Problems forming 300 Blackout brass??? Why results may vary. 

Great information, thanks for sharing. I am working on a 300 blackout build now and this information will come in handy when I get ready to reload.

Had the same issue with my Lee FL die. Ran my Hornady brass thru my Hornady die and it worked. Thanks for the valuable information.

I was talking about this to a friend who just built one. I gave him some reloads, most formed from 223 using a Lee resizing die. I use the Lee die sets. My guns chamber them fine but his is near the minimum. I asked him to measure factory rounds to mine, and he came up with .003-.004 larger at the base of the case. You explain it much better than I did. Thank you.

Thanks! Having issues and I checked my brass thickness. .14 to .19. Think I found my problem. Using Lee die too.

Just had this issue, thanks for the video!

A Faxon Match grade barrel is a little tighter in chamber. Some cases won’t fit using any die. The area of some cases that end up as neck after being cut down vary in thickness which were side wall of case. I bought Hornady Neck Turning Tool and turned down the neck. More time and trouble but it works. When SHTF days arrive you may need to be able to do it all. Solved my problems. There are several brands of neck turning tools, Hornady medium price NOT $600-$800 like some, or cheap ones that don’t work as well.

Good video educational👍 my luck was not good with the short base die in 5.56. I had to bottom the die on the ram and back off a full turn. Anything lower was crushing the shoulders.The Lee die I can bottom it and add a turn and it is good

Great demonstration!

I had some problems using the lee dies at first. I then polished the bell on the decapping pin and the inside of the die itself using a Dremel and some flitz polishing compound, now no more problems. The compound doesn't remove any material from the die, it just polishes to make it as slick as a baby's behind.

The most useful purpose of the small base die is sizing the area near the case head down to remove a bulge from brass fired full auto which often fire on an open chamber. Some well used M16 barrels will go out of spec creating a larger base after normal firing as well. Generally I've found the small base die sizes the top of the brass to normal spec. You can also remove the bulge of a 5.56 case using a Lee Bulge Buster kit with a .380ACP factory crimp die. It sizes the 5.56 bulged cases same as a small base die. A little hint. The Lee primer tool uses a specific shell holder. A #4 shell holder is for 380acp and .223/5.56. If the case does not fit well into the shell holder for the Lee priming tool it usually signifies the case is bulged as the base and needs to be run through a bulge buster or small base die. It is actually more accurate than the case gauges as a guide. After going through the bulge buster or small base die the formerly bulged cases will drop into the #4 shell plate of the Lee Primer Tool easily. If you are forming the 300 blackout cases with any die remove the decap pin and neck sizer to form the cut brass. Bevel the brass inside and out then resize and deprime again later to establish the neck tension for the bullets. It makes forming go easier and takes less effort.

I do all my full length resizing on a heavy cast press. I started reloading on a RCBS Partner press & I found out the aluminum cast frame isn’t robust as it flexes enough to cause problems when I resize larger calibers & reforming making new brass. I even surface ground .003 off one of my shell holders to push the brass up further into the die but found out my press was flexing. I now resize & form on a RCBS Jr heavy cast or on my Redding heavy frame press & all my full length sizing & reforming problems went away. I now use my Partner press for light duty work like decapping & bullet seating.

Thing about the RCBS SB die, it is only a small BASE die; and won't necessarily bump the shoulder back further than another given die. Using a 3 step Sheridan case gauge, I found that the RCBS die adjusted all the way down struggles to resize to SAAMI GO dimension, let alone somewhere between GO and minimum brass dimension which is where I try to form to. My Hornady die won't size the base down as narrow, but I can adjust it so the re-formed brass is where I want it via the headspace gauge. My new Dillon size die was delivered this morning and I am looking forward to trying it out.

Thanks for making this video, a friend of mine and I are getting into this new cartridge and since he has some experience in reloading we have decided to form our own brass rather than buy new. I have heard from some people at 300blktalk say they have problems with using the Lee dies to do the initial case forming while others say they swear by the RCBS. I think I found the die I need but I'm not too sure, its the RCBS .300 AAC Blackout Full Length Sizer Die #22429, is this the one that is also called the small base die? I have also read on websites that sell reformed brass from old military casings but they use a Forster die set, what's the difference other than the brand name? Does Forester go down to an even smaller tolerance than RCBS?

Subscribed good stuff

would you recommend annealing the brass before forming the 300 aac case. Or is it better to form the case first then anneal it?

Thank you for the info. I'm having serious issue with some not all of my 300's I make. I use a Dillon RT1500 to trim and reshape them into 300 BO and then run them thru my Dillon resize die on my 550. Some will shoot great. Some I'm breaking rifle down to pull the bolt out and free up case. I've been doin this for some time now and thought my issue was trim length. So I readjusted every thing and have it spot on. I have run all pieces thru case gauge and they are great. Go outside shop door and shoot some and I'm getting same issue. I'm really thinking I need a small base forming die at this point now. Then resize when I'm loading. Thoughts ???

I use the RCBS .300 AAC BLACKOUT SB T/C SET P/N: 22407 All my cut down 5.56 brass is reformed to 300 Blackout using this die set alone.

You can resize 223s or 556s using any 300 blackout die. Here's a tip. It takes a few tries, but if you set your cutting die on your saw correctly, you will make perfectly sized cases when you resize them in your die, and there won't be any need to trim them. Only thing you'll need to do is deburr the in and outside edges. Second tip, if you're going to make 300 blackout, buy a case gage. It's a must!..... Happy reloading!

Tree top flier is a great song!

Before cutting them down could you use a Lee 223 small base die to size the base then run it through a LEE 300 BO die after cutting them down?

I just made some from lc brass and my neck is higher than my actual 300 Hornady brass. Is this because my Lee full length die is to high?

hodgon data has mine for weight of 145 grain i was told to bump up to 150 grain have to seat the bullet part ways to 2.2350 18.8 loads but saammi shows 2260 . 11.5 grain seating bullet by harnady data according to the gunsmith

If you have a Daniel Defence DDM4 PDW don't waste your time on the Lee set, go straight to the RCBS small base die set. I've never had an issue with any of my lee dies until this gun. I was the 450th like!

When I use my Lee sizing/depriming die, it makes a shoulder much shorter than new brass. How come?

What do you know about light primer strikes on reloaded ammo?

Before forming , anneal brass first

Get a Sheridan case Guage

like

Mark up the brass with smoke

RCBS dies work the best for forming your brass

Just use 5.56 brass when the neck wears out and breaks

Rcbs small base resizing die

Taking a usefull cartridge and making it worthless? Sounds like a great use of time to me.