Mercury Recoil Suppressor

[montana_charlie]

Anybody have experience with handling one of these jewels?

I was given a small bottle of mercury, years ago...and have been wondering what to do with it. Then I experienced the recoil of a Sharps, shooting heavy bullets from .45-90 cartridges...and the rifle is more muzzle-heavy than I like.
Having heard that mercury recoil suppressors are much loved by shotgunners, a plan was born that should cure both problems.

There is a commercially made unit which is five inches long, has a 5/8" diameter, and weighs 11 ounces. Comparing those parameters to my rifle, it seems like a good match.

So, I have the stainless cylinder cut, and tapped on both ends. One end is plugged, and the (fancier) plug for the other end is ready for the Loc-Tite.

I've weighed parts to determine how much mercury is required to reach the 11 ounce target weight, but my calculations seem to indicate that the cylinder will be very close to full after adding 17.893777 ml, at 73.4° Farenheit. Maybe too full to seat the plug...
I could probably live with slightly less weight, but I don't know 'how full' one of these things is supposed to be.

If you hold the cylinder horizontally and tilt it, the weight at one end would change quite a bit if the tube was (say) 3/4 full.
If it only had a little space inside, the weight shift wouldn't be so dramatic.

My question is for those who have handled a mercury recoil suppressor, and felt the liquid metal slosh around inside.
Do you get the impression that the tube is basically full, or less so?

CM

[Johnch]

I have 2
1 is a Dead Mule , and the other is ............... Something Mercury recoil suppressor .
IMO both are about 2/3 full
If I remember my High school classes , the moving Mercury is what reduces the felt recoil .
The Mercury absorbes the kinetic energy of recoil as it starts to move forward in the tube .
As it hit's the end of the tube , it releases the energy , back into felt recoil .
But the Mercury is heavyier , so it takes longer to start moving .
So the felt recoil it transferrs is delayed .
So it makes the recoil feel lighter .

Also the extra weight reduces the felt recoil .

Johnch

[lovedogs]

Years ago after shoulder surgery I tried a mercury suppressor in one of my 12 ga. shotguns. I didn't find it that effective. You can tell the difference but, in my opinion, it's hardly worth it. I'd gladly sell someone the one I have. Yes, there is some slosh to them, they aren't full. The mercury has to be able to move under recoil. If you decide to install one be sure you read the "how to" instructions. They need to be installed at an angle to work properly.

[montana_charlie]

I have 2.
IMO both are about 2/3 full
Thanks, johnch...
Not only was your reply informative, it made me recheck my numbers...and that's a good thing.

It became apparent I couldn't squeeze 8 ounces of mercury into the tube with any space left over...and I (too) realize it has to be able to move. So, I went back to the C&H Research site and found that my memory was faulty. Their five inch, 11 ounce model has a 3/4" (not 5/8") diameter. Turns out my tube is too short to make an 11 ounce suppressor.

That stainless tubing was hard to come by, but I have some left over. So, the next one will be 6.25 inches long. That size gives volume numbers similar to the C&H units.


BTW, lovedogs, it's true that the shotgunners (some of them) angle their suppressors. But as I understand that, it is done to change the direction of the recoil, more than to absorb it. They angle it different ways to keep it from bumping the cheek, reduce muzzle climb, and other things that bother shotgunners. Also, a lot of them are made to just drop in the hole where the stock bolt is. Those are always drilled at an angle to the bore.

All of the advice I've found, regarding use in rifles, is to have it parallel with the bore for maximum reduction (not redirection) of recoil...and it's that way in shotguns where the suppressor is mounted on (or in) the magazine tube, or slipped into one of the barrels on a double gun.

I think I have everything I need to finish up, so thanks to all who replied.
CM

[Lloyd Smale]

John Linebaugh and my buddy AL had very simular 50 alaskans built and Johns has a mercury reducer in it and i dont like the way it changes the balance of the gun.

[montana_charlie]

No worries, Lloyd
Back during the first week I had this Sharps, one of the things I tried was to tape a lead ingot to the butt...to see how that changed the balance. That was a 14 ounce ingot, and I liked the difference, but it took the rifle past 12 pounds, 2 ounces.

I can add 11 ounces while staying in the weight limit...and the modification comes out of the stock just as easily as it goes in.
CM

[R.M.]

Many years ago when I was shooting a lot of trap, a buddy and I decided to make some. I had the mercury, and he was a welder with the pipe. He claimed, and I have no reason to doubt him, that mercury would leak past a threaded pipe plug. What he did, and I wouldn't do it because of the fumes, was install pipe plugs, then welded over them. No leaks.
We installed them in the hole for the bolt running through the stock. They were about half full. Did they work, don't really know. We thought so at the time, and that's all that counts.

Hope this helps.
R.M.

[frank505]

After shooting a 505 Gibbs for four years at 9.9 pounds, I decided to add two mercury recoil reducers, one in front of the barrel mounted recoil lug and one in the butt stock. The gun now weighs 11 pounds and the balance has not changed. Do they work or has the added weight made the difference? My perception is the "snap" has been taken out of the recoil cycle. I did shoot quite a few 600 grain gas check bullets at 2350 before the reducers, need to try that load now.
Also I think there is a reduction in the tube to slow the mercury which would slow the recoil.(maybe) It seems to be a worthwhile addition to a rifle that has some recoil.

[Scrounger]

Mercury is dangerous to handle, hard to find, and very expensive. I don't see how the same effect couldn't be achieved by using lead (shot) in a tube, paper plastic, brass, like a shotshell (dead primer, no powder, no wad). With a spring behind it (like a follower spring in a shotgun magazine tube) that slows the weight coming to the rear by compressing. Cheap.

[montana_charlie]

I don't see how the same effect couldn't be achieved by...
Could be that you're right, Scrounger. There are a number of designs out there which use methods similar to some of your suggestions...especially spring-loaded pistons, and pistons traveling through oil.

The people at Shiloh will install mercury suppressors, so there has been some discussion of that type on their forum. Those who feel they are a benefit, state that belief with certainty. Nobody has voiced the opinion that they have no effect...although some have said they didn't get as much reduction as they expected.

Sure, there are other types that may be cheaper to build, but (you see) I have this bottle of mercury, and...
CM

[Johnch]

A poor man's recoil reducer is easy to make .
If your rifle or shotgun has a hole under the butt pad .
Easyest if it is big enough for 12 or 20 gau shogun mag spring to fit and 6" deep or deeper
Or can be installed in a 3/4 or 1" tube and mounted to the barrel

Make a lead slug , I pour lead into a piece of 3/4" copper tubing
No need for a plug , just push the end in the ground and pour in 1/2 to 1 lb

Cut a piece of spring about 2" long , place in hole
Cut the lead slug 4" long and place in hole .
Cut another piece of spring 1" long
Place on slug , reinstall butt pad .
This compresses the 2 springs slightly , with the lead between

In my trap gun there is 1 in the butt and another in the magazine tube
Increases the 8.5 lb gun to 10.25 lb

Makes a world of differance after 200 rnds in a afternoon .

Johnch

[leftiye]

I was thinking of a real close , but still loose in the tube cylinder of lead with a hole drilled through it on the centerline and a light spring in front to hold it to the rear. Tube would be full of oil. You'd have to experiment with the hole diameter, it would act as a shock absorber.

[georgeld]

All these ideas and more have products listed in Brownell's using them.

I've decided to use two mercury capsules in this .358 U/M I'm building now.
Plans are to shoot 250gr @ near as it'll get to 3200fps.
Towsley claims in his 24" to get 3114 fps with 97.0 gr 7828.
He wrote me that 3200fps in a 26" shouldn't be too hard to reach.

This gun will weigh around 11-12# as designed. I prefer heavy, long guns to getting whacked by them.

Shucks, I don't even have a sling to my name on any of my guns. When they get too heavy and my knuckles start draggin on the ground, I just change hands.

My reach is 4" longer than my height, so there just might be some effect to this.
Would you suppose??? hehe

[lovedogs]

George... those long arms may mean you're a monkey's uncle. Or maybe we are really decended from apes. No, just kidding. Might be handy if you ever take up boxing though. Har, har!

[Dale53]

Mostly these recoil devices add weight. I believe the rest is hype. Weight DOES indeed reduce felt recoil. I have tried these mercury devices in the past but a similar amount of lead seems to be about as good.

Dale53

[4060MAY]

my friend made a living making recoil reducers for semi-auto pistols.
mostly to prevent muzzle jump for combat type shooting.
he claimed that just mercury doesn't work, he put balls in the reducer
not sure if steel or lead, seems to work on my 1911.
never tried one in my Sil. Rifle, I'm at 11.9 pounds and it's hard enough
to shoot offhand as it is.

[scrapcan]

lead will amalgamate with mercury. In the past mercury was used to clean severely leaded barrels. Works great, but the health risks of ingested or absorbed lead has reduced the availability and likely hood of using mercury for this purpose.

A class lost a vile to the floor in one of the local community college phyics labs and it resulted in a pretty hefty cleanup scenario. And to think when I was in grammar (elementary school to other parts of the country) and middle school we played with it in our science classes.

[montana_charlie]

Thanks to the estimates I received from contributors to this thread, I went ahead and finished my recoil suppressor project back around the end of March.
I stayed with the 5/8" tubing I originally bought because figuring a decent thread for the inside of 3/4-inch tubing turned out to be a cumbersome thing.

I threaded the ends of the 5/8 with a 9/16-18 tap and cut plugs from a bolt with the same thread, which were sealed in the tube with Loc-Tite.
I poured in enough mercury to get an overall weight of 9 ounces, and the internal space was about 3/4 full.
The hole in the butt of my Sharps was drilled parallel with the bore, and just deep enough to replace the buttplate.

I fired thirty rounds through the gun today (first session this spring) and found the recoil to be substantially reduced. Now, it's about the same as my eight pound 7mm Mag.

This proves two things to my satisfaction...
1. Mercury recoil suppressors are useful.
2. They aren't difficult to build.

The other advantage gained was...the extra nine ounces in the butt changed the balance so the barrel seems lighter. Shooting offhand is noticeably more comfortable now, even though the gun is heavier.

CM