neck with an arbor press, pulled it out, and did this a number of times with lapping compound on them. When it was nearly loose enough, chucked the brass in the mini-lathe (which is where I drilled and tapped the case) and spun a bullet in the neck with the lapping compound. Probably took 20 minutes to get the neck loose enough, but it worked...

 

[AccelR8]

I got this idea from somewhere else and it has worked well for me; hold a bullet in a collet type puller in your press, put the case in the shell holder and run the case up and down repeatedly on the bullet. It didn't take me long to get the proper fit.

 

[Richard Jones]

I’d do as dusty said. Go watch Alex wheelers video on the tube and don’t monkey with the modified case.

This.

 

[hogpatrol]

Guys, Alex's method is ok with a bolt action. I'm assuming the OP's is an AR platform with the Grendel. Then what?

 

[jkohler]

Have is smith cut a gizmo with the reamer that would work pretty good. That’s what I do with gas guns.

 

[Dusty Stevens]

Guys, Alex's method is ok with a bolt action. I'm assuming the OP's is an AR platform with the Grendel. Then what?

Steel wool the bullet and push it in by hand, remove it with the bolt and eyeball the land marks

 

[hoz53]

Guys, Alex's method is ok with a bolt action. I'm assuming the OP's is an AR platform with the Grendel. Then what?

the original post just says 6mm bullet

 

[hoz53]

Will be making a custom modified case for a hornady comparator. 6mm bullet. What size mandrel is generally accepted as the right size to open up the neck so the bullet moves freely?

2 thou over? 3?

so have you been using youre hornady comparator with ar-15s to get your touch dimension? i never could get consistent readings from those from one to another.

 

[epc308]

As others have said, I use a fired case, no sizing, from the rifle in question, drill and tap for the comparator stem, and it’s ready to go. It’s a slip fit for the bullet and fits the chamber. I do make sure it will chamber easily first.

 

[hogpatrol]

the original post just says 6mm bullet

Yes, my error. I meant to say I was referring to tobnpr's post.

 

[GenePoole]

I’d do as dusty said. Go watch Alex wheelers video on the tube and don’t monkey with the modified case.

I had to do a little searching to find this.

 

[tobnpr]

^^^^
Good stuff, there.