Getting Started with 7" Barrel Suppressed AR15 Pistol

[Alec]

Hi folks, first time posting here, bit of a lurker once in a while.

This is the first time I'll ever handload rounds - long term I want to have data for target, hunting, and self defense.

I just built a 7" pistol with the Q barrel they sell and from the research/information I've found online here's my target load for starting off some subsonic target loads
Powder: H110 9.2 g (this is apparently max load)
Bullet: Hornady A-MAX 208 gr
Casing: LC

Is the above info a good starting point for 7" barrel pistol build? When I first shoot these I will have the gas block in suppressed setting but won't have the suppressor attached because I don't have it yet.

[alamo5000]

I can talk specific load data later on but I am wondering about your choice of bullet (and powder).

Can you expand on your line of reasoning for selecting that specific bullet for self defense, hunting, and plinking?

What is your reasoning behind that specific powder as well.

Don't misinterpret me, I am playing a little devil's advocate right now so we can all learn from each other

Both that bullet and that powder are excellent. I've been reloading nearly 1000 rounds so far with H110. I also love that particular bullet you mentioned, and I especially love it's big brother, the 225 grain version.

[Alec]

I can talk specific load data later on but I am wondering about your choice of bullet (and powder).

Can you expand on your line of reasoning for selecting that specific bullet for self defense, hunting, and plinking?

What is your reasoning behind that specific powder as well.

Don't misinterpret me, I am playing a little devil's advocate right now so we can all learn from each other

Both that bullet and that powder are excellent. I've been reloading nearly 1000 rounds so far with H110. I also love that particular bullet you mentioned, and I especially love it's big brother, the 225 grain version.

Oh, no worries, I appreciate the devil's advocate approach I do that a lot.

So, like I said I've compiled a little bit of info from several Google searches and here's what I have:

• Apparently "best" projectiles are Sig Sauer, Discreet Ballistics, and Hornady - I went with Hornady because I know their factory ammo and because the other two manufacturers are pricey or lack info
• For powders I've compiled this: H110 good for lighter bullet < 135 gr, A1680 for subsonic, Lil Gun for > 150 gr - I went with H110 here initially because I found load data for the A-Max projectile with it for subsonic

I was just looking back at some of the threads on the website here and am already seeing I should most definitely start with A1680 for powder for subs especially.

How good are Sierra Bullets' projectiles?

[alamo5000]

Oh, no worries, I appreciate the devil's advocate approach I do that a lot.

So, like I said I've compiled a little bit of info from several Google searches and here's what I have:

• Apparently "best" projectiles are Sig Sauer, Discreet Ballistics, and Hornady - I went with Hornady because I know their factory ammo and because the other two manufacturers are pricey or lack info
• For powders I've compiled this: H110 good for lighter bullet < 135 gr, A1680 for subsonic, Lil Gun for > 150 gr - I went with H110 here initially because I found load data for the A-Max projectile with it for subsonic

I was just looking back at some of the threads on the website here and am already seeing I should most definitely start with A1680 for powder for subs especially.

How good are Sierra Bullets' projectiles?

The beauty of 300 BLK is that you have an extremely wide array of bullet choices. Your initial criteria were for a very wide array of uses. If you have a cash cow out back let me know where you live

Typically one will not use a heavy bullet for anything hunting or self defense related. You definitely want to stay on the light side for that. 110 grain or 125 grain are your friend there. Velocity is your friend for sure.

Sierra bullets are awesome. There is no problem there by any means. And like I said, my favorite bullet so far for a super quiet ninja subsonic load was the Hornady 225 grain.

Dellet put up a post recently that is super nerd like but that is right down my alley... It was about the noise bullets make when they fly through the air. Don't get me wrong you can make quiet rounds, then again you can make rounds even MORE quiet. I was amazed at how I was able to get very consistent velocities and still get to that ultra ninja quiet stage.

I am sure someone will come along and talk about powder choices... some of the faster powders are great for short barrels. I still want to buy and try some VV powders.

For plinking the cheaper bullets are going to be whatever is on sale. You could probably get some 147 grain for real cheap to just plink.

If you want to go even more cheap cast bullets are a thing. A lot of people here swear by them so I bought 1000 of them and have worked out the kinks. Just today with a load that was made for reliability not so much accuracy, I got a 3 inch group at 100 yards using a 1x red dot that has a 2 MOA dot. Definitely useable stuff there. I formed a lot of brass recently so I am using those cast bullets to plink and also ensure that my cases are reliable. So far I have only had two cases that I had to toss, but those were on my first run before I switched dies.

Put it this way, reloading for this caliber is a hobby unto itself. It's just a matter of shooting more for less money. Those 208 grain bullets are going to add up fast. They aren't bad by any means. In fact, quite the opposite. They are fantastic. They however might not be the best choice for your stated goal.

Of course it's just my opinion but you crossed into too much turf for an all in one expectation when you might be better served by breaking things up into smaller areas of excellence.

IE I want a hunting load. (then proceed)
IE I want a subsonic ninja load. (then proceed)
IE I want a plinking load (then proceed)

Those three are going to have totally different bullets and possibly different powders as well.

Honestly I am having a ball reloading for this caliber. I don't think I will ever be done developing loads, and I for sure need to make sure I keep good notes so I can get back to it when I need to.

[Alec]

Oh, no worries, I appreciate the devil's advocate approach I do that a lot.

So, like I said I've compiled a little bit of info from several Google searches and here's what I have:

• Apparently "best" projectiles are Sig Sauer, Discreet Ballistics, and Hornady - I went with Hornady because I know their factory ammo and because the other two manufacturers are pricey or lack info
• For powders I've compiled this: H110 good for lighter bullet < 135 gr, A1680 for subsonic, Lil Gun for > 150 gr - I went with H110 here initially because I found load data for the A-Max projectile with it for subsonic

I was just looking back at some of the threads on the website here and am already seeing I should most definitely start with A1680 for powder for subs especially.

How good are Sierra Bullets' projectiles?

The beauty of 300 BLK is that you have an extremely wide array of bullet choices. Your initial criteria were for a very wide array of uses. If you have a cash cow out back let me know where you live

Typically one will not use a heavy bullet for anything hunting or self defense related. You definitely want to stay on the light side for that. 110 grain or 125 grain are your friend there. Velocity is your friend for sure.

Sierra bullets are awesome. There is no problem there by any means. And like I said, my favorite bullet so far for a super quiet ninja subsonic load was the Hornady 225 grain.

Dellet put up a post recently that is super nerd like but that is right down my alley... It was about the noise bullets make when they fly through the air. Don't get me wrong you can make quiet rounds, then again you can make rounds even MORE quiet. I was amazed at how I was able to get very consistent velocities and still get to that ultra ninja quiet stage.

I am sure someone will come along and talk about powder choices... some of the faster powders are great for short barrels. I still want to buy and try some VV powders.

For plinking the cheaper bullets are going to be whatever is on sale. You could probably get some 147 grain for real cheap to just plink.

If you want to go even more cheap cast bullets are a thing. A lot of people here swear by them so I bought 1000 of them and have worked out the kinks. Just today with a load that was made for reliability not so much accuracy, I got a 3 inch group at 100 yards using a 1x red dot that has a 2 MOA dot. Definitely useable stuff there. I formed a lot of brass recently so I am using those cast bullets to plink and also ensure that my cases are reliable. So far I have only had two cases that I had to toss, but those were on my first run before I switched dies.

Put it this way, reloading for this caliber is a hobby unto itself. It's just a matter of shooting more for less money. Those 208 grain bullets are going to add up fast. They aren't bad by any means. In fact, quite the opposite. They are fantastic. They however might not be the best choice for your stated goal.

Of course it's just my opinion but you crossed into too much turf for an all in one expectation when you might be better served by breaking things up into smaller areas of excellence.

IE I want a hunting load. (then proceed)
IE I want a subsonic ninja load. (then proceed)
IE I want a plinking load (then proceed)

Those three are going to have totally different bullets and possibly different powders as well.

Honestly I am having a ball reloading for this caliber. I don't think I will ever be done developing loads, and I for sure need to make sure I keep good notes so I can get back to it when I need to.

Thanks for the info!

Right now first goal is subsonic ninja target load.

Based on what you said I think I'll go back to the drawing board and figure out a starting load/data for 125 gr or 147 gr for my target.

Thanks for your help

[flamatrix99]

I saw the max COAL is 2.260”. Most subsonic loads I see are around 2.1-2.25”. Is there a sweet spot for 208 gr Hornady HPBT projectiles? I am not sure where to start. This is for a PSA 8.5” AR Pistol upper.

I know ideally I need a Hornady gauge to measure my chamber but this mainly a range fun gun.

[Thom]

Following. I have a 7.5 inch.

[dellet]

I saw the max COAL is 2.260”. Most subsonic loads I see are around 2.1-2.25”. Is there a sweet spot for 208 gr Hornady HPBT projectiles? I am not sure where to start. This is for a PSA 8.5” AR Pistol upper.

I know ideally I need a Hornady gauge to measure my chamber but this mainly a range fun gun.

2.260” is a default to max SAAMI length or what will fit in an AR magazine. You have to pay attention when that is the given length because not all bullets can be loaded that long without hitting the lands, but the 208 Hornady is not one.

The 208 HPBT is reasonably jump tolerant so the sweet spot will likely be pretty wide. What will be more important is case fill ratio. Depending on the powder you choose, and how close to the bullet is seated to the powder for good ignition and burn will be first, then fine tune for accuracy and velocity by changing the depth.

[Alec]

I saw the max COAL is 2.260”. Most subsonic loads I see are around 2.1-2.25”. Is there a sweet spot for 208 gr Hornady HPBT projectiles? I am not sure where to start. This is for a PSA 8.5” AR Pistol upper.

I know ideally I need a Hornady gauge to measure my chamber but this mainly a range fun gun.

2.260” is a default to max SAAMI length or what will fit in an AR magazine. You have to pay attention when that is the given length because not all bullets can be loaded that long without hitting the lands, but the 208 Hornady is not one.

The 208 HPBT is reasonably jump tolerant so the sweet spot will likely be pretty wide. What will be more important is case fill ratio. Depending on the powder you choose, and how close to the bullet is seated to the powder for good ignition and burn will be first, then fine tune for accuracy and velocity by changing the depth.

Holy crap, I never even thought seating depth played a role in tuning.

Is there a general rule for bullet seating of 300 Blackout maybe? ie. if you seat the bullet more velocity goes up or down, etc.

[dellet]

I saw the max COAL is 2.260”. Most subsonic loads I see are around 2.1-2.25”. Is there a sweet spot for 208 gr Hornady HPBT projectiles? I am not sure where to start. This is for a PSA 8.5” AR Pistol upper.

I know ideally I need a Hornady gauge to measure my chamber but this mainly a range fun gun.

2.260” is a default to max SAAMI length or what will fit in an AR magazine. You have to pay attention when that is the given length because not all bullets can be loaded that long without hitting the lands, but the 208 Hornady is not one.

The 208 HPBT is reasonably jump tolerant so the sweet spot will likely be pretty wide. What will be more important is case fill ratio. Depending on the powder you choose, and how close to the bullet is seated to the powder for good ignition and burn will be first, then fine tune for accuracy and velocity by changing the depth.

Holy crap, I never even thought seating depth played a role in tuning.

Is there a general rule for bullet seating of 300 Blackout maybe? ie. if you seat the bullet more velocity goes up or down, etc.

In general, the less space between the powder and the base of the bullet, means more pressure and more velocity. With certain powders it just means more stable velocity, less variation between shots.

I use CFE BLK as an example. with low case fill densities it just flat out sucks. I'm talking velocity variations in the mid to high 100's. if you compress the powder, it drops into the teens or single digits. A 25 fps difference in velocity with a 200 grain bullet at 1000 fps will cause about 1" change in point of impact at 100 yards.

Depending on the powder/bullet combination used, you can change velocity about 100 fps by moving the bullet in and out. This will also change how much gas is available to cycle the action on an AR. In general on a questionable load, seating the bullet longer will make the bullet slower and increase the reliability of cycling with a fast powder like H110.

In your first post you mentioned 9.2 grains as being max load, that's a bullshit number. Most likely if you look at the data, that will be 1050-1000 fps in a 16" barrel. Most of the data out there for heavy bullets gives a max load for heavy bullets at a subsonic velocity limit, not a pressure/safety limit. Hornady goes by pressure and so does Sierra.



Since you will lose velocity in a 7" barrel, I would start around 10.5-11 grains, with the bullet seated long, around 2.250"

I will look for the thread later, but I have data and the process for getting full function with 178 grain Amax bullets fully functional in a 10" carbine gassed upper using H110/296 without a suppressor. It's all about manipulating gas pressure with bullet movement.
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