220 swift neck diameter

[taliv]

i am going to purchase neck dies with bushings and i need some info on which bushing to buy.

i have a drawing of the cartridge that shows the neck diameter is .260"
it's not clear if this is an ID or OD.

sinclair's recommends measuring the neck OD of a loaded round and buying a bushing that is .002 or .003 smaller.

i'm wondering 3 things:
1. what diameter does everyone else use ?
2. should i do anything to take into account my actual chamber? such as, measuring a case that has been fired in my chamber already instead of a loaded one. i'm guessing no; the neck-bullet relationship is more important than neck-chamber, (assuming they're all aligned)
3. would you generally use more neck tension for smaller bullets and less for larger? (e.g. should i favor the -.003 when loading 40-52g and maybe the -.002 for 55-60g+)

 

[shooting on a shoestring]

One out of three

T:

I can answer only the first question authoritatively. Your .220 Swift cases will have inside diameters of .220 plus or minus a thousandth (think bullet size). Therefore any diameter of .260 would have to be the outside diameter. However, that sounds large to me. It would indicate 0.020 thick case walls. I have not measured any rifle brass lately, but I have measured .357 mag and .45 Colt cases and found them to be 0.012 thick at the case mouth.

On your second, yes I agree. I would neck size according to bullet diameter and not chamber diameter. This I say as instinct and cannot declare it as fact.

As to your third question, I don't reload .220 Swift. Dad does. Amazing what the old guy and hit with it. He bought his years ago from what he describes as a disillusioned turkey hunter. Sort of paints a picture.

 

[zoom6zoom]

.260 is the outside diameter at the case mouth, according to "Cartridges of the World".

Never would have pictured .220 Swift as a turkey round...

 

[Ol` Joe]

What you want is to have the bushing that will size your case neck down ~0.003" SMALLER then bullet diameter. You will need to find the thickness of your case wall and add it (doubled because of it being on both sides of the bullet to your bullets diameter. Subtract 0.003" from this and that is your bushing size.
Example; a case with a wall 0.018" in thickness will total 0.036" of case wall to be added to say a 30 cal bullet of 0.308" diameter. This will come to 0.344" of case wall and bullet. Take 0.003" off to get the bushing size and you come up with 0.341" for a bushing size.
Keep in mind different cases will have different wall thickness and require different bushings. Turning/uniforming your necks to the same diameter as BR shooters do will prevent this. This purpose of the bushing die is to keep neck tension even between rounds and help reduce velocity deviation. Unless you have a custom chamber, uniform primer pockets, sort cases, ect you are not likely to see any gain over std dies. The bushing dies can also produce insufficent tension if the case wall is thinner then the one you measured to find the bushing size. This can happen within the same lot of cases and is the reason for uniforming the necks.