Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
I upped the copy i had saved immediately on seeing it .
This one worked for me the other day, no antivirus issues.
It looks like the hoop stress calculation is incorrect though; it doesn't account for the tube wall thickness. This calculator also doesn't account for volume of the gas in the stress calculations, using only muzzle pressure as a singular number.
Unless we're talking about different things, this calculator does account for wall thickness using the formula PDm /2t; where P = Pressure, Dm = Mean Tube Diameter, and t = Wall Thickness
I'm not following on your second issue. How is the volume of gas important when determining if a pressure vessel is capable of safely containing a known pressure. Pressure is derived from the volume of gas attempting to fill the volume of the container. What am I missing?
Sorry, not sure what I was seeing the first time, the hoop stress calculation is correct.
Re. the gas volume thing - it looks like your calculation for blast chamber pressure is solely dependent on muzzle pressure, with no accounting for the volume of gas causing that pressure. Your muzzle pressure calculation is based on volume of the chamber and bore; the blast chamber pressure should also be based on that volume. Imagine a short 9mm barrel and a longer 308 barrel that both produce the same muzzle pressure - blast chamber pressure on the 308 should be higher, because of the larger volume of gas.
Also - safety factor is typically applied at the end of the stress calculation, after using the actual pressure. You're applying it to the blast chamber pressure first, which is a bit misleading. Minor detail, just something that could be improved.
yondering wrote:
Re. the gas volume thing - it looks like your calculation for blast chamber pressure is solely dependent on muzzle pressure, with no accounting for the volume of gas causing that pressure. Your muzzle pressure calculation is based on volume of the chamber and bore; the blast chamber pressure should also be based on that volume. Imagine a short 9mm barrel and a longer 308 barrel that both produce the same muzzle pressure - blast chamber pressure on the 308 should be higher, because of the larger volume of gas.
Why would you not apply Boyles Law: P1V1 = P2V2? The pressure * volume of the chamber + bore must equal the pressure * volume of the blast chamber. Right? If not, why would this not be applied?
That's my point exactly. That would be more accurate (ignoring the thermodynamics) but your calculator doesn't do that. Your blast chamber calculation only uses muzzle pressure, without any reference to bore & chamber volume.
Also, for calculating muzzle pressure, your calculation assumes peak pressure in the chamber (the way an air rifle works); in reality peak pressure occurs when the bullet is several inches down the bore, and the powder continues to burn and generate more gas beyond that. The calculator appears to give approximately correct results in a couple scenarios, but I'm wondering if that's just a happy coincidence, and it might be way off for other bore and chamber values? I haven't looked into it enough to decide for myself yet.
So I think I strained something in my brain trying to figure this out.
does anyone just have a chart showing muzzle pressure at different barrel length
Samson104 wrote:So I think I strained something in my brain trying to figure this out.
does anyone just have a chart showing muzzle pressure at different barrel length
if you want to pm me any specifics, I can run it through Quickload for you
This worksheet may not be 100% reliable and some of the formulas appear to have been tampered with.
When I find time, I'll check my notes and try to bring it back to where it was when I first uploaded it a few months ago.
One item of concern, which I'm going to attempt to figure out, the muzzle pressure data doesn't always agree with QucikLOAD estimates. I'm not certain of why yet but I'm hoping to figure that out.
Yondering brought it to my attention this could be from my calculations not taking in to account the volume of the gas material itself. My formulas were a fairly simple derivation of Boyles law and don't account very well (at all) for thermodynamics.
At the same time, QuickLOAD estimates don't agree with some of the powder manufacturers published data either regarding chamber pressures.
Samson104 wrote:So I think I strained something in my brain trying to figure this out.
does anyone just have a chart showing muzzle pressure at different barrel length
if you want to pm me any specifics, I can run it through Quickload for you
Nothing special , factory 5.56 MK262 from a 10.5" and 7.5"
or any other stock 5.56
This worksheet may not be 100% reliable and some of the formulas appear to have been tampered with.
When I find time, I'll check my notes and try to bring it back to where it was when I first uploaded it a few months ago.
One item of concern, which I'm going to attempt to figure out, the muzzle pressure data doesn't always agree with QucikLOAD estimates. I'm not certain of why yet but I'm hoping to figure that out.
Yondering brought it to my attention this could be from my calculations not taking in to account the volume of the gas material itself. My formulas were a fairly simple derivation of Boyles law and don't account very well (at all) for thermodynamics.
At the same time, QuickLOAD estimates don't agree with some of the powder manufacturers published data either regarding chamber pressures.
The actual volume of gas produced varies a lot with different powders, but for the purposes of suppressor design, you could set up the calculator for the worst-case scenario. I would use the chamber and the first few inches of bore (maybe make that adjustable) as the initial "chamber" volume, to give a more accurate representation.
This worksheet may not be 100% reliable and some of the formulas appear to have been tampered with.
When I find time, I'll check my notes and try to bring it back to where it was when I first uploaded it a few months ago.
One item of concern, which I'm going to attempt to figure out, the muzzle pressure data doesn't always agree with QucikLOAD estimates. I'm not certain of why yet but I'm hoping to figure that out.
Yondering brought it to my attention this could be from my calculations not taking in to account the volume of the gas material itself. My formulas were a fairly simple derivation of Boyles law and don't account very well (at all) for thermodynamics.
At the same time, QuickLOAD estimates don't agree with some of the powder manufacturers published data either regarding chamber pressures.
The actual volume of gas produced varies a lot with different powders, but for the purposes of suppressor design, you could set up the calculator for the worst-case scenario. I would use the chamber and the first few inches of bore (maybe make that adjustable) as the initial "chamber" volume, to give a more accurate representation.
Guys, is there an updated download available for the new formula?
