How deep can a metal detector find bullets?

[230RN]

I'm trying to get a feel for how deep one could detect a bullet shot into the ground, by using the average hobbyist's metal detector.  I realize there are lots o variables such as soil type, bullet size and mateial, angle of entry, moisture, etc.

Assume a .357 sized jacketed bullet, regular backyard soil, midsummer "dry" moisture.

Just a rough idea. Obviously not 12 feet down, and not lying right on the surface.

Thanks for your insights.

Terry, 230RN

[Silver Bullet]

I want to say they can't find bullets at all because they're not iron; but metal detectors are used to find coins all the time, and they're not iron either. 

So I don't know.

[Ben]

I have a Garrett Ace 400 I've been meaning to break out again. Maybe on my day off this Sunday, I'll dig a hole in the backyard and drop a bullet in. I don't have any jacketed girl calibers, but I can drop a jacket .308 slug in it at a few depths and see where I lose the signal. I'm gonna guess a foot max.

[AmbulanceDriver]

Here's some info, not sure how reliable it may be:

https://detectingschool.com/how-deep-can-metal-detector-detect/

Mostly the answer appears to be "it depends".

[230RN]

Your "day off," Ben?  Heh.  That would be helpful, so TIA.  (Thanks In Advance.)

Silver Bullet, lots of things are mildly magnetic one way or the other.  Simple example, get a $1 coin from the bank,* balance it on edge, and slowly bring a strong magnet toward it and it will fall towards the magnet.  Apparently coin operated machines sense the magnetic properties of certain coins for verification (That's something I always wanted to look into in detail, but haven't.)

Some metals and alloys are even repelled by magnets.

Ambulance Driver, that was actually helpful.  Not knowing anything about metal detectors, I figured about a foot.

According to that article, the size of the coil and the type of soil seem to be the major factors involved. for any given bject.  (And I guess the power put into the coil.)

Terry, 230RN

*My bank only has them in $25 rolls.

[Brad Johnson]

Here's some info, not sure how reliable it may be:

https://detectingschool.com/how-deep-can-metal-detector-detect/

Mostly the answer appears to be "it depends".

This. Coil type, power, soil composition, bullet type, etc.. They all play a part in effective depth. Operator knowledge, error, and effectiveness play a big part, too.

I lurk on Friendly Metal Detecting Forum. Lots of good info.
https://metaldetectingforum.com/

Brad

[230RN]

That was a littlemore detailed than I needed, although I got down the zinc penny rabbit hole.

I guess for a practical all-round multiple-choice answer, I'm going to go with C. 

A. Twelve feet
B. Bacon
C. About a foot
D. Detcord

[Silver Bullet]

Isn't B always the answer?   

[230RN]

Prior recommendation by multiple-choice whiz kids is "When in doubt, choose C."  If C happens to be bacon, all to the good.

[RoadKingLarry]

While I was on instructor duty One of my jobs was writing formal tests for our curriculum. "C" was never the right answer on any of the tests I wrote. I did write one where the correct answers were A-B-D-E all the way down the answer page. I was "spoken to" about that one 

[Ben]

Okay, results with an Ace 400 with the standard coil, set to zero disc (detects everything) and my usual 75% sensitivity and a 200gr jacketed .45 bullet, buried in dry sandy loam:

Burying the bullet and then walking with the detector as if I DIDN'T know what or where I was looking for, I was able to detect it down to about 6". This is as if I was being a detectorist* and just walking around a larger site to see what pops up. Constantly walking and sweeping, so at best an area gets two sweeps from the coil.

Detecting as if someone told me, "I left my keys somewhere right around here, and somebody dropped a loader bucket of dirt on them", I was able to detect it at ~13". This comes from taking time and making multiple sweeps over the same general area, getting a slight ping, then using the pinpoint function on the detector, which put me over the bullet.

I'm just an amateur with a mid-range priced detector. Someone with better equipment could likely do better.



*Plug for one of the best TV shows ever - Detectorists:

https://youtu.be/NgN7z0SD8v8

[sumpnz]

If you have a chance I’d appreciate you doing that with wood, instead of dirt.  Maybe drive a nail into a piece of scrap wood and then pile more and more 2x’s on top until you can’t detect it anymore.  For a bullet, drill a 15/32” hole and drop the .45 bullet in it and do the same thing.

[Ben]

If you have a chance I’d appreciate you doing that with wood, instead of dirt.  Maybe drive a nail into a piece of scrap wood and then pile more and more 2x’s on top until you can’t detect it anymore.  For a bullet, drill a 15/32” hole and drop the .45 bullet in it and do the same thing.

Okay, I can do that. Maybe tomorrow or Tuesday.

[sumpnz]

Okay, I can do that. Maybe tomorrow or Tuesday.

Awesome!  That will help with whether to bother buying a metal detector before I get too deep into chainsaw milling.

[RoadKingLarry]

Have you asked around on the sawmill forums about that subject?

https://forestryforum.com/board/index.php

[sumpnz]

Not yet.  But since Ben was willing it was convenient.

[RoadKingLarry]

So far the worst I've found was a jacketed bullet in a medium size Ash tree.
I was able to finish the cut and make 2 more with the chain. The log was 8' long and about 12" in diameter.



The tree was on my range but no idea if it was one of mine or not as the area had been used as a range by the previous owners of the property.

[230RN]

This is all very helpful, so thanks everyone so far.  I hadn't thought about bullets in trees.  Special thanks to Ben for his measurement efforts.  Das Wissenschaft geht fort.

[Ben]

Okay, wood test:

I started out with 2x4s, but then my lamebrain realized I was standing 30 feet from my "to be split" wood pile, so used that. Hole drilled in a bucked log, then without going into boring detailed  I went through variations of different thicknesses turning that log around, putting other logs on top of it, etc. I set the detector to zero disc and 100% sensitivity, with the thought that using it for this purpose, the user knows where and what he's looking for, and any kind of metal is significant.

For the 200gr jacketed bullet, very loud, strong signal through 4". Good signal through 6-8". Then I was able to get to 15", but only using the pinpoint function, and even that signal was weak.

I additionally substituted a 230 grain lead only bullet. Surprisingly to me, that gave off an even louder signal through 4", but then quickly tapered off after 6", and while I was able to still detect it around 8-10", I think maybe it was only because I knew it was there.

I learned something myself, as I thought wood would have been much less of a blocker than dirt, but it really wasn't.

I also just now reread the thread and saw sumpnz was also asking for a nail, which I missed the first time. I'll try that in the next couple of days as well.

[sumpnz]

Fantastic!  Appreciate the info.

[230RN]

How great !  Real data on actual tests.  Muchos Danke !  Or ¡ sehr gracias !  And all like that there.