cast bullets in 300BO

[KenH]

Hello all. I've been shooting the 300BO a bit, testing loads, etc. I have a couple of questions here. With groove diameter slugging at .308, the cast bullet needs to be .310". If the brass neck thickness is .012" that's just right on the max of .334" for chambering. Some of my brass will chamber with a .310" bullet, but other is a tight .335/.336". Using PC'd bullets the neck ID needs to be at least .309" with a slight bell for the bullet to seat nicely without shaving any of the coating. The Lee die set has a collet crimp, but that only crimps the very front of neck leaving a larger diameter behind the crimp. I'm thinking to make a neck sizing die only for the final step in loading to squeeze the neck to be sure it's .334".... or maybe even .333" OD?

I've shot both an Ideal #311415, 170 grain cast, and yesterday worked with the Lee .309-230-5R mold. That BT just doesn't work! I beagled the mold so it's now a straight sided bullet at .310 for the last 1/2" with the lube grooves almost gone at 232 grains cast WW type alloy. Shooting sub loads - 4 rounds of 8.0 grains of IMR4227 which ejected shot brass, but didn't pick up next round from mag. Then 4 rounds of 9.0 grains IMR4227 which ejected and picked up next round, but didn't lock bolt back on last round.

I ran these 8 rounds thru the sizer die and it pulls the neck down nicely, but they didn't shoot good at all with a 3" group at 30 ft. Then I realized by squeezing the neck down with sizing die I was also squeezing the diameter of bullet down below the desired .310".

Does my idea of using a neck sizing die to squeeze the neck OD down for good chambering make sense?

Thanks to all for any suggestions 'n guidance,

Ken H>

[plant.one]

what headstamps of brass are you using that put you right at or just over the diamater?


have you verified that they're on the good list in regards to the good/bad/ugly brass conversion thread?

viewtopic.php?f=141&t=88599

[dellet]

I ran these 8 rounds thru the sizer die and it pulls the neck down nicely, but they didn't shoot good at all with a 3" group at 30 ft. Then I realized by squeezing the neck down with sizing die I was also squeezing the diameter of bullet down below the desired .310".

Does my idea of using a neck sizing die to squeeze the neck OD down for good chambering make sense?

Thanks to all for any suggestions 'n guidance,

Ken H>

Neck sizing a loaded round, in the most polite way I can say, is just plain stupid. What you have done is applied a super crimp. With the right powder and bullet combination, even in a subsonic load, you risk an unhappy day. Never mind the possibility if sticking a live round in your die and having to find a way to safely remove it.

Either turn the necks on the thick brass, use it for jacketed bullets or toss it.

Check the headstamps as plant suggested for a start.

[KenH]

In all politeness, maybe I ask the difference in "neck sizing" by .003" and crimping a loaded round? Much less stress/pressure is placed on cartridge with a .003" neck size than a fully crimp. Oh, wait, now I understand your comment, it was when I ran the 8 rounds thru the sizer die? Yea, that was sorta on dumb side. At least I did have top open with necks fully lubed for easy in, easy out..... still dumb.

The sizer die I'm referring to for .003" is a custom made die that fully encloses the brass with the top fully open just as a crimp die is. Only different is where the crimp die puts a crimp right on end of brass, this die "sizes" the neck full length so the max diameter is .333". We're talking only squeezing .002" or .003" or less. Very low stress.

I do realize even with the brass fully contained inside the body of a sizing die, where the primer to be fired, things would be more than interesting. That's why a crimp die should fully enclose the brass with the top of sizing die fully open (as all I've seen are).

Yes, they are on the "good" list with neck thickness of .012" - FC headstamp. Problem comes in when putting a .310" cast bullet inside the brass - .310" + .024" gives .334" which just doesn't seem to chamber very well in my Anderson barrel.

When you mention "turning the brass", do you chuck brass on a mandrel in lathe and turn outside diameter of brass so the neck thickness is only .010" range?

Ken H>

[dellet]

I think you are missing some fundamentals, I would encourage you to do a little reading. Or maybe I need a better understanding of what you're doing.

The best way I can explain the difference in crimping a bullet, and resizing the whole neck with a bullet inserted is this:

Go get a hanging scale or a set of weights. Pull the scale by pinching it with your thumb and finger, see how much you can pull. Now grab it with your fist and pull. That will give an idea of the change of firing pressure of your cartridge between a regular crimp and a full length neck resize with the bullet seated crimp.

If your cartridges are sticking on the neck in the chamber at .334, your chamber is undersize, it should have been cut at .335 as a minimum. Is it possible your bullet is sticking on the lands of the rifling?

If your necks measure .335-.336 and your brass is .012 thick, and your bullets were sized to .310, some how you are distorting the brass when seating the bullet.

A good explanation of neck turning will be in your reloading manual. It will be better explained there than I can do and will likely have photos of the equipment needed.

The open top of your neck sizing die may not help you of the round goes off. The pressure will take the path of least resistance. That might be the bullet exiting the top of the die, that might be pushing the case and press ram back the direction it came from. That will be determined on if it is easier to push the bullet out of the neck that is jammed in the die, or have the case rupture and leave the neck and bullet in the die while the rest blows out the bottom.

A neck sizing die is designed to collapse a hollow brass cylinder. It is not designed to swage a piece of brass around lead. Even .002-.003 will take a fair amount of pressure.

Hope that helps sort out why I think this is a really bad way of fixing a problem that you have really not identified.

[bangbangping]

If your cartridges are sticking on the neck in the chamber at .334, your chamber is undersize, it should have been cut at .335 as a minimum. Is it possible your bullet is sticking on the lands of the rifling?

If your necks measure .335-.336 and your brass is .012 thick, and your bullets were sized to .310, some how you are distorting the brass when seating the bullet.

This.^

Also, are you sizing your bullets or using them as cast? There could be variations in the bullet diameters, too.

And danger issues aside, if your brass has neck thickness inconsistencies, squeezing the necks down will just transfer the inconsistencies to the bullet diameter. That can't be a good thing.

[plant.one]

listen to these guys and stick with whats known to work - and do so safely.



i'd say you got very lucky shooting those neck sized rounds and likely your low charges is what saved your bacon. We'd rather keep you around for a while and that practic has a greatly increased probability of ruining your day, and maybe quite a bit more than that. Gods forbid you were to have tried that with a cast super round - eek!

stick with the lee FCD for removing belling. it works - and removes a properly applied bell for seating cast no problem.





what i would suggest, get yourself a slotted sheridan gauge. that will allow you to test your ammo before you attempt to chamber it. If they pass the gauge and still fail to chamber, then you need to have a chat with your barrel manufacturer (which already seems a possibility right now).

Makes a few dummy rounds and see how they go into the gauge (just bullet and brass - no powder/primer). .334 neck diameter is maximum cartridge, .335 is minimum chamber (what the gauge is cut for) so a .310 cast sub in a .012 neck should go in there no problem.


the .309 cast i've loaded into LC brass pass a sheridan just fine.

[KenH]

OK, I took a while to think about this some before responding. First allow me to say "Thank You" to all who posted and made suggestions. I think I was not able to accurately describe what I meant by a "custom neck sizing die". It is actually less than crimping die as far as stress on cartridge goes. I do see it can be a bandaid fix for a problem rather than fixing the problem itself.... I'm looking for plated bullets. Is there a source of plated bullets ya'll would recommend for 300BO shooting with loads <1300 fps or so. Not looking for fully sub-sonic, but low power loads, just enough to cycle the AR. I'd like to be able to find bullets in the 10 to 13 cent range.

Berry's has 30-30 150 Gr Round Nose Flat Point, but I've read FP are not good for AR feeding?

How well does 110 - 125 grain bullets work for 300BO for shooting paper?

I understand with plated bullets you use bore diameter of .308" just as with jacketed bullets? I've been shooting plated bullets in a 9mm with good results.

BUT - I did shoot a few rounds today using the 232 grain cast I've got. These were loaded with 9 grains IMR 4227, shooting about 50 yds from a good rest. The vertical spread was VERY good at less than 1/2", but the horizontal spread wasn't too good at a bit over 2" - not happy with that. Not sure what was giving the horizontal spread.

Thank ya'll again for help and suggestions.

Ken H>

[lawboy]

Stop beagling the mould and try gas checking the bullets. Mine shoot fine gas checked.