Fourteen (14) LDC Test

[mrbulk]

*UPDATE: the maker of the MM2 has provided more info on the unit, saying the internal core is -

“...3D printed with PETG material for the 2 baffle section and end caps, with aluminum outer shell and a coat of primer plus 2 coats of enamel. The baffles are of a standard cone shape with supports. The PETG material is like the clear soda bottle material. Very strong stuff.”

Jolly good! What about MM1? 

Yes, the known details on MM1 have already been posted in the OP, but if I know more later (esp. the COST) it will be shared here.

[WhatUPSbox?]

It seems safe to say that most any moderator with properly built internals (meaning not just an empty can) ...

That may actually be an interesting data point. Taking one of the larger LDC's that you can disassemble and comparing it as built and with the internals removed.

[subscriber]

It seems safe to say that most any moderator with properly built internals (meaning not just an empty can) ...

That may actually be an interesting data point. Taking one of the larger LDC's that you can disassemble and comparing it as built and with the internals removed.

The other question that tags the above is; is all volume equally effective?  Is longer better for more dwell time while the pellet is in the can; or is that only the case with baffles?  I suspect that there is a minimum diameter that is effective and does not affect point of impact or grouping ability. 

So, "accuracy" has to be another metric.  Yet, no formal LDC test seems to include effects on accuracy.  Some mention shifts in POI.  Some might mention groups tightening, but who is going to mention groups opening up?  Perhaps someone testing a dozen plus products by the same methods.  Hint hint...

[Earl]

Testing with the meter at 25 feet is a 2 person job.
You need someone to sit at the sound meter and record the results and reset the sound meter.
It is too difficult for one person to get up and walk to the meter and record it and then walk back and set up and shoot again.

Earl I heartily agree! Care to volunteer?

I would like to help but the trip from Kentucky to Nevada is too much for me.

[Earl]

Do LDCs change accuracy?
I have added a TKO to my Discovery and a Geo to my Maximus.
The point of impact did move a little.
The 10 shot group size may be the same or a little smaller.

[mrbulk]

It seems safe to say that most any moderator with properly built internals (meaning not just an empty can) ...

That may actually be an interesting data point. Taking one of the larger LDC's that you can disassemble and comparing it as built and with the internals removed.

Stan, actually I may have already had some experience in that arena. Long ago (mid-90's) someone among our local Hawaii airgunning group at the time decided to make empty "cans" for us to try out.

They were nicely machined and everything, and if we had 3D printing back then or even any basic knowledge of exactly "how" a silencer looked on the inside, we may have made more progress but as it turned out, the cans were not much quieter (you could tell the volume was a bit less, but it was still irritatingly loud and metallic sounding as we shot it through a PCP) and the main point was ... the pellets seemed to go all over.

The non-uniform turbulence going on inside the empty can was enough to throw the pellet path off, and not necessarily in a consistent manner (it's not like the POI just shifted, the pellets were landing all over the place).

[mrbulk]

So, "accuracy" has to be another metric.  Yet, no formal LDC test seems to include effects on accuracy.  Some mention shifts in POI.  Some might mention groups tightening, but who is going to mention groups opening up?  Perhaps someone testing a dozen plus products by the same methods.  Hint hint...

I shall endeavor to find this out at some point in the very near future - as I already saw POI shifts between moderators during this test...but I am supposed to test out a bunch of slugs which have been sitting on my "airgun man cave" desk for several weeks now...hey, maybe I could combine both...

[subscriber]

Do LDCs change accuracy?

They can.  They can tighten groups by virtue of improved air stripping and reduced internal and "muzzle" turbulence.  Or their internal structures can maximize cross turbulence to minimize report.  The latter can buffet light pellets and open groups.

Mounting anything to the muzzle is likely to change barrel harmonics.  Apart from shifting groups, the new inertia at the muzzle can open or close groups.

Rather than "dang" a very quiet moderator that appears to open groups, it would be fair to retune the PCP to a higher or lower velocity, to see if all potential accuracy is affected.  Grouping ability might be improved at exactly the performance level you had in mind; rather than what the reviewer used.  Or not.

Another approach would be to test all 14 moderators on a number of different air rifles; at different power levels.  As has been suggested.  At what point does the tester deserve a gofundme account to help pay for all the time and materials...

[mrbulk]

Do LDCs change accuracy?
I have added a TKO to my Discovery and a Geo to my Maximus.
The point of impact did move a little.
The 10 shot group size may be the same or a little smaller.

Testing for something like this may come up eventually. It is certainly intriguing.

[JungleShooter]

🔶 Well, Charlie, you've done it again!
THANK YOU! 😄

Great test, you greatly improved your test set up, NICE! 👍🏼👍🏼


🔶 And Subscriber, your technical background comments on the meaning of dB are always needed in posts like this — otherwise I (and many other people) are prone to misinterpret them.... THANKS! 👍🏼



OK, and now I want a new silencer. I want one NOW!! 😄

Matthias

PS: See what these posts do to me...?!? 

[mrbulk]

OK, and now I want a new silencer. I want one NOW!! 😄

Matthias

Hmmm, you know what Matthias, that's funny because it seems like this all makes ME also want "another one"...as the saying goes, you can't be too thin, too rich, or - have too many silencers! 
Thanks!

[OTmachine]

Thanks for the Great write-up and taking the time to do this.  It is appreciated.
Keith

[mrbulk]

Thanks for the Great write-up and taking the time to do this.  It is appreciated.
Keith

Much appreciated Keith, just wanting to further our wonderful sport - quietly...

[WhatUPSbox?]

For those that see a POI shift with an LDC, does the POI change when you rotate the LDC?

[subscriber]

Stan, I can see that such a POI shift with a partial can rotation would mean a lack of concentricity (or angularity in the mount). 

What I have seen had more to do with barrel harmonics being upset.

[KnifeMaker]

I must point out that a given ldc mounted on a given ag may give totally different results in regards to poi shifts.
thickness of barrel, free floated or not. Length of bbl. shot cycle in a given ag all make a difference. Across different brands and models of ag's things can vary greatly. Even in a given model.


All can give different results from harmonics alone. Not to mention a madrid of other things.

Knife

[subscriber]

Expecting zero zero shift (  ) when attaching a LDC may be expecting too much, in my opinion.  What is reasonable is that whatever POI is achieved with it on, is repeatable; no matter how many times the LDC is remove and reinstalled on the same airgun.

[Struckat]

I put a GEO on my HW95 and am very pleased.

Use I gotta a phone app, with the phone laying on the table about a foot below the muzzle I read 92.2 dba. With the GEO the reading dropped to 83.7 dba.
The sound reduction was dramatic even if the actual numbers would be different with a real meter.

This was with an untuned gun with less than 100 shots through it. I was shooting 7.9gr at about 920-930 FPS.

I haven’t checked since going inside the gun. It’s my 3rd GEO, and cost vs performance is very good.

POI shift, oh yes. You are adding weight to the end of the barrel. It makes me think about the adjustable muzzle weight from Hector that is being tested in another thread.
The POI changes and is repeatable if I remove and then reinstall.

[Rick67]

What are the dimensions on the silver LDC?

I am partial to silver, you know.

Thanks, MB sir 

[mrbulk]

What are the dimensions on the silver LDC?

I am partial to silver, you know.

Thanks, MB sir 

Thanks Richard, the dimensions are 1-1/8” x 7-3/8”