300 Black out help. Oblong holes with reloads

[nikdanja]

I have a Wilson combat 8” 1/7 twist barrel and I’m getting oblong holes using a 220g berrys bullet at around 975ish FPS using CFE black

First off, CFE black is complete dog shit. My SD is +/- 60 and yes, everything on my end is consistent. There’s zero powder I can even buy to try out. My buddy uses 1680 but I can’t find it.

The accuracy is great but the holes are oblong. Not tumbling but the bullet isn’t completely stabilizing. Could powder be the culprit? I had another 1/7 twist 8” barrel that I was having serious accuracy issues wjth so I ponied up and bought a Wilson. Accuracy issue is solved but now oblong holes.

 

[aslrookie]

Sounds like a bullet issue. I had no issues with Hornady 220eldm with 300blk powder. This was also with a seekins 8.3” 1:7 barrel. Clean holes at 150 yards on paper.

 

[aone]

CFE likes to be compressed. Try seating deeper.

 

[bluegrasspicker]

Your SD is ~60 ft/s, so your extreme spread is likely ~150 ft/s. That means your slowest bullets are probably coming out a little over 800 ft/s.

A good question to ask (and to answer) is "what is the percentage of bullets that are making oblong holes?"

If about 20% are making nice holes, I'd look to reloading details rather than hardware on your gun.

If this is the case, you might look at increasing your charge ever-so-slightly. You might get a lower spread and the minimal speed might be more stable, both big positives.

 

[aone]

It's pretty well known that cfe will have crazy ES unless compressed.

 

[db2000]

Here’s some data I got with Seekins 8” 1-7
Groupings we’re at 50 yd. No wobbles or keyholes.
69F 28% 30.07in
Berry’s 220 gr .300 Blk SP
A1680 powder various grains
BTO 1.6620

 

[nikdanja]

Here’s some data I got with Seekins 8” 1-7
Groupings we’re at 50 yd. No wobbles or keyholes.
69F 28% 30.07in
Berry’s 220 gr .300 Blk SP
A1680 powder various grains
BTO 1.6620
View attachment 7749207

Thank you very much! This is helpful and I’m headed to the range to try out different stuff. I got my hands on a little bit of 1680. Going to try out different powder

 

[db2000]

Thank you very much! This is helpful and I’m headed to the range to try out different stuff. I got my hands on a little bit of 1680. Going to try out different powder

1680 pops up not infrequently on the Hodgdon sales site.

 

[nikdanja]

Range report.

I think the 220g bullet is to heavy for this barrel. I loaded them to 2.190 OAL and same results. I tried using 1680 pushing a 220g and I had the same results.

My best group was with a 208 hornady match bullet but I don’t want to pay .50 cents per bullet. I just ordered some 200g berrys bullets to see what happens.

300 black out is by far the most pain in the ass cartridge to load for.

 

[nikdanja]

Range report.

I think the 220g bullet is to heavy for this barrel. I loaded them to 2.190 OAL and same results. I tried using 1680 pushing a 220g and I had the same results.

My best group was with a 208 hornady match bullet but I don’t want to pay .50 cents per bullet. I just ordered some 200g berrys bullets to see what happens.

300 black out is by far the most pain in the ass cartridge to load for.

 

[r.tenorio671]

...hope you're not using a suppressor, you're risking a baffle strike if those bullets aren't stabilizing....

...IMR 4227, 300MP and #9 can all be used for sub loads, even LilGun and case fill will be low enough you can seat the Berry's even deeper, just be mindful of the feeding when seated deeper..

...Speer, Hornady and Nosler all have bullets in the +175gn-220gn range that are comparably priced to the Berry's, check out Grafs. The Hornady 190gn Sub-X bullets is only a cent or 2 more than the Berry's you've used.

Even 150gn FMJ's can be made subsonic...

 

[r.tenorio671]

....from the Hodgdon Reloading Center website, sampling of powders/bullets/for subsonic, the variety of compatible powders is the info you need:

 

[bluegrasspicker]

OP, I'm not buying the "220 grain is too heavy for this barrel" argument. A lot of folks throw 220 grain bullets from a 1:7 twist barrel.

 

[nikdanja]

OP, I'm not buying the "220 grain is too heavy for this barrel" argument. A lot of folks throw 220 grain bullets from a 1:7 twist barrel.

What do you think the problem is?

 

[Clayman]

What do you think the problem is?

You can buy a MOS tek 1:5 barrel to eliminate the slower twist rate issues (if that's the issue). They'll make whatever length and profile you want.

 

[bluegrasspicker]

What do you think the problem is?

I don't know, but I doubt that it's the barrel because mine works great with 220 grain subsonics. I made absolutely double-damn certain before slapping my suppressor on there.

My first guess (I said I don't know, not that I don't have suspicions!) is that some of your rounds are going too slow to stabilize. Did you read my response in Post #4? That's what I think. Until you answer those questions I'll keep thinking that. If you up the charge a little and still get the same % of keyholes, I will furl my eyebrows and move on to the next possible culprit.

In the meantime, and because I love a good mystery, how confident are you in the chrony data?

 

[fast freddy]

somethings got to be up, all i shoot is 220 grn sierras over 1680, in everything from a old 8 inch 300 whisper barrel to a aac 300 blk upper rem 700 aac sd and a new sig canebrake rattler they all work very well.

 

[hlee]

My odin works barrel is 8.5” and 1-7” twist. No instability from 220gr Hornady eld bullets as slow as 850fps. No issues with my thunder chicken can on it either. I doubt speed and twist are your problem. But, you can use the tool below to sanity check your setup.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[wadebrown]

I have seen key holing in a tried and true long range F-class rifle if I allow the barrel to get very dirty, it was a surprise to me when I heard that I was keyholing from the guy pulling the target at 1000 yards. I had shot at least 3,000 rounds of that loading amongst three barrels with the same 1-8" twist with no key holing I was very happy to see all was good after a decent cleaning.

 

[Fighting the good fight]

I have a Wilson combat 8” 1/7 twist barrel and I’m getting oblong holes using a 220g berrys bullet at around 975ish FPS using CFE black

First off, CFE black is complete dog shit. My SD is +/- 60 and yes, everything on my end is consistent. There’s zero powder I can even buy to try out. My buddy uses 1680 but I can’t find it.

The accuracy is great but the holes are oblong. Not tumbling but the bullet isn’t completely stabilizing. Could powder be the culprit? I had another 1/7 twist 8” barrel that I was having serious accuracy issues wjth so I ponied up and bought a Wilson. Accuracy issue is solved but now oblong holes.

Ive done light weight subs and heavy subs just playing around. Everything from 110 v max 168bthp both sierra and hornady 175s and heavier and have always had the best results with 1680 imr 4198 and RL 7 never used the berrys 220s bit have used others with 7.5 10 and 16" have never had a keyhole or a tumbler. I dont have my data in front of my at the moment but will give it to you when i get back from hunting. Bought 2#s of cfe black cause it was supposed to be the next best thing when it came to the BO but its garbage. 1680 is the way to go

 

[5pins]

Are you crimping your bullets? It has been my experience that plated bullets are very sensitive to crimping at least in 9mm. I have no experience with plated rifle.

 

[Mike_in_FL]

Everglades Ammo sells a 220 plated bullet under .300BO on their site. You might want to check out the reviews for some load data.

300 Blackout 220gr Plated Bullets

Designed for use with the AR platform, boasts a profile that is perfect for loading 300 Blackout ammunition. .309 Diameter, 220gr plated bullets. Max Velocity - 1,300 fps.These are new bullets.

www.evergladesammo.com

Here's an AA9 load: https://forums.brianenos.com/topic/248785-best-load-data-for-subsonic-300-blackout/

Pretty interesting: https://ultimatereloader.com/2020/03/27/tested-berrys-220gr-330-blk-bullets/

 

[Fighting the good fight]

Most of the time if not all the time. Ill use a very little crimp where you can almost not even feel it and when i put a slight chafer on the inside of the neck and just enough crimp to close that up a little. When i say very little crimp its very little. My plinking rnds like 150 fmjbt that has a cannalure ill crimp that a little more just enough where the brass is in the cannelure but as well is a very light crimp. The subs the neck tension should be enough to hold it there i crimp just cause its semi auto and dont want to take the chance of the projectiles moving with the action or whatever else and change the seating depth

 

[Fighting the good fight]

Are you crimping your bullets? It has been my experience that plated bullets are very sensitive to crimping at least in 9mm. I have no experience with plated rifle.

Ive never used the plated bullets with the black out. I said ived used every grain projectiles from various manufacturers but never berry in a BO. I wouldn't crimp a plated bullet

 

[Fighting the good fight]

Ive never used the plated bullets with the black out. I said ived used every grain projectiles from various manufacturers but never berry in a BO. I wouldn't crimp a plated bullet

I think they actually make then the diameter a touch larger then 308 so u have a little more neck tension so u dont need to crimp. Thats with berrys and probably other plated bullets

 

[r.tenorio671]

...FWIW, I've found that chamfering my cases with a VLD type deburring tool made for easier seating of bullets, jacketed, plated and cast. I don't use cast bullets much, but I did try some early on "just because"...one never knows. Any type of crimping, taper or Lee FCD, will require measuring and appropriate adjustment when bullet or brand of casing changes, bullet diameters vary as does case mouth wall thickness. Case mouth wall thickness can also increase as amount of firings increase due to brass flow. I prefer to adjust my seating die so the "taper" never comes into play and then VERY lightly use my Lee FCD die to apply a very minimal crimp if any to prevent bullet set back during the load/chamber phases of cycling.

 

[Fighting the good fight]

...FWIW, I've found that chamfering my cases with a VLD type deburring tool made for easier seating of bullets, jacketed, plated and cast. I don't use cast bullets much, but I did try some early on "just because"...one never knows. Any type of crimping, taper or Lee FCD, will require measuring and appropriate adjustment when bullet or brand of casing changes, bullet diameters vary as does case mouth wall thickness. Case mouth wall thickness can also increase as amount of firings increase due to brass flow. I prefer to adjust my seating die so the "taper" never comes into play and then VERY lightly use my Lee FCD die to apply a very minimal crimp if any to prevent bullet set back during the load/chamber phases of cycling.

Being that i use alot of range brass and make my own BO brass you are exactly correct if im just making plinking stuff i dont sepreate head stamps. Now that ive been doing it for a while i can tell what kind of brass it is without even looking at it. LC brass is nice and smooth wolf brass is pretty thick stiff and has a thicker case mouth and so on. So if you set your die off a piece of LC brass you will more then likely get different amounts of crimp with each case unless u sepreate them. If im making some more accurate rnds. Then just plinking ill sepreate them but still set my dies where there is hardly any crimp if any at all

 

[PusherX11]

Hodgdon Powder HP38 - CASE OF 10LBS

Check out the deal on Hodgdon Powder HP38 - CASE OF 10LBS at Bruno Shooters Supply

www.brunoshooters.com

 

[Fighting the good fight]

Thats the good stuff right there. I normally pay bettween 30 and 35$ the local shop is always changing the prices depending on inventory