Cart before the horse? Have a barrel blank...

[JimB..]

Not sure what you’re trying to accomplish. A heavy barrel won’t reduce muzzle pressure, and a long barrel won’t be as effective at doing so as adjusting the powder charge. Low pressure means low velocity, I imagine a 158gr 9mm subsonic round will barely make it out of a 24” barrel.

But, doesn’t mean it can’t be a fun project. Me, I’d back bore that barrel about 16” and then put a cap on it, that’ll give you the look you want, the pressure you want, and drop half the weight. Worried about NFA, don’t cap it.

[Barry54]

Not sure what you’re trying to accomplish. A heavy barrel won’t reduce muzzle pressure, and a long barrel won’t be as effective at doing so as adjusting the powder charge. Low pressure means low velocity, I imagine a 158gr 9mm subsonic round will barely make it out of a 24” barrel.

But, doesn’t mean it can’t be a fun project. Me, I’d back bore that barrel about 16” and then put a cap on it, that’ll give you the look you want, the pressure you want, and drop half the weight. Worried about NFA, don’t cap it.

Post 4. I want low muzzle pressure.
Again I’m not trying to get this lighter. What have I said to make people think that?
I’m not trying to skirt any nfa rules nonsense. 24” barrels are a fairly standard length. Or at least they were once upon a time.

I respectfully disagree back boring 16” into the 24” barrel will effectively give me a shorter barrel and increase the muzzle pressure.

I never said anything about a look I want. Where did you come up with that???

[Hannibal]

People who want to do strange projects should invest in a lathe and mill.
That is what I did.
I do some really strange things.

Here's your answer Barry.

[Barry54]

Here's your answer Barry.

You are correct.
I’m just amazed at the assumptions when I thought I asked clear questions...

Currently I like the thought of the captured nut on the barrel for an ar, but I dislike the aluminum upper receiver plan. I like the thought of a steel bolt action rifle being sturdy. I have a concern about someone carelessly opening a brake action and causing damage with the large bull barrel.

[Moleman-]

There's also the Rock Island 22TMC rifle, rebarreled to 9mm. It comes in walnut stock and a tactical version. I'm good at spending other peoples money.

[Barry54]

There's also the Rock Island 22TMC rifle, rebarreled to 9mm. It comes in walnut stock and a tactical version. I'm good at spending other peoples money.

Thanks. I’ll look into it. Could be a head start to get me going!

[dverna]

Just curious as I cannot offer constructive help with your build.

What is the advantage of low muzzle pressure? I have not seen muzzle pressure as a criteria before.

[JimB..]

Your question was about selecting a platform, so I’d suggest the H&R single shot for the reasons stated above.

But what I was trying to get to was an understanding of what you’re trying to accomplish, and “low muzzle pressure” isn’t a goal. If that really is all you care about, then just port the barrel starting a few inches in front of the chamber, ta-da zero muzzle pressure…but I’m guessing that isn’t your goal.

Your project is odd, and that’s great, but why not explain why you’re considering what you’re considering? As you’ve explained it, you’re not going to achieve anything that can’t already be done with a stock handi rifle or contender and a 9mm or 38/357 barrel. You’re intentionally adding bulk, length and weight that seem to achieve nothing. I assume that you’re not striving to accomplish nothing, so can you explain what you’re chasing?

But if it’s a secret that’s fine to and I’ll just stick with answering the question you asked.

[Barry54]

Low muzzle pressure correlates to low blast. Won’t disturb the neighbors who moved from the city if they have their windows closed. I’m just looking a more pleasant shooting experience. Nothing secret. Just a new project.

[Barry54]

Your question was about selecting a platform, so I’d suggest the H&R single shot for the reasons stated above.

But what I was trying to get to was an understanding of what you’re trying to accomplish, and “low muzzle pressure” isn’t a goal. If that really is all you care about, then just port the barrel starting a few inches in front of the chamber, ta-da zero muzzle pressure…but I’m guessing that isn’t your goal.

Your project is odd, and that’s great, but why not explain why you’re considering what you’re considering? As you’ve explained it, you’re not going to achieve anything that can’t already be done with a stock handi rifle or contender and a 9mm or 38/357 barrel. You’re intentionally adding bulk, length and weight that seem to achieve nothing. I assume that you’re not striving to accomplish nothing, so can you explain what you’re chasing?

But if it’s a secret that’s fine to and I’ll just stick with answering the question you asked.

“Seem to achieve nothing”
Ahh. Glad you asked! The added length lowers muzzle pressure.
It doesn’t need to be heavy. I just bought a heavy blank and I want the weight.

[JimB..]

Low muzzle pressure correlates to low blast. Won’t disturb the neighbors who moved from the city if they have their windows closed. I’m just looking a more pleasant shooting experience. Nothing secret. Just a new project.

An admirable goal.

In addition to your design, consider playing with light charges of titegroup under a standard or light weight bullet for caliber. A subsonic 9mm 90gr or 115 gr bullet with a powder that’s consumed in the first 25% of the barrel should be pretty quiet.

[Barry54]

Thanks!

I’ve started with 1.2 grains of a fast powder. Worked down to 0.8 grains. Velocity got erratic. A member here with quick load ran some numbers for me.
Shortening the oal increases pressure. So I’ll “work up” by seating deeper.

[JimB..]

I think that’s the right approach, in fact I was guessing that 1gr of TG under a 115gr LRN seated flush is probably close to what you want. Just don’t seat down into the web of the case as that may either swell the case or deform the bullet.

You could also do this easily with a DEWC in a 38spcl case, the advantage being the availability of published load data.

[Tracy]

I get where you're coming from. If you don't want a break action, how about an old Remington Rolling Block? IMO that would be a great choice.
Or, a Savage bolt action. Some of them are pretty cheap, and there are all sorts of factory and aftermarket parts for them, including some excellent triggers. Barrels are easy to swap, too. So you could also have a .223 (or whatever) barrel to swap when you want to. In fact I would probably look for a short action Savage in .223; that way you already have a .223 barrel. From what I've seen you can probably find a complete rifle for about the same price as just an action.

I would probably use a .380 chambering. I know 9mm brass is cheaper, but .380 is cheap too. Plus it's easier to reload with its straight wall case vs. the 9x19's tapered case. And at low pressure, those straight cases should last a looooong time.

[Barry54]

I think that’s the right approach, in fact I was guessing that 1gr of TG under a 115gr LRN seated flush is probably close to what you want. Just don’t seat down into the web of the case as that may either swell the case or deform the bullet.

You could also do this easily with a DEWC in a 38spcl case, the advantage being the availability of published load data.

I’ll be going out into no mans land with the loads. The objective is to get 100% case fill by seating the boolet deep. Pretty sure I can’t seat deep enough in 38 special without going up to 250 grain or heavier projectiles. And then there’s no published data there anyway.

[dverna]

Before investing a lot of money it might be wise to check the twist rate on the barrel you have. Check if the bullet length you want to use will stabilize at the lower velocity. It seems you are going to be in the 600 fps range rather than 1000 fps range of most subsonic 9mm loads.

Have you considered adding a suppressor $350-500 (plus $200 tax stamp) to a .22LR. You will have a more accurate platform that is cheaper to shoot. It will be quieter than a long barreled 9mm and more neighbor friendly.

As others have mentioned a front heavy gun that weighs 15 lbs will not going to be fun to use.

[JimB..]

I’ll be going out into no mans land with the loads. The objective is to get 100% case fill by seating the boolet deep. Pretty sure I can’t seat deep enough in 38 special without going up to 250 grain or heavier projectiles. And then there’s no published data there anyway.

Help me out again, why are you targeting 100% case fill? With a fast powder that creates a bunch of pressure problems in a hurry. Also, as I said above I’d go for lighter weight bullets even if you have to seat them below the case mouth, or just trim the case to create your very own wildcat.

[Barry54]

Help me out again, why are you targeting 100% case fill? With a fast powder that creates a bunch of pressure problems in a hurry. Also, as I said above I’d go for lighter weight bullets even if you have to seat them below the case mouth, or just trim the case to create your very own wildcat.

I’m trying to achieve lowest muzzle pressure possible. Seating the boolet against the powder helps according to quick load. Get a copy and play with it. I think it’s worth the price I paid.

Yes. I’m aware seating deep drastically raises pressure.

[Barry54]

I get where you're coming from. If you don't want a break action, how about an old Remington Rolling Block? IMO that would be a great choice.
Or, a Savage bolt action. Some of them are pretty cheap, and there are all sorts of factory and aftermarket parts for them, including some excellent triggers. Barrels are easy to swap, too. So you could also have a .223 (or whatever) barrel to swap when you want to. In fact I would probably look for a short action Savage in .223; that way you already have a .223 barrel. From what I've seen you can probably find a complete rifle for about the same price as just an action.

I would probably use a .380 chambering. I know 9mm brass is cheaper, but .380 is cheap too. Plus it's easier to reload with its straight wall case vs. the 9x19's tapered case. And at low pressure, those straight cases should last a looooong time.

I know nearly nothing about a rolling block. It sounds romantic though.

A bolt action savage is a great candidate. 380 brass might fit into the 223 bolt?

[Barry54]

Before investing a lot of money it might be wise to check the twist rate on the barrel you have. Check if the bullet length you want to use will stabilize at the lower velocity. It seems you are going to be in the 600 fps range rather than 1000 fps range of most subsonic 9mm loads.

Have you considered adding a suppressor $350-500 (plus $200 tax stamp) to a .22LR. You will have a more accurate platform that is cheaper to shoot. It will be quieter than a long barreled 9mm and more neighbor friendly.

As others have mentioned a front heavy gun that weighs 15 lbs will not going to be fun to use.

True words of wisdom. I should check the twist rate. I know what I ordered, but I should check it.

Pretty good guess on velocity. I don’t remember but 700 FPS comes to mind from quick load.

I’ve been exposed to three different people and suppressors. Two suppressors disappointed me. I loved the third one! Great on 300 Whisper subsonic. Amazing on 22 long rifle, even on a pistol!! I’d be interested in one but all the permission and travel restrictions and such is more of a deterrent than the $1,100 price tag.

Back to this again. I think a 15 to 40 pound rifle will be great sitting on sandbags and shooting out back!