I Need a Better Backstop

[guero_gordo]

Looked at tire mulch from HD when I built mine, but  here I could only get it in cubic yards, delivered. Seemed a little excessive for my needs ;-)

[rsterne]

I tried out the backstop today with my .457 Hayabusa…. At 500 FPE with a 336 gr. bullet it penetrates about halfway through the wood, so there is plenty of stopping ability there.... It will be interesting to see how much punishment it takes before bullets chew a big hole in the wood and get to the steel plate.... Right now I am spreading the shots out through the Chrony, so it's not an issue, even when they make adjacent holes....

Bob

[triggertreat]

I shoot into a box of premixed drywall clay and just move the target to 1 of six sides till its really messed up then dig out the lead. I dont care what the fpe is it wont go threw the box.  like this Bob https://hardwareonlinestore.com/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=5414&virtuemart_category_id=14603&gclid=EAIaIQobChMIoPeu3e6t3wIVDZRpCh1hmQPhEAQYBCABEgIhK_D_BwE

While not finding that exact match locally, it did give me an idea of using some of the moist clay dirt we have around here in a bucket or box.  This stuff is quite dense with having very fine granules.

[Kinetic45^]

I'm going to note that I tried multiple materials for backstops down through the years and while many things do work well to stop projectiles what I like best are those that refill the impact cavity which the clays, duct seal or Sheetrock mud, wood blocks, etc tend not to do.  That leaves it forming a deeper and deeper hole til it gets all the way through.  Yes, you can take the time to repack/re-condense/replace it but I am basically lazy and that was too much work... I read of others success with the rubber mulch and tried it and since it fills itself in on the penetration cavity and had a very very long service life before having to be replaced it won the contest.

The nice thing about all these we are talking about is they are basically silent which even if you are in the country is nicer than the loud clangs of metal targets.  I HAVE had a variety of metal backstops, ranging from the 22 Long rifle weight traps to a monstrosity I built with a piece of 3 foot by 7 foot, 3/4 plate that was at a 45 degree angle and the bullets went into a 'snail' trap at the bottom where I collected the lead. (I left it there when I sold the property... too heavy to move!!!).. I used to shoot a LOT of rounds every week, like 300 or 400, 52 weeks a year {some guys would come home and drink a six pac, I would come home and go out back and shoot 50 round of pistol every day and reload something every evening} (EXPENSIVE!!!) and after 6 years the back was starting to bow slightly and I had punched through it with rifle bullets and re-welded the holes multiple times.
Mulch is better for me, nowadays.

[triggertreat]

Those are good notes Peter.  I think with your experience and input on this, I will focus on the rubber mulch.  No need to try and reinvent the wheel.  I want to build a box within a box design though so that when the mulch starts falling out of the hole(s) created from repetitive shots, it will fall into the outer box so it can be reclaimed easier instead of having losses on the ground or creating a mess on the floor and having to sweep it up.

[Tater]

Those are good notes Peter.  I think with your experience and input on this, I will focus on the rubber mulch.  No need to try and reinvent the wheel.  I want to build a box within a box design though so that when the mulch starts falling out of the hole(s) created from repetitive shots, it will fall into the outer box so it can be reclaimed easier instead of having losses on the ground or creating a mess on the floor and having to sweep it up.

I've seen PB videos online (just google it, I shouldn't post a PB video link here) where  they used a plastic storage box like the one below from Walmart filled with mulch. It stopped a 9mm, .38 and most various rifle sizes. Check out one of those videos, it makes for a nice big target area.

[Lion]

Am I the only one that uses sandbags as a backstop?
It's save, cheap and the lead is easy to separate from the sand with a sieve.

[rsterne]

DUH!!!.... That may be the best idea I have heard so far.... 

The only drawback is the cleanup of having sand trickle out through the entrance holes.... 

Bob

[triggertreat]

I have thought about using play sand in a double box sorta design too (to catch the spillage).  It would fill back in on impact better than the clay dirt idea.  Much easier to reclaim the lead too, as I one day want to try my hand at one of Bob's designed molds from NOE.  Digging out the lead from the rubber mulch could be more challenging though I do have a DIY sift I might could use.

[rsterne]

The problem I see with sand is that once you get a sizeable hole in the bag / inner sand container, the sand will run out through it, emptying the bag above the hole by gravity.... Shots above that level will go straight through the empty bag / container.... Yes, an outer container would catch the sand, but it could get dangerous for penetration completely through within a few shots....

Sand will, after all, flow through an hourglass.... RATS!!! …. We need a self-sealing container, but I can't imagine one that would stand a lot of shots in the same place....

Bob

[triggertreat]

Yes that's true.  However, what if the box was tilted so the sand didn't flow out of the holes.  Just to be clear, I'm still leaning towards the mulch build lol.  I have found some rubber mulch locally for $5.97 per 0.8 cu. ft bag in stock no less.  A few bags should do it pending the box/tub build.

[rsterne]

You will still end up with an entry hole, and anything above that can run out, right?....

Bob

[Lion]

I use sandbags as a backstop for years. The natural corner of sand is 45 degrees, or 1:1, so it will not leak away like water.
I have layed down the bags with a smal angle backwards to prevent that the sand leaks out. After a lot of shooting, I repair the front bag with ducktape.  One or two times a year I clean the sand and fill new bags. My sand backstop is aboud 3/4meter thick in 4 layers of bags. It has no problem with slugs out of my Texan 45 on full power.

[triggertreat]

You will still end up with an entry hole, and anything above that can run out, right?....

Bob

No, not with the correct tilt, but yes that's too much math to have to deal with when just wanting a no nonsense backstop.  The mulch setup must fail before taking the sand approach.

[Kinetic45^]

A sheet of rubber 'on top' of the mulch, behind the lid/face still gets holes but they tend to be smaller and close close up with the round nose stuff and adds 'depth' to the front that lets the mulch bridge the holes.
Then I use a replaceable facing in front of that.
I have one of these outside and one in my garage chrony station
This one will get some duct tape before the next session

[subscriber]

Hatcher's Notebook has some useful data on sandbag and other media penetration.  Below is a table for the .30-06 ball round.  Note that penetration increases with range in some media.  This is due to bullet distortion or yaw at close range in some media.

Pertinent is the distinction between dry and moist sand; and loose earth: 

From: https://books.google.com/books?id=yESNUKSg5aMC&lpg=PP1&pg=PA408#v=onepage&q=sand&f=false

Am I the only one that uses sandbags as a backstop?
It's save, cheap and the lead is easy to separate from the sand with a sieve.

I was scrolling through the comments to see if anyone mention sand, and you beat me to it. 

Good old sand bags have been know to be very effective at stopping projectiles, for well over 100 years.  They are the low cost alternative to rubber mulch.  Even if sand bags are just a back-up to your sacrificial backstop.

[subscriber]

Sand will, after all, flow through an hourglass.... RATS!!! …. We need a self-sealing container, but I can't imagine one that would stand a lot of shots in the same place....

An hour glass only works if the sand is uniform, clean and dry:

Now, water wetted sand is a bad idea for many reasons.  However, oil wetted sand; as used to make sand molds for casting metal parts, should stay clumped together much better.  Even if you don't used the same oil as for sand molds,  I think that 5 liters of used engine oil in 50 liters of sand, would be very effective at making the sand grains just sticky enough to prevent them running out of your trap. 

The best oil to sand ratio is something to experiment with on a small scale.  Wet, but not so wet that the oil runs under gravity to pool under your trap.

If you could find cheap grease to bond your sand, that may work even better.

Also, make your sandbags small, so that you can easily replace the ones that are torn up.

Ultimately, if you end up with sand heaped up at a 45 degree slope, that you rearrange with a spade every so often, that would not be so bad.   Now, indoors, you would want to construct a "sandpit" to contain the sand, and to allow for some "splash".

The above is intended only as food for thought; to break you loose from the hourglass mental model...

[rsterne]

The 30/06 M1 "Ball" round is a 174 gr. pointed bullet at 2630 fps (2675 FPE).... At 600 yards it was still travelling about 1600 fps.... and drops subsonic before reaching 1000 yards.... Somewhere around 950 fps at 1600 yards would be a good guess, I can't find the exact number....

What is interesting is the huge difference between Oak and Sand when supersonic or subsonic.... Compare the penetration at 1600 yards.... It appears to me that sand is great the higher the velocity.... Just an observation....

A "sandpit" isn't going to happen.... too big for indoors, the "splash" would be a non-starter.... but I get your point about dry sand running out through holes easier than wetted with something....

Bob

[triggertreat]

Thanks for the chart!  Based on that chart, using clay is a very bad idea.

[subscriber]

Other than depth of penetration, clay is not "self healing", unlike rubber mulch.  A few shots in the same place on a clay block, and you end up all the way through it...