Subsonic Unsuppressed 300blk from 8.3" Barrel

[TRshootem]

Maybe I missed it, didn't see what primer you are using. When I tested the 150 GD with 1680 and CFE, switching to a magnum primer tightened 1680 to single digit. CFE went from ES 0f 50+ to hovering either side of 15. These were compressed loads, of which 1680 seems to be most suitable. The store house of BLK info called Dellet is certainly one who can assist you in this quest.

[dellet]

Heres a post from when I first got some of the CFE BLK and a link to the thread.
viewtopic.php?f=141&t=100097

Another round today and almost there, ready for fine tuning.

Still at 50 yards, back to the original powder charge of 11.2 grains.

208 Amax
11.2 gr. CFE BLK
2.185" COL
Rem 7 1/2 primer
LC converted 1.350"

1067 fps
1047
1056
1064
1040
1049
1063
1059
1063
1038
1011
AVG 1050
56 ES
16 SD

11 shots, 1" dot, flyer was all me.


Original load, Hodgdon data.
208 Amax
11.2 CFE BLK
2.255" COL
Rem 7 1/2
LC converted 1.350"


892 fps
896
848
801
1007
AVG 888
ES 206

5 shots 1"dot (unmarked)


The powder is growing on me in a carbine gas system. I really think the answer seems to be 100-110% case fill to get reasonable spreads.

A little more tuning on this load and it will be time to stretch it out.

One other tidbit is my last shot has continued to be an anomaly. It is likely bolt speed and compressed powder moving the bullet forward due to moving faster on an empty mag.

Honestly I would go buy a box of UMC supers and shoot those just to see what the rifle does. I would expect a group no more than 1.25 MOA. I have have sub MOA groups often with that ammo and use it as a measuring stick.

Subs are tricky, not too many people can consistently shoot sub MOA groups with them past 50 yards.Look up member “Bob the Nailer”. He shoots crap bullets and questionable powders just to show it can be done and gets some good results.

[fancygunz]

Maybe I missed it, didn't see what primer you are using.

I am using CCI #41 labeled "for 5.56 ammunition" primers, I had just assumed they should be OK for 300blk as well.

The powder is growing on me in a carbine gas system. I really think the answer seems to be 100-110% case fill to get reasonable spreads.

Honestly I would go buy a box of UMC supers and shoot those just to see what the rifle does. I would expect a group no more than 1.25 MOA. I have have sub MOA groups often with that.

Subs are tricky, not too many people can consistently shoot sub MOA groups with them past 50 yards.Look up member “Bob the Nailer”. He shoots crap bullets and questionable powders just to show it can be done and gets some good results.

I will go back and compress a bit more. The 208gr you used is slightly shorter than my 220gr so I think I'm pretty close to leaving a ring shaped dent on the bullet.

Supersonic doesn't seem to be a problem, I have a 130gr load with H110 shooting 0.8 MOA at 50yd.

[dellet]

What bullet are you using?

The Amax/ELD are both very jump tolerant.

The loads you posted, I would work the B/C load for the CFE.

To keep compression the same I change seated depth .010" for every .10 grain of powder. So my C load would have been 110.0 @ 2.218".

I think with that bullet powder combination load density will be more important than jump. I like velocity close to 1000 fps, maybe a bit below, less turbulence. You are not shooting subsonic, you are shooting transonic, and is a good indication of why distance shooters try to stay above 1350 at the target. You want a bullet that is proven stable in the 1350-950 fps range if accuracy is your goal.

[fancygunz]

What bullet are you using?

The Amax/ELD are both very jump tolerant.

The loads you posted, I would work the B/C load for the CFE.

To keep compression the same I change seated depth .010" for every .10 grain of powder. So my C load would have been 110.0 @ 2.218".

I think with that bullet powder combination load density will be more important than jump. I like velocity close to 1000 fps, maybe a bit below, less turbulence. You are not shooting subsonic, you are shooting transonic, and is a good indication of why distance shooters try to stay above 1350 at the target. You want a bullet that is proven stable in the 1350-950 fps range if accuracy is your goal.

Once again, thank you for the detailed replies. I am shooting 220gr blems from Midsouth, but they are unlabeled Hornady ELD. Are these stable in that velocity range? I have not been able to measure any noticeable "defects" in the box... lengths are consistent and I have been weighing the bullets but they're all within +/- 0.2gr with the occasional 0.3, which I set aside.

I will test a couple more loads this weekend based on your suggestions, and report back. I'm hoping a little more compression will improve accuracy. I am also doing a deep clean of the barrel with some Wipeout, which has solved some mysterious accuracy issues on my .308 in the past.

Different question, is there a specific brand of brass you have had luck with? My stash is starting to get worn from repeated loadings. I don't want to convert 5.56.

[rebel]

If I want the best brass I can get - Lapua. If I want decent brass cheaper - Hornady is OK. I have all the stuff to convert .223, but that is a slow monotonous task I don't enjoy. I think dellet has used some Norma, also premium brass. You might try a CCI 450 primer to see if it has better ignition - i.e.tighter group. ( as TRshootem mentioned)
Are you bagging this rifle? On a bench or shooting sticks? Bipod?

[dellet]

Brand of brass does not matter much to me, it's mostly in the prep. Uniforming primer pockets and flash holes goes a long way to make cheap brass reasonably accurate.

I use a lot of Norma and Lapua because it seems to last twice as long as most of the others with supers.

One thing I try really hard not to do is mix headstamps.

CFE BLK is a bit of a strange powder. It can be very accurate with really dense loads, the problem most sub loads aren't that dense, so it's erratic. I use it for a lot of other things and other than being loud, I like it. But My opinion is Hodgden missed the mark with this powder. Loud, dirty and erratic with low load densities is not desirable for shooting subs suppressed.

What it has going for it is a ton of gas, so it will cycle anything. That again is a reason not to use it, nobody I know like shooting with a gas mask on and with CFE you need to.

[cdl]

FYI - The 220 ELD-X is a really long bullet leaving little case capacity in a magazine.

I load them with 10.4 gr of A1680 at 2.220" for 1005 fps out of my 8.3" BA Hanson barrel. Single digit SDs too. That OAL has the bullet pretty much sitting on the powder with no crunch and just fitting in a magazine.

I'll be looking for a way to load less of something when I revisit it.

[TRshootem]

Dellet mentioned Norma brass, some of which I set aside(.223) to convert to BLK. After weighing/sorting, it was 98.6-101 ish which seemed heavy for my purposes. This brass also had a primer crimp. Perhaps this sample is not the best example of the Norma brass. I have not seen any in 300 bLK, but did pick up a nice quantity of Nosler BLK which seems to be of good quality. Are the Nosler a Norma product like some of their larger cases....?

[2manyToys]

Not all Norma brass is equal. The latest Norma Tactical 223 brass is made in a different factory and has a higher zinc content as well as laser marked headstamps . This is not the same as virgin Norma brass that you would use for reloading, and, in my opinion, low on the list of brass that I would consider converting to 300 BLK or even reloading as 223.