Modifying Precision Micron die - how hard are they?

[LVLAaron]

I have a 6.5 PRC Precision Micron die that I need to open the neck up on to fit a 7mm.

How hard are they? What kind of tooling should I use? Carbide boring bar? chucking reamer? I'm one to experiment but don't want to botch a 300 dollar die

 

[AlNyhus]

I use a carbide chucking reamer when opening the necks up. -Al

 

[msalm]

I use a carbide chucking reamer when opening the necks up. -Al

That’s what I’ve used, works well

 

[Alex Wheeler]

They are going to make a 7-6.5 but I have opened many with a carbide boring bar.

 

[762plinker]

just remember you paid for precision machine work...are you going to be able to maintian their stds ??

 

[LVLAaron]

just remember you paid for precision machine work...are you going to be able to maintian their stds ??

Yes.

 

[TylerFromMS]

Not going to lie… a twist drill works pretty well, and if you use one big enough to just leave a little bit of the shelf, the neck never hits it. Not pretty if you scope it, but it makes good ammo. If you’re doing it for a customer, I’d do it right

 

[gunsandgunsmithing]

Not going to lie… a twist drill works pretty well, and if you use one big enough to just leave a little bit of the shelf, the neck never hits it. Not pretty if you scope it, but it makes good ammo. If you’re doing it for a customer, I’d do it right

Clearance is clearance, right? I typically use a carbide chucking reamer to open a bushing shelf but I've done as you mention...buy a few good drill bits and get after it. If it doesn't touch, who cares. It's clearance. Not sure about those dies, though. Most are cased or otherwise very thin hardening.

Any method will benefit from deburring the edge, particularly at the bottom.

 

[LVLAaron]

Yeah. I don't want to open it too much either, the part I'd be cutting away sizes the shoulder

 

[gunsandgunsmithing]

Yeah. I don't want to open it too much either, the part I'd be cutting away sizes the shoulder

True, but you gotta be way over before it matters. Nice to keep it within about .010 but that's better than necessary. But yes, you can get too big if you load really hot. I use several redding 6.5 Grendel bushing dies for the 6mm Grendel cartridge. The factory hole is about .308 iirc, and my 6mm necks are no smaller than .271, fired. No problem unless I'm way hotter than I should be but I've found that magic spot on more than one occasion.

 

[jackieschmidt]

I am sure they are case hardened, so you already know a regular HSSdrill or reamer won’t touch it.

Years ago I used one of these in O size solid carbide to make my 30BR bushing sizing die out of a Redding 6BR body die.

So an L would work great for you.

L Solid Carbide Stub Drill

www.shars.com

 

[LVLAaron]

I'd need something closer to .315 diameter for the neck to pass through (7mm turned to .310).

I'll bore it out. Once my power comes back on....

 

[TylerFromMS]

I'd need something closer to .315 diameter for the neck to pass through (7mm turned to .310).

I'll bore it out. Once my power comes back on....

I’d probably go bigger so it doesn’t possibly scratch on the shelf on the way up after being fired and neck expanded.

 

[boltfluter]

I have modified quite a few Redding body dies to take bushings. A solid carbide boring bar is the way to go. In my experience.
Paul

 

[LVLAaron]

Micro 100 boring bar snipped the couple thou I needed removed like it wasn't even there.