Adventures in forensics

[RicinYakima]

Not trying to interrupt, but catching bullets has been going on for over 125 years. Water was eliminated early on because of its incompressibility. Even at relatively low rifle speeds of 1400 f/s with jacketed bullets they tend to mushroom. Julian Hatcher developed the vertical water trap for police forensics, but it only worked for low speed handguns. Lead revolver bullets had to have a reduced powder charge to prevent changing the rifling marks. Snow, with enough depth over 12 feet, works well, but most don't want to wait till spring time and mark bullets. So, as of now, oiled soft wood sawdust appears to be the best. Myself, I think one of the new plastics would be good, but I'm to old to go looking for it.

 

[Ian]

What indication did you see that would suggest that you had alloy flow from base to tip area of bullet rather than the whole bullet being shortened? Also do you think this is the best target media or have you seen any drawbacks? Several of us have talked about milk jugs set at angle to match bullet arc.

Good question and there is no indication on these bullets because the ones that did exhibit flow into the grooves at the nose base experienced too much nose damage to determine final length. I have, however, made the determination of how lead flows up a bullet from base to nose in other bullets I've recovered from my berms in the past. Noses don't typically change length or "set back", but tend to bulge into the grooves starting from the nose base and moving forward as pressure is increased.

This bullet trapping business is difficult, and for the most part I am having to figure it out from scratch. I tried Neoprene crumb rubber but it proved too destructive, stopping rifle bullets from 2200 fps in only 20". Any cardboard in the system damages the bullets severely until they are slowed considerably. The fiber media (cotton or Kevlar) tend to send HV rifle bullets off on a tangent, damaging the trap. The oiled, softwood sawdust was the next, least expensive option for me to try and seems to be working the best so far, but still might make a better intermediate media rather than an initial media. Bullets are stopping in about 40-42" at 1850 fps (no mushrooming) and the same distance at near 2200 if they are mushrooming. I began with essentially no useful information so I didn't know if it would take two feet or 20 feet to stop a rifle bullet with any of the media, and much of my work has involved just generating data points about that with the different media. Now I have a much better idea of what I'm doing. I'd like to add about 2-3' of a lighter, granular media of some sort and use the oiled sawdust past that for final stopping because the sawdust is very easy to pick through and isn't very messy. My trap is in a nice wooded area by my rifle range and I much prefer a biodegradable media.

 

[pokute]

Not trying to interrupt, but catching bullets has been going on for over 125 years. Water was eliminated early on because of its incompressibility. Even at relatively low rifle speeds of 1400 f/s with jacketed bullets they tend to mushroom. Julian Hatcher developed the vertical water trap for police forensics, but it only worked for low speed handguns. Lead revolver bullets had to have a reduced powder charge to prevent changing the rifling marks. Snow, with enough depth over 12 feet, works well, but most don't want to wait till spring time and mark bullets. So, as of now, oiled soft wood sawdust appears to be the best. Myself, I think one of the new plastics would be good, but I'm to old to go looking for it.

Oiled sawdust goes back at least to Phil Sharpe. Maybe even Franklin Mann.

Yep, just checked. Franklin Mann. So at least 110 years.

 

[pokute]

The snow thing is very interesting. Since I've never seen fresh snow, It's a complete mystery to me. We used to go skiing in Big Bear. Skiing on ice is a lot of work. Fun skewering those pesky slow snowboarders however.

 

[Eutectic]

The snow thing is very interesting. Since I've never seen fresh snow, It's a complete mystery to me.

Snow indeed works well as Ric stated....... And light Rocky Mountain snow is the best... Wet snow not as good. I've seen these plastic tip wonders barely opened from a flat penetration into deep snow behind the target frames. Interesting 'jewels' on the ground in the spring.... Some even keep the tip! I found a .338 Partition one time that must have flipped as the base lead was missing! Looked like it was shot backwards!
If it's winter and I want the best of details as Ian does I'll plug a flat snow pile...... there is no shortage! And if I wanted the answer fast quickly like dynamic bullet fit I may shovel after them! I may be old but I'm a snow shovelin' machine!

Pete

 

[Ian]

Pete, if you have any of the powder snow left, could you send me 100-lb drum of it?

 

[Eutectic]

Sorry Ian.........This winter's deposit is about gone and even on the Divide is too crunchy for best results. About Thanksgiving there may be enough good texture stuff to do a good test..... I should make a metal trough on legs I could shovel full (or let Mother Nature do it). Drain holes in the bottom...... Do the test and melt the snow out with a weed burner or two and then pickup the jewels...

What you are seeing is why I like about a 1/8" length of bore ride in front of the throat fitting design. This has helped for me. Our bullet will act like a forktruck given half a chance and steer from the rear.

Pete

 

[Ian]

What you are seeing is why I like about a 1/8" length of bore ride in front of the throat fitting design. This has helped for me. Our bullet will act like a forktruck given half a chance and steer from the rear.

Yes!

 

[Rick]

Pete, a much better idea than sending a drum of snow would be to build your trough and invite Ian to your place for a news years day of shooting. Keep the weed burner handy as there can be little doubt Ian will need defrosting.

 

[pokute]

Mann shot into his oiled sawdust at 100 yards. He put paper screens every 25 yards so that he could detect odd bullet behavior. If you haven't read Mann's book, it's a goldmine for ballistic testing methodology. It's public domain. Google digitized it:

https://books.google.com/books/down...owder_to_Targe.pdf?id=QdQqAAAAYAAJ&output=pdf

 

[fiver]

I tried talking Ian into a snow making machine, but I somehow think it would just water his range.

 

[Rick]

I tried talking Ian into a snow making machine, but I somehow think it would just water his range.

Well sure, that's why we gotta get Ian to Montana. In January so there's lot's of snow. When he get's there I want to see the video.

 

[pokute]

I have a colleague who has a snow making machine. Unfortunately, it only makes one snowflake at a go:

http://www.snowcrystals.com/designer/designer.html

He could, given a few thousand years, make a snowbank out of snowflakes designed to maximize bullet surface artifact preservation. He's only a casual shooter, however, so getting him motivated might be difficult. Also, sometimes he gets distracted watching them melt, which would slow things down.

 

[Ian]

Well sure, that's why we gotta get Ian to Montana. In January so there's lot's of snow. When he get's there I want to see the video.

I have a house in Ouray, CO. and I don't even go there in January. It's nice in July, though, I don't even need a jacket unless I go above 8,000 feet

 

[Rally]

I still have 5' piles in the driveway if you want me to send you some Ian. Boxes might be wet when they get there!

 

[Eutectic]

I have a house in Ouray, CO. and I don't even go there in January. It's nice in July, though, I don't even need a jacket unless I go above 8,000 feet

And there in January you will find the correct 'texture' of snow for your tests! I know quite a few Texans who have become mountain men. A certain grit, a certain mentality, stubbornness......... can get you through a winter in Ouray! You are listening to Texas....... I know the language; I've lived there. Don't listen to can't....... "Can't never could!" If fact listen to this real advice:
"For everything there is a season, a time for every purpose"

Pete

 

[Ian]

That's why we bought the summer house. Couldn't pass up the deal, rent it out a few times a year to pay the bills, taxes, and property manager, and the rest of the time it's there when we need it. One day I'll probably become a "winter Texan", but not for a long time and I swore a long time ago I'm not going to shovel any more snow unless it's between me and Texas.

 

[Rick]

And I thought you didn't go to Ouray, CO in January because Ouray, CO is unobtanium in January, in or out.

 

[Ian]

You can get there from anywhere but the in/out is from the north end, and is the long way around. Not much reason to go, all you can do is sit inside and try to keep warm. They kind of frown on discharging firearms within the city limits anyway

 

[John]

Bob Hagel's bullet box alternated damp sand with oiled sawdust. He used cardboard at 12" intervals to measure where mushrooming occurred and as a separator from each.