Thread: Loading for .300BLK

A cobber of mine just got a Ruger American 300BLK (secondhand for $700) and it shoots really well, you'd be hard pressed to build anything for that money (even new they are only $900)

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.