Air Gun Home :: View topic

rsterne · Moderator

I took three typical hunting pellets and fired them into blocks of parafin wax at an energy of about 17 FPE.... This might be typical energy delivered to a Grouse with a Discovery or similar gun at 20ish yards.... Here are the results:

Left to right Predator: 16 gr - JSB Heavy 18 gr - Beeman Crow Magnum 18 gr

The front cup of the Predator separated and peeled back over the skirt - it mushroomed to 0.27" - total penetration 19 mm

The JSB remained virtually unchanged - head measured just 0.23" - total penetration 21 mm

The Crow Magnum mushroomed perfectly to 0.32" with the cup rolled back over the body - total penetration 14 mm

Obviously, parafin is a lot harder than flesh, but it sure produces some neat results.... Cool

In the real world, the further away the target, the more energy the JSB round nose would have remaining compared to the other two.... and eventually the Predator and Crow Magnum wouldn't expand very much.... so for long ranges, the JSB would outperfrom.... I'm going to have to find a better medium to compare the downrange performance of pellets.... Ballistics gel is too soft and lacks the "skin" of an animal.... I've heard of good results with 2L pop bottles full of water.... the thin plastic of the bottle acting like skin.... Wink

Bob

AirGunEric · Site Admin

I'd be interested in seeing if there's any difference between say a PCP at 17fpe vs. a springer @ 17fpe shot from the the same distance at the same substance. Sure, there shouldn't be a difference, but I'm still curious...

Slavia · Moderator

Dust · Member

Why not use an old pair of pants?

Here's something that may inspire

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=504301&fpart=1

rsterne · Moderator

I've home-made "ballistics gel" before, using Knox Gelatin in a very high concentration as per instruction I found on the Internet.... It's temperature sensitive (only consistent right out of the fridge) and pellets penetrate a long ways and the wound cavity collapses behind the pellet.... All it is good for is measuring penetration, and to be honest I think the penetration is maybe half what you would get in just water.... It might represent what a pellet would do in soft tissue, but I have to believe muscle is a lot tougher, and certainly skin (hide) is, let alone bone.... Rolling Eyes

Wood is inconsistent, phonebooks are better, but they are both too hard, as is parafin wax.... Duct Seal putty is also way too hard.... one of the best I have found is plumbers putty, but again it is VERY temperature sensitive.... It is also difficult to cut open without distorting the wound channel and/or moving the pellet around.... One thing I like about the parafin is that you can see the area affected by the "shock" of the pellet because it turns white (micro-cracks).... You can clearly see if the "wound channel" is deep and narrow or wide and shallow.... and it's easy to cut apart, measure, and photograph.... Plus, it's reusable.... Wink

Anyone used bars of soap?.... What brand and how does it work?.... Twisted Evil

Bob

Slavia · Moderator

http://www.pyramydair.com/site/articles/pellets-vs-round-balls/

rsterne · Moderator

Interesting test with the Neutrogena.... I would have preferred they used a JSB Exact 8.4 gr instead of the Chinese domed.... There is a BIG difference in penetration between domed and a true round nose (in favour of the round nose).... My guess is that the round nose would have been very close to the ball.... what a surprise.... Rolling Eyes

The Neutrogena soap bar looks like a good medium for testing low-medium power rifles.... would have loved to see a hollow point.... Twisted Evil

Bob

Bozo · Veteran Member

rsterne,

Go to your library and check out "Handgun Stopping Power, The Definitive Study" , by Evan Marshall and Edwin Sanow (Paladin Press) ISBN 0-87364-653-3. There is an exhaustive discussion on testing mediums and methodology, and why, despite it's flaws, 10% ordinance gelatin is the most accurate representation of bullet behavior. (10% ordinance gelatin is 1 pound of gelatin in 9 pounds of water. Some studies have used 20% gelatin; the book discusses the problems with it.)

Although the book is discussing handguns and human bodies, I think the principles would hold through to pellet behavior, at least until the velocity got below about 4-500 fps or so (and that's just my guess). The problem with *any* test medium is the presence of too many variables to reproduce artificially, so you need to find the medium that will reflect what actual results you have in the field most accurately. The authors of the above book have research thousands of actual street shootings in many calibers, and have found 10% gelatin to represent what happened in those shootings the most accurately. It sounds as though you may have found some bad info on the use of gelatin if you were getting very long penetration. A .380 Silvertip only penetrated 8 inches of gelatin, and that's a lot more power than any normal pellet will have.

Water will give an accurate representation of how a pellet will expand in living tissue, but penetration is difficult to measure, along with temporary crush cavity, and permanent crush cavities are impossible.

Doc Sharptail · Member

Here's a slightly Wink

un-scientific trial- somewhat related to the topic subject.

.22 Crosman Field/Hunting Point, 14.3 gr. on a sun-bleached white-tail deer verterbrae I picked up in the gravel pit. M/V +720 fps @ 15 paces.

The entry hole is at right, and the plowed out exit is at left.

.177 Crosman Field/Hunting Point, 7.9 gr. M/V +860 fps @ 15 paces.

This pellet failed on all counts- it left a lead smeared crater on the bone, about 1/32" deep, and did not penetrate at all.

For my purposes, in case I have to- the .22 Crosman Field/Hunting Point at least has a chance of making it through grouse wing bone, and into vitals... The .177 version was more of a disappointment than I had expected.

Just as a side-note, I quite accidentally found a 10-15 % velocity increase by letting the pumped up tube on my hopped-up 22-89 warm in the sun for 10 minutes. Air temperature was 70 F.

Regards,

Doc Sharptail

kanyon · Silver Status Member

http://www.myscienceproject.org/gelatin.html

fritz · Silver Status Member

Bozo, using soap as a test medium does usually show the permanent cavities created. So does clay/putty, but due to their densities realistic penetration figures could be discounted.

Gelatins act more like water and animal flesh. They do show some deformation of the cavity, and capture the projectile for accurate penetration measures.

Wood has to be the most common, with the simple test of "shoot different ammo at the wood" and "measure what went in further". I have noticed that when fresh (wet) wood is shot the fibers have a sand type effect on it. The pellets come out with small dents like when shot into sand. I think that this is due to the fibers breaking apart during the impact.

sniper · Silver Status Member

i've always used water filled containers. wet news paper is also a good medium.

with cans/containers crowmags expand reliably to roughly .25 everytime. however pentration is very low. through only 1 can they often don't stick into my wooden back stop.

donwalk · Veteran Member

penetration vs expansion has always been debated and has been extensively tested in many ways by many people thru the years.

it's odd that most states require expanding or soft nose bullets for the taking of "big/large" game, whitetail deer, black bear, elk yet the truly big animals in africa, elephant, cape buffalo, crocidile, lion, leopard, solid slugs are used for deep penetration.

in most states, you may take small game/predators with either, normally...based on scientific proof? supposedly so.

it all comes back to what works best on your target. you want good penetration? usually a 'solid/pointed' or "shock" (what ever that is) use an expanding HP. (and of course, pertinent fish and game rules.)

another bit of "food for thought"...the military recently opted to re-up it's 9mm as a 'standard' issue sidearm. how come? when there is the highly effective, long proven, .45 ACP, or .40 caliber, and even 357 Sig. their tests and preference is due to the penetration of the 9mm (that and NATO commitments)...go figure.

expanding points seldom outpenetrate solids. to get more penteration with an expanding point ya gotta have more "power"...it's that simple

more power=more penetration/expansion no matter the meduim or projectile design (solid/HP)

Neutral

rsterne · Moderator

I shot two 18 gr. pellets at a 4L vinegar container (similar to a milk jug but a bit heavier plastic) that was filled with water.... pellet direction across the 8" width of the jug.... at 25 yards from a starting velocity of 715 fps.... The JSB Heavy was travelling 664 fps at impact and the H&N Crow Magnum was travelling only 583 fps because it has a much lower ballistics coefficent (0.041 measured vs 0.015 measured).... the JSB penetrated both sides of the jug and was imbedded in the second layer of corrugated cardboard behind it.... The Crow Magnum put a large dent in the back without creating a leak, and remained within the jug.... Here are the recovered pellets:

Remember, both pellets had the same initial velocity and energy - 20 FPE.... I measured the head diameter, and the JSB was 0.219" (about 0.002" expansion) while the Crow-Magnum was about 0.227" (about 0.010" expansion).... Other than a slight tilt to the face of the Crow Magnum, both pellets looked almost new, except for the polished skirt from penetrating the plastic.... When you consider the plastic wall of the jug is probably tougher than skin, and that animals are mostly water (unless you hit bone).... the huge difference in retained energy in favour of the JSB really isn't offset in any way by noticable expansion from the Crow Magnum.... Shocked

I remain unconvinced that even in moderately powered guns you get any real expansion from pellets unless you hit something pretty hard.... The difference between this test and the first one I posted using paraffin wax is like chalk and cheese.... Rolling Eyes

Bob

fritz · Silver Status Member

I fail to see expansion in .22 CPH at 15 yards into the skull of a groundhog. The nose of the pellet actually became smaller... I think it's the hard lead and small void in the nose.

My opinion of water testing: It's not really proving much. Water by nature is too viscous. It does not provide the muscle fibers which give solid resistance not liquid. Of all the cheap mediums (none of which I have tested...) the wet newspaper seems the best.

The real moment of truth, is when you make contact with that squirrel or bad guy. If they don't drop when you pull the trigger then something has failed. When that projectile meets flesh it needs to either A: expend enough to impart its energy into the target fast enough to create a deadly shock force, or B) penetrate far enough to reach vital organs which will turn the lights off.

Nothing beats taking the projectile out into the field and seeing what happens in the real world.