issue with seating .223

[NY700]

I'm running RCBS competition dies with the micrometer seater w/window on a rock chucker. Full length sized brass with 77gr SMK. I'm feeling a lot of tension when seating and it appears to shave just a tiny bit of the jacket so after its seated I can run my nail around it and pul off a small ring of copper from the bullet. I used my calipers and measured the inside diameter after sizing it and it measure .221. My sizing die is set to manufacturer directionsand I've played with setting it a litle deaper and shallowerwith no real change. Inside and outside of the case mouth is debured nothing excessive. I've used my. Way cutter and also a wilson hand camer tool with no real change. The case mouths are smooth and clean and not excesivly sharp

 

[SpencerC]

I'm guessing there are a few firings on these cases? If there is, this is the time to anneal your brass. If not, you need to look into a new sizing die, preferably a collet neck die or a bushing FL size die. Make sure you have a little chamfer on the neck but not too excessive, or you will "shave" your bullets. You really only need to chamfer it enough to clean it up if you are using boattail bullets, more chamfer for flat base to aid in seating.

 

[fdshuster]

Yes, you're destroying the accuracy of those 77 SMK's. You said, "I'm feeling a lot of tension when seating", tells me the necks may be reduced to too small of a diameter. Measure the outside neck diameter of a loaded round, then measure the outside neck diameter of a case after it's been sized. Should not be more than about .002" smaller. The typical RCBS, Lyman, etc. case mouth deburring tool, ( looks like a rocket ship) does leave a sharp edge on the inside of the case mouth, the reason I inside taper neck ream all my brass using the K&M tool. Are you also getting a ring around the forward portion of the ogive where the edge of the seating stem would make contact? Not being familiar with the RCBS Competition dies ( I use Redding with the neck bushings) I just reviewed them in my Sinclair catalog and see they are not bushing dies, so you're stuck with whatever dimension RCBS decided on. If I had your problem I'd just use a larger neck bushing. You did not say what brand of brass you are using. If it's Lapua it will be thicker than Winchester, for example.

 

[treeman]

as one poster already said annealing brass will help. also a larger diamiter expander, which rcbs can furnish will also help. when brass becomes work hardened it will "spring back" more makeing the expanded neck size smaller takeing more pressure to seat bullets. by the way flat base bullets require less chamfer than boat tails. take a look at base of f.b. bullets and the transition from bearing surface to boat tail with a magnifying glass and you will see why

 

[NY700]

What should the inside diameter of the brass be for .223 should it be exactly .224 to match the projectile or .001 smaller? I know with bushings this can be adjusted with bushing dies but what range would be acceptable. I'm thinking this issue is from the 3way rcbs trimmer I'm using

 

[ronemus]

It helps to use a "VLD chamfer" instead of the 45 degree chamfer most tools produce. The shallower angle provides a cleaner entry for the bullet and avoids shaving or scratching it. The tools are inexpensive and work the same way as the 45 degree tools. I can't recommend a specific tool because I trim, chamfer and debur simultaneously usin a Gracey power trimmer with a Giraud carbide blade.

 

[ronemus]

The neck ID should be 0.001-0.0015" smaller than the bullet, but you can accomplish that by using an expander that's bullet diameter (.224 for the .223 Rem); they're usually available on custom order from the manufacturer of your dies. Another option is to have the neck of your die opened up so that you don't need an expander, but you'll need multiple dies if you use more than one kind of brass. Bushing dies can cause problems if you reduce the neck more than 0.003" in one step; since most factory chambers allow the brass to expand 0.007" or more, you're looking at sizing in 2 or 3 steps.