300 Blackout subsonic loading getting the best of me.

[HandgunHTR]

Thanks for all of the replies.
I just had the box of Berrys thinking of inexpensive load.

I am going to try some 208 AMax 2nds from Midway I have.

I don't shoot 300 BLK in an Ar platform. I use the RAR to demo the suppressors I sell.

All shots that record low on the chrono print on paper considerably low.


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?

Just because you are using a bolt gun doesn't mean you shouldn't be crimping them, especially if you are using a magazine and feeding them.

Berry's bullets, even the plated ones, are soft. They can and will move under recoil or during chambering if there isn't a crimp. It is a pretty easy thing to check off the list as it doesn't require a lot of work to do. Either use your seater to crimp or buy a cheap Lee factory crimp die.

 

[Dave in WI]

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.

I do have some 110 Vmax here. Starline brass inbound. I don't have Red Dot here, but have some Unique?
Also, in bound is some Accurate #9 as suggested above.

 

[padom]

Just because you are using a bolt gun doesn't mean you shouldn't be crimping them, especially if you are using a magazine and feeding them.

Berry's bullets, even the plated ones, are soft. They can and will move under recoil or during chambering if there isn't a crimp. It is a pretty easy thing to check off the list as it doesn't require a lot of work to do. Either use your seater to crimp or buy a cheap Lee factory crimp die.

Never crimped a 300blk round in my life. Proper neck tension is key.

7 5rd groups in a row at 100yd with a 0.5" agg says no crimp required...

https://imgur.com/SC8J3FG

https://imgur.com/scIEA5v

 

[Walt Krafft]

If you are using it to demo a product you are selling, I suggest you find an ammo that is available for your customers to buy.

 

[Dave in WI]

If you are using it to demo a product you are selling, I suggest you find an ammo that is available for your customers to buy.

Walt, I understand what you are saying. I stock at minimum the Sellier & Bellot 200gr subsonic factory ammo that works and functions fine in the bolt and the Ar15 platform. I'm just trying to see how quiet I can get the bolt platform for customers that want to reload it for themselves.

 

[Dave in WI]

Got to run some of the Berry’s over Unique this afternoon. 7.0 gr of Unique with everything else the same, yielded 1026 fps avg and SD of 29. No wild swings in velocity. Accuracy not the best. When new brass shows up I’ll start playing with jacketed.

 

[padom]

I tested 4 or 5 300blk barrels in an AR15 when I first got into 300blk. Accuracy was terrible, I mean horrible in the first few barrels i tested. I was about to agree with the crowd saying 300blk isnt accurate and just a fun range plinking toy.

I decided to try one more barrel, its a 10.5" Rainier Ultramatch and its a tack driver (used in target posted above). I have actually tested additional samples of the exact same barrel from Rainier and they all shot exactly like this.

The barrel does matter...

 

[mic2377]

I do have some 110 Vmax here. Starline brass inbound. I don't have Red Dot here, but have some Unique?
Also, in bound is some Accurate #9 as suggested above.

Unique will likely work too, although I haven't personally tried it in particular. I used Red Dot because it burns so fast the sound signature is ZILCH from residual muzzle pressure after the bullet exits.

What works best for these loads is a fluffy, fast burning powder that is position insensitive and burns completely at low pressures. There are several shotgun/piston powders that work for this. I have even used extruded handgun powders like N340 with good success.

Because they combust more completely and evenly than slow burning double base powders like AA1680, the ES/SD will be much better too.

One thing I would say (that I am sure you know) is DO NOT use these powders with heavier bullets, and do not double charge. They can pressure spike and potentially explode things.

 

[dantiff2]

Unique works well. My “go to” load right now for quiet backyard plinking is 4.0 grains of unique, under a powder coated cast 150 gr boolit using servicios small pistol primers (I have a large supply). These are giving me consistent 2” groups on steel at 150 yards. Very quiet suppressed! Quieter than my PCP air rifle. Cast boolits can use a lower charge weight due to less pressure required to drive the bullet down the bore, so you will need slightly higher charges for heavier and jacketed bullets. If you want the most quiet, than go lighter on bullet weight and go with cast boolits.
Dan

 

[Sumtoc]

I fiddled around with 300 BO in a R700 and in an AR 10.5" build. I have actually used coated bullets for subsonic practice rounds BUT I had to bell the mouth of the cases a bit before seating the bullets. (Like pistol rounds). I shot a lot of USPSA with coated bullets and learned that if you don't bell properly you will scrape off the coating and that debris will foul the chamber causing FTF and FTC issues.

In any load I found that the crimp (absolutely required if you bell the mouth) was important to get right. These were accurate enough for subsonic practice on 4" steel at 50 yards and USPSA targets at 25 yards with nice little (1" or so at 25 yds) groups. I never cared about or measured accuracy at 100 yards. Don't think I'd ever use it for that. I have other MR/LR match and hunting rifle/cartridge systems for those purposes. All with suppressors, and IMO the 300 BO is for close in self defense or hunting. I'd not think it useful in subsonic trim beyond about 50 yards. My test data and others show a subsonic 200 gr bullet is around what you'd expect from a 10 mm pistol round so consider that......

 

[dellet]

I would try some outside the box testing. Not doing it with factory ammo, may be a false flag.

Shoot a single factory round, then your load. If it’s still low velocity, try two factory. Trying to eliminate barrel temp.

You might also try cleaning the bullets you’re using with acetone or brake cleaner. Don’t use carb cleaner as it has oils mixed in. Maybe there is a coating on the bullets left over from manufacturing. Wipe with a clean cloth or paper towel so you can see.

Trying other bullets is of course a clue if the problem follows the bullet. But doesn’t really answer why.

A lube issue with the bullets might make the most sence.

Starting with a clean dry barrel might also help if it’s a lube issue

Be aware that changing bullet weight significantly, will probably also call for a change in powder.

 

[Oso]

I fiddled around with 300 BO in a R700 and in an AR 10.5" build. I have actually used coated bullets for subsonic practice rounds BUT I had to bell the mouth of the cases a bit before seating the bullets. (Like pistol rounds). I shot a lot of USPSA with coated bullets and learned that if you don't bell properly you will scrape off the coating and that debris will foul the chamber causing FTF and FTC issues.

In any load I found that the crimp (absolutely required if you bell the mouth) was important to get right. These were accurate enough for subsonic practice on 4" steel at 50 yards and USPSA targets at 25 yards with nice little (1" or so at 25 yds) groups. I never cared about or measured accuracy at 100 yards. Don't think I'd ever use it for that. I have other MR/LR match and hunting rifle/cartridge systems for those purposes. All with suppressors, and IMO the 300 BO is for close in self defense or hunting. I'd not think it useful in subsonic trim beyond about 50 yards. My test data and others show a subsonic 200 gr bullet is around what you'd expect from a 10 mm pistol round so consider that….

Easy solution to avoid shaving off lead or coating from bullets without having to “bell / flare” the case mouth. You need a NOE Plug (.310”) which will expand case mouth and short section (maybe 3/16” down) of neck to exactly .310” and leave a slight shelf that base of bullet will sit vertically inside the neck. The NOE plug gives an exact expansion with no excess brass workage and eliminates the issue of bullets falling out or tilting as shell plate advances in a progressive. I use a Lee Universal Expander die as the host die for the NOE plug. After seating the bulllet, I use a Tapered Crimp Die and just barely kiss the case mouth to remove any residual flare. I am not giving the cartridge any crimp, but you could at this point if you wanted to. This setup works great in a single stage press or a progressive

Edit: the NOE Plug expands a limited length of the case neck. Before using the NOE Plug you will need to size the entire neck for desired neck tension with either an expander ball or expander mandrel. Typically, I use an expander mandrel in my load process. However, when the situation requires additional care/assistance for the initial seating of the bullet then I will use the NOE plug as well.

 

[Hoser]

I built up a Desert Tech Covert chambered in 300 Whisper mid 2023. The barrel is a Benchmark 7 twist chambered by TS Customs.

Working up loads with Berger 215 Hybrids, Vhit N-110 and Lapua brass. S&B 5-25 and TBAC Magnus-SR. Powder thrown by a Prometheus and verified on an FX-120i scale.

I found a solid load going about 1065 with a single digit ES/SD. I played with seating depth a bit and found a depth that was about 5/8-3/4 MOA out to 300 yards which is a far as I was planning to go.

The first first shot at 300 goes about 2.3 mils low. The rest are fine. Nice little round group. If I let the rifle sit for 4-5 minutes, shot #1 again goes 2.3 mils low and the rest are back normal.

I re-torqued all the barrel screws, checked the brake and can, scope mount, completely cleaned the barrel, etc. I even checked the loose nut behind the scope and had another solid shooter shoot 10 shots. 1st one low. 2-10 were normal.

Virgin brass, same.

Fired brass, same.

Coated bullets, same.

Different primers, same.

Different powder, same.

Different bullets, same.

Different scope, same.

I even tried just burning super sonic bullets through the barrel to see if it needed to get over the 150-200 round hump. Last round count was over 600.

Really accurate, really quiet. But that first shot is an ass kicker.

I chased my tail on this for a long time. Never did figure it out. Currently the rifle is in the corner of my safe enjoying a time out while it thinks about what it has done.

 

[1lessdog]

I was loading up some 300 Blackout ammo today. I started with Hornady 190 gr SubX bullets and IMR 4227 at 10.1 gr and CCI small rifle BR-4 primers. I was shooting it more for function and it cycled great dropping the empty cases in a nice little area. I'm shooting a AR-15 with 10.5 inch barrel. With a Silencer Central Banish 30 suppressor.

Anyone else have a load they found that is sub sonic? The SubX bullets cost 69.00 a 100. Would really like to find a cheaper bullet and keep the speed at 950 to 960 fps

I have never had a 300 Blackout short cycle or a feeding issue. They always run good. Don't over think it. I'm running a 10.5 inch barrel with standard gas block and pistol length gas tube. A carbine buffer sp and buffer. And dropping the empty casing at 4 or 5 o'clock and 6 ft away in a nice little pile.

 

[padom]

Yep... 220 SMK from American Reloading. I shoot tons of them in subsonic 300blk for years out of my 10.5" AR with CFEBLK...


250ct for $90 shipped to your door (have to add to cart to see full discount)

308 220gr SMK HPBT PULLED - 250ct

Pulled Projectiles May contain: Mixed Lots, Discolored Finish and/or Minor Deformities Any specific pull marks will be noted and pictured

americanreloading.com

https://imgur.com/sPCZMLB

 

[Sumtoc]

Easy solution to avoid shaving off lead or coating from bullets without having to “bell / flare” the case mouth. You need a NOE Plug (.310”) which will expand case mouth and short section (maybe 3/16” down) of neck to exactly .310” and leave a slight shelf that base of bullet will sit vertically inside the neck. The NOE plug gives an exact expansion with no excess brass workage and eliminates the issue of bullets falling out or tilting as shell plate advances in a progressive. I use a Lee Universal Expander die as the host die for the NOE plug. After seating the bulllet, I use a Tapered Crimp Die and just barely kiss the case mouth to remove any residual flare. I am not giving the cartridge any crimp, but you could at this point if you wanted to. This setup works great in a single stage press or a progressive

Edit: the NOE Plug expands a limited length of the case neck. Before using the NOE Plug you will need to size the entire neck for desired neck tension with either an expander ball or expander mandrel. Typically, I use an expander mandrel in my load process. However, when the situation requires additional care/assistance for the initial seating of the bullet then I will use the NOE plug as well.

Oso, thanks for the info. I used several 30 cal expander mandrels that I had on hand until I found one that worked with the least amount of neck belling (don't want to over work it, right?). Well, it appears that the NOE expanders will simplify the process without undue working of the case mouth. I'll have to try one the next time I set up for 300 BO. Good catch.

 

[boltfluter]

I built up a Desert Tech Covert chambered in 300 Whisper mid 2023. The barrel is a Benchmark 7 twist chambered by TS Customs.

Working up loads with Berger 215 Hybrids, Vhit N-110 and Lapua brass. S&B 5-25 and TBAC Magnus-SR. Powder thrown by a Prometheus and verified on an FX-120i scale.

I found a solid load going about 1065 with a single digit ES/SD. I played with seating depth a bit and found a depth that was about 5/8-3/4 MOA out to 300 yards which is a far as I was planning to go.

The first first shot at 300 goes about 2.3 mils low. The rest are fine. Nice little round group. If I let the rifle sit for 4-5 minutes, shot #1 again goes 2.3 mils low and the rest are back normal.

I re-torqued all the barrel screws, checked the brake and can, scope mount, completely cleaned the barrel, etc. I even checked the loose nut behind the scope and had another solid shooter shoot 10 shots. 1st one low. 2-10 were normal.

Virgin brass, same.

Fired brass, same.

Coated bullets, same.

Different primers, same.

Different powder, same.

Different bullets, same.

Different scope, same.

I even tried just burning super sonic bullets through the barrel to see if it needed to get over the 150-200 round hump. Last round count was over 600.

Really accurate, really quiet. But that first shot is an ass kicker.

I chased my tail on this for a long time. Never did figure it out. Currently the rifle is in the corner of my safe enjoying a time out while it thinks about what it has done.

Been through this exact scenario with a 22BR trying to find a good sub-sonic load. 1st shot 2" low, next 4 in a .25 bug hole 2" away. Shooting at 50 yds. Tried everything I could think of and even called Sierra to pick their brain. No joy. They seemed to think it had something to do with bore condition of first shot or oxygen in the suppressor? No clue to this day. Not much help, but you are not alone with this situation.
Paul

 

[dantiff2]

^^^This, What Paul said.^^^
Never hit me until now, I may be able to help!
I noticed after getting my suppressor that I get a drastic first round "POP" shooting my subsonic with my Black Out. Not sure why, but it's the worst out of all of my suppressed subsonic loadings. I remedy this by placing an earplug over the end of the straw on a can of compressed air and that helps to seal up the chamber. I then blow about 5 seconds worth of the canned air down the barrel. This helps to remove all of the O2 that's in the bore and suppressor so that I no longer get that first loud shot. Try this to see if it helps you with you first shot deviation.
Dan

 

[dellet]

Those with bolt actions and low velocity first rounds, have you tried loading single shot?

Part of the reason I use pistol powder for subs is that it is less position sensitive, less erratic in low density loads.

The first round off the magazine in a bolt action has not been subjected to recoil, the powder lays different in the cartridge. In an AR, even the first round the powder moves forward while chambering.

Powders that throw high ES/SD numbers are telling you they are not stable. You can get way with an SD in the 20’s at 50 yards for subs and 100 for supers, but if you plan to shoot any farther, expect vertical strings.

 

[CaptJim]

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.

I am interested in loads like this for 300blk. I don’t have Red Dot but do have some Hodgdon Clays and Winchester Super Target, Alliant Bullseye, and some 110-135gr 30cal bullets I used for supersonic loads in 300 Blk and 308. Thanks for the info.I always thought subs needed the heavier bullets.
CJ