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300 Blackout subsonic loading getting the best of me.

Dave in WI

Runs with scissors
Gold $$ Contributor
I have a Ruger Ranch bolt gun. For my control loads I shoot the factory Sellier & Bellot 200gr FMJ. They shoot really well in my rifle. I'm trying to reload some Berrys 220 plated. Experimenting with both H110 and A1680. It seems no matter what I do, the first round out of the 5 shot groups can be 150-200 fps slower than following rounds.
I load 5 cartidges weighed on my RCBS Chargemaster Supreme. When they get loaded in to magazine they are at random, so not first charged vs first fired. it is always....ALWAYS...the first round of the group that is slow.
Not much hair left to pull out......:rolleyes:

I've reloaded subsonic 458 Socom before in an AR15 platform and had the first round out of the magazine go to a different point of impact. But charging an AR is different for the first round vs rest of the magazine.

Am I missing something completely obvious, is it dementia setting in....
 
220 SMK's
11.5gr CFEBLK
2.13" COAL
1xLC brass
CCI 450

1031fps

Stupid accurate and stupid quiet out of my 10.5" Rainier Ultramatch SBR
 
Condition of barrel, for first shot?
I remove the Break Free CLP with hoppes #9 & patch dry.

Use a mag primer. Hodgdon has sub data now.
 
Not cleaning in between groups. Load five, shoot them. Rifle sits only while I go back inside, load five more and shoot next group.
 
Could use some additional information:
1) What was weather conditions? What was temperature?
2) What is source of brass (range or new bought used only in this rifle) … annealing?

I recently did a work up on Rem 700 (300BO) that I bought. I was working on a load with 125gr TNT and H110. I’ve shot a fair amount of 300BO and this was first time I had noticeable 1st round deviation (50-100 fps). I was using brass that I had converted. I refocused my effort on brass prep (annealed, trimming, neck expander die, etc). I started weighing each charge twice using 2 different scales. I kept track of all cases a retained firing order. The inconsistent velocity continued. I noticed these “troubled cases” had a little more resistance during extraction, and upon inspection displayed a roughened surface banding around the top of case webbing…. It was incredibly frustrating. Dellet was a huge help as I plodded doggedly forward trying to get to the root of the problem,

Finally, I pulled all of these problem cases and loaded all of them together to shoot as a group. They all performed as they alway had in previous firings. The group didn’t show any cold bore, but instead all shots showed consistently low velocities. All that I can deduce is that the drop in velocity was due to these cases spending the energy over-expanding the case resulting in lower velocity. By coincidence these problem cases were the first shot for each group and continued to be so as I maintained the shooting order. In my case it was just dumb luck.

After determining this was case specific issues, I threw out these bad cases. I started up a new batch of brass (LC same year) and the problem did not reappear.
 
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I have a Ruger Ranch bolt gun. For my control loads I shoot the factory Sellier & Bellot 200gr FMJ. They shoot really well in my rifle. I'm trying to reload some Berrys 220 plated. Experimenting with both H110 and A1680. It seems no matter what I do, the first round out of the 5 shot groups can be 150-200 fps slower than following rounds.
I load 5 cartidges weighed on my RCBS Chargemaster Supreme. When they get loaded in to magazine they are at random, so not first charged vs first fired. it is always....ALWAYS...the first round of the group that is slow.
Not much hair left to pull out......:rolleyes:

I've reloaded subsonic 458 Socom before in an AR15 platform and had the first round out of the magazine go to a different point of impact. But charging an AR is different for the first round vs rest of the magazine.

Am I missing something completely obvious, is it dementia setting in....
Here are a few which work for me. 1745662642608.png
 
Wipe chargemaster with dryer sheet every time you use it. Check first load against the next 5 with a balance bean scale and make sure the charge weight is the same, with in reason as the others.
 
Confirm velocity loss against drop. 150-200 fps will be significantly lower. It may actually be the chrono needing time to warm up and stabilize.

Are you Shooting suppressed?
Is it the same without the suppressor?
What happens after the last shot of your 5, if you plug the muzzle end of the suppressor and close the bolt until you’re ready to die again?
This keeps 02 from getting into the barrel and suppressor. Also helps get rid of any first round pop. I use tape so you don’t need to remove it, just shoot through it.

Personally I’d move to a different powder. Faster pistol powders are designed for low capacity load, generally giving you less ES/SD numbers. They will also be noticeably quieter and get more loads per pound. They will burn cleaner, carbon fouls less. Powders like 1680, CFE BLK that seem to be the go to powders for AR’s make you wonder if a suppressor is worth the cost.

Go to 300 Whisper data, it was developed for Contenders for the most part and will have data for #9, 2400, N105, N110 all much more superior for subs than those needed to cycle an AR.

N120 is another good choice, I think it’s the only rifle powder I use. About the same burn rate as 1680, but a bit bulkier and requires just a little more powder by weight for the same velocity. That gives you better case fill and more consistent numbers. Much cleaner and quieter than the normal suspects.
 
Are you using a solid crimp? That will improve your sd and prevent any bullet pushback. Very important with an AR.
Plated projectiles don't like a heavy crimp. Manufacturer's data usually warns against much of a crimp.

Under some conditions you can strip the plating off the projectiles. I have recovered bullets with no plating left.

Your mileage may vary.
Paul
 
Thanks for all of the replies.
I just had the box of Berrys thinking of inexpensive load.
Use a non plated bullet and see if the results are the same. Easy enough to test.
I am going to try some 208 AMax 2nds from Midway I have.
Are you using a solid crimp? That will improve your sd and prevent any bullet pushback. Very important with an AR.
I don't shoot 300 BLK in an Ar platform. I use the RAR to demo the suppressors I sell.
Confirm velocity loss against drop. 150-200 fps will be significantly lower. It may actually be the chrono needing time to warm up and stabilize.
All shots that record low on the chrono print on paper considerably low.

Could use some additional information:
1) What was weather conditions? What was temperature?
2) What is source of brass (range or new bought used only in this rifle) … annealing?
Cases are once fired Gemtech cases fired from one of my rifles.

What really confuses me is the fact that it is always the first shot of a 5 shot group. They are all loaded at random in the magazine in relationship to order they were charged. I would expect minor variations in numbers from poor loading techniques, neck tension, static on dispenser, warm bore, silencer vs no silencer, etc.
But it is 20% or more difference from the first round only is baffling. Again, factory ammo doesn't do this?
 
This was my frustration as well. Why am I getting these flyers that are 2”-3” lower than rest at 100 yards?! I tried everything you are. I even treated the loads like single shots with 3-5 minute interval between shots while also using a Chamber Chiller … that was long range day for 30 rounds.

While you are waiting for new bullets &/or powder, try loading with brand new unfired cases (store bought virgin 300BO brass)… buy a bag of Starline. See if this doesn’t make a difference.
 
Factory ammo will have a different powder and most likely a crimp, or excessive tension. That may somehow show up in the suppressor, that’s why if you haven’t tried without you should.

Also eliminate first round feeding possibilities by hand feeding it as a single shot. This will also eliminate the possibility of bullet set back in the magazine. Firing a couple rounds from the magazine, then checking the length of the others in the magazine is a good idea.

I’ve never really been a fan of gemtech brass, I think OSO had some problems also.

If you’re selling suppressors, you need to work up loads with faster powder, 1680, CFE BLK, Shooters World Blackout all have a sound signature that sucks. Your not doing your product demo any good using them.
 
This was my frustration as well. Why am I getting these flyers that are 2”-3” lower than rest at 100 yards?!
I’m seeing this at 50 yards!
If you’re selling suppressors, you need to work up loads with faster powder, 1680, CFE BLK, Shooters World Blackout all have a sound signature that sucks. Your not doing your product demo any good using them.
I plan on acquiring some #9 as you suggested.
 
If your order of firing rounds is truly random, then the issue must be with the mechanics of the rifle. As you suggest in the OP, the AR platform - and other self loaders suffer from 1st round issues. Some expensive match pistols had this problem too - the first round, having the most tension from the magazine spring, slowing the bolt. Are you loading through the magazine? Does the problem go away if you single feed? I'm not a fan of the Ruger Ranch action, as it uses the bottom lug to strip the round from the mag - but my limited experience of them is a friend's 223 that is a tack driver!
 
I load for a friend's .300 Blackout subsonic, WW296, 220 gr. Sierra RN. He gets excellent groups.
I've loaded the same as above for my .300 Whisper for 35+ years. Still get excellent groups. Maybe it's the barrel problem.
 
Use a jacketed bullet, and a NON-ball powder. AA1680 is really inconsistent in terms of ES/SD, and needs a hot primer. Also crimping is marginal for plated bullets, and try some factory 300 BLK brass.

As some have suggested, try a faster-burning extruded or flake type powder. You don't even necessarily need to use a 200+ gr bullet if you dont care about enough gas pressure to cycle an AR, since you are shooting a bolt gun.

If you want to sell suppressors and demand the utmost in quiet...
Try a 110 VMAX over 3.8-4 gr of Red Dot. BB gun quiet and zero recoil. As quiet as a 22 LR CCI Quiet, except slinging a 110 gr bullet at 1000 fps. Oh and suprisingly accurate and consistent. I know of no load as quiet as this. It has been "alleged" this has been used for basement target practice, and the loudest part of the sound signature is from the impact.
 

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