Help! My head is spinning- load info needed

[Roadrunner1969]

I have been reading tons of posts on these threads and my head is spinning with all the 8.5", 12", pistol gas system, etc. etc. There are so many variables that I can't keep up with them.
I am only interested in heavy (190 and up) subsonic loads for bolt action 300 blk. My 2 top priorities are ACCURACY and QUIET. I would appreciate any information you have that will help in getting me there. I currently have Hornady 190 Sub-x for sub bullets, but I'm not stuck on those. Not interested in subsonic lightweight bullet loads. Rifle is RARR w/ 16 " 1:7 barrel. I shoot suppressed. CCI Magnum SRP, Hornady or Starline brass.
So, considering powder only for heavy subs. What powder is your most accurate?, most quiet?, and best compromise for both?
Thanks in advance for your input.

[30plinker]

You are seeing gas and barrel length references from the guys/gals that are concerned with all the normal aspects of reloading (safety, accuracy, etc) but also with having a certain amount of gas volume (and therefore pressure) when the bullet hits the gas port so that their semi-auto (or full, I guess, tax stamp collectors are everywhere) will function reliably. Then add using a suppressor - or not, or just sometimes - to the mix which changes the behavior and gas pressures involved.

With a bolt gun, you only really need to worry about the bullet exiting the barrel each time, and that it has enough velocity to get enough spin from your rifling to stabilize - you do NOT want a baffle strike on your can....

So in that case, I'd simply stick with published data. You'll have enough issues getting powder, etc.

Favorite reference, filter-able by powder and bullet weight - https://shootersreference.com/reloading ... -blackout/

Unfortunately I can't give you exact load info - 20 rounds into testing my first reloads my 300bo bolt gun died (RAR) and I've been too busy with hunting season, work, and then spring turkey season to worry about it.

[BJK]

Until you prove the load you're testing remove the can and look for bullet stability on paper. Then put the can back on once you're happy that you won't ding a baffle.

In general fast powders will be quieter than slow powders. They build pressure fast and the powder is used up quickly, that leads to less pressure when the barrel gets uncorked. It has to do with Boyles Law. Double the volume of the gas and the pressure is halved. For example, if the powder burns and pressure peaks in 5" of barrel and is @ 46k psi, at 10" it's 23k, and at 20" it's @ 11.5k.

A bolt gun should be easy for the reasons 30plinker stated. You just need to get the bullet out of the barrel and assuming that, work on the rest.

You know to start supersonic and work down to subsonic, yes? A chrono is pretty much mandatory to "see" what's going on. You need the data a chrono' gives otherwise you're just flying blind. Maybe I'm missing something (if so please correct me ) but I can't imagine loading for 300BLK or ANY subsonic cartridge and not have a chrono' to feed me data.

[Roadrunner1969]

Yes, I have a chrono, but I keep it at my place in Texas. I loaded some rounds (H110 supers and CFEBLK subs) that I had already documented the speeds to shoot for groups this week (in Arkansas). When I was shooting them across the chrono, even though they were 1050 fps or below, I still got a "crack". So I am trying to get rid of that pop. Part of it may have been that I was shooting off of the porch of the metal building and only a few feet away from the wall.
Anyway. going to load some subs this week with the faster H110 and see what it does.
Accuracy was real good with the 190 Sub-X and 12.1 or 11.7 grains of CFEBLK, just want to eliminate that pop noise.
Thanks for your responses, and keep them coming.

[BJK]

Is it 1st round pop that you're getting and want to eliminate?

if so, some things to try... It only happens first round because the can is full of spent gas after that, or if enough time passes for the gas to leave the can it'll happen again. So fill the can with inert gas and get rid of the first round pop. I'm trying to remember some gas dispensers I once knew of but I just can't recall. If the can can run wet follow mfgr instructions for wetting it. I have one can that states to dunk it (or pee in it) and shake it out, but that's a rarity. The others are OK with putting approx 5cc of water in the back of them. Or cable pulling lube will also act as an ablative. But so will ultrasound electrode gel and it comes in a squeeze bottle so that a string of it can be lowered into the can.
https://www.amazon.com/dp/B0093J2GWO?ps ... ct_details

If it's not that, maybe this? One range I shoot at has a corrugated metal building that has structural corrugations maybe 6-8" deep. Shooting outside that building means that the shot echo gets bounced back to the shooter from each corrugation. It makes each shot sound like a fabric ripping or a freaky supersonic crack, even with proven subsonic loads.

Hey, I'm grasping at straws here.

[dellet]

If you want accuracy and quiet, in a subsonic load, the first thing to do is throw the CFE in the garbage can.

It’s very difficult to isolate the sonic crack shooting less than 50 yards, basically pointless. It lasts just a few milliseconds. If you wear noise canceling ear protection, you’ll never hear it. That’s why you have to have a chronograph.

The H110 can work well, but it’s always a balance between staying under 1100 and accuracy. Then with a bullet like the Sub X, you have to worry about the lower end of the expansion velocity and effective range. How far will you shoot? And will the velocity still be over 950 fps?

Seat the bullet to the cannalure and probably around 9 grains for a 16”.

If you hand fed vs gas fed systems as completely different cartridges, it all makes more sense. There will be a lot more 300 whisper data out there that was developed for Contenders that can be helpful.

[Roadrunner1969]

BJK
It is not first round pop. I was getting a pop on every shot. The metal building may have had something to do with it.
I'm going to a range tommorrow and will see what it does there. Unfortunately, it is usually too noisy with the muzzle brake shooters to hear yourself think. That is why I do most of my shooting at my place.

[Roadrunner1969]

Dellet,
Unfortunately, I bought the CFE before I understood that most 300blk shooters consider a "good" powder to be one that cycles the action, not necessarily one that is very accurate or quiet. I am also a long range shooter and am used to 1/2 moa or less accuracy. My son shoots an AR, so I have a place to use the powder. Reloading for subsonic is a new area for me, so it has my mind cranking. Thanks for the help.

[dellet]

You might be surprised what the cartridge can teach or reinforce about long range accuracy. MOA at 200 yards is tough with subs. Whatever tolerance you used for load work up before, think of it as percentage. 1 grain change 50 grain cartridge, 2%. 1/2 grain change in 25 grain blackout cartridge, same 2%.

Plow through this when you have time. There is a lot of off the chart data.
https://www.300blktalk.com/forum/viewto ... 28&t=98191


Look up members “walkers bay” “tikablk”. Red deer at 400 meters subsonic in New Zealand.

Best loads for CFE will be compressed. Light supers with as much powder as you can stuff in the case and seat the bullet with a Redding super magnum boss V press with 6’ pipe added to the handle and you will get very accurate loads but about 150 fps slower than say H110. I have never been able to flatten a primer with it. But don’t take that as a challenge.
Once you can hit 100% + case fill, the powder changes dramatically. Goes from triple digit ES numbers to single digit. Never loses loud tho, and always slow in an already velocity challenged cartridge
https://www.300blktalk.com/forum/viewto ... 1&t=100097

It’s an interesting cartridge, makes you think

[Roadrunner1969]

Very good information. Thanks for the help? I'll digest this info.