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[Rustys0702Services]

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[a_canadian]

So bear with me, I'm 'spitballing' in trying to understand what you're doing. For comparison, the infamous Jesse James sweet potato can supposedly follows the 'natural' shape of the pressure wave as it exits the muzzle, and in his mind this enhances gas expansion via the shape of the cast ovoid can. Which I doubt does anything of the kind, but that's another discussion. Anyway, with your bore variation it seems you're actually doing what he was after, which is to say modulating the pressure front in such a way that you maximally exploit the length of the tube using varying patterns of gas expansion, controlled by varying the bore size and entry point shape. Is that about right, or am I talking twaddle?

Seems to me something along similar lines is happening with that really interestingly shaped monocore featured in the recent SmarterEveryDay video with clear suppressor tubes. The one where the first half or so is largely expansion volume, then there's a narrowing/controlling smaller monocore which is almost like a secondary barrel, then lastly a very complex maze of monocore vents. The pressure is being manipulated in such a core in several different ways, ultimately contributing to extremely little pressure exiting the end cap. From appearances it would seem that one doesn't vary the actual bore size, and surely a larger mid-bore would be challenging to cut in a monocore, but the principle may be similar in the way it manipulates pressure in profoundly different ways at different points in the system, breaking up what might otherwise be a strong standing wave which was able to exit the end cap.

[John A.]

I enjoy discussions such as this.

I'll share my experience.

I mostly am referring to lower pressure rounds like 300 blackout subs, 9mm, 38 special, 22lr, etc., so the bulk of the pressure is going to be the first part of the can out of the barrel muzzle. I do like larger chambers to allow the lower pressure more room to expand nearer the exit of the can. By then they've already lost some of their pressure so having a larger chamber makes sense to me to allow them to further expand and do its' thing.

I have even been known to rearrange my baffles and put the largest chamber in the middle of the baffle stack about 3 or 4 inches from the barrel muzzle too, which we've discussed here before. I think the topic name was secondary expansion chamber or something along those lines. Rusty, you may be interested in trying to find that topic since some of your thoughts were covered in there.

I have always used a tighter bore at the muzzle but the reason for that is to account for machining goof ups. Larger diameter nearer the can exit so I don't get a baffle strike if something went wrong.

Though I believe from a pressure viewpoint, would probably be better if it were the opposite. Tighter at the endcap and larger at the muzzle. Especially for helping "snag" more of the gas that has went straight through the previous baffles uninhibited.

My "real world" example would be thinking about a garden hose. You turn the water on and a stream of water comes straight out. But if you use your finger at arm length to try to touch the stream of water, will redirect some of the water stream causing it to splatter out of the straight line that it was going and causing the water to change direction and better help direct some of it to fill your chamber up better.

Or at least not allow it to travel through the silencer bore from end to end in a straight line.

I know, liquid pressure and hot air pressure behave differently, that is the best analogy that I could think of to try to explain what I meant when I said to try to "snag" some of the pressure in the center of the stream that had went straight through previous baffle bore uninhibited.

The tight expansion baffle bore does increase back pressure in the barrel some though. Which is not a terrible thing where flash and noise suppression is concerned. The silencer baffles are doing their job and will hold some of the initial pressure back. While perhaps not a large meaningful amount, every little bit helps. The less the silencer has to deal with initially, the better. I also think that's the same concept why ported barrels and integral chambers are so effective. The less gas that initially goes through the silencer and the longer it takes the hot gas pressure to exit the endcap, the more quiet it's going to be.

OK, enough rambling on for the time being.

[John A.]

Oh, I wanted to add, the diamond shapes in the monocore can in a few of the videos was an awesome idea. Should bounce everything around real good in there.

I was thinking the diamond shapes were protruding from the bore. Rather than cut "into" it.

[doubloon]

Kinda looked like those diamonds did trap and bounce everything around pretty well.

That one can looked almost like it had two expansion chambers. Big flower of fire in the back then a jet and a big flower of fire in the front. Very cool to watch.

[1rosta]

I usually just lurk around here but I have a question. Are the first 2 baffles after the blast chamber clipped or are they just bored through?

[garredondojr]

I usually just lurk around here but I have a question. Are the first 2 baffles after the blast chamber clipped or are they just bored through?

most clip all baffles except the blast baffle. I think the theory behind this is to not disrupt the bullet when pressures are at their highest.

however it seems rusty does his DHC on all baffles. I've also seen commercial cans that all baffles are clipped

[Holescreek]

I'm far from being an expert on this stuff since I'm just finishing up my first form1 30 cal suppressor. I had a similar baffle clipping question just a couple weeks ago and didn't get much help here.

I ended up using the DHC (double hybrid clip) on all of my step cone baffles and the through passages are all .08" over bullet diameter. I have found no negative effect on accuracy so far. Last weekend I took it out for a test run comparing it to my Rugged Surge 7.62. Using my handloads with the Form1 build I was able to keep my groups under 1" at 100 yards with the best 5 shot group at 1/2". Video: https://www.youtube.com/watch?v=b-6m4a7OsfA

[Rustys0702Services]

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[Rustys0702Services]

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[John A.]

I noticed straight lines down each side of the baffle where there isn't as much fouling.

You can see the base metal in that area, and the fouling is noticeably thicker or darker around the rest of the face of the baffle.

Not sure why that would be.

I would expect more or less fouling on other locations on the baffle, but it was peculiar to me to see a "space" or a "gap" of fouling on the face of the baffle specifically.

[Rustys0702Services]

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[yondering]

Rusty - do you clock your baffles so the clips are aligned, 90 deg apart, or ?? Have you experiemented with different clocking with your DHC, and does it matter?

Seems like with the blast pattern mentioned in the posts above, clocking consecutive baffles 90* apart would be the way to go, but I haven't tried that clip style.

[a_canadian]

Rusty quoted a customer in a post higher up in this thread who said he'd tried a bunch of differing alignments but found an X pattern with about 25° offset alternating worked best. Not quantified, just subjective without exposition of the criteria being appraised as best... The guy goes on to say he'll have dB numbers in April. What year, well, that's not given, nor are the dB numbers, so I suppose it'll be 2018?