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Science Fair Project Safety Assessment

Discussion in 'Handloading and Reloading' started by manithree, Dec 3, 2012.

  1. manithree

    manithree Well-Known Member

    My 13 year-old son who thinks that "Science Fair Project" comes from the latin root meaning "Excuse to re-load and chronograph" doesn't like to shoot my current loads out of our S&W snubbies. So, for next year's project he wants to make a .38 Special load that's light enough to be fun to shoot, even for him.

    We already use Trail Boss to make some really soft .22-250 loads. But based on the massive case capacity of .38 spl, even published TB loads would still be pretty similar to what we're getting with a 158g bullet over 2.7g of Clays.

    So, he wants to wildcat. Sort of. Since most reloading books and manuals I've seen warn against going too far below the published minimum loads, he decided to try lowering case capacity of .38 spl by just cutting the case down. Then we'll measure the usable case capacity and apply Hodgon's published 70% rule for Trail Boss using our new .38-based wildcat.

    The lowest published Trail Boss load (that I've found) for a 158g lead bullet is 2.7g (661 fps). We're wondering if we can get usable case capacity down to 1.0-1.5 grains since Trail Boss is not very dense.

    Does anybody know of a reason why Hodgon's published Trail Boss rules for any pistol cartridge wouldn't be safe for a shortened .38 spl cartridge? We plan to be very careful not to compress the powder, and watch closely for squibs. Those seem like the biggest safety risks for this project, but I've only been re-loading for a few years, so I'll be interested to hear how more experienced re-loaders would assess the risks involved. Especially while we still have plenty of time to choose another science project for next year.
  2. rcmodel

    rcmodel Member in memoriam

    661 FPS is about as low as you can safely go and insure a bullet doesn't get stuck eventually.

    No matter how short or small the case is.

    Then there is the matter of seating & crimping a much shorter case, cause your standard .38 Spl seating die will no longer do it.

    Then there is this:

  3. snakeman

    snakeman Well-Known Member

    the only thing I can think of is that the bullet might not ever leave the bore. this would result in the next shot blowing your gun and possibly the shooter to heck. I would play it safe and teach him to handle recoil. I know that may sound mean but if he's not ready to handle 38 special then let him shoot a 22
  4. rcmodel

    rcmodel Member in memoriam

    BTW: If you want less recoil, use 125 RNFP or 148 WC grain bullets instead of 158 grain bullets.

    It will make more difference in recoil then trying to download them to unsafe velocity levels.
  5. ScratchnDent

    ScratchnDent Well-Known Member

    I've no experience with Trailboss powder, so I can't offer any advice there.

    I am just curious about why you would use 158 gr bullets if the goal is lighter recoil?

    Wouldn't a 110 or 120 or so bullet be better suited?
  6. greenlion

    greenlion Well-Known Member

    As a science teacher, I would point out that science fairs always, in my experience, prohibit the use of explosives, firearms, weapons, and flamable substances in experiments. He will definitely will not be allowed to conduct that as a school science fair experiment. If he is, you need to question how far behind the times your school system's safety procedures are. The school would be held liable if he injured himself during a science project they have approved.
  7. manithree

    manithree Well-Known Member

    First, my son is a fine shooter. He shoot's 9mm and .40 handguns, .22-250, 7.62x39, 7.62x54r and .30-06 almost as well as I do.

    Second, we'll probably start with 158g because I have over a thousand 158g bullets (they were on sale!). I may end up getting some lighter projectiles, but since we can't actually measure recoil, for a science project, it really won't matter much.

    Third, last year's (6th) grade science project involved chronographing a whole bunch of reloads and commercial ammo. He got first place in his school, placed at district, and went to the Central Utah Science and Engineering fair. We are well aware of Utah's science fair rules.

    What I'm really looking for is technical advice on safety issues that I haven't already thought of. I did mention in my initial post that we're aware that ultra-light loads have the potential for squibs. Some failure and re-configuring parameters isn't a bad thing in a science project, and occasionally leads to whole new avenues of exploration.

    One thing I did neglect to mention is that we will probably never put more than one round in the cylinder at a time since we won't be able to crimp them. And we plan to check after every shot for squib/barrel obstruction.

    Are there any equations or rules for determining the minimum velocity required to exit the barrel?

    I've never pushed a squib out, and I don't really want to, so we'll probably start high and work down.

    My son has seen the Magtech Spcl Shorts. That's one of the things that influenced him to do this. That and we couldn't really decide if putting a gas check on a wax bullet was feasible or not. We have shot a few hundred wax bullets, but the primers always backing out is quite irritating.

    Measuring powder density, calculating how much of the case to remove to get the desired usable volume, and measuring velocities are all good math and science for a project. I don't expect us to make something commercially viable, or even anything we'll ever use again. I just want him to have fun and learn. Safely, of course.
  8. greenlion

    greenlion Well-Known Member

    I still cannot imagine a school teacher/school/system signing off on a science project that encourages a very young student to go try out experimental handloads, that his father is also not too sure about, in a firearm. (Even if it is in Utah, which might as well be Mars if this is true)

    In today's litigious world, you cannot even have then put their hands behind their heads when they do sit-ups in PE class for fear that they would crick their necks...
  9. 56hawk

    56hawk Well-Known Member

    Lyman 49th lists a 38 S&W load at 451 fps. I shot a few rounds at this velocity in other calibers and they worked just fine. For an experiment you are only going to be shooting one round at a time, so getting a squib won't be any big deal anyway. Just have a brass punch and a hammer on hand.
  10. rcmodel

    rcmodel Member in memoriam

    You have to drill out the primer flash holes with a 1/8" drill to prevent that.

  11. jmorris

    jmorris Well-Known Member

    You might try SASS forums for very light load data. Cowboy action loads are super soft, a spit ball fired by a 4th grader have higher power factors.

    I'll never forget a friends story about a derringer side match where the shooter fired 2 shots at a 3/8" plywood target (105 grain bullet under 600 fps), finished and waited on the RO for commands, then looked around to find him on the ground because the bullet bounced back off the wood and hit him in the jewels.

    Come to think of it the old SSR loads in IDPA (before ESR existed) was a 230 grain going under 550 fps making 125pf, shot thousands and thousands of them, never stuck a single one.
  12. manithree

    manithree Well-Known Member

    Very nice. Thank you.
  13. manithree

    manithree Well-Known Member

    Heh. I own that manual, too. I go to hodgdon.com first for my re-loading data and just never got around to finishing my dead-tree searching.

    One of the original ideas was to cut to nearly .38 S&W, then use a Lee .38 S&W trimmer to clean up. Then we should be able to safely use any published .38 S&W load. Right?
  14. 56hawk

    56hawk Well-Known Member

    Should work, especially since the 38 S&W runs at lower pressure. By the way, since this is just for a science fair project you could use full length 38 special cases and just seat the bullet deeper. The 38 Special case is about the same length as a 38 S&W loaded with a 158 grain bullet.
  15. kingmt

    kingmt Well-Known Member

    The more you shorten the case the faster the pressure will climb. So even tho recoil goes down the pressure is still going up. Instead of cutting the brass off just push the bullet deeper. I'd also look at 9mm data. If there it's 9mm TB data it would give you some good data to reference. The heavier bullet will gone you less recoil unless it is to light to allow any pressure to build.
  16. rsrocket1

    rsrocket1 Well-Known Member

    A shorter case would do the same as what kingmt recommends, but watch out. I did a sample run of what would happen if you pushed a .63" bullet flush with the .38 case and loaded it with 1.5g Clays in a 4"bbl:
    seat depth Max press MV
    .53 8,7665 542fps
    .63 12,062 578fps
    .73 19,812 625fps

    +/- 0.1" seat depth get you from too little pressure with unburned powder and sooty case to going over the SAAMI limit for the 38 special gun. Much more than that and you get a Kaboom.

    I would instead do an experiment of "how low can you go" before you get a stuck bullet. You are only shooting one at a time and hopefully you know how to drive a stuck bullet out of a barrel w/o damaging the gun. If you use a standard bullet seating and start with 2.5g Clays, I'll bet you can get down to 1.5g Clays and still get a chrony reading.

    With a hardcast lead bullet, I once had an accidental squib load with just the primer and I chrony'ed the bullet at 231fps.
  17. Andrew Leigh

    Andrew Leigh Well-Known Member


    just a thought, with all of the negative issues being experienced in schools with firearm related incidents do you think such a project will be welcomed? Your son could be marked down as a result or the project may well not be accepted. Also how does he demonstrate the results of the project?

    Good luck with the project.
  18. manithree

    manithree Well-Known Member

    Well, maybe I'm not remembering this correctly (I don't have my manuals handy), but Richard Lee says don't go below 10% less than the published starting load. I thought that was because of the un-reproduced but widely believed to be possible kaboom on super light loads. That's why I'm nervous about just reducing the charge with a powder like Clay's. Am I remembering wrong or misunderstanding that?

    That's why Trail Boss has so much appeal. According to Hodgdon documentation, even if there's not published load data, for any rifle or pistol round you can safely make your own Trail Boss recipe by measuring the usable case capacity. My thinking was, reducing case capacity should reduce, if not eliminate the ultra-light kb possibility, and if Hodgdon is correct, our new "eargensaven mauseflatulenz" should be safe with 70-100% of the case capacity filled with Trail Boss. If that's really true for a shortened case, the only other danger is loads so light they dont't push the bullet all the way out of the barrel. And as I and others have pointed out, that's an easily manageable risk.

    That's the logic I was hoping to get some feedback on. My son and I have discussed the "how low can you go" and still exit the barrel project, but I didn't think it was safe to just reduce the powder charge very far below published minimum loads without reducing the case capacity.
  19. manithree

    manithree Well-Known Member

    I don't know how to say this any more clearly. I have open carried to my kids schools. In Utah, public schools are legally prohibited from regulating carry by employees or others. This is a free state. We've done one shooting and one re-loading/shooting projects already, and the second one was especially well-received.

    Even if we did live in a more hopolophobic area, I still wouldn't care. As long as he does some math and science, learns something, and has fun (safely), we would do it anyway.
  20. Andrew Leigh

    Andrew Leigh Well-Known Member

    Hey Manithree, I was not being critical of your project choice I was simply concerned.

    bear in mind I am from a different continent and the press we get here is probably a little unbalanced. Also I am not aware of the differening laws in different states.

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