Advice on subs CFEBLK

[Ghostman]

I have been loading up some 300 blk with LC Brass and using some Sierra 168grain TMKs. I'm using CFEBLK powder. I know this bullet isn't "designed" for the 300BLK but I bought some a while back when bullets were scarce and think they should work. Also, at sub velocity levels I don't really think any of the advertised bullets expand or explode well from what I have seen others post. After testing the speed on a few different loads this is what I put on paper. The windage drift on these was around .75-1", but elevation was 2.25" at 50 yards. Using a table and bags.

So anyways I'm using a RCBS RC2 press with lee full length sizing dies and I did not taper crimp these. Just using neck tension, seated at 2.20" COAL
I'm using a hand trickler and RCBS digital scale to get 11.5 grains, velocity as follows
917, 942, 949, 979, 995
I am using a suppressor and I also have an adjustable gas block, but it's set to full open and my brass is ejecting at 3:00-3:30 position. The rifle is fully functioning and this tells me I just have the right amount of gas for cycling.

I've read some people state that the CFEBLK likes to be compressed. I'm wondering if I should continue upping the powder charge or am I wasting my time on these bullets? How can I get some more consistency and accuracy. Open to all suggestions. Thanks.

[Marksman1941]

Keep your velocity where it is, play with seating depth a bit and see what happens.

[dellet]

If you’re just target shooting, there’s nothing wrong with the bullets. If you expect to hunt, they are a poor choice. You’re correct that there are no exploding bullets designed for subsonic speeds, but there are some fracturing and plenty that will expand. Some as much as 3 calibers.

Your bullet powder combination is questionable. Accuracy will suck until you can get your velocity spread cut by 50%, 75% would be much better. When you’re ES is basically 100 fps at < 1000fps MV, all you can expect is what you got. With a short bullet like the 168, all you can do is add powder and possibly a bit of crimp.

I would add a grain of powder and check velocity, all working up a 1/10 or two at a time will do is waste time and components. It’s much easier to work down than up.

Knowing your barrel length would also help.

[Ghostman]

10.5” barrel with pistol length direct impingement system.

Yeah I’m trying to not waste more components is why I’m posting.

I guess I’m partly baffled why the ES is so great. I feel like my QC is pretty high. All the cases are prepped and trimmed to the same length. I haven’t seen this in other calibers I have reloaded before.

All I would be doing is plinking or shooting small varmints/hogs within 50 yards.

Would I be better off with some coated lead bullets or am I just wasting my time here? I didn’t want to spend a ton of money on a sub gun for only 50 yards.

Maybe I should just drop the sub load and load supers only . . .

I also have some H110 powder, would I be better off trying that?

[dellet]

It’s an inherent problem with CFE BLK. Low density loads, throw odd numbers. The only quality it really has is that it produces a lot of gas, so lighter bullets are more likely to cycle the action.

I had good results once I could compress the powder. With 208 AMax and Hodgdon load data it was a 3” group at 50 yards. Dropped the bullet down into the powder and shrunk the group to under an inch.

You might take a fired case, drop in 12 grains and then drop a bullet in. See if the bearing surface is above the end of the neck.

Lots of ways to make it work.

The H110 might be just a bit fast to cycle a 168, but it might. 175 and above should be no problem.

[Ghostman]

Ok so I took y’all’s advice and I loaded up 5 more at 12.5 grains and seated the bullet as far as I could. It still wasn’t quite compressed. I also had some Xtreme brass and I know those are thicker walled so I loaded 5 of those at 12.5 grains. I also measured from the end of the case to top of powder on each case and it’s atleast .010-.015” difference. It seemed to be slightly compressed with xtreme brass. Hard to tell.

LC brass gave these speeds- 1079, 1035, 1050, 1088, 1067. A little bit better ES but not great. It shot a much better group. At 50 yards I got a 7/8” group except the 1035 was a flyer of about 1.25” below the group.

The Xtreme brass gave these speeds- 1178, 1149, 1189, 1131, 1148.
The ES on this group was worse but it actually shot better than the above group. At 50 yards I got a 5/8” group and the 1131 bullet was the furthest off. The other 4 were dang near all touching.

At this point I’m tempted to try loading 5 more in the Xtreme brass at 13.0 grains and see what happens. The sound difference wasn’t much that I could tell going from the first group to the second. So if they’re still pretty quiet, but maybe a tighter ES and tighter group I would be happy.

As for when I run out of these Sierra bullets I’m looking at using the Hornady Sub-X 175 grain bullets. Would I have good luck with these do you think using cfeblk? The barrel is 1-8 twist but it won’t stabilize any factory ammo I’ve shot over 200 grains.

Also, is there any way to post pictures directly to here?

[BJK]

I don't know about direct posting of pix. I use postimage and link to them.

[Ghostman]

LC brass


Xtreme Brass

[dellet]

I would say you had some pretty good success.

Made basically one adjustment, fill ratio, and your groups, ES and SD numbers all improved by more than 30%. Your LC load has an SD of 19, that’s a number you can work with. A bit more work with the brass and it might just drop some more.

Sort the brass by capacity or weight, uniform the primer pockets and flash holes.

I don’t think that low shot was all velocity. Maybe a bit of trigger control on the horizontal, and that group would look pretty good.

With a 10.5” pistol gassed barrel the H110 should work.

There is no reason that a 1/8 twist won’t stabilize a 240 SMK, and I shoot 208 AMax from a 1/10 with great success. So if your having trouble, something else might be going on.

With the 168 and CFE, you can likely fill the case with the bullet seated at 2.260” and not worry about pressure. probably around 1600 fps. or more.

[Ghostman]

So out of curiosity I loaded some Xtreme brass with 13.0 grains. Seated to the same COAL as the 12.5 grain load. Shot a 5 shot group and speeds as follows, 1158, 1163, 1173, 1184, 1187. Not much better ES or SD. I also noticed several times that the speed would increase from the first shot to the last. Is that due to heat maybe in the chamber? Anyways. It didn’t group any better so I think the 12.5 grains is the load to go with. It was also noticeably louder.