question about case mouth expansion

[BombthePeasants]

Dear reloading experts,

I am at the stage where I've charged my cases with powder (the correct amount, for those who've seen my previous post), and am now loading the bullets. However, I believe I've belled the case mouths too much, the bullets just slide down into the case on some, and are so loose that I can push them down further, or pull them out with little effort. Question is, Do I need to dump the powder from all the cases, and resize them, and start all over again? Or is there a shortcut to reducing the amount of belling on the mouths?

[highvel]

Yes, those cases should be sized again to regain the neck tension.
Set your die so that the bell is just enough to allow the bullet base to sit straight on top of the case.

[Sevens]

Absolutely, you need to resize them fully.
With most sizing dies, this will remove your primer. Depending on what brand of dies you have, it makes more sense to remove your decapping rod rather than punching out all of those good primers and trying to re-prime.

Your loading dies came with instructions for setting up the flare die. You should use as little flare as possible. Excessive flare shortens case life (problem) and also, as you have seen, it removes case mouth tension on the bullet. (BIG PROBLEM)

Case mouth tension on the bullet is CRITICAL to avoiding unintended bullet setback. Bullet setback will exponentially raise pressures and could cause a catastrophic failure.

If you are using jacketed bullets, a tiny amount of flare is all that is needed to easily get a bullet started. If loading lead bullets, a little more flare is necessary to avoid shaving lead from the sides of the bullets.

[jepp2]

Which die expander are you using (and cartridge)?

When I am loading plated bullets for 9mm on my Dillon RL550, I only have to bell the case a few thousandths. For lead bullets I have to increase slightly.

The Dillon expander just expands the case right at the mouth. So most of the case neck is not affected at all.

[BombthePeasants]

that's what I thought. Oh well...back to the drawing board.

Jepp2, I'm using the RCBS 3 die set, with the taper crimp die included.

[mongoose33]

This is why, IMO, it's a very good idea to make up a couple of dummy rounds (no primers, no powder) to check that everything is good to go before you prime and powder the cases.

[Uncle Buck]

Getting the mouth expanded is an interesting process for people who have just started reloading. Like other have said, you expand just enough to get the bullet to enter the mouth of the cartridge.

When I started I did the same thing, only to the point that I could not even get the case to enter the seating die. (Scrap brass will eventually go back up in price )

Empty the powder, remove the decapping pin from your resizing die and run the brass through it again.

NOTE: I have also run into this problem with brass that has been shot multiple times. Sometimes I just can not resize it properly and it gets tossed.

[longranger]

Buy a decent set of calipers and measure all dimensions of your brass before and after each operation.It is very helpful to know exactly what the die is doing in each step.This avoids the problems of prcoessing your brass and learning something isn't right.
I just bought a new set of RCBS "Cowboy" dies .38 S&W. They are mismarked .38 Special. different animal.Have been waiting for RCBS to fix the problem.

[BombthePeasants]

I just need to be more thorough. My main problem is that I can never get uninterrupted segments of time to work at the bench. Having a 12mo. old means never having time to yourself...

[drail]

Measure the expander plug in your expander die (on the part below the flaring step, about 1/4 in from the tip). It should be 3 to 5 thous. smaller than your bullet diameter. Your problem sounds like your cases are either not being sized down enough, are being over expanded or your bullet dia. is on the small size. You absolutely should not be able to push a bullet deeper into the case after seating it without using considerable force. (not with your fingers)

[BombthePeasants]

man, I give up!!

I went and resized all the cases, re-expanded them, recharged them with powder, and reseated all the bullets. Then, when I went to use the taper crimp die, the bullets became loose, and they can fall out easily...

I just don't get what I'm doing wrong.

[brickeyee]

Could be as simple as over crimping.

The taper crimp should only remove the belling and reduce the case mouth to freely chamber.

[Uncle Buck]

Did you measure the bullets? It is very possible that you bought a box that was mislabeled, or that you accidentally picked up the wrong diameter bullets.

[jepp2]

My RCBS set is old (over 30 years), and on it, the expander has a ~.375" long portion, followed by a wider section that is only ~.125" long.

IF they are still using the same style expander, the .375" long section should be the 3-5 thousandths smaller than your bullet diameter. The shorter wider portion should actually do the bell and just barely enter the case.

BUT, they may have changed the design from what I have.

[Sevens]

What is the caliber here? And what is the headstamp of the brass and what exactly are the bullets?

Theoretically, you should seat the bullet and not feel looseness or setback even bore you "crimp" and Uncle Buck made a good point -- over crimping them with a taper crimp can make them loose.

[BombthePeasants]

Today at lunch I should have some time to revisit my setup, and this time I'm going to take measurements. And probably do just 5 at a time, from resizing to finish.