Home Forums Hunting & Shooting Ask The Gunwriters Penetration differences- 17 rem vs 204 in bullet proof steel

I built a bullet trap probably 30 years ago for pistol shooting in my back yard, and about 10 years ago I moved it to my Dad's place for shooting at 100 yds. The trap is 36" wide, 24" tall and has a removable back sloping plate to deflect projectiles into the dirt. During it's career it has taken many centerfire hits penetrating the 1/4" mild steel plate, which had destroyed it's usefullness for it's current use.


I have 2 panels from a helicopter that were access type doors ( 1/4" thick), and I placed them across the back of the trap, and I decided to add some mild steel backers 3/4" thick to help absorb some of the energy, and as a potential back-up in case the armor wasn't enough to stop everything.


So I have a load of 27 gns Varget pushing 40 grain ballistic 204's, and I also had loaded some ammo w/ 20 grain 172's from a 17 rem.

Inspection of the bullet proof steel showed the 40 Ballistic tips blew through the 1/4" BP steel and left globs of lead in the hole showing the cr steel stopped them. The 20 grain 17's left "marks" of lead and removed very little steel, probably striking the steel at 3500 fps.


So I am thinking of adding a piece of rubber hanging behind the targets to hopefully start the explosive bullets to loose energy and do less damage to the BP steel.


Any suggestions or thoughts to share?


Thanks


Allen

How many rounds are you shooting at this target before it fails?

Accuracy would play a important role - because the more you concentrate the area with bullets - the more it is going to fail.

The way I see it, you are shooting in the same place all the time.

Why not replace the bullet trap with a big old pile of topsoil and just build a back stop and shoot into the pile of dirt.
IN my mind - it would be a lot safer then shooting at steel plate.

Get (3) 5 yd. loads of dirt and sand and build a berm.

Hang your steel in front, that way if you miss like Duqueenie often does, you'll still be ok.

LOL

I set this up in my Vineyard. Pretty hard to put a berm on my property.

Yea, I am sure it is due to repeated impacts. I usually can keep all 20 of a box of generic white box ammo in the same hole, unless the snow is so thick I can't see the target anymore. If that happens.

Thanks for the suggestions, though.

BTW, How is the snow down in Pa? I planned to drive south to Clearfield, but the snow here is supposed to get worse tonight.


Allen

What it looks like to me is the high velocity small bores melt their way through the plate-17 rem, 220 swift etc.

Anything that would induce fragmentation or act as a heat sink before hitting the steel should help.

You need a thin layer of small gravel in front of the steel. Space it about 4 inches thick in front the steel with a plywood sheet. After each impact, the gravel sifts down to protect the steel from the next bullet.

It could be tilt-up, so it would be easy to replace the plywood once in a while without having to shovel all the gravel back in. But even that wouldn't be too hard.

http://en.wikipedia.org/wiki/Plastic_armour

Plastic armour (also known as plastic protection) was a type of vehicle armour originally developed for merchant ships by the British Admiralty in 1940. It essentially consisted of small, evenly sized rock or stones in a matrix of bitumen. It was typically applied in a layer two inches thick and backed by half an inch of steel.

Plastic armour was highly effective at stopping armour piercing bullets because the hard particles would deflect the bullet which would then lodge between plastic armour and the steel backing plate. Plastic armour could be applied by pouring it into a cavity formed by the steel backing plate and a temporary wooden form.
...
On 27 August, Terrell, Glanville and a Dr Lee drafted a report detailing their efforts and giving a recipe for plastic armour � the entire development cycle had taken just ten days. The recipe required 55% granite, 38% limestone and 7% bitumen; it was important that the stone was carefully graded and free from grit. The backing plate was vital; it would usually be a 1/4-inch (6 mm) thick mild steel. Since this was what vital parts of the ships� superstructures was made from it was possible to cast plastic armour in situ between existing plates and temporary wooden shuttering, usually to a thickness of 4 inches (100 mm). Where this was not possible, armoured plates could be factory made. In a few instances a wooden backing plate was used when non-magnetic protection was needed near the ship's compass
...
Plastic armour went into full production in October; facilities were soon in place in every major port involving every major road-building contractor in the country. Word spread abroad to Britain�s allies. By the end of the war, plastic armour had been fitted to some 10,000 ships.

Thank you very much.


I was thinking the rubber would be somewhat self sealing, and start the destruction process of thin explosive bullets which is my guess on why the Ballistic tips were so much more damage to the BP steel than the hollow points.


Sounds like a second thing to try if the rubber fails to help


Thanks

Allen

I'm thinking that manganese wear plate (what bulldozer blades are made from) might be real interesting. The stuff is about 10% manganese, and tends to work harden rapidly as it contacts abrasive media. It isn't cheap, but should last a long time. If you can't find any then maybe get a piece of 12 x12 x 3/4 tool steel, have it hardened to Rc 60 or so, and bullets won't do much to it.

I don't know the source, but I've seen several ranges that use shredded auto tires to stop rounds, including the 100 yard indoor range at Barrett Firearms Manufacturing

"You need a thin layer of small gravel in front of the steel. Space it about 4 inches thick in front the steel with a plywood sheet. After each impact, the gravel sifts down to protect the steel from the next bullet.

It could be tilt-up, so it would be easy to replace the plywood once in a while without having to shovel all the gravel back in. But even that wouldn't be too hard."

This is a lot like the baffles we use on our range. We have found that small rock like 3/4" to 1" serves well to disintegrate the bullet so it is not in ballistic flight even if it makes it through the baffle. The small rock is orders of magnitude better than sand or earth which do not deform or disintegrate the bullets. The rock is self-settling so you don't get a vacant area worn through it. With rubber front and back panels instead of plywood, it would probably last longer between needed maintenance.

Thanks for the idea's.


I like the free tire suggestion, but will probably try some form of rubber sandwiching gravel.


Thanks

Allen

Stack up some old tires as high and wide as you want a backstop, then fill them up with #2 crushed stone.

old conveyor belting would be cheap.....