Please critique my 300BLK design

[ThaDoubleJ]

I just got my Ti-Rant out of jail, and now I want something for a 300BLK that I don't have yet. I really like the Leonidas, but I really want some more barrel, so I thought a form 1 reflex can would be the way to go. This forum says volume is your friend, so my design is huge. I figure on a stainless tube, stainless blast baffle, and aluminum monocore. Please tell me what's good and what's bad about this design. I would want very quite subs, but enough strength for supers.

[redtazdog]

How long is the barrel itself ?
I'm thinking more like a7 inch barrel with less reflex area and more baffles up front would suppress better.

[ThaDoubleJ]

I'm planning on a 12.5" barrel. The Leonidas uses an 8.2 or 8.5, and while it suppresses great, supersonic velocity suffers as it's primary designed for subs. Their design also puts the rear endcap behind the gas block, which makes it impossible to use with a longer barrel, hence my Form 1 idea. I know that common knowledge says the 300 uses all it's powder in 9", but the chrony don't lie, and max velocity is achieved around 16", so I'm splitting the difference. I'm not locked on a 6" core either, I just figure my 18" SPR clone is still fairly handy, so I went with 18" total length as a starting point.

[Dr.K]

I shoot a lot of suppressed blackout. I think that that can would be overkill.

I have a 9 inch x 1.5" with 7 cone baffles, and when I shoot a sub thru my handi rifle, it's literally quieter than a red ryder bb gun. It lowers the supers sound quite well also.

[ThaDoubleJ]

So you think I could get away with less reflex portion? The HG I'm after is 1.875" ID, and I don't figure the empty reflex portion would add much weight, so really the only concession I'm making is the short-ish barrel. Does the large volume of the can add any small gains in suppression?

[MCKNBRD]

So you think I could get away with less reflex portion? The HG I'm after is 1.875" ID, and I don't figure the empty reflex portion would add much weight, so really the only concession I'm making is the short-ish barrel. Does the large volume of the can add any small gains in suppression?

The reflex portion is there...therefore, it adds weight.

The volume behind the muzzle won't help suppression noticeably, but will reduce backpressure. Might not be a bad thing with supers, but could lead to issues with subs, if the pressure curve is such that the port won't see enough gas for long enough to cycle the rifle.

Byrdman

[Dr.K]

So you think I could get away with less reflex portion? The HG I'm after is 1.875" ID, and I don't figure the empty reflex portion would add much weight, so really the only concession I'm making is the short-ish barrel. Does the large volume of the can add any small gains in suppression?

I think you can get away with no reflex portion, also, 1.875" will add no noticeable suppression. Length always trumps diameter, so I'd go 1.5", and maybe longer....In fact, I did exactly that with my blackout can, and everyones jaw drops when they shoot thru it.

[ThaDoubleJ]

Bird: Good point about the possibility of cycling issues, I hadn't considered that. So there is a point when dealing with a gas gun where volume could become your not-friend. Is there any formula to determine an ideal chamber size, or is it trial and error? If I make it too big, is there a filler that can be used?

K: I'd probably be cool with another 2" on the can, would that help? Do you know if the Leonidas uses that rear portion as a chamber, or is it just a mount for the rear of the can?

[Historian]

So you think I could get away with less reflex portion? The HG I'm after is 1.875" ID, and I don't figure the empty reflex portion would add much weight, so really the only concession I'm making is the short-ish barrel. Does the large volume of the can add any small gains in suppression?

I think you can get away with no reflex portion, also, 1.875" will add no noticeable suppression. Length always trumps diameter, so I'd go 1.5", and maybe longer....In fact, I did exactly that with my blackout can, and everyones jaw drops when they shoot thru it.

Yes. An empirically derived design figure of merit that should be highlighted more often for a
calculated volume.

This brings up an interesting question. If, say a given efficient suppressor such as the Sparrow,
one kept the same length but increased the diameter of the can by 50%, what would be, if any, the
corresponding lowering of output Db?

In passing, saw last night the Red Jacket Titanium .22 suppressor being shot on a high rate of fire
machine pistol. The design is a monocore. For those who may have also seen it did it not
seem to be rather noisy? It will be interesting to see test results on its actual sound reduction.

[ThaDoubleJ]

Ok, so less to no reflex chamber and some more length. Can I get away with a stainless blast baffle inside the aluminum monocore? Simple slanted baffles like that will work? I've also been reading the crazy idea thread, and there was mention of cooling fins in the reflex chamber as well as an atmospheric equalizer on the front, they seem easy enough to apply, would they be worth it?

[Dr.K]

Let me make it super simple for ya.

Direct thread on.
1.5" OD.
.060-.070 wall diameter.
9" OAL
2" blast chamber length.
#7 60 degree cone baffles with the ends clipped.
Not aluminum.

This will win, anything outside of these parameters will not yield an increase in the benefit:negative aspect

Like if you went 2" diameter, the return in suppression will not outweigh the fact that it's a brick....or if you packed in 15 baffles, you lose too much volume. I've built the described can on form1, and it is fantastic. I've shot it with other peoples cans, and it performs as well, or better to everyone who was present.

[ThaDoubleJ]

Thanks Dr. K, but if I go that route, I'd be better off just buying a can off the shelf. Is there no way my design can work? Liberty made something similar work, just with a shorter barrel.

[CMV]

Thanks Dr. K, but if I go that route, I'd be better off just buying a can off the shelf. Is there no way my design can work? Liberty made something similar work, just with a shorter barrel.

Follow the recipe above. No way to know if yours works until you try it & see. I don't remember seeing anything similar so there's nothing to compare it to. There is a way to know if what Kyle suggested will work - several of us here have built a variation of that 300 BLK can and they all make big grins. Mine reflexes over the barrel so you can still have that part, but beyond that it's spaced 60° stainless cones.

I wouldn't put AL in there either. Maybe right now all you want to shoot are subs, but maybe down the road you'll want to play with some Lehigh Defense controlled chaos or Barnes TAC-TX bullets and a permanently attached AL suppressor won't be what you want for that.

[57fairlane]

I wouldn't put AL in there either. Maybe right now all you want to shoot are subs, but maybe down the road you'll want to play with some Lehigh Defense controlled chaos or Barnes TAC-TX bullets and a permanently attached AL suppressor won't be what you want for that.

Very true.

If I was doing an integral 300blk, I would spring for a titanium tube and do my baffles out of 17-4.


I personally don't see an issue dedicating an upper with a reflex design as it would either do nothing or help and if you can hide it under a handguard then who cares.

Figuring out your gas port location and size will be a trial and error deal.

[ThaDoubleJ]

Can Ti be welded to a barrel?

Edit: Nope

[57fairlane]

Can Ti be welded to a barrel?

Edit: Nope

Why are you welding anything to the barrel?

A blind pin is essentially a set screw into a divot that is welded over preventing someone from removing whatever the pin is holding in place . . . you don't have the design of the rear cap you are using but you shouldn't be welding anything to the actual barrel itself.

[gunny50]

Can Ti be welded to a barrel?

Edit: Nope

One could however make the tube or vented shroud out of steel / stainless….
That allows for a well designed silencer with core that you like and even go back over the barrel for 2-3 inches.
Coming to think of it, vented shrouds on these short uppers with free float tubes are kind of sexy.. in a manly way of-course.

Gunny

[ThaDoubleJ]

I have a blind pinned brake on an AR, but I was concerned about strength with the size of the shroud. Looking at the leonidas, they weld the core to the barrel, so I figured my shroud should be too.

[sendit]

Let me make it super simple for ya.

Direct thread on.
1.5" OD.
.060-.070 wall diameter.
9" OAL
2" blast chamber length.
#7 60 degree cone baffles with the ends clipped.
Not aluminum.

This will win, anything outside of these parameters will not yield an increase in the benefit:negative aspect

Like if you went 2" diameter, the return in suppression will not outweigh the fact that it's a brick....or if you packed in 15 baffles, you lose too much volume. I've built the described can on form1, and it is fantastic. I've shot it with other peoples cans, and it performs as well, or better to everyone who was present.

x2
If you build a can with those features you will be happy. Don't feel that you must follow that "exactly" there is some give and take, but don't go too far as in the examples of the OD and #of baffles he has given.
Mine has a blast chamber of about 2.1" the cone angle is less than 60 deg(sorry I can't remember the angle) because I wanted a "taller" cone feature. When I first shot with friends that have AAC's an Surefire's they were amazed by my "home made" can.

Good Luck

[ThaDoubleJ]

Thanks Dr. K, but if I go that route, I'd be better off just buying a can off the shelf. Is there no way my design can work? Liberty made something similar work, just with a shorter barrel.

The design I've got up there's uses a removable monocore for cleaning, and I'm not sure how I'd even make cones and such.

If we assume that I'm going to build the above design, aluminum is a no go for the core, Ti is a probably not since I can't attach it to a barrel other than pinning, leaving stainless as the only option. It'll be heavy, but I can reduce that weight by shortening or removing the reflex chamber, and everyone recommends some extra length?

[CMV]

Thanks Dr. K, but if I go that route, I'd be better off just buying a can off the shelf. Is there no way my design can work? Liberty made something similar work, just with a shorter barrel.

The design I've got up there's uses a removable monocore for cleaning, and I'm not sure how I'd even make cones and such.

If we assume that I'm going to build the above design, aluminum is a no go for the core, Ti is a probably not since I can't attach it to a barrel other than pinning, leaving stainless as the only option. It'll be heavy, but I can reduce that weight by shortening or removing the reflex chamber, and everyone recommends some extra length?

A 60° cone is pretty simple - assuming you have a lathe. Don't want to sound like a dickhead, but if you don't think you can make a cone how are you going to make anything else that's equally or more complex? Set your compound at 30° (or just leave it at 29.5° if that's where you have it) and practice on some scrap. You'll quickly see how to make a cone shape, both inside & out by feeding with the compound.

[ThaDoubleJ]

I made a brass cannon in shop class in 1995, that was the last time I've touched anything but a brake lathe. I still haven't figured out how I'm going to get the machine work done, but I know I can turn down something round and I figure working a mill can't be too tough, hence the monocore idea. I also plan on using the shroud as the body of the silencer, then thread the monocore to the barrel, into the body, then thread an end cap over that into the body. What I'd really like is for Liberty to say "We can just put a Leonidas on a 12.5" barrel for you" then I'd be happy, but they can't, so I guess I gotta make a can on my own.

No dickheadedness taken, totally valid question.

[sendit]

The design I've got up there's uses a removable monocore for cleaning, and I'm not sure how I'd even make cones and such.

If we assume that I'm going to build the above design, aluminum is a no go for the core, Ti is a probably not since I can't attach it to a barrel other than pinning, leaving stainless as the only option. It'll be heavy, but I can reduce that weight by shortening or removing the reflex chamber, and everyone recommends some extra length?

I have seen and heard a form one monocore design that was very effective. The entire build was 304 stainless.

My can with the cones and spacers is entirely of 304 stainless, it's weight is completely in line with commercial .308 cans.
Alum is a no go, Ti and inconel would be awesome but if you are unsure of your machining capabilities both would present a challenge. If your machining skills are up to executing a monocore design the the option of cones will not be a problem.

As far as removable cores, I am no expert but no commercial can bodies are threaded. Center fire cans do not require cleaning and the pressures encountered from use on a bolt gun makes me hesitate to have small fine threads holding the thin tubing together.
IMO the only reason people thread the bodies of their center fire cans is because they are not sure of their baffle design/configuration and they want the option of dumping the guts and trying again.

[ThaDoubleJ]

IMO the only reason people thread the bodies of their center fire cans is because they are not sure of their baffle design/configuration and they want the option of dumping the guts and trying again.

This sort of applies to me, but the legalities are a bit fuzzy to me. If I build this, and it sucks, can I destroy the core and start over? So long as the serialized tube remains, of course.

[sendit]

IMO the only reason people thread the bodies of their center fire cans is because they are not sure of their baffle design/configuration and they want the option of dumping the guts and trying again.

This sort of applies to me, but the legalities are a bit fuzzy to me. If I build this, and it sucks, can I destroy the core and start over? So long as the serialized tube remains, of course.

Bendersquint will have to chime in on this but it is my understanding that ,once finished, you cannot make more parts for repair or mods unless you are a FFL/SOT.