.300 BO powder

alucard0822 · Sep 26, 2018

John from MD said:
I have been shooting the 300 BO for some years now in a 16 inch carbine gas set up. I have no problem using standard SR primers with h110 or Lil Gun. In .44 Magnum pistol, I use magnum primers to get better burn efficiency but I have never had a problem in the 300BO. Perhaps pistol gas setups and pistol length barrels may need magnum primers but I don't see the need in a carbine.

Was getting some vertical stringing, and about 100fps variance with CCI400 and CFEBLK out of 110, 150, and 208gr(sub), worst was with 150gr supers, CCI450 magnum primers cured it, and shrunk the group size noticeably. I am shooting/testing out of a 9" with pistol gas, so that may be some of the difference. Already switched to magnum primers when working up H110(110-150gr) and A1680(150, 208, 220plated), and both powders did fine, but being I never loaded them with std CCIs, I don't have standard primer data to compare them to. In the past with H110 in nuclear 357mag loads for my 16" lever Carbine(similar loads to 300BO), I had no problem in the summer when working up the load, but groups opened up, mostly vertically when shooting in the fall/winter, switching to magnum primers cured that too.

ADCOLE · Sep 27, 2018

kstone803 said:
Oddly enough I am getting horrible results with 220 subs and cfe BLK. Like 150 fps deviation in velocity consistently. I'm going back to 1680.

I'm curious to know what barrel you are using? I have a 16" and 10.5" Black Hole Weaponry barrels with 1x7 twist. I've never experienced any deviations like that.

alucard0822 · Sep 27, 2018

kstone803 said:
Oddly enough I am getting horrible results with 220 subs and cfe BLK. Like 150 fps deviation in velocity consistently. I'm going back to 1680.

Magnum primers? I had the same issue before I switched to them, CFE BLK usually gives a compressed charge of what is essentially a really fine grained slow pistol powder, 100+FPS variance on CCI400s, shrunk to about 25FPS out of 10 shots with 450 magnum primers.

Magnumite · Sep 27, 2018

Are you fellas using cannulared bullets and crimping into the cannular?

John from MD · Sep 27, 2018

Yes, I crimp both my lead and jacketed bullets with a medium crimp. While I don't crimp on precision rifle cartridges, I do on semi autos because of the knocking around that they get.

OLM-Medic · Oct 4, 2018

what are you guys using for cheap plinking boolits?

It looks like 147gr .308 FMJ is the cheapest. I usually like my plinking ammo to be similar to my primary ammo for POI reasons, which is currently 123gr, but whatever can go boom.

I might load some decent ammo but I mostly just want to get some close range drills, and steel plinking at 200, cheap ammo for more trigger time right now.

OLM-Medic · Oct 4, 2018

I'd also like to also load some supersonic defensive loads, but I haven't decided which yet. I have a philosophy to only trust factory ammunition for true SD/HD, so defensive reloads would just be to supplement that so I could afford practicing with the good stuff assuming POI is roughly the same. Unfortunately, Barnes TacTX is just too damn expensive. I have one mag of it for HD but my go to ammo is just FMJ for now.

I need more trigger time with this anyway, so my primary concern is just practice ammo, but I'm open to suggestions here too.

John from MD · Oct 4, 2018

OLM-Medic said:
what are you guys using for cheap plinking boolits?

It looks like 147gr .308 FMJ is the cheapest. I usually like my plinking ammo to be similar to my primary ammo for POI reasons, which is currently 123gr, but whatever can go boom.

I might load some decent ammo but I mostly just want to get some close range drills, and steel plinking at 200, cheap ammo for more trigger time right now.

I use lead 150 grain bullets. I have a NOE four cavity mold which makes a bullet similar to the one that Lee designed for the 7.62x39. They are great for short range trigger time. :party29:

Muleskinner · Oct 4, 2018

H110 is what I use for my 120grn. I haven't taken possession of my can yet so I haven't worked up a sub load

kstone803 · Oct 4, 2018

ADCOLE said:
I'm curious to know what barrel you are using? I have a 16" and 10.5" Black Hole Weaponry barrels with 1x7 twist. I've never experienced any deviations like that.

10.5" off brand barrel. Honestly don't remember the mfg right now.

alucard0822 said:
Magnum primers? I had the same issue before I switched to them, CFE BLK usually gives a compressed charge of what is essentially a really fine grained slow pistol powder, 100+FPS variance on CCI400s, shrunk to about 25FPS out of 10 shots with 450 magnum primers.

Standard small rifle. I'll pick up some magnums next time I order. I haven't really had time to mess with it in the last few months. Between the Nosler 220 Ballistic tips keyholing, my RAR keyholing literally everything I put through it and the inconsistent velocities from the AR build I kinda back burnered most of my 300 BO projects.

Speedluvn · May 10, 2020

I’m new to reloading. I’ll be loading rifle; .223 & .300 blackout. When ranges open I’ll be testing a newly built .300 with a 10.5 inch barrel and newly made reloads. It seems that I’ll be using some Winchester 296. I just received some Winchester 748.
Reading this old thread, it seems I should be using magnum primers for the .300? Rifle magnums, correct? The bullet is 147 gr, if memory serves me correctly.
Looking for input.

outrider58 · May 10, 2020

Speedluvn said:
I’m new to reloading. I’ll be loading rifle; .223 & .300 blackout. When ranges open I’ll be testing a newly built .300 with a 10.5 inch barrel and newly made reloads. It seems that I’ll be using some Winchester 296. I just received some Winchester 748.
Reading this old thread, it seems I should be using magnum primers for the .300? Rifle magnums, correct? The bullet is 147 gr, if memory serves me correctly.
Looking for input.

I only use hot primers for subsonic 300 Blk. Supers get standard SRPs.

John from MD · May 10, 2020

For a 16inch barrel, I have always used standard primers. Since you are using a 10.5 inch, you may get a more efficient burn with magnums but I don't know for sure. It can't hurt anything but your pocket book to try.

Speedluvn · May 10, 2020

Thanks for the responses!
These will be my first batches of rounds that I’ve reloaded.
So when I purchase the magnum rifle primers, there’s no small or large magnum rifle primers, only magnum rifle primers?

John from MD · May 10, 2020

You want small rifle magnum primers as the 300 BO case uses the same primer as the .223/5.56.

Speedluvn · May 10, 2020

John from MD said:
You want small rifle magnum primers as the 300 BO case uses the same primer as the .223/5.56.

Thank you! The learning curve is steep.

John from MD · May 10, 2020

May the Force be with you.

Kirkster · May 10, 2020

Good thread. I finally got my 300BO running as my first stab at a 300BO build would not run on the superlative arms piston with the carbine gas length op rod. With a piston length gas system barrel and op rod it is running great with 1 and 3/4 turns out on the block to have it run and lock back the bolt with no issues. Next up will be me loading up subs... and getting a can or two.

.300 BO powder

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