.310 sized bullet in a .308 case????

[Willyp]

If you size cast bullets to .310 and resize the 308 win. cases with a regular set of dies,how do you squeeze the cast bullet down into the neck???? How do you tell if a .310 bullet and case will fit the neck of your chamber?

[nicholst55]

You'll need to slightly expand the case mouth after sizing. A lot of folks like the Lyman 'M' die for this purpose, although RCBS has a similar expander in their Cowboy die sets, and Redding also has a similar expander now, as well.

Do a search for 'M die,' and you should have plenty of reading for a day or so.

The way you tell if a particular combination will work is to measure the inside neck diameter of a case fired in your rifle. Say that you get a reading of .312"; you subtract (a minimum of) .001" for clearance, and then you can use bullets of .311" maximum diameter.

Once you've determined that, load up a dummy round (no powder or primer), and see if it will chamber and extract with no problems.

[Larry Gibson]

If the bullet is sized .309/.310 I use a .30 M-die. If bullets are sized .311 (my go to size for most .308/.309 barrels) to .314 I use the .31 M-die.

Larry Gibson

[nicholst55]

If the bullet is sized .309/.310 I use a .30 M-die. If bullets are sized .311 (my go to size for most .308/.309 barrels) to .314 I use the .31 M-die.

Larry Gibson

Good point, Larry. I do the same thing, but neglected to mention it.

For that matter, all you need are two 'M' die bodies - short and long - to cover 99% of cartridges. The expander plugs are interchangeable between dies.

[P.K.]

Lee makes one too.

http://leeprecision.com/xcart/Universal-Case-Expanding-Die.html
http://leeprecision.com/xcart/images/P/UniversalExpandingDie.jpg

[3006guns]

P.K...isn't that Lee's case mouth flaring die, not a neck expander?

[462]

In my opinion:
There is a huge difference in function and outcome between Lyman's neck "expanding" M-die and Lee's neck"flaring" die, and comparisons should not be made.

Seating a square boolit base into a case mouth that is also square is a superior method than seating a square boolit base into case mouth that is funnel shaped.

[P.K.]

P.K...isn't that Lee's case mouth flaring die, not a neck expander?

Lee calls it both, in the link it's refered to as an "Expanding die" while in the description its a "Flairing die." Go figger, silly me. Sorry for the misdirect.

I have one on order because of a bad run of HS-6 in my .40. Crimped cases need not be wasted. ;-)

[Adk Mike]

I have an RCBS 30 06 die with a .310 expander plug. I only use this die for cast .311 in the model 1917. this works good for me. I also use a 31r Lyman expander plug when loading cast for this rifle. The system works good for me

[leadman]

Once you have the Lyman expander body the expanding plugs can be purchased seperately from Lyman for about $6 each.