Author Topic: Liberty Baffles (Read 7503 times))

Madd Hatter · « **Reply #20 on:** October 04, 2019, 09:58:56 PM »

Quote from: tracker1955 on September 28, 2019, 06:10:46 PM

Thought I'd share what I got from Dave EZman when at the fun shoot this spring, noticed how quiet his Liberty was, told me it was a scotch brite pad held in place by a half inch spring from Lowes. I reproduced the same after coming home from the shoot and am still pleased at how quiet it is, cheap easy fix. I shoot out my family room window all the time at a target 30 yards away and it doesn't even frighten the birds on my feeder not 10 yards from the window, that or the birds are deaf.

What OD spring did you use? I using washers and copper tubing spacers to quite my Liberty down along with drilling passages through the muzzel end shroud/barrel support along with a couple of 1/8" holes through the shroud near the receiver. I'd like to try tracker's method and see if it's quieter. Even with the garage door closed my wife still hears me when I'm doing some crono work.

BackStop · « **Reply #21 on:** October 04, 2019, 10:19:00 PM »

Quote from: larspawn on October 02, 2019, 02:35:53 PM

I was wandering around the Dollar Store and found these two items. I home rolled three and they fit perfectly in the Freedom shroud after I trimmed 1" off the scrubby pad. I didn't take sound test but will try to later. But it seems only slightly quieter. What I've concluded is much of the sound is the ping and not the pop. It really isn't that bad but given the size of the air tube I'm guessing there isn't much you can do to eliminate the ping?

Exactly what I have been using in the Freedom shroud and my DIY 1" PVC pipe LDC.

The LDC does make a difference, but working with the shroud only, does not make much difference.

Actually, I am starting to believe that leaving the shroud alone and simply adding the DIY LDC works better.

I think that may be because leaving the shroud alone leaves more volume for it to work as the first expansion chamber.

Orion · « **Reply #22 on:** October 04, 2019, 10:43:09 PM »

I have a video on a custom LDC I build for my Liberty but the admins on the forum doesn't allow posting that type of video on this platform. That still my go to LDC on my Liberty works really well!

SILENT SQUIRREL · « **Reply #23 on:** October 05, 2019, 08:25:52 AM »

Quote from: Orion on October 04, 2019, 10:43:09 PM

I have a video on a custom LDC I build for my Liberty but the admins on the forum doesn't allow posting that type of video on this platform. That still my go to LDC on my Liberty works really well!

You can publish the video on Youtube, allowing public access; and the post the link here ( & provide the title.)

SILENT SQUIRREL · « **Reply #24 on:** October 05, 2019, 09:14:05 AM »

Quote from: BackStop on October 04, 2019, 10:19:00 PM

Quote from: larspawn on October 02, 2019, 02:35:53 PM
I was wandering around the Dollar Store and found these two items. I home rolled three and they fit perfectly in the Freedom shroud after I trimmed 1" off the scrubby pad. I didn't take sound test but will try to later. But it seems only slightly quieter. What I've concluded is much of the sound is the ping and not the pop. It really isn't that bad but given the size of the air tube I'm guessing there isn't much you can do to eliminate the ping?

Exactly what I have been using in the Freedom shroud and my DIY 1" PVC pipe LDC.
The LDC does make a difference, but working with the shroud only, does not make much difference.
Actually, I am starting to believe that leaving the shroud alone and simply adding the DIY LDC works better.
I think that may be because leaving the shroud alone leaves more volume for it to work as the first expansion chamber.

Agreed BackStop
An LDC trumps baffles!
I'm not much of a DIY guy; but I have Froggy 6 inch LDC that float from rifle to rifle.
The LDC makes the guns quiet whereas the baffles do not

That's an interesting idea of yours that an LDC is more effective without baffles in the shroud

Ed

Madd Hatter · « **Reply #25 on:** October 05, 2019, 01:32:49 PM »

Quote from: BackStop on October 04, 2019, 10:19:00 PM

Quote from: larspawn on October 02, 2019, 02:35:53 PM
I was wandering around the Dollar Store and found these two items. I home rolled three and they fit perfectly in the Freedom shroud after I trimmed 1" off the scrubby pad. I didn't take sound test but will try to later. But it seems only slightly quieter. What I've concluded is much of the sound is the ping and not the pop. It really isn't that bad but given the size of the air tube I'm guessing there isn't much you can do to eliminate the ping?

Exactly what I have been using in the Freedom shroud and my DIY 1" PVC pipe LDC.

The LDC does make a difference, but working with the shroud only, does not make much difference.

Actually, I am starting to believe that leaving the shroud alone and simply adding the DIY LDC works better.

I think that may be because leaving the shroud alone leaves more volume for it to work as the first expansion chamber.

The thing I don't like about adding a ldc is it makes the rifle so long. It's not like I hunt so the length would not be a problem but just don't like the look. Just my personnel opinion.

KnifeMaker · « **Reply #26 on:** October 05, 2019, 03:45:09 PM »

Be very careful of which type of scouring pads you use. they are avaliable both with and without grit or cleaner in them. Any suppression type used will cause back flow into the bore. Carrying the grit into the bore. Exactly where you don't want it.

You don't want grit entering the bore. Ever! I found the non abrasive pads at the General Dollar store for about half the price of the versions with abrasives in them.

Knife

Bob Pratl · « **Reply #27 on:** October 06, 2019, 07:18:05 AM »

Quote from: KnifeMaker on October 05, 2019, 03:45:09 PM

Be very careful of which type of scouring pads you use. they are avaliable both with and without grit or cleaner in them. Any suppression type used will cause back flow into the bore. Carrying the grit into the bore. Exactly where you don't want it.
You don't want grit entering the bore. Ever! I found the non abrasive pads at the General Dollar store for about half the price of the versions with abrasives in them.
Knife

Very GOOD advice.

FuzzyGrub · « **Reply #28 on:** October 07, 2019, 11:02:38 AM »

Ok, some time for testing today.

The set-up is my basement 10yd range. Please ignore the mess.

I mounted the sound meter to the front of the chrony. It is about 2' past the muzzle, perpendicular to the shot. Set on the 90db range. For each test, I took 8 - 10 shots to get a relative consistent reading and recorded the analog meter with my iPhone.

Please note, this is a modified sound meter from my old speaker design obsession days. The importance, will be relative to each other, vs any absolute value.

FuzzyGrub · « **Reply #29 on:** October 07, 2019, 11:12:58 AM »

So, you always hear me compare the Liberty to the Mrod, so tested a 25 cal Mrod as a baseline. This is a regulated gun, tuned to 40fpe, for a somewhat efficient 32+ shots from a 3K fill, using 25g Kings. It has only the stock baffle system. I got readings that ranged from 89 - 91db, with 90db being the most consistent.

Next was a 22 Liberty, tuned to 30+fpe w/JSB 18.1g. Shooting them at the 860fps range. The readings were between 94 - 96db, with 95db the most consistent. The first couple of shots did not behave any different than the follow on.

Next was the Ebay baffles. This included the barrel stand-off, with four 25 cal baffles, not 22. Testing showed a range of 92 - 94db with 93db the most consistent.

Up next will be a test with Rod's AS with the oem spacer removed.

Results so far:

25 Mrod (40FPE): 90db
22 Liberty Stock (30FPE): 95db
22 Liberty Ebay Baffles (30FPE): 93db

Subjectively, I'd say the results so far, the Mrod seems quieter than both Liberty configurations. The Ebay baffles, make an improvement, but not close to the baseline Mrod.

FuzzyGrub · « **Reply #30 on:** October 07, 2019, 11:55:44 AM »

22 Liberty (30FPE), Removed OEM spacer, installed Rod's AS, no baffles: 92 - 94db, with 93db being the most consistent.

22 Liberty (30FPE), Removed OEM spacer, installed Rod's AS, 3 Ebay 25 cal baffles, baffle spring: 91 - 93db, with 92db being the most consistent.

Next up, venting the shroud.

RDB · « **Reply #31 on:** October 07, 2019, 12:12:06 PM »

Cool comparisons John. Your sneaking up on 90db.

superchikn · « **Reply #32 on:** October 07, 2019, 01:18:43 PM »

Cool testing Fuzzy.
I have three of Rods spacers on the way. Rod will they be here today??? Hah! Can't wait.
My Liberty has a monocore designed and printed by GEO. I absolutely love it, and we were working through a few iterations with me taking sound readings with my phone.
I learned a few things in the process:

The sound readings don't mean as much as they would seem. Meaning perceived sound levels and measured sound levels are not the same.
Shooting location can make a big difference. My bench is under a deck on a paved driveway with a car on one side and a wall behind and next to me (about 8' wide). my targets are 30 yds out about 5 yds to the right of a small bar.All of my guns sound quite loud at the bench due to sound bounce, even off of the barn. When I take them out in the wide open away from buildings they become extremely quite. Including my 40 FPE Liberty. I am still wary when shooting from the bench of noise levels.

I am not discounting sound level measurements as they are perhaps the only way to make a comparison, but when I shoot without the baffles and with the differences sound like more than 2 decibels. (By the way I had very similar results).

Fun stuff This!

FuzzyGrub · « **Reply #33 on:** October 07, 2019, 01:28:05 PM »

I modified the shroud, with three 0.150" holes, about 1 1/4" from the shroud end. They should be about in the middle of the 1" magic eraser.

22 Liberty, vented shroud, Rod's AS, no baffles: 92 - 94db, with 93 db being the most consistent.

22 Liberty, vented shroud, Rod's AS, three Ebay 25 cal baffles, baffle spring: 91db - 93db, with 92db being the most consistent.

So, from a db standpoint, no improvement going to a vented shroud. Subjectively, the tone seemed lower though. This is consistent with experiments I did on a prod shroud, years ago.

FuzzyGrub · « **Reply #34 on:** October 07, 2019, 01:42:30 PM »

The next test I want to do, is moving the shroud forward and adding baffles. That requires taking the barrel off and modifying the rear shroud mount, so it can slide forward on the thicker part of the barrel. No time for that, right now.

I pulled my first 22 Liberty out. This gun has the shroud moved forward 1 3/4", six Mrod baffles and baffle spring. It has a short section of mrod shroud in it to keep baffles centered. It has a Mrod AS with a washer in front of it. It still has the oem spacer with no holes in it.

This gun is shooting the JSB's a little faster than the 22 above, in the 880's.

22 Liberty (31FPE), six Mrod baffles, spring, shroud shift 1.75": 89 - 90db, with 90db the most consistent. Subjectively quieter than the other Liberty, in any of the configs.

FuzzyGrub · « **Reply #35 on:** October 07, 2019, 01:53:15 PM »

Results:
25 Mrod (40FPE): 90db
22 Liberty Stock (30FPE): 95db
22 Liberty Ebay Baffles (30FPE): 93db
22 Liberty, R's AS, no oem spacer, No Baffles (30FPE): 93db
22 Liberty, R's AS, no oem spacer, 3 Ebay 25 cal baffles w/spring (30FPE): 92db
22 Liberty, R's AS, no oem spacer, No Baffles, vented shroud (30FPE): 93db
22 Liberty, R's AS, no oem spacer, 3 Ebay 25 cal baffles w/spring, vented shroud (30FPE): 92db
22 Liberty (different gun than above), 6 mrod baffles, 1.75" shifted shroud (31FPE): 90db

My conclusions:
- Not going to bother venting any more shrouds. The tone is lower, and this vented one will go in the 25 cal build.
- Liberty needs more shroud and baffle space in front of muzzle
- My 177 and 22's will be modified like I did with my 1st Liberty. I have the shroud section and crosman baffles are very inexpensive.
- The 25 build will use the seven ebay 25 cal baffles, Rod's AS, and associated spacing with the shorter 20" barrel.

FuzzyGrub · « **Reply #36 on:** October 07, 2019, 01:59:42 PM »

Ray, the environment will always play a role. Outdoors, sound is reflected and absorbed differently than in the basement range. If it wasn't raining, I was going to shoot off the back porch (1/2 space), but that also gets tricky with background noise. If you are away from the house, that would be full space. The grass covered ground does not provide any reflection.

I can say subjectively, my mrod, and mrod baffled Liberty are still much quieter, when shooting outdoors.

BackStop · « **Reply #37 on:** October 07, 2019, 02:02:39 PM »

Quote from: FuzzyGrub on October 07, 2019, 01:53:15 PM

Results:
25 Mrod (40FPE): 90db
22 Liberty Stock (30FPE): 95db
22 Liberty Ebay Baffles (30FPE): 93db
22 Liberty, R's AS, no oem spacer, No Baffles (30FPE): 93db
22 Liberty, R's AS, no oem spacer, 3 Ebay 25 cal baffles w/spring (30FPE): 92db
22 Liberty, R's AS, no oem spacer, No Baffles, vented shroud (30FPE): 93db
22 Liberty, R's AS, no oem spacer, 3 Ebay 25 cal baffles w/spring, vented shroud (30FPE): 92db
22 Liberty (different gun than above), 6 mrod baffles, 1.75" shifted shroud (31FPE): 90db

My conclusions:
- Not going to bother venting any more shrouds. The tone is lower, and this vented one will go in the 25 cal build.
- Liberty needs more shroud and baffle space in front of muzzle
- My 177 and 22's will be modified like I did with my 1st Liberty. I have the shroud section and crosman baffles are very inexpensive.
- The 25 build will use the seven ebay 25 cal baffles, Rod's AS, and associated spacing with the shorter 20" barrel.

Thanks for posting your test results!

FuzzyGrub · « **Reply #38 on:** October 07, 2019, 03:37:45 PM »

FWIW: 3db is equal to a doubling of sound pressure. It is not a linear scale.

Hawkeye51 · « **Reply #39 on:** October 07, 2019, 03:53:37 PM »

Fuzzy

Thanks for all the great work you did. Always quite a subjective subject. Everyones ear is a little different (frequency response and amplitude etc).

The best information I have ever read about moderators, was a post in AGN, by Sto who designed powder burner moderators for the industry. In a multi page comparison of airgun moderators titled "Moderator Design,Testing & Evaluation, he tests almost all of the commercially available moderators for air guns. Long, difficult to read and somewhat difficult to interpret, my take away was LEGNTH HELPS.

If I'm reading your conclusion right, it's simmilar? Distance past the barrel improves sound attenuation. Therefore moderators become a compromise of legnth, diameter, weight, looks and expense. For me, cheap and easy to obtain 95 % effeciency is O. K..

Again thanks for doing the comparison, it helps me accept the theory of diminishing returns.

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Liberty Baffles

Author Topic: Liberty Baffles (Read 7503 times))