Author Topic: Suppressor styles and how they effect performance  (Read 1827 times)

Steelhead

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Suppressor styles and how they effect performance
« on: April 14, 2020, 08:14:50 AM »
Much time, minutia, charts, graphs, math, tooling knowledge, ammo type, air pressures, internal machining, etc. is given to making airguns perform. Some pay off more than others. Some very simple cheap tricks pay big dividends (lubing ammo with 10 wt. shock oil) and some are very expensive with questionable dividends (upgrades for massive power, barrel lapping, carbon fiber tanks/barrel shrouds, etc.) 

One thing that I rarely if ever see discussed is the effect of suppressors on performance. There are many types of LDC's out there with a lot of different mounting styles. Speaking from experience, there are at least four common styles of suppressors that are used for the Texan and they all are vastly different in how they mount. I know this applies to other airgun types as well, but I'm going to use the Texan as an example here because a) it's what I know, and b) in a .308 long range setup everything is exaggerated with regards to performance. Results change with the smallest tweaks and therefore can be easier to diagnose and isolate. 

I'll use suppliers of LDC's to identify the examples: DonnyFL (threaded), Hunter Supply ('slide on' clamped can), R&L (integrated in the chassis requiring barrel removal), and Neil Clague (slide on/shrouds the whole exposed barrel)  I only have first hand experience with the HS can on my gun and shooting Steve's .257 with the NC.

As much as I hate to admit it, my gun does not shoot worth a crap unless I have the HS can on it. It's been proven over and over that my results both short and long range are exponentially better with the LDC mounted. I've been told by gurus that it shouldn't make a difference, but it absolutely does (I wish it didn't, because packing it around sucks ass. I can't sling it because the LDC makes it top heavy and it wants to flip over) I'm convinced that the clamped ring about 5" down the barrel coupled with the weight of the LDC somehow helps the barrel harmonics. Dramatically. I'm going to approximate but I would say the difference is a 2.5" to 3" five-shot-group average at 200 yards with the LDC and 4.5" to 6" without it. That's a rough guess, but you get the idea. The POI changes with and without as well, which to me confirms that it is indeed having an effect on things.

All of the above leads me to this question: Why isn't more focus placed on LDC's and how they add to or detract from the performance of an airgun? Obviously big bore demonstrates this more than pellet shooters because as I said before everything is amplified. But for all of the focus placed in other areas to increase accuracy, it seems as if this is never brought up. Something as simple as the type/brand of LDC used that will double the accuracy is a big deal.

Just curious if any of you have any thoughts on this as well.


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steveoh

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Re: Suppressor styles and how they effect performance
« Reply #1 on: April 14, 2020, 08:37:03 AM »
I’d be interested in hearing from some of the suppressor makers. Neil Clague is fairly opinionated on the subject as he’s done a lot of experimenting and he’s made suppressors for many brands and types of airguns.

The suppressor he sold me for the Texan was a newer design for him and integrates felt wipers. Brand new these wipers have no holes and require a few shots to poke holes threw them. First few shots were infinitely quiet, as in, did this thing fire?

All of my rifles fitted with suppressors have a different point of impact with suppressor on vs off. As a result of this I index my shrouds by adding a dot of white paint at the top, so the suppressor always is indexed to the same spot. The Texan is very consistent from outing to outing.

I have had three bad suppressors over the years. Bad because of clipping. Two of these I  ended up drilling out, but once again indexing helps me keep things consistent when taking off the suppressor and later reinstalling.

I think we have several factors that might effect accuracy with a suppressor.

1. Proper fit
2. Turbulence
3. Barrel harmonics

That big heavy suppressor you put on your 308 Texan surely affects barrel harmonics perhaps to a greater extent than the rubber rings you used to use.

Somewhere I saw a high speed video of a Texan barrel whipping as it was fired. I bet that can is preventing or minimizing that barrel whip.

The turbulence that a suppressor might or might not create surely affects accuracy. Question is to what extent and how the internal design plays a part.

Lot to chew on here.


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Alan

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Re: Suppressor styles and how they effect performance
« Reply #2 on: April 14, 2020, 09:08:11 AM »
The most important attribute a suppressor must have, is concentricity. Even a few thousands can cause pellets to either hit the suppressor's elements, or veer off due to uneven airflow around the pellet as it exits the suppressor.

The second most important item is how the gasses are routed and disbursed. There are some very sophisticated designs, which may have a few dB advantage over more standard baffle designs, but they're darn expensive as well.

Internal volume is important. Designs which vent air back inside the barrel shroud tend to offer better suppression, but the actual suppressor portion often lack in internal volume. And strictly from experience, designs which vent the gasses forward rather than radially, tend to offer better (perceived?) suppression.

Although we all want a physically light weight suppressor, if we want efficiency (less muzzle report), plastic assemblies aren't the answer for several reasons. The main reason is, machining tolerances are easier to control when using aluminum. Titanium or aluminum-lithium-copper alloys could be used, but their cost makes them relegated to the military. I suspect you could use magnesium if the use was limited to airguns.

To expound on plastics and maybe carbon fiber too, is how they're constructed. Without mentioning any names, I have one made with a carbon fiber tube and innards, with the ends being some sort of acetyl. It did its job just fine, but after about 1,000 round shot through it, one of the baffles failed. Wanting to know what happened, I cut it apart. Turns out the baffles had become almost shredded due to the impact of the air hitting them, and not from pellet strikes. I won't own another one.

I have had three slip-on suppressors, and I've never had good luck with any of them. Part of that, as mentioned above, may indeed be a lack of concentricity. And, the slip-ons tend to be heavier as well.

There are two other issues, and you brought up one of them—barrel harmonics. I won't get into that issue, as Bob Sterne has covered the subject very well. The other one is proper tuning.

I shouldn't need to mention it, but the more gas used, the louder the report! Let's face it, we can't always "tune" a specific airgun to minimize the amount of air used, especially big bores. As a result, the suppressor has to be big, and sometimes, really big! The one on the 338/458 I once owned, was 3 inches in diameter, and 14 inches long! And the darn thing was still way too loud!

Personally, I like the DonnyFL I have mounted on my FX Impact. I have a Huggett on my 9 mm, and I'm sure it is well made inside. None the less, it is still loud as there really isn't any way of tuning the airgun it is on. So we sort of have a double-edged sword. I suspect this issue (too much air use) causes some folks to blame the suppressor, rather than the real cause.

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761xl

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Re: Suppressor styles and how they effect performance
« Reply #3 on: September 11, 2020, 04:21:27 AM »
i know im months late but seems like right thread. i finally got beeman chief shooting good. put tko slip on on it and somehow it wouldnt shoot. monkeyed with everything i could imagine and finally drilled out the innards very slightly larger and it is a deathray now , actually got more accurate than without and still plenty quiet. [ the tko did great job quieting the chief both stock and drilled out].
i figure my barrel may be rifled a bit off center thereby making pellet be a few thousandths closer to one side of silencer and if so making the pathway larger might have reduced turbulence or flyer fairies hate big holes and left the rifle for greener pastures. btw dont get results as good as experts but pretty satisfied with 23 shots , 808.8 high, 779.3 low, with 18.13 grain jsb.

best wishes to all.
i've done a lot of stupid things in my life , but i'm probably not quite finished :)

Alan

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Re: Suppressor styles and how they effect performance
« Reply #4 on: September 11, 2020, 05:12:53 AM »
In the above, I didn't mention the bore diameter pf the suppressor.

I think in some cases, designers of suppressors (not always real engineers), make the suppressor bore too small. This makes misalignment (concentricity) ever more important. The DonnyFL on my .25 FX Impact was actually made for a .30 caliber. Yet, as it sits, it is almost dead quiet. You hear the click of the hammer, and the hiss of the regulator. The only "real" noise is the hybrid slug hitting its target.
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Alan

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Loren

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Re: Suppressor styles and how they effect performance
« Reply #5 on: September 11, 2020, 01:41:04 PM »
I think the greatest impact is on barrel harmonics with the weight, length...etc of the suppressor making significant changes to harmonic freqency of the barrel. 
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Alan

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Re: Suppressor styles and how they effect performance
« Reply #6 on: September 11, 2020, 03:13:09 PM »
Loren, you're correct. But given the correct tune and pellet (slug) weight, suppressed airguns are still very accurate.
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Alan

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