300 BO brass issue

zenmariner · Oct 1, 2020

So I reloaded some 300 BO for some tests using 230 gr berger and a 185 berger with 7-9 grns of win 296 for the 230 and 14-15 grns of the same. Shot it thru a BCM 9" upper with an aero m4 lower. After shooting 5 rounds of each I noticed the brass was flattened on one side. Anyone have an idea as to what may cause this? All this cycled through the gun just fine though no bolt lock on the 185's.

DizzyJ · Oct 1, 2020

Shell deflector?

What's the ejection pattern?

zenmariner · Oct 2, 2020

Was throwing them slightly behind and about 2-3 feet

DizzyJ · Oct 2, 2020

zenmariner said:
Was throwing them slightly behind and about 2-3 feet

So 4-o'clock?

T22 · Oct 2, 2020

Deflector Brake Kit: Guides Spent Brass into Pile, Protects Rifle Paint/Coating, Saves Brass for Re-Loading, Prevents Brass-Burn, Fits Standard Brass Deflectors (Black) Amazon.com : Deflector Brake Kit: Guides Spent Brass into Pile, Protects Rifle Paint/Coating, Saves Brass for Re-Loading, Prevents Brass-Burn, Fits Standard Brass Deflectors (Black) : Sports & Outdoors

Yes, it's over-priced. No, you don't need it. Just resize and it'll be fine.

zenmariner · Oct 2, 2020

Right around 4 oclock

zenmariner · Oct 2, 2020

Never heard of those was going to anneal and resize just wondering why this would happen. Didn't have an issue with the 110 gn RN i loaded or any of the factory ammo I have shot thru it

T22 · Oct 2, 2020

Looking at it a little closer, your loads might be a little hot. The only suggestion I have is drop your starting load by around a grain and see what happens. When I first started reloading 300blk I was WAY overcharging and it sounds a lot like your scenario.

Helocat · Oct 2, 2020

T22 said:
Looking at it a little closer, your loads might be a little hot. The only suggestion I have is drop your starting load by around a grain and see what happens. When I first started reloading 300blk I was WAY overcharging and it sounds a lot like your scenario.

I second this line of thinking if other loads don't have this issue with the same gun.

zenmariner · Oct 2, 2020

Interesting i was following Hornady's recipes bit using Berger bullets thinking 230 grn bullets would be similar in powder weights. Now I wish my chronograph worked as it was giving me lots of err or readings. Will need to go back and revisit the loads but was working a ladder from 7 grns win 296 to 9 grains. This happened on 16 of 29 rounds I had fired. Need to redo and check each piece of brass now

T22 · Oct 2, 2020

I've started checking Hogdon, Hornady, and Lee load data and making an average start point from all of their combined info. There is always the possibility that your load is fine and you just need a heavier buffer or spring. Or, if you have an adjustable block, that you reduce the gas flow. However you choose to fix it, it seems like there's too much gas and you're cycling faster/harder than optimum but that is just my best guess based on personal experience.

zenmariner · Oct 2, 2020

T22 said:
I've started checking Hogdon, Hornady, and Lee load data and making an average start point from all of their combined info. There is always the possibility that your load is fine and you just need a heavier buffer or spring. Or, if you have an adjustable block, that you reduce the gas flow. However you choose to fix it, it seems like there's too much gas and you're cycling faster/harder than optimum but that is just my best guess based on personal experience.

I believe i have an H2 buffer may need to go up 1 more as well as a green spring. Shooting those rounds felt like it was cycling really fast. The 110's i loaded did not want to eject and they had the most powder. Unless I totally screwed up and mixed everything up

. This is my first black out build and I want to make sure everything works as far as my loads go especially the subs as my can should be freed here by Nov/Dec. appreciate the help

Rockys · Oct 3, 2020

Welcome to the short barrel 300 black out world. They can be finicky beasts. I've had bolt bounce and double feeds with pistol length gas tubes with large ports and higher power loads. Each combo has its sweet spot. Just take your time and work the loads carefully. I've had factory fiocchi ammo that popped primers. My go to load is 10.5gr aa 1680 with Hornady 208 amax.
And lancer mags are the best I've found for feeding and bolt hold back.

zenmariner · Oct 3, 2020

Rockys thanx for the info. The crazy part is i got good groupings with most of the different rounds. Will be revisiting my loads again to see if I can cure this problem. I bought 3 different powders for this project and win 296 was the first go round. The 110's had a feeding problem I think more due to the really short COAL. Going to stay with the heavier bullets and see if I can find a good load to use with my can whenever it shows up.

DizzyJ · Oct 3, 2020

Generally a 3-4 o-clock ejection pattern is desirable. Generally that means you're not over gassed. However, the ding in the brass looks like it's from the deflector and over gassed, so.....