Precision Grinding??

[chris.tyne]

Adam you do what you think needs doing,you have turned into the shoulder a bit more than I do and it will be fine,if you can't detect any thickening of the neck shoulder junction then load them up and fire form them.
Size them,run them over a mandrel and turn then again if you like,if you are using bushing dies then they won't size right to the neck junction anyway, you can turn that brass of if it worries you, at the moment it appears you are trying to solve a problem you don't have,its good to muck around and try these things though.

[Brad Y]

Adam

Firstly, can I suggest you turn the case to provide more clearance. I have spoken to alot of experienced long range shooters in the USA who have found that if you dont provide adequate clearance on the neck especially on large cases you may have problems with vertical stringing (if your shooting targets and worried about it) I run 3 thou on a 6mm dasher, 4 thou on a 260 improved and 5 thou on a 284 shehane. None have issues with vertical. Also with that size case and amount of powder burning I would definitely err on more clearance than less. I also see there is a pressure ring where you are seating the bullet- looks like far too much neck tension to me?

Anyway aside from that if I were you and was worried about donuts forming after a couple of firings, I would run a 6.5mm K&M expander mandrel through all your cases to force any potential donut to the outside of the case. Then turn the donuts off the outside with your neck turner and make a small turn into the shoulder to prevent donuts forming again. Then when you resize your necks, set your bushing to have some room to lift up and only size half or 2/3 of the neck, leaving the bottom section at chamber diameter. This does 2 things- 1 the chamber diameter section just above the shoulder will align your cases in the chamber straight, and 2 the bottom half or third of the case you dont resize will be large enough that any potential donut wont contact the projectile. A bloke from Victoria won the second day aggregate of the F class world championships in the USA and I know he only sizes part of his case neck to avoid any unwanted problems with donuts.

Good luck

[aaronraad]

My chamber size is 2965, the neck size of a loaded cartridge is 294. My calculations are after the normally accepted spring back after firing (1 to 1.5 thou), a fired case should be less than a thou larger than the sized case at about 295. There is no way the standard Wilson reamer of 267 will fit into the neck of a fired case which will be 2645 to 266.

I cannot detect a donut in the neck despite having measured it every which way, and having done visual inspections. I'm just aiming for that belt and braces approach that makes me happier about this particular wildcat.

2.5 thou neck clearance does sound a bit tight. You've probably noticed that most of the 6mmPPC BR shooters get away with a tight neck and no reaming because they never seat the short flat base projectiles that far, let alone apply minimal if any neck tension.

I did some fireforming recently with my 25/60 SMc made from Winchester 270WSM brass necked down to .257 and shortened to 1.8" with a SMc radius shoulder. It does have at least 0.354" of neck though to seat +130gr VLD projectiles. So I've got a reasonable idea where you're coming from. I fireformed nearly 300 cases with a projectile to save my barrel and the cost of projectiles. Have you considered maybe fireforming a few cases without a projectile to see what result you get?

This may or may not end being an ongoing issue for you, so addressing the LE Wilson neck reamer is more like addressing the symptom. It might make life easier in the long run to address the chamber neck and tickle it up by another thou with something like a PT&G T-handle type Neck Reamer - http://www.pacifictoolandgauge.com/unip ... m#nandtrmr

[adamjp]

My chamber size is 2965, the neck size of a loaded cartridge is 294. My calculations are after the normally accepted spring back after firing (1 to 1.5 thou), a fired case should be less than a thou larger than the sized case at about 295. There is no way the standard Wilson reamer of 267 will fit into the neck of a fired case which will be 2645 to 266.

I cannot detect a donut in the neck despite having measured it every which way, and having done visual inspections. I'm just aiming for that belt and braces approach that makes me happier about this particular wildcat.

2.5 thou neck clearance does sound a bit tight. You've probably noticed that most of the 6mmPPC BR shooters get away with a tight neck and no reaming because they never seat the short flat base projectiles that far, let alone apply minimal if any neck tension.

The chamber is a proven performer and I am already running a rifle with clearance of 2.5thou in dia. The reamer was specced by Dave Kiff of PTG from the cartridge dimension that I sent him. PTG got the first reamer wrong, but the second one is perfect. A fired case is obviously looser than an unfired one, but I am sizing the neck by only 1 thou or so which means long neck life. The rifle is certainly accurate enough.


And yes, the seated bullet is tight, the formed cases have 3 thou neck tension on them. The pressure ring is from the damn Redding dies - there is a specific seater stem for VLD bullets and the front of the AMAX is thin enough to need it. I have the same problem in my 7mm SAUM with 162gn AMAX, but not with 168gn Berger Hunting VLDs. The stem is in my next order from Sinclairs.

To be honest I will shoot the cases as they are at this time and only resort to inside neck reaming if I experience problems.

[Dr G]

Got me stuffed why you blokes bother stuffing around with those wildcat thingos. Get ya selves a 22lr, that's all you need.

There is no why. (Master yoda I think ) the only reason you need is cause you can

[kickinback]

So, did you end up getting the donut out?

The reason I ask is if you have a K&M neck turner, you can get a pilot with a cutter on the end to remove said donut.

https://www.kmshooting.com/catalog/foo/ ... pilot.html

[adamjp]

So, did you end up getting the donut out?

The reason I ask is if you have a K&M neck turner, you can get a pilot with a cutter on the end to remove said donut.

https://www.kmshooting.com/catalog/foo/ ... pilot.html

I am waiting for the rifle to arrive and put a couple of shots downrange before I get too excited. I need to inspect a couple of fireformed cases.

With a little luck I will be shooting it before the end of July.