Low Weight 300Blk Can - Ti and 17-4

[daPhoosa]

Hello All,

I am expecting my form 1 to be approved soon so I thought I'd share my latest design. It is more conventional than the designs I was thinking about last year (viewtopic.php?f=10&t=133147), but still a little different.

I wanted this design to be relatively light while still having reasonable (but not Hollywood) noise reduction. It should be good for supers and subs. The light weight is driven by my aversion to paying $200 for my SBR stamp and then having it still feel way heavier than a standard rifle.

I will be using 17-4PH SS for higher wear parts like the muzzle device and first baffle. All other parts will be Ti for weight savings. I will not be using it on a full auto lower or doing excessive mag dumps, so I see no need for high temp alloys (inconel). This will be going on my 8.5" barrel.

Here's the muzzle device:


Cross section view:


This design is a slight reflex design as it is easier for me to make it light this way and I don't want to do a trepan as is often done in these cases. I did not model the threads, I'm lazy that way.

Here's the main tube (1.625" OD):


The most significant feature can be seen in the cross section:

This will be machined from solid Ti bar stock and there will be a divider that separates the blast chamber from the baffle stack. This can be seen better in this section view showing the muzzle device and the outer tube:


This center divider provides an additional point of contact to insure the suppressor is aligned to the muzzle device. The alignment of the suppressor is determined by two diameters (blast chamber divider and a section of the tube ID right next to the threads). Both of these will be held to fairly close tolerances, but given their relative spread in the z-axis, I do not need to be extreme to maintain reasonable alignment. The outer tube stops against the large diameter face at the back of the muzzle device.

This dedicated blast chamber reduces the maximum pressure (force) exerted on the entire baffle stack so they do not need to be strong enough to handle the pressure observed at the muzzle. The holes are sized such that immediately after the bullet passes the muzzle device, it is 3x easier for the pressure to enter the blast chamber compared to continuing on down the bore (when using a fluid flow through orifice analysis). I don't know if this ratio is ideal, but I think it is an good starting point and I can always make the radial holes bigger if I think the expansion chamber is being under utilized.

The baffles have integral spaces that are reduced in diameter compared to the tube ID:


The reduced spacer diameter is intended to save weight while providing the gasses easy access to the outside surface to enhance heat transfer out of the can. The face of each baffle has a step that the spacer of the next baffles seats against/around. This ensures that the baffles cannot tilt even if the baffle stack gets slightly loose. The concentricity of the baffles is maintained on the OD. I can very easily make this baffle design as a single operation on the CNC machines I have available to me so it should be concentric to itself and the front and rear surfaces should be parallel.

Here are all of the baffles stacked together:



The first baffle will be 17-4, while all of the others will be Ti. All of them will be clipped.

The end cap is not conventional:


Due to physical limitations of the CNC machines I have access to, I cannot make the outer tube long enough to house all of the baffles. By making this "bulged" end cap I can solve this problem. The diameters on either side of the threads will be a precision fit to aid in axial alignment and concentricity. The hex on the end of the can is to save weight and provide a means to tighten the end cap on the baffle stack.

Here is a cross section of the entire assembly:


Assembled outside view:


Projected specs as modeled:
OAL: 6.75"
Length beyond muzzle: 5.625"
Dia: 1.625"
Weight (w/o muzzle device): 10oz
Weight (inc muzzle device): 13oz -- this compares favorable to the GMT-300BLK

I have access to off cuts of Ti and 17-4, so my material costs will be fairly low.


Additionally I have designed a concussion redirection device for times when I don't have my can installed:

Since my free float rail will cover part of the muzzle device, this should help protect my hands if they get a little far forward.

Let me know what you think.

Phil

[Capt. Link.]

I like it but why did you deviate from the Omega baffle which is so very close in design.Using a approved copy I think Hollywood quiet is not far off.You can still incorporate many of the features you have and keep the light weight.I can see a few changes that would save weight and improve performance.I like the fact that you are paying attention and using a mixture of different alloys only where they are needed.I'm all for high performance and making what fits your needs best.
-CL

[DrScott]

That looks awesome. I like the ingenious way you overcame materials limitations with the endcap.

Can you show the muzzle device/attachment?

[daPhoosa]

I like it but why did you deviate from the Omega baffle which is so very close in design.Using a approved copy I think Hollywood quiet is not far off.You can still incorporate many of the features you have and keep the light weight.I can see a few changes that would save weight and improve performance.I like the fact that you are paying attention and using a mixture of different alloys only where they are needed.I'm all for high performance and making what fits your needs best.
-CL

I was just trying to stay away from the inevitable "somebody already has a patent on that design..." comment. I'm not sure I want to go through the hassle of getting approval from Omega, but maybe it's not as bad as I imagine it would be.

[Historian]

Compliments on the well thought out, elegant, and compelling
visual presentation. It is clear that one can infer enviable machining
skills. Thank you for presenting and inspiring.

You bring up the notion that cans need not be single tubes
but like Leica Macro Close Up tubes many can be threaded
together.

When the Hearing Protection Act Passes one can envision many
creative variable size tubes and innards.

Best.

[mattman0o0o]

Approval from them was easy, I emailed saying I wanted to build a one off using their Omega and they said I had permission to build 1 can with it. Printed that and threw it in the safe with the original tax stamp.

[Capt. Link.]

I like it but why did you deviate from the Omega baffle which is so very close in design.Using a approved copy I think Hollywood quiet is not far off.You can still incorporate many of the features you have and keep the light weight.I can see a few changes that would save weight and improve performance.I like the fact that you are paying attention and using a mixture of different alloys only where they are needed.I'm all for high performance and making what fits your needs best.
-CL

I was just trying to stay away from the inevitable "somebody already has a patent on that design..." comment. I'm not sure I want to go through the hassle of getting approval from Omega, but maybe it's not as bad as I imagine it would be.

The inventor Joseph D. Gaddini has allowed copies.He has been very nice to the F1 crowd.One of the cool things about the Omega is you can build it two piece the top 17-4 the bottom titanium.Working off a proven design has advantages.Using the muzzle brake to help feed the ports would possibly increase the performance in the first chamber.Suppression is the total of the good and bad features.I was not saying your design was anything but good.
-CL

[tmc4065]

Great drawings, my only comment would be on the 4 holes to the co-axial area.

I understand your reasoning of trying to get heat absorbed into the tube, I just think (from experience mostly) that you have too much venting.

I'd probably drop it down to one port . . . typically when you have too much co-axial porting the first round pop becomes substantial and the subsequent shots are still louder as the gas doesn't get trapped very well up there. I'd lean more towards trapping gas than heat absorption

[CMV]

You should anodize all the TI pieces those exact colors!

Sorry - no useful input since I've never built anything like that. Looking at the brake part - would it work better either as more of a traditional brake similar to AAC's:

OR with many more but smaller holes to be more of a 'diffuser'?

The way the brake's chamber is separated from the rest I think (but am just speculating) the more traditional brake would do more for you.

[daPhoosa]

Great drawings, my only comment would be on the 4 holes to the co-axial area.

I understand your reasoning of trying to get heat absorbed into the tube, I just think (from experience mostly) that you have too much venting.

I'd probably drop it down to one port . . . typically when you have too much co-axial porting the first round pop becomes substantial and the subsequent shots are still louder as the gas doesn't get trapped very well up there. I'd lean more towards trapping gas than heat absorption

My original intention was not to trap gas but allow it to move freely between inner and outer sections. Really, this shouldn't be any worse than a standard Cone type baffle with spacers at the OD.

Having said that, I have changed the design to an Omega Baffle design as it seems getting approval should not be an issue.



I now have a single smaller hole opposite the cone clip. My thinking on this location is that the low pressure area created by the port will work with the clip in the cone to promote cross jetting. It's at a theory. I'm not sure if there's an advantage to moving the fore/aft position, I'm still thinking about that.

Here's the cross section showing all of the baffles with spacers ports positioned opposite the cone clips.



I thinned the spacer sections slightly since I have dropped from four large holes to a single smaller one to save a little weight.

[daPhoosa]

...
I can see a few changes that would save weight and improve performance.
...

I am curious as to what you'd suggest for saving weight.

I could save a little with turning the tube down a little where there are no threads, which is worth ~0.4oz. The end of the endcap doesn't need to be quite as thick, which I think is worth ~0.05oz. Is there something else that I should look at?

The blast baffle is 0.080" thick on the front face. The rest of the baffles are 0.060". I suppose the ones near the end of the can could be a little thinner.

Thanks,

Phil

[sizulku]

What is your spacer diamater (OD/ID) ?

[daPhoosa]

What is your spacer diamater (OD/ID) ?

1.000" ID
1.060" OD

OD bumps to 1.100" just before touching the next baffle.

[Capt. Link.]

...
I can see a few changes that would save weight and improve performance.
...

I am curious as to what you'd suggest for saving weight.

I could save a little with turning the tube down a little where there are no threads, which is worth ~0.4oz. The end of the endcap doesn't need to be quite as thick, which I think is worth ~0.05oz. Is there something else that I should look at?

The blast baffle is 0.080" thick on the front face. The rest of the baffles are 0.060". I suppose the ones near the end of the can could be a little thinner.

Thanks,

Phil

Hi Phil
The 300blk is a gentle cartridge compared to others so you can thin a few pieces without causing problems and you can toughen a few areas for durability.If you are adapting the Omega you need to look at the porting very closely.Its not just a cone and a clip with a port.He figured out a gas re-circulation system that reduces FRP and gave very good performance.I'm sure the use of a brake will enhance this effect adding to the performance.
You can save a little weight by thinning the blast baffle and making the top from 17-4 H900 and its spacer from titanium.Adding a 17-4 cone only sections to the next two baffles would harden the stack from wear and can be .050 or a bit thicker while the rest of baffle is titanium.The balance of baffles made from .060 titanium or less should work fine.
The end cap design I like very much and made from titanium can be paper thin if you lessen the forward thrust of the baffles.By running the end caps thread back into your "chassis" a thrust shoulder will be made for the baffles eliminating most of the forward thrust and take up any slack.
I like the "uni-body" chassis system.
Bravo sir!
-CL

This last green baffle will be better supported allowing very thin cap construction.You may have already thought of this I'm just pointing it out.

[daPhoosa]

...
I can see a few changes that would save weight and improve performance.
...

I am curious as to what you'd suggest for saving weight.

I could save a little with turning the tube down a little where there are no threads, which is worth ~0.4oz. The end of the endcap doesn't need to be quite as thick, which I think is worth ~0.05oz. Is there something else that I should look at?

The blast baffle is 0.080" thick on the front face. The rest of the baffles are 0.060". I suppose the ones near the end of the can could be a little thinner.

Thanks,

Phil

Hi Phil
The 300blk is a gentle cartridge compared to others so you can thin a few pieces without causing problems and you can toughen a few areas for durability.If you are adapting the Omega you need to look at the porting very closely.Its not just a cone and a clip with a port.He figured out a gas re-circulation system that reduces FRP and gave very good performance.I'm sure the use of a brake will enhance this effect adding to the performance.
You can save a little weight by thinning the blast baffle and making the top from 17-4 H900 and its spacer from titanium.Adding a 17-4 cone only sections to the next two baffles would harden the stack from wear and can be .050 or a bit thicker while the rest of baffle is titanium.The balance of baffles made from .060 titanium or less should work fine.
The end cap design I like very much and made from titanium can be paper thin if you lessen the forward thrust of the baffles.By running the end caps thread back into your "chassis" a thrust shoulder will be made for the baffles eliminating most of the forward thrust and take up any slack.
I like the "uni-body" chassis system.
Bravo sir!
-CL

This last green baffle will be better supported allowing very thin cap construction.You may have already thought of this I'm just pointing it out.

Thanks for the input CL! Valuable as always. I will have to play around and see what I want to do. I'm trying to balance the KISS principle with wanting to make it as awesome as possible.

[Samson1044]

I have a piece of Grade 5 titanium (bored solid bar) that might sever your need an help simplify things , I'll make you a great deal. I was gonna make a brake/blast shield but it won't work with my hand guard.
Its currently 1.625" OD x 1.450"ID , 6.100" long , one end is threaded .650" deep , with a .125" shoulder recess , 24 tpi
Shoot me an E-Mail if ya like , [email protected]

[daPhoosa]

I have a piece of Grade 5 titanium (bored solid bar) that might sever your need an help simplify things , I'll make you a great deal. I was gonna make a brake/blast shield but it won't work with my hand guard.
Its currently 1.625" OD x 1.450"ID , 6.100" long , one end is threaded .650" deep , with a .125" shoulder recess , 24 tpi
Shoot me an E-Mail if ya like , [email protected]
...

Thanks for the offer, but I made my muzzle device and blast shield yesterday since I am happy with that part of the design (and they are not silencer parts).

[propeine]

I have a piece of Grade 5 titanium (bored solid bar) that might sever your need an help simplify things , I'll make you a great deal. I was gonna make a brake/blast shield but it won't work with my hand guard.
Its currently 1.625" OD x 1.450"ID , 6.100" long , one end is threaded .650" deep , with a .125" shoulder recess , 24 tpi
Shoot me an E-Mail if ya like , [email protected]

That sure is the expensive way to get a tube! Nice and round though I bet.

[fastfire]

[quote="Samson1044"]I have a piece of Grade 5 titanium (bored solid bar) that might sever your need an help simplify things , I'll make you a great deal. I was gonna make a brake/blast shield but it won't work with my hand guard.
Its currently 1.625" OD x 1.450"ID , 6.100" long , one end is threaded .650" deep , with a .125" shoulder recess , 24 tpi
Shoot me an E-Mail if ya like , [email protected]
[/quote


That's the cleanest looking threads especially in TI I have seen.

Nice job, what's the secret?

[Samson1044]

Razor sharp carbide threading tool , 260 RPM , Moly Dee cutting oil
Its on a manual Lathe but it's a big ass old LeBland that's very ridged

[Samson1044]

Using solid bar to make the tube does make for a perfectly round tube which makes a HUGE difference with matching threads , and the grade 5 is a fair bit stronger than grade 9.
Solid bar can be found on E-Bay for reasonable prices.

[propeine]

Using solid bar to make the tube does make for a perfectly round tube which makes a HUGE difference with matching threads , and the grade 5 is a fair bit stronger than grade 9.
Solid bar can be found on E-Bay for reasonable prices.

I've bought all my bar from Ebay as well. Still 100 bucks for 10" vs say 30 for tubing unless you've got a much better source than me. I'm not equipped to bore that deep either though.

[gunny50]

Using solid bar to make the tube does make for a perfectly round tube which makes a HUGE difference with matching threads , and the grade 5 is a fair bit stronger than grade 9.
Solid bar can be found on E-Bay for reasonable prices.

I make all my Ti tubes from bar, Only way to make sure they are up to my quality specs.

Gunny

[daPhoosa]

I was reviewing my form 1 submission and realized I had written it for a 6" oal, not the 6.75" oal I had remembered. I'm not really sure how I remembered it incorrectly, but I did submit it a long time ago...

I think the easiest solution is to remove a baffle and shorten the end cap:


I'm kinda sad to see that that baffle go, but the design gets very crowded looking if I just try to compress the spacers.

On the bright side, the weight drops to 8oz (11oz with muzzle device).

[daviscustom]

You could gain most of your .75 by flipping the threads forward on your rear cap. I'd do that LONG before removing a baffle.

You can always drill holes to remove material in between your threaded mount and the threads for the outer tube.....or put it on rotary table on a milling machine and cut it out.....no accuracy required in that recess...just removing weight.