forming 300 blackout brass

[257]

hi there when forming 300 blackout brass from 223 lakecity brass it seems that they will fit the gage but when you let them sit a couple days the o.d. of the necks grows about .0045 and then when you try to seat a bullet it expands the o.d. even more then the don't even fit in the chamber.were using redding dies. maybe anneal the necks first ? or change to commercial brass (rem) I would not think we would have to neck turn the o.ds. or ream the neck i.d.s any help would be appreciated thanks

[andremajic]

Your LC brass should work just fine.

The 300 BLK was designed so that LC brass could be used without the additional neck reaming/turning that was required for the 300 whisper.

I've never had to anneal mine, but other members here do. Never had a problem with un-annealed.

Is it brand new once fired LC with the primer crimps or has it been reloaded before and possibly work hardened?

Is the barrel new and possible just not reamed deep enough? Have you tried chambering a factory round?

[Djs3909]

I just made some with lee dies. No problems here. I did anneal mine first however. If your only making a few use the torch/water method. I have a Giraud ;)

[petroid]

More info please. If you give details of your process it will help determine what the issue is and help find the solution. Have you done a chamber cast/throat slug. What is the OD of a fired case mouth? What size are your boolits. My factory loaded cases measure about .330" at case mouth with a .308 jacketed bullet. My formed loaded cases measure about .333" at case mouth with a .310 boolit. Formed unloaded cases measure .328" I anneal after forming so I don't know what they measure without annealing. A fired case in my gun has a mouth OD of .335 so I know mine will chamber.

[Djs3909]

I did not do a slug. I usually seat long and use sharpie until I no longer get rifling marks. I am using Nosler 125gr ballistic tips in a R700. I haven't fired this new batch yet. I will give you all the measurements after the range on Tuesday. My loaded neck is .330 and the bullet .308

[Djs3909]

Try annealing first. I do every time. I don't think you will get the springyness and maybe the mouths won't grow as much. That's why I do it before sizing

[W.R.Buchanan]

Maybe you should PM Grumpa. He makes and sells the stuff by the carload. Maybe if you ask real nice he'll share some of his technique with you.

Randy

[petroid]

Methinks if the bullet is still expanding the brass when seated then the neck is not oversize to start with. SAAMI spec for neck OD is .3340 and chamber should be .3350 at mouth and .3370 at start of shoulder. If you are getting fatter necks than that then there is something wrong with your brass or dies. Lake City brass shouldn't give neck thickness problems. Some .223/5.56 brass is thicker in the body and when forming BLK brass gives thick necks which must be inside turned and resized. If your loaded round is .330 neck this is not the case. You may have a tight chamber or throat. 300 BLK usually requires long ogive bullets/boolits to achieve published OAL without engaging the lands. Many bullet profiles will have to be seated to a shorter OAL to allow chambering. A throat slug would tell you what you need to know to make your rounds chamber properly

[runfiverun]

even with .0012 brass a 308 bullet should easily chamber.
I got some .0010 brass for shooting cast sized to 310, and made some L/C brass for jacketed loads.
my chamber/neck is cut tight though. [on purpose]

I have seen some issues with older hornady dies not making brass work properly, it may be corrected by now but I bought a set of rcbs dies and put my unopened hornady dies away until I get a better handle on what is exactly what with this little round.

[GRUMPA]

I saw this and then I noticed the date on when it was posted and figured it may be just a tad on the late side. I've never experienced the growth in the neck area at all, nor have I ever heard of this issue.

Maybe it may be the technique I use but from the other folks that make their own, I've never heard of it either.

If a person were to form brass in just 1 step I can see this issue, but not likely.

When I do mine they go through 4 different dies to take out what's called "Spring Back". Brass can and will want to move when forming into something else. This has always been the case and with all the cases I form I have to use a different technique when I form them. This is where notes come in and I have to keep it updated because even though it may work just fine the first time, a person notices subtle changes when the head stamp changes. Which is why when forming any kind of brass, always use the same head stamp.

When I do my conversions I use an indicator and check the new gauge dimension all the time throughout the run. To some this is completely overboard but I want to know what the brass is doing at all times till it gets completed.

Out of all the 300BO brass I do in an average year I have yet to hear of a fail to function from a bad case.

And with most of my brass, annealing is the very last thing I do to them just before they go into the shipping box. I wont say I do this with all of them, but I only anneal I think 1-2 conversions before hand and the 300BO isn't 1 of them.

[6bg6ga]

Since this is a thread on forming the 300 brass I will mention that I formed my first cast this morning. The result is the decapping rod got stuck in the case and I had to wreck a case in order to get it out. It simply seems too small and I pulled the rim off the case trying to extract the case. The dies are new RCBS $22401's Any ideas?

[dragon813gt]

Did you lube the expander and the inside of the neck? If not, that's why it stuck. I usually just put a little bit more lube on the inside neck of the first case to lube the expander up. This is a simple conversion which takes very little effort.

[6bg6ga]

Did you lube the expander and the inside of the neck? If not, that's why it stuck. I usually just put a little bit more lube on the inside neck of the first case to lube the expander up. This is a simple conversion which takes very little effort.

Yes the case expander was lubed properly. Upon measuring it I am too long and the neck is actually distorted a little at the top of the neck. I'm going to cut some off a little shorter and try it again and see if there is a difference.

I believe that I read the length was supposed to be 1.370 when cutting down .223/5.56 brass.

[Gunor]

Same stuck expander in a Lee. Now I just form w/o the expander. De-prime with 223 FL dies, and use a Sinclair expander (from neck turner) to get the right ID, with a lube every few cases.

then to the dillon super swager for the other end. Gracey trimmer.

geoff in Oregon

[rockshooter]

I deprime/resize with a .223 sizer die, cut the shoulder off, resize/form with a 300 die that has a .223 depriming pin, get the ID with a Lyman "m" die. Once the case is made, I reload it without the initial.223 step. The initial .223 step may be redundant but since 300 and .223 have the same body at the bottom, it makes for really easy .300 sizing and I don,t have to worry about the regular 300 inside sizer getting stuck, having had the same issue as the OP.
Loren