300 Blackout reloading questions

[Lefty Trigger]

This round is new to me and reloading it. I have a few questions...
Is that tiny little shoulder measured or is it a "set die and forget it" type of shoulder?
Does the brass ever need annealed?

 

[DngBat7]

Bump. I have the same questions.

 

[rebel]

I treat it like every other cartridge I load for. Prep the brass right and it's accuracy may surprise you.

 

[DngBat7]

I treat it like every other cartridge I load for. Prep the brass right and it's accuracy may surprise you.

Funny you say that. I bought a cheap 300blk. Bought some Remington 220 subsonic and was shooting sub moa at 50 yards out of 12.5 inch barrel. I don’t know if that was good or not, but I was shocked.

 

[rebel]

I've reloaded for it since 2012. Components were near impossible to get after Sandy Hook so people got innovative. Lots of good information came out of that few years.
You can learn more here - http://www.300blktalk.com/forum/index.php?sid=3df576e9553bb58fcf6d8accbddb9540

 

[DngBat7]

I've reloaded for it since 2012. Components were near impossible to get after Sandy Hook so people got innovative. Lots of good information came out of that few years.
You can learn more here - http://www.300blktalk.com/forum/index.php?sid=3df576e9553bb58fcf6d8accbddb9540

Believe me. I know. I live 20 minutes from there.

 

[dellet]

This round is new to me and reloading it. I have a few questions...
Is that tiny little shoulder measured or is it a "set die and forget it" type of shoulder?
Does the brass ever need annealed?

I treat it like every other cartridge I load for. Prep the brass right and it's accuracy may surprise you.

Without knowing Lefty, but knowing Rebel, I think a bit more information would be useful. Rebel is more likely to produce ammo that would considered “match grade”, not “plinking”

In theory, with good dies and press, it’s set it and forget it, after you’ve measured. Not needing to be changed until you change brass. It’s very beneficial to pay attention the shoulder, maybe more than other cartridges.

With a wide variety of brass available, including converted 223/5.56, and dies made to size the thickest case to the minimum dimension, it’s easy to make ammo that flops around in the chamber like a fish in a bucket. That tiny shoulder needs all the help you can give it.

Another consideration is primer cup hardness or anvil depth. Some single shots and bolt actions have trouble igniting the primer on minimal sized cases do to light primer strikes.

 

[Lefty Trigger]

My rifle is a bolt gun not an auto feeder. Curious though about measuring the shoulder if its a critical dimension. I assume there are specific tools for this like shoulder tools for other rifle calibers. I have never seen any yet in my searching around for reloading supplies.

 

[Lone Hunter]

You might want to contact F. GUFFEY. That would be a shoulder to measure for him since HE is the only one that can do it. I set my dies and forgot it. I'm using an AR platform though. That would be tough to measure the shoulder and I wonder how many different measures you would get.

 

[dellet]

Just about anything you might want is available. It would seem that the smaller the shoulder, the more critical it might be to get it right. But that's an opinion.

Wilson makes their gauge for fired cases. Sheriden makes a very nice loaded cartridge gauge, that will also check sized brass.

Datum diameter is .352" so a .350 bushing in a comparator. In a pinch you can use a 9mm casing that has been sized. Inside diameter will be about .353".

Redding makes a fixed, neck only sizing die, Wilson makes a full length bushing die, Whidden makes a nice set of off the shelf dies. If you want a body only die, use one for a 223.

Annealing can be very helpful for subsonic loads, not uncommon to have a peak pressure in the low 20k range, expanding hard brass in a loose chamber can be difficult to get a seal.

The cartridge has 1/2 MOA potential with a certain amount of work. The tools are available. it just depends on how far you want to take it.

 

[Lefty Trigger]

I got my die set yesterday and was playing around with some junk brass from my recycle bucket and cutting/resizing them. I have no way to measure but they look exactly like my Hornady "length gauge" brass as far as the shoulder goes. I guess I could resize to fit the gun when it arrives, tight bolt,.. screw in die till I get it right. I have a case gauge on the way but it's not here yet.

 

[dellet]

SAAMI base to datum is basically 1.071"-1.082".

If you have any pistol brass that shoots a .355 bullet, size a piece. Zero your calipers on that then case, then invert that over the neck on your Blackout case. Set your shoulder at 1.082".

Redneck engineering at it's finest, but that will give you a piece of brass that is probably within a few thousandths of max, on the long side. Then you can use whatever process you like to shorten the length. Competition shell holders, feeler gauges, screwing the die down.

Or you can wait for the proper tools.

Something to keep in mind converting brass, you might want to run it through a 223 die first to get it sized all the way to the base. otherwise what will happen is the base on a piece of brass fired in another chamber more so if it was a gas gun, will have a good chance of being too big for yours. Then to get the base sized, you will need to set the shoulder shorter than you wanted if you are using the Blackout die to form.

 

[#40Fan]

I bump the shoulder .002" for my gas gun. Annealing helps if you crimp.

Don't go down the subsonic route. You'll be giving the government $200 in a hurry.

 

[rebel]

I bump the shoulder .002" for my gas gun. Annealing helps if you crimp.

Don't go down the subsonic route. You'll be giving the government $200 in a hurry.

Your to damn late man! I needed that advice 6 years ago

 

[628jessejames]

Hey guys I’m new to reloading and to this forum,(just joined this morning). I’m having an issue reloading some of my 300 blackout and was hoping for some help. I’m using 165 grain Speer flat tail bullets on once fired s&b brass with Hodgdon cfe black powder. Their site is telling me to use 17.4 grains to start, whenever I use that much the case swells and is too big for my case gauge. I found that using about 15 grains will allow me to keep it the same COL as my s&b rounds and doesn’t cause the case to swell. It’s not consistent though. I made 10 rounds last night and 4 of them wouldn’t fit the case gauge. I’m using the FL RCBS die for these. Unfortunately my scale is a cheap harbor freight model that doesn’t measure down to tenths of a grain. Is my scale the problem or should I try to hold the bullet out a little farther to prevent the case swelling?

 

[Oso]

Hey guys I’m new to reloading and to this forum,(just joined this morning). I’m having an issue reloading some of my 300 blackout and was hoping for some help. I’m using 165 grain Speer flat tail bullets on once fired s&b brass with Hodgdon cfe black powder. Their site is telling me to use 17.4 grains to start, whenever I use that much the case swells and is too big for my case gauge. I found that using about 15 grains will allow me to keep it the same COL as my s&b rounds and doesn’t cause the case to swell. It’s not consistent though. I made 10 rounds last night and 4 of them wouldn’t fit the case gauge. I’m using the FL RCBS die for these. Unfortunately my scale is a cheap harbor freight model that doesn’t measure down to tenths of a grain. Is my scale the problem or should I try to hold the bullet out a little farther to prevent the case swelling?

Quick answers / suggestions - general quick & dirty:
1. Powder: CFE Black is good. There are some other proven powders as well.
2. Bullet: Blackout performs best with light bullets (110gr - 125gr) for supersonic loads, and heavy bullets (195gr - 220gr) for subsonic loads. Some proven supersonic performers are the 110gr Barnes TAC-TX (hunting), 125gr Speers TNT (good practice round), 125gr SMK (target), 150gr Speers Gold Dot (best heavy supersonic). Subsonic bullets are less picky so long as barrel twist is fast enough to stabilize heavy bullet.
3. Brass: S&B cases are pretty, but the brass alloy is extremely tough. It has a lot of spring back... case doesn't resize easily. Annealing the brass may help, or just moving to different type of brass may be easier. You may be doing everything right and the brass may continue to frustrate your efforts. I discovered the chalkenges with S&B brass when I first started forming 300BO cases from 223/5.56 cases. You could tell it

Additional Resources to read:
Do a search on this forum for posts by member DELLET, who is a resident expert in 300BO.
Johnny's Reloading Bench (YouTube channel) did extensive series on 300BO covering all aspects, heavy on reloading/Testing different powders and bullets.

 

[628jessejames]

Quick answers / suggestions - general quick & dirty:
1. Powder: CFE Black is good. There are some other proven powders as well.
2. Bullet: Blackout performs best with light bullets (110gr - 125gr) for supersonic loads, and heavy bullets (195gr - 220gr) for subsonic loads. Some proven supersonic performers are the 110gr Barnes TAC-TX (hunting), 125gr Speers TNT (good practice round), 125gr SMK (target), 150gr Speers Gold Dot (best heavy supersonic). Subsonic bullets are less picky so long as barrel twist is fast enough to stabilize heavy bullet.
3. Brass: S&B cases are pretty, but the brass alloy is extremely tough. It has a lot of spring back... case doesn't resize easily. Annealing the brass may help, or just moving to different type of brass may be easier. You may be doing everything right and the brass may continue to frustrate your efforts. I discovered the chalkenges with S&B brass when I first started forming 300BO cases from 223/5.56 cases. You could tell it

Additional Resources to read:
Do a search on this forum for posts by member DELLET, who is a resident expert in 300BO.
Johnny's Reloading Bench (YouTube channel) did extensive series on 300BO covering all aspects, heavy on reloading/Testing different powders and bullets.

Right on, thank you for the info! I’ll check that out. I was wondering if it could be the brass too. I’ll try more out tonight and post some results hopefully.

 

[SDDasher]

Hey guys I’m new to reloading and to this forum,(just joined this morning). I’m having an issue reloading some of my 300 blackout and was hoping for some help. I’m using 165 grain Speer flat tail bullets on once fired s&b brass with Hodgdon cfe black powder. Their site is telling me to use 17.4 grains to start, whenever I use that much the case swells and is too big for my case gauge. I found that using about 15 grains will allow me to keep it the same COL as my s&b rounds and doesn’t cause the case to swell. It’s not consistent though. I made 10 rounds last night and 4 of them wouldn’t fit the case gauge. I’m using the FL RCBS die for these. Unfortunately my scale is a cheap harbor freight model that doesn’t measure down to tenths of a grain. Is my scale the problem or should I try to hold the bullet out a little farther to prevent the case swelling?

Welcome to the forum. Also, Welcome to reloading. The best advice I think I’ve received over thirty plus years reloading was to research your cartridge thoroughly before embarking on producing your own ammo. Reloading is tremendously satisfying when successful and deadly dangerous when attention to detail and caution are ignored. You’re in the right place among some of the most knowledgeable and helpful Reloader/Shooters you could hope to find. Good luck and be safe.

 

[Bill K]

You load it and set your dies up, for it, just like you do anyother bottle neck cartridge, big or small shoulder.
Back you sizing die off, 1/4-1/2 turn, so as to not bump the shoulder back, after it has been fired in your chamber and leave it there, unless after a few reloads it does need a slight bump back.

 

[dellet]

A few things that need to be checked first.


[QUOTE="628jessejames, ]I found that using about 15 grains will allow me to keep it the same COL as my s&b rounds
Loading a different bullet generally requires a different COL. Even using the length from Hodgden may get you in trouble, since they list a completely different bullet also. There is a way to use the same seated depth, but you still need to make sure it will not hit the lands at that length.

I’m using the FL RCBS die for these. Unfortunately my scale is a cheap harbor freight model that doesn’t measure down to tenths of a grain.
If your scale will not weigh down to a tenth of a grain, 0.1, throw it in the garbage before you get hurt. Scales are only accurate down to the second to last number. A scale that will not read 0.1 will be read 1+/-.5, plus or minus 1/2 grain. Your 15 grain load could be 14.6-15.4 grains.

Is my scale the problem or should I try to hold the bullet out a little farther to prevent the case swelling?
Doubtful, unless you are seating really deep/short. Knowing what your COL is a must.
[/QUOTE]

First and foremost, what exact bullet are you using, or length. Speer makes three different 165 grain bullets, 2 are flat base and what is your COL?

At 17.4 grains the powder will not be up to the bottom of the neck, so that is not likely the issue. unless you are seating very short.

My guess is that it is more of a bullet seating issue than compressing the powder so much it's expanding the case. Brass may be too thick if it's converted, you can measure that and it should be less than .335". You can also seat a few without powder and see if they fit the gauge. If you are using a seating die that crimps at the same time or crimping too much are also good possibilities for trouble.

Side note, never start at the top of the load data.

Below is a link to one of the Speer bullets, it has the length listed, Is that your bullet or the other one?

https://www.speer.com/bullets/rifle_bullets/hot-cor_rifle_bullet/19-2035.html

This is Speer data for their 165 grain bullets, loading to that length is probably not a bad idea.

https://reloading-data.speer-ammo.c...e/30_caliber_308_dia/300_AAC_Blackout_165.pdf

Again pretty sure that it's not powder compression, and there are ways to confirm that also, but let's start at the basics.