450 Bushmaster Subsonic Load Data

[Edgedweapon88]

I have been unsuccessful at finding any load data in the forums or in my current load books about subsonic loads for the 450 bushmaster. Specifically, a 395 grain sub-x projectile from Hornady.

Based on the factory sub-x round I took apart it looks like roughly 19-20 grains of mystery powder. H110, Vhint 110, lil gun and Accurate #9 all seem to be a possibility.

Anyone have experience loading subsonics for this T-Rex cartridge?

 

[85MikeTPI]

Ammo Factories don't have to use factory powders.

If I was going to make 395gr subs for my big board AR, I would start at 19-20gr of Accurate 1680 and work down a ladder with a good Chrono and checking for squibs along the way.

 

[Edgedweapon88]

Ammo Factories don't have to use factory powders.

If I was going to make 395gr subs for my big board AR, I would start at 19-20gr of Accurate 1680 and work down a ladder with a good Chrono and checking for squibs along the way.

Good copy. That’s my plan

 

[Harrys]

I have been unsuccessful at finding any load data in the forums or in my current load books about subsonic loads for the 450 bushmaster. Specifically, a 395 grain sub-x projectile from Hornady.

Based on the factory sub-x round I took apart it looks like roughly 19-20 grains of mystery powder. H110, Vhint 110, lil gun and Accurate #9 all seem to be a possibility.

Anyone have experience loading subsonics for this T-Rex cartridge?

Shooter's Reference Load Data for .450 Bushmaster

shootersreference.com

Reloading Data Center

www.hodgdonreloading.com

Based on the recomendations of all the above 325 gr heads are the maximum size to be used safely.

 

[Edgedweapon88]

Shooter's Reference Load Data for .450 Bushmaster

shootersreference.com

Reloading Data Center

www.hodgdonreloading.com

Based on the recomendations of all the above 325 gr heads are the maximum size to be used safely.

Hornady sells a factory 395 grain factory loading as well as selling the subx projectile itself. Just can’t find any reference data.

 

[smdub]

Message Hornady for load data. They provide it for their other bullets. https://www.hornady.com/support/load-data/

 

[elwojo]

Message Hornady for load data. They provide it for their other bullets. https://www.hornady.com/support/load-data/

I'm not sure if it was there or not when you posted this, but 450 bushmaster loads for the 395 sub-x projectile are there now. They only list speeds down to 1300fps though. Not quite "sub". I'd be curious what people find for getting down to 1050fps.

 

[RAW TOW]

Talked to a Hornady rep from the factory about reloading the 395gr sub-x bullets, and they are blending powders to get the below the speed of sound performance. They explained that they are working on getting data for the public to load the bullets which they have sold on the market all year long. Don't hold your breath fellas.

 

[Jerry M]

Is it possible to safely download a .450 Bushmaster to .45 ACP speeds?

 

[1MIGHTYJOE]

Is it possible to safely download a .450 Bushmaster to .45 ACP speeds?

I have been loading what I call plinking rounds - 230 grain plated round nose ball under 8 grains of bullseye. Light recoil, accurate to 100 yards, average muzzle velocity is 1150fps. - Going to try this load with a 300 grain jacketed bullet and try to get under the sound barrier....

 

[Growler215]

As I described in another post, I loaded up some 395 gr Sub-X bullets using 5 different powders and 5 different charge weights for each powder. Intent of this was just to find which charge weight for each powder would yield about 1050 fps in my rifle (Ruger AR with 18" 1:16 twist barrel). I finally managed to get the factory muzzle brake off this thing and a thread protector installed, so I took it to the range today with my handloads and a box of Hornady factory Sub-X cartridges.

For A1680, A5744, CFE BLK, and IMR 4227, I used the Hodgdon load data for this bullet as the central charge, and went up 0.3 and 0 6 gr and down 0 3 and 0.6 gr. For N120, I extrapolated down from the Hornady 1300 fps data to find a 24.1 gr central charge, and went up and down 0.4 and 0.8 gr, since Hodgdon didnt have sub loads for this powder. All loads were fired from highest to lowest charge.

For the most part, this process worked fine and "captured" the 1050 fps point. The exception was for Accurate 1680. For A1680, even 0.6 gr above the Hodgdon recommended load of 21.4 gr only got me 1023 fps. By the time I got down to 21.4 gr the bullet was only going 895 fps. So I didn't bother to shoot the 21.1 (-0.3) and 20.8 (-0.6) gr loads.

Because factory Hornady Sub-X didn't cycle when I was sighting in, all loads were single fed. CFE BLK and N120 both ejected all loads, and may well have cycled. None of the other powders did. With a supressor, CFE BLK and N120 may have locked back, and some of the other powders may have cycled.

Below is the target from today. The factory Hornady ammo shot "ok," but was a little hot. With an average velocity of 1094 fps and an SD OF 15.4 fps (not including cold bore sighter), some shots are going to go supersonic. I want an average velocity at least 2 and preferably 3 standard deviations below the speed of sound (1110 fps this morning).

No great significance to the other "groups" since every round was a different load. Doesn't hurt to practice trigger mechanics aiming at a target anyway.

So, how about a graph? Not as pretty as I would have hoped, but the data is what it is. Disappointingly, the two powders which looked like they will have the worst SD were CFE BLK and N120 - the two powders with the best cycling function. And the powder that looks like it may have the best SD is A5744 (the most expensive). Still, it looks promising that a decent load can be achieved.

Next step for me will be to use the data to come up with a single charge weight for each powder, load them up and have a "shoot off." Looks like 22.2 gr A1680, 21.7 gr A5744, 21.7 gr 4227, 23.6 gr N120, and 24.2 gr CFE BLK. May drop CFE BLK, for now, though, and test a different powder. Might try CFE BLK again when I want to experiment with some tricks to get more consistent burn . . .

 

[Growler215]

PART 2:

Made it out to the range today to continue testing 450 Bushmaster Subsonic loads with the 395 gr Sub-X bullet.

I used the same gun, same bag of brass (new Starline), same primers (CCI #41), same box of 395 gr Sub-X bullets, and the same jugs of powder as last time. My dies haven't been touched since last time, either. I even had the same bench at the range. All loads were again weighed to +/- 0.01 gr.

The only real difference was the ambient temperature. It was 14°F colder this morning (40°F vs 54°F when I did the initial testing 9 days ago.) That, and I adjusted my scope 1 moa to the left prior to doing any shooting today.

Attached is the target from today's testing. Shot at 50 yds again. Velocities and standard deviations marked on target. It appears to me that the Hornady factory Sub-X loads, as well as the A1680, IMR 4227, and Vihtavuori N120 loads were all impacted by the temperature change.

For the factory Sub-X ammo, the lower velocity was a positive, since they were a little too fast last time. Today they were around 40 fps slower.

For the A1680, IMR 4227, and N120 loads, the lower velocities put me below the 1050 fps goal, which the charges used today were intended to give. For the IMR 4227 and N120 loads, the average velocity was about 40 fps below the target velocity, which could be acceptable if I didn't ever intend to shoot this bullet when it was even colder than today. For the A1680 load, though, the average velocity was more than 100 fps slower than intended, and there was a lot of vertical stringing in the group.

As I mentioned after the initial testing, the CFE BLK powder showed a lot of velocity scatter and inconsistency. For today, I replaced it with Lil' Gun. I used a center charge of 16.7 gr, (as recommended by Hodgdon to get 1050 fps,) and went up and down by 0.3 and 0.6 gr, and fired 1 round at each of these 5 charge weights. I knew from past experience that Lil' Gun is pretty temperature sensitive, and it turned out that 17.3 gr of Lil' Gun still did not reach the 1050 fps target velocity.

The real bright spot today was the Accurate 5744 load. It performed as expected, showing almost no temperature sensitivity, a low Standard Deviation, and a decent group to boot.

Attached is a velocity vs charge weight graph for the powders tested today. Extrapolating the Lil' Gun data, it looks like about 17.7 gr of Lil' Gun would get to 1050 fps under today's conditions. But, as I already know this powder is temperature sensitive, I'm not sure that I'll bother testing that load.

I'm not really interested in having different loads for different weather conditions. So, unless I can get my hands on some other promising powders, e.g. Shooters World Blackout, Shooters World Socom, Shooters World Buffalo Rifle, Hornady 4198, IMR 4198, or Ramshot Enforcer, I think I'm done with load development for 395 gr Sub-X for this rifle for now. I went through a box of 50 bullets for this load development; now I'm going to load up another box with 21.7 gr of A5744.

TLDR: Accurate 5744 won the shoot off.