Thread: Loading for .300BLK

Yip even a custom barrel job will cost you most of that.. best to find something factory made and customize to your taste

So with two great shooting subsonic loads sorted I moved my focus to a supersonic load.



Back when I first started out in this cal (.300 Whisper) the go to hot round was the 125gr Nosler ballistic tip. I got 2450fps from a 1-8" twist 17" tube and they were bullet on bullet accurate at 100y. I still have a box of 50 of those loads loaded up but they have never been as accurate in the 1-7" twist Remington 16" barrel and show flat primers at 2230fps.
This has lead me stray from the tried and true to search for a new high velocity bullet to suit this rifle. I wanted to stay with the 125 to 130gr weight range as anything lighter is way over stabilised at high velocities in the 1-7" twist and accuracy often falls apart on the longer ranges.

First up I tried 130gr Speer TNT HP which always shot well in my old 1-8" Whispers but after trying a few powders and seating depth combos I concluded they were also just mediocre in this Remington.

I have seen a bit of online hype around the 125gr Hornady SST and how the Fiocchi factory ammo loaded with this bullet seemed to be the go to in the USA for a very accurate supersonic load.



While personally Im not a fan of Hornady bullets or bullets with cannelures in general but I thought Id give them a go.
Unfortunately I couldn't find any 125gr SSTs in stock in NZ when I went looking but I did find the 123gr Z-Max 310" 7.62x39 version. Close enough.. I lubed them and pushed them through my .308 cast bullet sizer which was actually easier than I expected it was going to be and loaded them up with my favourite 125gr bullet charge of 19gr of H110.



I loaded 5 to the cannelure groove like Fiocchi do but being a fairly long flat based bullet I could see that I could also pull them out closer to the lands too which has help accuracy in many other bullets Ive tried in this rifle. The closer I can get them to its long throated lands (designed around the longer subsonic bullets) the better I have found.
Here's the 123gr Z-max along side my trusty 125gr Nosler BT and the 240gr SMK both loaded 20 thou off the lands.



As you can see the Z-max seated to the cannelure has a lot of jump.
The pic below shows them pulled out to the same 20 thou jump as the 240gr SMK sub beside it.


I only sized 10 bullets to .308 and put two of the cannelure groove seated ones over the chrono to test velocities so there was only 3 of them left to put on paper. I clocked them right on 2200fps which is a tad low for a 123gr in a 16" barrel but the primer was flat so Im picking the 1-7" twist lfts the pressure substantially compared to my older 1-8 twist barrels.





So the 3 remainder short seated bullets were shot out to 100 yard and gave me just over an inch group. Nothing to rave about there.



The next three long seated bullets however were one ragged hole.. I chickened out sending the last two and walked to the target board to get a photo first.



Back to the bench I shot the last two expecting to ruin the nice group.. pleasantly surprised it was still under a 1/2 MOA



The difference in pressure between the two seating depths was massive though, the flat primers were quite bad on the cannelure seated bullets.
I feel I could lift the powder weight another .5gr in the longer seated ones and maybe grab a bit more velocity.




Now I know what you are all thinking.. that shoots great why would you try anything else???
Because I'm not sure how clear I made it at the start of this thread but Im a total bullet snob.... AND I HATE SST's!!!!
The price you pay for them v/s weight and dimension deviations in a box of this crap is nothing short of dog shit.. and yes I did scratch through the whole box to weigh and measure off bullets to get 10 that were close to the same weight and dimensions...

So next up is a bullet Ive been dying to test... the 125gr Sierra Tipped Match King.
Specifically designed for the BLK round these are supposed to be the ducks nuts and from my observations they are very similar in makeup as the noslers that went so well on game in my previous guns.

Black Hills match make a factory loading with this bullet but I have been unable to find any reviews on it.




Here's Sierra's info on their new 125gr Tipped MatchKing

.343 @ 2580 fps and above
.338 between 2580 fps and 2180 fps
.332 @ 2180 fps and below

The 30 caliber 125 grain MatchKing was created as a flat based bullet for the .300 AAC Blackout cartridge designed for the AR platform. With the addition of the acetal resin tip to improve ballistic coefficient, this Tipped MatchKing (TMK) bullet is designed to expand the diversity in our lightweight .30 caliber offerings for AR and bolt action chamberings. The jacket was specifically designed to handle velocities ranging up through common .30 caliber mid-level cartridges.
While they are recognized around the world for record-setting accuracy, MatchKing® and Tipped MatchKing® bullets are not recommended for most hunting applications. Although MatchKing® and Tipped MatchKing® bullets are commonly used for varmint hunting, their design will not provide the same reliable explosive expansion at equivalent velocities in varmints compared to their lightly jacketed Hornet, Blitz or Varminter counterparts.



Now the flat base gives me hope that these can be pulled out longer and get close to the lands while still leaving enough in the neck to hold them concentric.
I know many frown upon using such frangible bullets like these TMK's, nosler ballistic tips and V-Max etc on larger game but anyone who has done so will know that the BLK actually benefits from bullets like this.
The Relatively low muzzle velocity of the BLK doesn't grenade these rounds like a .308 win does, they start out much slower and wash of even more speed over 100-200 yards so frangible varmint bullets actually hold together and form a nice mushroom like a heavier hunting bullet does at higher velocities in bigger "powder wasting" cals.

I just saw this from Winchester web site:
https://winchester.com/Products/Ammu...per-X/X300BLKX

Interesting find.. I wonder if they sell the projectiles.. would love to test them

I reckon 300 BLK "has arrived" with a decent range of projectiles and loads specifically tailored to its performance now readily available and cheap - the Fiocchi is $36 for 25 rounds and its high quality ammo with good brass. We can probably put this down to suppressors becoming "possible" and therefore popular in the "land of the free" haha. Its popularity will only grow now I think.

I've tested the Fiocchi 125 SST ammo in two rifles now, it shot groups of about 40mm in my AR, in the Ruger American it shot 19mm groups. Hopefully I'll have a report on its performance on some Reds soon.

This has got me interested. I'm looking for a second rifle to shoot at the range while I wait for mine to cool done.
This seems to tick the boxs. Plus with the fun of reloading.
Couple of questions @Wingman
1. The blackout rifles that are for sale here in the uk are over priced and in the wrong twist rate 1.7 from every thing you and others have said 1.8 is the go. So would you buy a barrel in .300 or .338? Also why.
2. I'm restricted here in the uk to bolt action........feck it can't remember the second question must have been a lie
Cheers

1-7" is fine but 1-8" is more versatile over a broader range of projectiles.
.338 is a pricey plinker and has no where near the range of projectiles.. its more of a hunter than a range toy.
Build a custom CZ 527 with a 1-8" 17" barrel and you will have a great all round rifle.
Wait.. what was the question again?

Interesting read. I got back today from a hunting trip a mate and I both run 300BLK we got six stags between us I gave him some 194gr Lehigh ME to try for the first time as he’s been using the 208gr A-max for the last 4-5 years in his Rem 700 mostly for head neck shots. It was the first time he’s shot over 180m with his blackout, and I dailed out to 260m on a 26 degree up hill shot in the lungs. We both lined up the stags and fired 2 shots each in 5 seconds after they dropped and slid off the hill the hill erupted in other stags bolting up the hill. The first for the trip we shot two Hummel spikers fighting in the fog at 60m.

Back to reloading I’m running ADI 2205 for everything supers and subs, home made 300BLK brass from LC 223 cut down, sized, trimed to spec then I weight each case into 3 weight groups to get the lowest ES for best long range. My 12” barrel shoots the 194gr ME 9.1gr of ADI2205 @ 1018fps, with the same batch my mates rem 700 16” barrel is doing 1070fps. Going super I’ve only used nosler 125gr BT @ 2005 fps, I do know of a guy down south using hornady 110gr v-max and has shot 100 deer with his AR 300BLK.

So as you see the new 125gr TMK is about the same length as the nosler 125gr BT but the flat base meant more case room and less compressed loads.
I loaded the TMK to a little over half way down the neck which gives me about 30 thou to the lands. While some may think that is quite a big jump, keep in mind this projectile was designed for the .300blk in the AR15 platform. These Sierra bullets apparently cope with big jump just fine. Either way I loaded them toward the long side as I have a non restricting AI mag so just set them up the same as my 240gr Subsonic base to ogive measurement.







Next I loaded up some test loads with H110 in 0.5gr increments from 18.5gr to 20.5gr.
Yes I know that's a big increment but I know this cal well and knew what I was looking for.



Out of interest I looked up Sierras load data for this 125gr TMK and they state a max charge of 18.7gr of H110 in a 16" 1-8" twist with an COAL of 2.260 giving somewhere in the 2200fps range.
However I have mine loaded at 2.322" which will drop the pressure and velocity compared to their loads and considering my nosler 125gr load is running 20.5gr of H110 I knew I wasnt pushing any new limits with my loads. The pic below is a case from each of the loads showing pressure clearly increasing from left to right. Even the load of 20.5gr wasnt showing any high pressure signs other than a slight primer crater typical of the Rem 700s but the group and velocity spread was the tightest at 19.5gr giving me an average speed of 2390fps.








Out to 100 yards I put them on paper along side my Nosler 125gr ballistic tip loads. The Noslers have always been my best shooters in all my .300 Whisper/BLK rifles but they have never done better than a inch in this one. Today was no different.. they shoot at 2420fps in the 1-9" 16" barrel but the same load used to give me 2500fps in the 1-8" 17 inch whisper barrels with tiny ragged holes at 100 yards.
Here's the Noslers cherry picked group..





I was very happy to see the new TMK halved that inch group on a very moderate load. I may still push it a bit faster and try some ADI 2205 behind them as one of my BLK AR15's seemed to favour that powder over the H110 with the 125gr loads.

Hi Wingman have you tried lil'gun in your supersonic loads, I've had good results with both 110gn vmaxs and nosler 125gn
Thinking of trying the 135gn fmx heard they work well

Originally Posted by 300MAG

Hi Wingman have you tried lil'gun in your supersonic loads, I've had good results with both 110gn vmaxs and nosler 125gn
Thinking of trying the 135gn fmx heard they work well

Lil'gun really sparks things up

If you are after a cheap projectile for general range work try the CMJ Frontier 155g .308 Projectile.
At $184 per 1000 they are hard to go past.
Its all I shoot through by 300 blackout.

Originally Posted by Simon

If you are after a cheap projectile for general range work try the CMJ Frontier 155g .308 Projectile.
At $184 per 1000 they are hard to go past.
Its all I shoot through by 300 blackout.

+1
Great price and they work mint 🖒

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@Wingman

Awesome post, my 5R 300 Blackout should be here later this week. Next time I’m in Hamilton I’d love to buy you a beer, there’s a neat brewery not far from TJ’s place...

:-)

@Wingman

Awesome post, my 5R 300 Blackout should be here later this week. Next time I’m in Hamilton I’d love to buy you a beer, there’s a neat brewery not far from TJ’s place...

:-)