PUBLIC Forums => Research Proposals => Topic started by: Michael Courtney on September 08, 2006, 10:29:28 AM
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It seems to me that there may be a need for inexpensive methods to minimize the damage in test fired .223 bullets. There are expensive ways to solve the problem, but such capital expenditures are probably not realistic for examiners who only encounter the need to test fire .223 bullets once a year or less.
I am bouncing around some potential ideas to reduce damage in test fired .223 bullets using inexpensive and common materials that would be useful for examiners who encounter the need to do so infrequently.
What do y'all think of the value of this research idea? Is this problem already solved?
Thanks,
Michael Courtney
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The cotton box seems to work fine.
CMC
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I agree with Charles - the cotton box is a very cost-effective and practical way of collecting high velocity projectiles.
Another alternative is safely downloading the propellant charge such that the velocity is reduced to the point where shooting into a water tank is now practical - below 1700 f/s rings a bell...
Good luck, and best wishes to all,
Geoff.
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We have done the downloading for years until we found out that downloading might influence (.... not as intense as ... ) traces on the bullet surface. From this moment on we went to the full load and the moving cotton box.
Cotton seems to work best. But it also depends on the different typs of cotton.
Greetings
Axel
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http://www.afte.org/forum/smf1/index.php?topic=1797.msg8164;topicseen#msg8164
The post above offers another option.
For non-members here's the gist:
Why the foam?
This design is one that I used as the basis of an AFTE seminar presentation in Houston, Texas in 1991.
The presentation was entitled "Recovering High Powered Rifle Bullets at Full Velocity Without Damage".
The reason for this experiment was to find a method to replicate most closely the interior ballistic conditions of the shooting without destroying my test shots in the process. High powered rifle bullets, particularly the soft points and 223s, tend to come apart in the water tank - unless they are downloaded.
Downloading cartridges was found to affect the markings on the casework bullets in question so I experimented with different bullet collection methods until I came up with the system in the drawing.
My experimental setup was more humble than the system in the drawing. It consisted of two open-ended four foot tall stackable plywood boxes packed with blocks of open cell polyurethane foam and placed on top of a 55 gallon plastic drum full of water. I did my shooting from a construction scaffold.
My cheapo setup was total Rube Goldberg, plus I had to do my shooting on the weekend (when no one else was in the building) in our vehicle inspection area with the works down in the grease pit. This was not the best test firing arrangement for the long term because some of my co-workers are nervous of discharging firearms.
The foam will take a considerable number of bullet passages before replacement is necessary.
The foam stays in place quite well with no (or very little) foam falling from the array into the water tank.
I have attached a photo of two 69 grain Sierra boat tailed hollow point bullets fired back in '91 for this experiment. The bottom bullet was fired directly into water. The top bullet passed through eight feet of foam before being stopped by the water. Both bullets were fired in their factory load condition with no downloading or modification of the ammunition or firearm.
click on the photo for a larger view
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Inexpensive Bob . . . inexpensive. :)
CMC
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Inexpensive Bob . . . inexpensive.
A couple sheets of plywood, some 2 by 2 lumber, a large plastic barrel, and a few cubic feet of poly foam, and you are in business. O0
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You forgot the ladder. ;D
CMC
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OSHA would require a safety harness and hard hat too.
It sounds like something cool to set up and demonstate at the state fair in our State Police "Safety Town". All of the kids on trikes would really get a kick out of it!
All kidding aside though it looks like a good concept.
Scott
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You forgot the ladder
No ladder is required, but an umbrella helps keep you dry when the water splashes back. :D
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Wow, you guys up in Alaska have some really nice uniforms. O0
Is that lil' Debbie hanging on your leg? What's that about?
CMC
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Good discussion, and lots of good ideas. But do the cotton box and opened cell foam really stop the more fragile (including plastic-tipped bullets) like the Hornady VMAX with minimal damage?
I haven't tried it, but a 40 grain VMAX at 3600 FPS would seem to be the extreme validation test for any bullet stopping method.
It seems like one might have to split the difference here: download to 2800 FPS or so so as to not overly affect the rifling marks and use an improved stopping medium to slow the bullet to 1200 FPS before it hits the water. I guess the open question is what length of styrofoam peanuts is needed to slow a .223 bullet from 2800 FPS to 1200 FPS.
Thanks,
Michael Courtney
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I have rigged up a method of shooting through an old BP vest. It seems to slow down the bullet ennough that it comes out in one piece almost every time. I have done this with .223 and 7.62 and hadd success with both....
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I have personally fired the 223 Remington caliber Winchester 50 grain Ballistic Silvertip which has a polymer tip and a muzzle velocity of 3410 fps into the cotton box with zero deformation. In fact, I can't ever remember having a problem with bullet deformation in the cotton box.
Having said that, this is still a worthy research topic. I always enjoy hearing about alternative methods. It's always good to have a backup plan.
Keep up the brainstorming.
CMC
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I guess the open question is what length of styrofoam peanuts is needed to slow a .223 bullet from 2800 FPS to 1200 FPS.
I am not sure you could make a box long enough using styrofoam peanuts. What you need is tightly packed layer's of cotton or cotton fiber waste with a few of phone books at the back. I have only had one time that a bullet went completely through an eight foot box and that was shooters error, forgot to replace the phone books at the end. The only problem I have had with a cotton box is when I have used all lead bullets. The cotton or cotton fiber waste tends to leave wipe marks on the bullets. It also helps to partition the box with a sheet of paper about every foot to help find the bullet easier.
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Instead of phone books...I have "outdated" vest, donated by a local PD, stacked at the back of my cotton box.
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Armor Forensics sells a recovery tube made from steel and filled with shredded kevlar. I was first introduced to it at Oakland and we purchased one here at ATF. It really is very effective at stopping 223 and others within a reasonable distance and in excellent condition.
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If you are looking for something to research that is cheap and non-cotton, check-out my article directly related to your inquiry in AFTE Journal, Vol. 30, #2, 1998, Pp. 280-282.
-INGTLI
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Up here in northern Minnesota I see quite a variety of firearms that don’t make themselves amenable to firing into water. I just wanted to make a comment regarding optimizing results from a cotton box. I have had great success obtaining test fired bullets covering a wide range of velocities and energies, all in excellent condition, in my cotton box (including lead and polymer tipped). One key is packing the cotton as tightly as possible. Loosely packed cotton will result in “burnishing” or rub marks on the exterior of the bullets. As mentioned, paper dividers save time in bullet recovery. Also, if you are using rolled cotton batting, you need to stagger the shots and then reposition the batting after 3 or 4 shots so you don’t get bullets tracking down holes, following the path of least resistance and slamming into previous test bullets.
I also believe that tightly packed cotton reduces the potential to have a fire start in the cotton box. I have never seen this but I have heard stories. This could be an urban legend, but it seems that air space in loose cotton would promote this (maybe back the muzzle off a few more inches too).
Our lab has two very nice 8 foot stainless steel boxes that were manufactured based on our specifications for about $1500. They were made for us by W.J. Haas Manufacturing in St. Paul (Mark Haas – 651-224-8552). Prior to these boxes we got by with a wooden box that was very inexpensive and worked very well. The only problem is the occasional round sneaking down the side and exiting the trap.
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Have found high power BTSPs fired into snow that appeared perfectly decelerated. Don't know how dependent the effect is upon type and condition or even thickness of snow, but it you're up north in the winter and need to do this in a pinch real fast it might be worth a try. A common metal detector should aid in recovery. Have never tried this. Just observed the effect.
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Thanks Charlie
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The cheapest solution I can think of is, that is if you already have a water tank, is to use Federal "Tactical" 223 ammo. This stuff is designed to be fired through windshields and not fragment too much. It really holds up well fired into water.
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Dang Bob, I'm just getting used to your other invention...the discount water tank. :-0
Tk
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Hi everyone,
My name is Derek, I recently made a post about possible ideas of a graduate school forensics thesis. I have had a course in Pattern Evidence/firearms/toolmark analysis and I also collect and regularly shoot. I came across this interesting discussion and was wondering if this idea of a "cotton box" could somehow become a thesis topic/project?
If so, does anyone have any information/background that I could look in to? Thank you all very much.
~Derek
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Unfortunetely, I would say no because the cotton box has been a standard in the field for about as long as the field has been around. We already know that it works.
CMC
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Something I have never attempted, but wanted to.
Wind tunnels used in aircraft development can generate velosities in the supersonic range. Has anyone thought of constructing a scaled down wind tunnel and test firing into the wind? I would assume one could get maximum resistance from the moving air without destroying the projectile. I doubt the bullet would travel more than a few yards before forward motion was overcome, Just a thought !!...HW
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While at AFTE in Chicago, it was mentioned that at the original Chicago PD Crime Laboratory, there was a small desktop cotton box on wheels that examiners test fired handgun bullets into. (archive photos??) Supposedly, the energy of the bullet was dissipated by the cotton and forward motion of the box. If so, maybe this would work as well with high velocity bullets, but on a larger scale.
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OK.... although this is outside of the normal work we do in Firearms examinations but based on the posting by "winterh" and Evan Thompson, I would suggest a search on Wikipedia for those that are interested.
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I would start with "Ballistics" and this will have links to "Exterior Ballistics", "Interior Ballistics", "Transitional Ballistics" and "Terminal Ballistics". The "Exterior Ballistics" section is 9 pages long and very good. It also has links to some freeware that you can download and use. Notice the mention of Sandia Labs here in Albuquerque.
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take care.. I prefer to say that I am not a Ballistics Expert.
nelson. 505-771-2878 or cell 505-288-0000
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ps
I did do a demonstration once for some medical examiners to show them that a person would not be "knocked" backwards by getting shot by a .45-70 wearing a bullet proof vest. I took a 15 pound piece of railroad tie and shot it with a .357 Magnum ;D .
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Prior to shooting it, I measured the coefficient of friction for the railroad tie on the table top and calculated for them that the distance the tie would move would be about 2 inches. After shooting it.. the measured distance was about 1.75 inches which was close enough for government work. ;D
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Again, replying to an old topic.
If you need to safely download ammunition for any reason, check out this information for Hodgdon Trail Boss powder:
https://www.hodgdon.com/PDF/Trail-Boss-Reduced-Loads%20R_P.pdf (https://www.hodgdon.com/PDF/Trail-Boss-Reduced-Loads%20R_P.pdf)