Thread: Hornady sub-x 175gr load data...

So, I have a box of 100 of these little critters loafing here. Interested to try them out in .308W simply because I have them there...

I can find subsonic load data for the heavier 190gr version of this pill but nothing for the lighter, this seems a little strange to me as the pill is ID'd for sub work and I'm wondering if I'm missing something. Equivalent weight cast lead pill looks to run about 1.5-2gr less powder for the speeds listed in the supersonic data, which in my brain kind of makes sense for a fully jacketed pill. The swiss jew tightarse in me doesn't want to start loading up 20 pills to find out what's reliably subsonic, I'd rather use them for accuracy and grouping test so if they are going to play nice I have a good 70 or so to keep me going. So, has anyone been using these in .308, 1-10" twist and 20" barrel?

Have Red Dot and Trailboss on hand.

Cheers

10.7gr trailboss works well for the 190gr subs. Sorry no data for the 175gr ones.

My best bet would be to get a chrono (garmin) and just shoot a couple. start drom the top, lower in 1 or 0.5 gr increments to quickly get you into the ballpark. should only require 3 or 4 bullets. After that interpolating should get you close enough to the actual velocity.

For me the 190 shoot sub-moa at 50m but range is severely limited, so inwould not worry too greatly about accuracy

I guess you will be subsonic somewhere around 9gr (just a guestimate and might be completely off)

12.7 gr TB for 1061 fps

found at
https://hodgdonreloading.com/rldc/

although I note that at
https://hodgdonpowderco.com/wp-conte...ta-final-1.pdf

it is 10.5 gr TB for 1039fps with the 190gr sub-x


FWIW I use 10.0 gr TB with 165gr projectiles for subsonic .308, 18" barrel, 1/10 twist.

Originally Posted by longshot

12.7 gr TB for 1061 fps

found at
https://hodgdonreloading.com/rldc/

although I note that at
https://hodgdonpowderco.com/wp-conte...ta-final-1.pdf

it is 10.5 gr TB for 1039fps with the 190gr sub-x


FWIW I use 10.0 gr TB with 165gr projectiles for subsonic .308, 18" barrel, 1/10 twist.

Yep seen that, hence why I'm cross checking.

Their data off the website doesn't appear to make sense...

190gr Sub-X - TrailBoss - 2.690 length - Max powder 10.5gr - Vel. 1039fps - Pressure 30100psi
175gr Sub-X - Trailboss - 2.495 length - Max powder 12.7gr - Vel. 1061fps - Pressure 27200psi

2.2 gr extra powder for the 175gr pill, I realise it's a little shorter than the 190gr but seated almost 5mm shorter for 22fps extra speed yet 2900psi lower pressure? I think I'm missing something or overthinking it, but 2.2gr extra powder for 2900psi less pressure indicates something I haven't experienced with Trailboss before. This is why I've asked on here if someone has actual real world results, as the info I have is basically the opposite of what I'd expect!

I use 6gn of ICI Nobel Shotgun Powder No 78 which is quite bulky and very close to both Red Dot and AS70N. I'm using the same load for both 204gn HP GC and 185gn FP GC cast bullets from Robert Walker. I can get 5 of either into a 2- 2.5in group at 50m..the 204 gn are doing 920fps, the 185gn are doing 960 fps on average. Both sound exactly like a suppressed subsonic 300BLK from a DOC Culler's expensive rig according to my mate who has had to listen to a stash of Fallow on the Nth Shore get decimated at 3am in the morning. Not his stash but he has been enjoying the venison. I nailed the old Stag at 36m with a shoulder shot with a 204gn. Bang Flop. Having run out of my 25ct sample pack of those I got from Robert a few years back I picked up some subX to try also. Havnt got there yet but will start with the same load. For subsonic thats where I would also start with powders like Red Dot or AS30N. For jacketed bullets check they leave the barrel each shot.

Interestingly the Walkers were cast at .313dia for 303B..I found by accident that my old Interarms Mark X just loves them in that dia. It won't shoot .309 cast worth a damn.

Anyway FWIW

That's not surprising, cast bullets in my experience work best when over groove diameter for some reason

They fill the grooves better is the explanation I have heard. A bit of squash longways as well as side to side, helps the pills to obturate into the grooves accurately and get a full seal of the bore I guess is the technical version...

Originally Posted by No.3

Yep seen that, hence why I'm cross checking.

Their data off the website doesn't appear to make sense...

190gr Sub-X - TrailBoss - 2.690 length - Max powder 10.5gr - Vel. 1039fps - Pressure 30100psi
175gr Sub-X - Trailboss - 2.495 length - Max powder 12.7gr - Vel. 1061fps - Pressure 27200psi

2.2 gr extra powder for the 175gr pill, I realise it's a little shorter than the 190gr but seated almost 5mm shorter for 22fps extra speed yet 2900psi lower pressure? I think I'm missing something or overthinking it, but 2.2gr extra powder for 2900psi less pressure indicates something I haven't experienced with Trailboss before. This is why I've asked on here if someone has actual real world results, as the info I have is basically the opposite of what I'd expect!

In theory if 10.5gr can push a 190gr projectile out, it should push a 175gr projectile out.

Given that 10.0gr works for me with 165gr projectiles, I think if you try 10.5gr on the 175, it should be close to what you want.

it works out with quite a few smokeless powder cartridge combos ..... pretty darn close to ten grains of projectile weight added = minus 1-2 grn of powder....so its not at all out of the ordinary

Meh, in supersonic loads yes I'd agree but in this case we are setting the powder amount to control velocity. All other things being equal, it's not the weight of the projectile but the bearing length causing friction in the bore which gives the powder requirement in this case. So for a shorter projectile, less bearing length, less friction, less powder - the listed loads seem to be the opposite for the similar velocity in this case. I can't find any real-world loads to cross check that but it seems wrong to me... Starting at 12.5gr might end up with a wildly supersonic load so what I'm wondering is if Hornady has listed the 'max load-work down' but a subsonic velocity or something else is not kosher.

Info for the Speer round nose 180gr pill is generally noted at 10-10.5gr TB across the web from what I've seen for about 1040FPS depending on barrel, so where I'm getting a little confused/curious is why the maker of the 175gr Sub-X pill is stating 12.7 for 20FPS more than what would be considered normal a relatively similar pill, and then 2.2gr more than a heavier similar design pill from the same brand for only the same 20FPS more speed. It seems like an anamoly to me, and where my thinking is with this is trying 10gr as a start point, testing for stability and velocity and going from there - risk being a bore lodge. The 151gr cast 'Tokoroa special' load is about 8.5gr TB, so 2gr more for the 175gr Sub-X kind of fits the rule of thumb above.

This is where I started with TB which was in the same month as when I started reloading.

https://hodgdonpowderco.com/wp-conte...ads-2018-2.pdf

Note the instructions rather than the data, basically stating anywhere between full non compressed case capacity and 70% of same is where you want to be.
So by my logic, if you want to try a given powder weight that deviates from the single given weight (as opposed to min/max) then these instructions give you the min/max that you can play with.

While I am reluctant to table the following as a definitive, it is a possibility that the data given is the max data (generally with TB one works down rather than up) so is therefore the starting load. The greater case capacity being afforded by the shorter projectile. This may explain the apparent anomaly.

Just noticed the shorter projectile gives less OAL rather than greater powder capacity.

The other option is to email the tech department at Hornady, every time I email them looking for data on an unpublished powder, they come back with the information but also information about what powder they have found is best for the particular projectile for the particular cartridge.

Originally Posted by longshot

This is where I started with TB which was in the same month as when I started reloading.

https://hodgdonpowderco.com/wp-conte...ads-2018-2.pdf

Note the instructions rather than the data, basically stating anywhere between full non compressed case capacity and 70% of same is where you want to be.
So by my logic, if you want to try a given powder weight that deviates from the single given weight (as opposed to min/max) then these instructions give you the min/max that you can play with.

While I am reluctant to table the following as a definitive, it is a possibility that the data given is the max data (generally with TB one works down rather than up) so is therefore the starting load. The greater case capacity being afforded by the shorter projectile. This may explain the apparent anomaly.

Yeah that's what I assumed as well (listed the max load and work down) but then I thought about the likelihood of ballsing it up when you assume with anything reloading and had the old ACC hmmm... That and looking at the listed velocities - something just ain't right. Less bearing surface = less friction = less powder to overcome the friction to get to the desired velocity, with the proviso that the barrel length is long enough to consume all of the powder (which mine should be at 20").

With supersonic loads, the equation works out a little differently as the time in the barrel is critical to getting enough powder burn for the expansion to drive the pill while it's still in the barrel and the gasses can push without dispersing (which is why we often run a slightly faster powder with a lighter bullet in any given case size). In the case of subsonics, from my (admittedly somewhat limited experience) two bullets similar profile but with one having a longer bearing length - if loaded with the same powder charge the shorter bullet will leave the muzzle faster. That's what has got me confused with the Hornady data, why are they getting virtually the same speed (22fps difference) when loading the lighter bullet with 2.2gr more TrailBoss?