Brass & accuracy

[Nomad88]

Not looking at long range precision here.

But for 300BO subsonic out of a bolt gun. I’ve always used alpha, Peterson or lapua in my higher end rifles. I recently picked up a Ruger in 300 and locally the only brass I could source was Winchester. I’ve never used it before and have never really heard good things about it, but that was always at matches where most people use the highest and stuff they can get. I had a group with 190 sub X that shot 3/8 of an inch, so I loaded up some more and I have 3 to 4 inch groups, some with verticals stringing mixed in with the same load now. Is it possible that poor brass quality could be causing this or was it just a fluke when it shot the good group?

 

[Jager]

Doubtful it's the brass.

 

[RegionRat]

Likely you have a lucky group if that was for a 190 SubX and it was going subsonic. Is your twist rate dedicated for the subs or is it also for high velocity loads?

That twist rate issues bites a lot of the folks who ask for help at the clubs. If you optimize for one, it will shoot the other but do it poorly. Which is your rig built to shoot?

 

[Nomad88]

Likely you have a lucky group if that was for a 190 SubX and it was going subsonic. Is your twist rate dedicated for the subs or is it also for high velocity loads?

That twist rate issues bites a lot of the folks who ask for help at the clubs. If you optimize for one, it will shoot the other but do it poorly. Which is your rig built to shoot?

The ruger comes with a 7 twist.

Im guessing thats better for supers?

 

[Texas Solo]

I use Winchester 223 brass that I cut down to 300 BO. I an NOT running sub sonic. 125gr Hornady bullets gets me 2300fps and small groups. 1/8 twist. Never had a brass issue. Minute of Coyote.

 

[K22]

I am not a benchrest or competitive rifle shooter but a precision varmint shooter (1/2 to 5/8 moa range).

I have used Winchester brass for many years, 223 Rem, 243 Win, 308 Win. In my experience, it is more consistent than other non-premium brass, i.e., Remington, Federal, and Hornady but I have often found 3 to 5% defects per bag. By defects, I mean unloadable condition - cold laps in the shoulder, incipient splits in the necks.

However once those defective case have been removed, I've obtained consistent results with my reloads using Winchester brass.

 

[LCazador]

I doubt it's the brass. I would look at trying a different powder or powder charge.

 

[chkunz]

I am not a benchrest or competitive rifle shooter but a precision varmint shooter (1/2 to 5/8 moa range).

I have used Winchester brass for many years, 223 Rem, 243 Win, 308 Win. In my experience, it is more consistent than other non-premium brass, i.e., Remington, Federal, and Hornady but I have often found 3 to 5% defects per bag. By defects, I mean unloadable condition - cold laps in the shoulder, incipient splits in the necks.

However once those defective case have been removed, I've obtained consistent results with my reloads using Winchester brass.

This has been my experience also using Winchester brass for NRA High Pwoer Rifle competition.

 

[Oso]

3/8" group for subsonic 300BO is the rare exception. MOst of the heavier bullets used for 300BO subsonic were designed for supersonic out of a 308, where 3/8" group would be well appreciated at 100 yards. Out of 300BO most people are thrilled with 1" groups at 50 yards when using shooting 190gr - 220gr bullet subsonic. Depending upon the tip of the bullet (specialty with blunt nose cavity for expansion) these groups can get much larger.

I think your 3/8" group was a fluke.... frame the target Brass can make an impact, but with 300BO I find that consistent neck tension with the heavy bullets is important. If you're shooting at 100 yards then 3"- 4" group is reasonable. What powder are you using?

note: I am waiting for Dellet to provide you with solution to tighten your groups.

 

[Doug Casner]

Working in the 7.62 case area at L.C. for years, the anneal on the shoulder can effect the hardness. I always thought you could find good brass or bad brass in any kind depending on the lot. Doug

 

[SeabeeKen]

Neighbor has some Win 223 brass that is consistent and needs no neck turning. I recommend annealing it first thing. Seems to me to be on the hard side. ymmv

 

[Nomad88]

3/8" group for subsonic 300BO is the rare exception. MOst of the heavier bullets used for 300BO subsonic were designed for supersonic out of a 308, where 3/8" group would be well appreciated at 100 yards. Out of 300BO most people are thrilled with 1" groups at 50 yards when using shooting 190gr - 220gr bullet subsonic. Depending upon the tip of the bullet (specialty with blunt nose cavity for expansion) these groups can get much larger.

I think your 3/8" group was a fluke.... frame the target Brass can make an impact, but with 300BO I find that consistent neck tension with the heavy bullets is important. If you're shooting at 100 yards then 3"- 4" group is reasonable. What powder are you using?

note: I am waiting for Dellet to provide you with solution to tighten your groups.

Good to know. This is my first time messing with subsonic 300. I’ve shot it in 22 but for whatever reason, thought the 300 would being more consistent accuracy at 100

 

[WV Hitman]

I've been using a .300 Whisper (aka Blackout) for over 35+ years and killed over 120 deer out to 275 yards , several hundred groundhogs, 4 turkeys, and several coyotes using only subsonic suppressed rounds. My brass has been a combination of cut down .223, SSK .300 Whisper, and Blackout brass. I've seen minimal difference in the type of brass I've used with the distance of kills and grouping of bullets. I've never used any of the newer subsonic rounds. I've found the Sierra 220 gr. RN and Lehigh Defense 186 gr. Controlled Chaos bullets give me 95% DRT shots on all the above game.
What I did notice is that shooting a lot of shots quickly caused my shots to string vertically. Scratched my head on this. BUT, last year ,Dave Emory of Hornady, reported his testing of subsonic, suppressed rounds caused shots to string vertically, usually shooting higher. I stopped shooting quickly each year when checking the sighting of my Whisper and found no further vertical problems.

 

[Oso]

Suppressor acts can act like a heat sump at the end of the barrel. If I am shooting precision then I shoot slow and give barrel cool off time with chamber fan. If it is a hot day (over 90F then I will also remove the suppressor between groups.

More aerodynamic bullets tend to fly straighter. SMK bullets are more accurate than blunter nosed bullets that are designed to maximize expansion. Using same brass, H110, CCI 450, I have a noticeable difference in the groups which I primarily attribute to the bullet profile. Lehigh Defense 195gr Max Expansion bullets consistently produce a 2"-3" group at 50 yards, whereas my 220 SMK loads is a 1"-1.5" group at 50 yards. By comparison the same rifle shooting 125gr Speers TNT's and Barnes 110gr TC-TX just stack up on each other at that range. I determined to focus on bullet velocity (supersonic) over bullet mass (subsonic). Ensuring a accurate, well placed shot is my goal.

Dellet has a great description of loading for 300BO... you are basically loading for two different types of firearms. Subsonic cartridges perform like handgun loads. Supersonic cartridges perform with modest velocity and significant drop. Lets not even go into the potential impact of the excessive bullet jump in the 300BO chamber (300 Whisper has less) that is required to facilitate subsonic loads.

 

[Nomad88]

3/8" group for subsonic 300BO is the rare exception. MOst of the heavier bullets used for 300BO subsonic were designed for supersonic out of a 308, where 3/8" group would be well appreciated at 100 yards. Out of 300BO most people are thrilled with 1" groups at 50 yards when using shooting 190gr - 220gr bullet subsonic. Depending upon the tip of the bullet (specialty with blunt nose cavity for expansion) these groups can get much larger.

I think your 3/8" group was a fluke.... frame the target Brass can make an impact, but with 300BO I find that consistent neck tension with the heavy bullets is important. If you're shooting at 100 yards then 3"- 4" group is reasonable. What powder are you using?

note: I am waiting for Dellet to provide you with solution to tighten your groups.

I’m out of town now but will shoot these at 100 when I get back. This was at 50 yards, using n120 and 190 sub x

I think the first group would have been really tight without the cold bore shot.

The long range shooter in me couldn’t handle 3-4” at 100 lol.

 

[Oso]

I’m out of town now but will shoot these at 100 when I get back. This was at 50 yards, using n120 and 190 sub x

I think the first group would have been really tight without the cold bore shot.

The long range shooter in me couldn’t handle 3-4” at 100 lol.

View attachment 1586314

I agree!

Shot placement is everything to me. The suppressor neutralize the noise effect that scatters animals (pigs) so I get follow-up shots throughout the night as pigs keep moving through foraging throughout the night.

Once I figured this out I stopped fooling around with the subsonics. I then went and built a 300 HAM'R to gain +300 fps compared to 300BO. I like both cartridges.

Edit: My subsonic load development only went far enough to test a couple of powders I had on hand, and determine charge weights. I stopped before doing any seating depth tests. Listen to Dellet - he is incredibly thorough.

 

[dellet]

There’s a fine line between poor brass and poor brass prep. If the brass is poor, all the best prep in the world may not turn out consistent brass. It’s the basic argument in favor of annealing.

Subsonic brings it’s own challenges in brass prep. On your targets, you have a ladder of .2 of a grain. So you’re pretty anal about load changes. Or maybe not.

People use .2 grains for loads that are 50 grains and over. What’s the percentage? What’s the percentage on a 10 grain load?

You didn’t say if this was all new brass, or first load was new, next loads fire formed, or just shot and resized. You can’t really fire form with subsonic loads and rifle powder. You can but it will take at least 5 shots.

So it goes back to load density. The difference between out of the box new brass, and fully formed brass equates to about 1 grain of powder, in .010” of case growth. 1/10th grain of powder changes load density as much as .001” of shoulder bump.

I use 50 grains because it’s easy. If you have a 50 grain load and use a .2 grain ladder, that’s a .4% change in powder. On a 10 grain charge .2 change is 2%.

All that to say, even very small changes in case capacity or charge weights, are magnified. Until fully fire formed, It’s hard to get a consistent base to shoulder length. I have had much better success with the cartridge by looking at percentage of change vs some random measurement change. I’ve really tightened tolerances. It’s best to fire form as supers, before loading subs.

This is a fifth yard group with subs, I think it was a 208 AMax, I know it was N120. Note the first 6 shot group, cold bore included , then the second five shot group fired inside the first. The difference was a .005” change in seated depth.


Subs at a distance are a challenge, sub MOA at any distance takes work. But if you want precision results, treat it like any thing else you shoot. Quality components, attention to detail assembly. Pay attention to the chronograph. Run some numbers through a ballistic calculator and look at the difference in drop at 100 yards that 10 fps will cause

 

[BobT]

When I was messing with subsonic .300 BO the best load I found was the Nosler 200 grain Accubond, 10.5 grains of Shooters World Blackout and a CCI 450. From an 8.5" 8 twist barrel (AR pistol) and a Banish 30 suppressor they would usually stay around 5/8" as long as I didn't let the can get too hot. I only shot paper with them. I have never hunted with subs. I didn't use premium brass but I can't remember off the top of my head what brand, I think it was Remington but I couldn't say for sure. I lost interest and sold the gun so the data is in storage.

 

[philip brousseau]

190 sub x would not stabilize in a rem 700 7 twist 300bo . Fliers at 100yds and no hits on 3x3ft board at 200. Next time I do this I will start at 200 to confirm stability.

 

[dellet]

190 sub x would not stabilize in a rem 700 7 twist 300bo . Fliers at 100yds and no hits on 3x3ft board at 200. Next time I do this I will start at 200 to confirm stability.

If it’s a Remington 700, you need to check the twist rate. You wouldn’t be the first one that ended up with a 1/10 marked 1/7.