Posted this on /k/, got no decent response.
I'm going to make an airgun pellet trap as in pic related (not my design btw)
Now, I want to replace the steel backing plate with Lexan, because I'll be using silhouette-style targets and that'd mean I'd have to repaint the steel backing plate over and over again.
I want to be able to use this thing indefinitely. I'll be using a Diana Mod 75, which has about 7.5J(5.5 ftlbs). I'd like the backing plate to be able to take at least double that, so 15J/11ftlbs.
How thick should that Lexan plate be? I can't find any penetration tests with airguns that I should go by, and this stuff gets exponentially more expensive the thicker it gets, so I want to use the bare minimum.
Also, do you guys think it'll scratch eventually? Would angling the backing plate result in a significant reduction in necessary thickness?
Similar design I found. This is supposedly capable of taking 1000ftlbs. It's also got half an inch of steel backing plate, and it's angled a lot more too.
Now, what you're seeing in pic related are the full-size bullet traps. They get hauled up to the top of the poles, and then shot at by a 12 gauge single shot bolt action rifle. It uses a 39mm bullet (overall length), and it's about a 35 gram projectile going at a maximum of 230 m/s (540 grain, 750 ft/s. Total energy of about 675 ftlbs/900J).
Targets look like pic related. You want a clear background because we're using standard Olympic style sighst, so no magnification, and a diopter and the rear and a globe sight at the front. I'll post the gun we're using next.
What I want is a similar setup for airguns for indoor winter practice. We're using standard 10m olympic-style target airguns, with the exact same sights as the full size guns. Now, the downside is that all the airgun bullet traps currently in use don't have a clear backing plate, which means it's not 100% similar to the fullsize shooting we're practicing for.
Pellets are standard lead 4.5mm/.177'' flathead diabolo's shot from several different airgun models, all in the 10J range.
Gun looks like this. It's a single locking lug(bolt) Mauser-style design. SIngle shot, again, using a 12 gauge, brass case slug with a total cartridge length of 399mm. Rear sight is a standard airgun diopter, front sight is a globe.
The targets we're shooting (with the fullsize rifle) at are 10x10x10mm or 15x15x15. There's six people ina shooting team, doing three shots each, for a total of 18. Miss, and you're out of the competition.
For airgun shooting, this gets downscaled to 5x5x5mm targets on toothpicks at a range of 7m.
CDs are lexan.
so why don't you take a stack of AOL CDs and mis-burned coasters out into the garden and do it yourself? my guess is you'll need about 5 discs at 45º to stop a 12ftlb 177 and the front two will have chunks shatter off.
I'm trying to get a clear background though.
Sounds like a great idea, but keep in mind I only have a 6ftlb .177. How do I account for thousands of rounds beig shot over the lifetime of the trap?
How can any prevent any chunks/shattering, so I can reuse the targe, amd have it remain clear to see through? Will angling them more help?
Eh...so my first issue would be does the trap actually still work with a material like lexan instead of steel? When you change the hardness of the material you're shooting at, you're going to change how it bounces off.
My next thing'll be, it'll break at some point. It's kind of the same idea with ballistic plates -- they're only good for one shot yo. I'm not saying lexan will fail that fast, but it will fail at some point.
I think the more simple solution would just be to stretch butcher paper across the back. Maybe paint the back white too, but with a couple of dowels you could make it follow the curves, the shit's cheap, and it'll give you the extra visibility you want.
As said in >>945002, a proper Lexan bullet trap will hold up to shot energy in excess of 600ftlbs, and will keep doing it for thousand of rounds. I'm shooting with less than 6. There's around 100 of these installations I know of, and none have failed so far, with most shooting clubs firing about 10000 rounds a year into them. They've been around for just over a decade now. That's 100000 rounds since most of the fullsize shot traps have been made. If you design it right, with the correct thickness, it simply cannot fail.
>How can any prevent any chunks/shattering, so I can reuse the targe, amd have it remain clear to see through?
You can't. It will wear out over time pretty much no matter what you do. While you are using much less powerful projectiles, one of the issues is that you're likely using steel BBs/pellets in your airguns, yes? This will wear your trap much faster than lead, due to it being far harder.
What you might consider is using a sacrificial sheet of polycarbonate in front of a much thicker structural sheet in the back. Say a 1/8th sheet (although I suspect even a 1/16" sheet would work) in front of a 1/2" sheet.
Kind of pulling this out of my ass since I've never had to do anything where the idea was that it was SUPPOSED to have bits of metal flying at it very fast, but I do a fair bit of work with plastics and don't see any reason why this wouldn't work.
That being said, I'm not sure why you're so opposed to just spraying the thing with a rattle can of paint every now and again. Your airgun pellets are going do marr the finish MUCH less than an actual bullet, and a single can of white would last you a long time...
Nope, we use lead pellets.
Again, trying to get a clear background so it's similar to the fullsize shooting. Sure, the lack of maintenance would be neato, but the main goal is a clear background. I'll look into the sacrificial sheet though.
OP, do not take offense to what I'm about to say. I promise this is constructive criticism, read it all before going off.
First, do you mean a 39.9 (or in your case I'm guessing it's 39,9) mm cartridge case? 399 is about the length of a man's forearm...
Now, you are too invested in the idea of the clear background. I know, you say it's so it looks exactly like the fullbore version: but you're not shooting the fullbore version in ANY other aspect of this endeavor, other than the sights. Different rifle alone means NO recoil, no report, different trigger, different hold, weight, balance, etc. (I'll bet your sights won't be at the same settings, either...) You're shooting inside, not out in the sun, the wind, the sounds, and so on. Why would you think that if the target has the same presentation that it will negate all of that?
OP, I have dry fired literally 1000's of shots, completely recreated entire matches, put on the coat, target looks the same, called every shot, everything. It helps, but it is NOT like shooting a real match. You're worrying about the part that probably matters least. Paint the steel backstop white and the target black, watch your front sight, squeeze the trigger when your on and don't when your off, and you'll be fine. If it were me I'd be shooting into a cardboard box filled with newspapers in the basement. WAY cheaper and you'd get the same results.
399 was a typo. Pic related is the ammo, 39mm.
The fullsize guns have next to no recoil impulse too. Subsonic cartridge, very heavy gun that's locked into a wooden beam with a very heavy rasp. Besides, if they can shoot straight with the recoil impulse, they can do it without.
Both airguns and fullsize gun have triggers I can adjust. I can get them within an ounce of each other.
>weight & balance
weight of the rifle is completely supportd in both cases.
We will be shooting this setup outside eventually. It'll be good training for the kids (who aren't allowed to shoot fullsize yet) and it reduces training cost. Bullets cost 50 eurocents, pellets are like 5 euros for 1000. This setup will also eventually be used for matches between the kids.
Targets are already black, and we've used white backgrounds, but the targets just aren't clearly visible to most shooters, or, not as visible as they are with a clear background. That's the complaint I'm trying to address. Fullsize shooters don't want to shoot against the white background because it's extremely confusing to them. I know how to shoot, I'm actually one of the few people giving courses for kids around here, and this isn't for my own practice. I'm already shooting indoors against a sheet of Dyneema, but others just can't seem to wrap their head around the fact that this could actually imrpove their shooting, so I'm trying to make it appear as similar as possible.
Well good for you. As I said, I meant no ill will, and trying to show new shooters, especially kids, how to shoot can be... daunting? Sorry for jumping to conclusions. In that case I'm going to agree with the sacrificial layer idea, and my bet is also that the more you tilt it (the closer the backstop and the bullet path are to parallel) the longer life you'll get. Good luck sir!
>Mauser-style design. SIngle shot, again, using a 12 gauge, brass case slug with a total cartridge length of 399mm. Rear sight is a standard airgun diopter, front sight is a globe.
Are you even speaking English?
If you are shooting an air rifle, buy a bale of hay for $5 , it will stop anything you throw at it.
If you are shooting some kind of .72cal Mauser, scale up to a round bale so you don't exit the side.
Fullsize shooting involves a 12 gauge single shot rifle. Mauser-style bolt with a single locking lug(the bolt itself). Not really hard to understand, is it? The cartridge is about 19x39mm. If we're shooting that, we're shooting against targets like >>945003 which are backed by a highly angled Lexan plate about 2 inches thick (50mm).
If you'd read the thread, you see I'm trying to downscale that for kids, using an airgun, miniaturised targets, etc. I'm trying to get a clear background for that. Correct me if I'm wrong, but I'm pretty sure a bale of hay isn't a clear background.
OP, have you considered plastic bbs instead of pellets? I know in the U.S. most pellet rifles can handle bbs, even though I get the feeling you're using better than average air rifles. If you would like to try them Google ".177 plastic bb plinkers." Possibly where you are try 4.5 instead of .177. You'll have to try them to see if the plastic ones can hold up as far as accuracy goes, I have no experience with them. You from the Netherlands, OP?
So Op, here's my confusion about this clear background:
if you're going to be doing this inside, it won't be the same as having a clear background outside anyway.
If you're trying to make things more visible, then just go with high contrast coloring.
Yellow background and black targets is one of the highest contrast combinations to the human eye.
Also, if you're doing something for kids, there's no reason to not make the indoor stuff easier to see than the outside. Let that be part of the difficulty curve that they will get used to when they "graduate" up to the real deal.
I'll be using it outside too.
I'm not trying to make things more visible per se, I'm trying to make things similar to shooting fullsize. If I'd use white backgrounds, then have the kids go outside and shoot, they'd fail miserably because of the change of background. Been there, tried that.
I can always use yellow paper behind the lexan, and then remove it to create a difficulty curve.