300WM Design Help

[MMH]

I am designing my first suppressor for a 300WM and am basing the design on something that delta9mda posted several years back. It will be a stepped baffle design. I am starting with an OD of 1.5" and a length of 11" and interior room is tight. I am using 6 stepped cones plus a blast chamber.

I am beginning to work thru some details. and have some general questions:

Tube: will us a 316 tube, 1.5" OD, 1.37" ID (0.065" wall). Is there an advantage in going seamless vs. welded?
Blast baffle: How long should the blast chamber be (i.e. what should the blast chamber volume be)? Should blast baffle be made out of 17-4 & not just 316? I am planning to make the blast baffle 0.125" thick
Baffles: will make them out of 316 & they will be 0.065" thick

Bore: what should the bore for the baffles be? Is 0.36" enough?
Spacers: was going to use 316 tube, 1.375" OD 1.245" ID (0.065" wall). I will work the OD down so it easily fits into the 1.5" tube.

In general I plan on using 316. If I use 17-4 can I use thinner material? It seems like 316 is readilly available, but all of the online 17-4 sources are asking that I e-mail them for a quote so I am guessing that it will be significantly more expensive.

What materials should I use/. I was thinking about 316 al the way around, or, should I be using 17-4 for at least the blast chambers

What are the tradeoffs on size vs. sound. I don't mind going larger (length and/or diameter). This suppressor will go on a rifle that weighs 14 lbs.

I will post design drawings as the become available

Thanks!

[whiterussian1974]

I am beginning to work thru some details. and have some general questions:

Tube: Is there an advantage in going seamless vs. welded?
Blast baffle: How long should the blast chamber be (i.e. what should the blast chamber volume be)? Should blast baffle be made out of 17-4 & not just 316? I am planning to make the blast baffle 0.125" thick
Baffles: will make them out of 316 & they will be 0.065" thick

Bore: what should the bore for the baffles be? Is 0.36" enough?
Spacers: was going to use 316 tube, 1.375" OD 1.245" ID (0.065" wall). I will work the OD down so it easily fits into the 1.5" tube.

In general I plan on using 316. If I use 17-4 can I use thinner material? It seems like 316 is readilly available, but all of the online 17-4 sources are asking that I e-mail them for a quote so I am guessing that it will be significantly more expensive.

What materials should I use. I was thinking about 316 al the way around, or, should I be using 17-4 for at least the blast chambers

What are the tradeoffs on size vs. sound. I don't mind going larger (length and/or diameter). This suppressor will go on a rifle that weighs 14 lbs.

Welded will split under pressure. Seemless is your only option.

Blast volume is a personal choice. Depends upon many factors. 1.5-2" should be good starting point and fine tune to taste. Use others' builds to guage yours against.

17-4 or 316 are both fine at that thickness. 17-4 will last longer and suffer less erosion.

Bore of .36" is ok IF you are concentric.Many hobbyists instead use .375 further down the stack to account for slight variances.

17-4 Suppliers want to sell volume. They don't want to sell by the foot. So look for a distributor that prices by the foot. (I don't know any.)

You should drill holes in your spacers to save weight. In fact, if you make your tube thickness .085-125" @ blast chamber, then step down to .065" for the baffle stack; you'll have a tank strong Mag suppressor w extra strength where needed, like the webbelt on your .300WM.

Some people like to make the OUTSIDE of the tube where the step is. But that's Patented. Plus, I feel that it unnecessarily obstructs the sightline. A smooth exterior is just more visually pleasing. Make the entire OD the same to maximize volume. Make the step on the INSIDE of the outer tube.

As for size/weight vs sound, for the high pressure in Mags you might want 1.65-1.75" OD. @ 11" length you've got that covered. But P=VT/t means that you need 20xs the volume of your barrel as a guide, and mags need even more.

Others can answer your ?s better than me. I just wanted to answer since noone else has.
And no Replies kills a Thread.

[curtistactical]

We buy small pieces of 17-4 for custom jobs from onlinemetals.com , you can also buy the 316L seamless tube there. The 17-4 actually machines nicer than 300 series stainless, the price will be a little higher but you will make up for it in the tooling you save. Personally I would make all the baffles and end caps from 17-4.
Joe

[T-Rex]

We buy small pieces of 17-4 for custom jobs from onlinemetals.com , you can also buy the 316L seamless tube there. The 17-4 actually machines nicer than 300 series stainless, the price will be a little higher but you will make up for it in the tooling you save. Personally I would make all the baffles and end caps from 17-4.
Joe

Don't forget yardemetals dropzone. There are incredible deals in there.

[MMH]

What about titanium vs. 17-4. Cost wise & strength wise. Would I be able to go down to 0.05" (instead of 0.065") to try to keep the weight down?

For that matter would I be able to go down to a thickness of .05 even w/ 17-4 or is 0.065" as thin as is advisable.

[T-Rex]

Burst Calculator

[whiterussian1974]

Burst Calculator

Where is the Chart for Materiel Strengths?
I don't see one on the Page.
Do we just Google: "Material Tensile Strength Yeilds?"

[T-Rex]

Yeah, your gonna have to get your own material data. Aksteel.com is a good source as well as asm.matweb.com.

[MMH]

Burst Calculator

Thanks for the link. The calculation is the easy part. Getting the correct input values is a little harder.

I can get the yield, tensile, and fatigue strength from a lot of sources. I personally like www.matweb.com. I would think that for a suppressor that I would design from a fatigue strength perspective. To a certain extent, the safety factor depends on what the assumptions were for fatigue strength. What about the pressure? I will be designing for a 300WM with a 26" barrel.

[whiterussian1974]

I personally like http://www.matweb.com. I would think that for a suppressor that I would design from a fatigue strength perspective. To a certain extent, the safety factor depends on what the assumptions were for fatigue strength. What about the pressure? I will be designing for a 300WM with a 26" barrel.

QuickLOAD states 12.5kpsi from 24" bbl. It varies depending upon powder burn rate.
And Safety Factor is generally 1.5 for suppressors, but 1.9 for aircraft wings.
One could increase to 1.6-1.9 to calculate for full-auto fire to compensate for heat fatigue depending upon how many mag dumps. (30-120rds.)

316 SS=56kpsi
Grade 5 Ti=120kpsi
Correct?

[MMH]

QuickLOAD states 12.5kpsi from 24" bbl. It varies depending upon powder burn rate.
And Safety Factor is generally 1.5 for suppressors, but 1.9 for aircraft wings.
One could increase to 1.6-1.9 to calculate for full-auto fire to compensate for heat fatigue depending upon how many mag dumps. (30-120rds.)

316 SS=56kpsi
Grade 5 Ti=120kpsi
Correct?

WOW. I never would have guessed that there was 12.5 ksi at the end of a 24" barrel. I would have thought that it is much much lower.

As far as your strength numbers go, 316 typically has a yield around 40 ksi & an ultimate of 80 ksi. The Ti is usually close for the yeild & ultimate and 120 ksi seems about right. It varies significantly based on the specific alloy & heat treat.

[kbillet]

As for size/weight vs sound, for the high pressure in Mags you might want 1.65-1.75" OD. @ 11" length you've got that covered. But P=VT/t means that you need 20xs the volume of your barrel as a guide, and mags need even more.

I'm curious about this formula. The Form 1 I am working on is 1.5" by 8" for a 22-250. Based on my calculations it has an internal value of 9.3 C.I. Using .223 as the barrel diameter and 24" as length the barrel volume is .937 C.I. That's only 10 Xs. Is my build that much undersized? Or am I misunderstanding something?

[whiterussian1974]

As for size/weight vs sound, for the high pressure in Mags you might want 1.65-1.75" OD. @ 11" length you've got that covered. But P=VT/t means that you need 20xs the volume of your barrel as a guide, and mags need even more.

I'm curious about this formula. The Form 1 I am working on is 1.5" by 8" for a 22-250. Based on my calculations it has an internal value of 9.3 C.I. Using .223 as the barrel diameter and 24" as length the barrel volume is .937 C.I. That's only 10 Xs. Is my build that much undersized? Or am I misunderstanding something?

V=Pi(r^2)
bore=0.93737" can=14.1372" delta=15.082"
So your can is roughly 15xs. If we take your barrel @ the std 20" this b/c 0.7811".
14.1372/.7811=18.09
So even closer to the 20x std.

[kbillet]

Thanks Whiterussian 1974. I was using net internal volume of the can. Thanks for the explanation.

[silencer_kid]

V=Pi(r^2)
bore=0.93737" can=14.1372" delta=15.082"
So your can is roughly 15xs. If we take your barrel @ the std 20" this b/c 0.7811".
14.1372/.7811=18.09
So even closer to the 20x std.

i'll just assume math wasnt your best subject in school.