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Thread: 12 bore from heck/ magtech brass, .730pb ball, smokeless, marlin bolt

  1. #1
    Boolit Buddy Radarsonwheels's Avatar
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    12 bore from heck/ magtech brass, .730pb ball, smokeless, marlin bolt

    Howdy Castboolits!

    It’s been awhile since I posted anything here, but now I find myself doing something stupid again and want to share. Extensive web searches tell me that I am not exactly alone in my dumb project but I might have stumbled on a new exciting permutation that hasn’t been done- who knows?

    I watched the 12g from hell boys with great interest but never wanted to test the velocity limits of my shoulder that way. I am fairly recoil insensitive- I will shoot 45-70 all day, even a good amount of marlin only data stuff, but full power or magnum 1oz slugs are just not so fun. I cast a ton of Lee 7/8 and 1oz slugs and tried many different loads through a mossburg 500 rifled scoped pump 12g. They were super fun at trap shooting velocity- soft shooting and nice big holes in paper- but the accuracy just wasn’t there.

    I’m finally getting around to a project I’ve wanted to do for a long time but never got around to doing because it’s stupid and pointless and even a little bit of theater or dress-up or whatever.

    The idea is, like 12gFH, to exploit the shotgun bore “loophole” and have what would otherwise be a destructive device. I want decent but not necessarily amazing rifle accuracy and a bolt action rifle look and feel to the shooting experience. The end goal is a reasonably soft shooting .730 caliber bolt action rifle, hopefully launching a full bore 12g round ball at slightly supersonic speed. I’d like to hit a pie plate at 100 and ring steel often if not always at 200 with some hold over.

    So far I have a bolt action marlin 512 with a 2-7x scope. This is not an especially beefy action with a single rear locking lug that is part of the bolt handle, but it has a thick barrel with crisp rifling. 1 in 27” iirc.

    I have magtech brass, LP and magnum LP primers, longshot, and just got some blue dot. I have 11g over powder, cushion, and lubed fiber wads from dixie. I also got some .730 balls from Dixie- I haven’t decided if I want to invest in the full bore spitzer slug of my dreams with driving bands, grease groove, and even maybe a crimp groove, so these will do nicely for now. They’re pure lead I think meant for brown bess shooting? They stuff through the marlin bore with a good equator of engraving that gives me confidence they will both swage down without excess pressure, and hopefully not blow through and smear into the rifling at the moderate speeds I plan.

    So that’s what I have! My first nervous range trip was a great success. Safety, accuracy, and a very soft shooting load:

    CCI Magnum LP
    26 grains Longshot
    1 thick overpowder card, seated firmly by hand
    3 thick greased fiber cushion wads, ending 3/16-1/4”ish from top of brass
    .730 PB roundball

    The load was compressed and crimped over the equator of the ball using a brass plumbing fitting- 5/8” FLR cap, which simultaneously pushes the ball down and crimps the brass over.

    I did buy the RCBS cowboy tool which is useless- just get their shell holder to make priming easy. Decapping is peg & hammer and crimp removal requires annealing and a tool steel mandril off my lathe.

    So that’s my adventure so far. The 26gn load was very accurate at 25 yards but shot soo soft like 38 special in a levergun. Tomorrow is my 2nd trip and I’m turning up the heat very slowly with a handful of 26, 27, 28, and 29 grain Longshot loads to try.

    Longshot book loads go into the low mid 30s in smaller plastic hulls with more efficient plastic wads, so I know I’m way safe, but I think if 29-30 grains doesn’t get me to 100 yards without measuring drop in feet compared to 50 yards I will switch to the blue dot and work up slowly again.

    Any suggestions or comments are very welcome but please be aware that I am chasing fun, safety, and some modest accuracy. Top loads and scary pressures are not on the menu and warnings against wildcatting are not helpful.

    Thanks!

    Radar

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    Boolit Buddy Radarsonwheels's Avatar
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    Boolit Buddy Radarsonwheels's Avatar
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  4. #4
    Boolit Grand Master


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    Nothing you do will flatten the drop dramatically, and it doesn't have to. As odd as it sounds, a full bore round ball is actually one of the more aerodynamic slugs in a 12 gauge besides the pistol bullets in sabots, and really not as far behind as you would think. Even at 1000 fps a full bore ball is plus or minus 3" to about 95 yards. 1400 fps is about the most rip snorting hottest you can shoot them with normal shotgun powders like bluedot, and that only flattens it out to plus or minus 3" to about 110, maybe 115 yards. It does make a difference at 200 yards, but we are talking about 4 foot of drop vs about 5 1/4 foot of drop. I've shot one deer with a load about 1300 fps, and my brother shot one with the same gun and slug but loaded to 1000 fps, and honestly there's not a ton of difference on the deer. Both make pretty good 3/4"ish holes all the way through and plenty of damage to the lungs.

    About a month and a half ago I was out shooting at 200 and kind of 300 yards. I was trying a few different slugs including some round ball. I say kind of at 300, since nothing I've ever found has been consistent enough to hit steel at 300. A 9" steel plate at 200 yards is a plenty challenging target for a slug, especially in anything besides dead calm wind. I was shooting some slugs that were north of 1400fps. The round balls at 1000 fps were every bit as effective at 200 as the faster slugs. Once things dry out I have a ton of things loaded up. I plan on doing some group testing at 200 yards this year, which I have not done in a long time.

    I don't know a lot about Marlin, but 1:27" is an odd twist. Most 12 gauges were either 1:28 or 1:35.

  5. #5
    Boolit Buddy Radarsonwheels's Avatar
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    Hey MegaSuper!

    Thanks for the experienced words! Oops yes the Marlin is 1:28 twist- I apparently did not recall correctly.

    I have read much about the deadly effectiveness on game of big bore hardcast at moderate speed- a large holepunch instead of the different terminal effect of a fast rifle pill. In imagining the usefulness of this load (that I intend to personally use only to add ballast to the berm at my club) I thought of a couple things: the anecdotal effectiveness of 45acp and this load equaling almost three 1911 slugs making a lead fist; and idea that this setup has the potential to combine the horrific bone breaking and bullet expansion of the brown bess with a slightly range handicapped version of the accuracy of the Baker rifle. I think a real factory style 1oz slug at 1500+fps or something like a full power 500 S&W would be better bear medicine or less likely to skip off an armored or super tough critter, but as you said a 590 grain roundball would nicely double lung a deer and provide plenty of blood trail if dinner was miraculously not DRT.

    Of course this is all fantasy providing a rationale for the usefulness of this rig/load. For my use it will punch big round holes and hopefully slap steel with incredible authority.

    I am greatly encouraged to know that increasing velocity beyond trapdoor style catapulting of dumptrucks full of slow lead in a rainbow trajectory is a waste of time and I can continue working up a moderate load with confidence that I’m not missing out on a flatter shooting recipe

    Thanks again and if anybody else wants to chime in or if anybody else is playing in this sandbox I’d love to hear more about it (paging Longbow?)

    Radar

  6. #6
    Boolit Bub Jungle Dave's Avatar
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    Looks like a great set-up in that bolt action bore rifle. I've long ago concluded that a round ball of any bore size is at optimum speed when it's got the same fps as a 'normal' 40-grain .22LR. They seem to drive further in at that speed, and can traverse an entire Caribou from one end to the other and still keep going into the scenic distance, only to be lost to time, albeit, this is considering the limited range at which these are used, especially against things that can stomp back and make you dead very quickly. As far as heavier weights for the 12-bore, NEI 'had' some great molds, if one is lucky enough to get their hands on one these days. The magtech brass would not be suited for them, however. I'd keep the magtech brass limited to those velocities, and with a plastic base wad inserted around the balloon head primer if using smokeless.

  7. #7
    Boolit Grand Master

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    I have no expeience with brass hulls so can't help there except to agree that the larger volume likely results in lower pressure than with a plastic or paper hull, all else being eual.

    I do have to mention that some changes to components can increase pressures quite a bit... or I should say change pressure quite a bit. Both can be an issue, if load pressure is near max. the change may push it to dangerous pressure and if pressure is mid range or low and pressure drops you may get a blooper with the payload or maybe just wad not leaving the barrel so a follow up shot meets a bore obstruction.

    Beyond that, I have been looking for load data for brass hulls and really not finding much if anything pressure tested. I know a fellow who is developing low pressure loads for his vintage guns and he educated me some on pressure testing and why there is little to no pressure tested data for brass hulls.

    The short story is that you are kind of on your own there. Others have posted their load data but of course most is a bit suspect as to what pressure it is running. Personally I thjink it is a safe assumption to use load data for plastic or paper hulls in the larger volume brass hull as pressure should be lower in the larger volume. That is just me though.

    Other things to consider are:

    - Primer ~ I am not sure just how a large pistol primer compares to a shotgun primer but I'd have to think there is less brisance... again, just my opinion.
    - Wad column ~ replacing a cushion leg wad with a solid card wad column can increase pressure significantly. This is something I would like to see tested with everything being the same except removal of the cushion leg.

    Megasupermagnum did some pressure testing using all card wad columns so that is worth reading. Some results are not what I expected.

    Having said all that, there are several people who have loaded undersize and bore diameter to larger than bore diameter round balls in 12 ga. I have used 0.662". 0.678", 0.690" and 0.735" RB's in 12 ga.

    An undersize ball like 0.662" in shotcup may work for you if the fit is right to bore. I found the 0.662" RB's were undersize so cloth patched themn into hulls with trap wads seated. The cloth patch made for a nice firm push through the bore. Those worked well in smoothbore. Also to consider is that 0.662" RB's are a snug fit in steel shot wads like CAD wads.

    0.735" Rb's are somewhat oversize but swage down that extra few thou easily as there is little meat at the equator. I got good results using 0.735" RB's in both smoothbore and a borrowed rifled gun. No issues with pressure and a nice "belt" around the equator of recovered balls. I base my load on Precision Rifles Piledriver load which is a bit vague and I did not approach their max. listing of 44 grs. of BD under a 610 gr. full bore slug. I topped out at 40 grs. which had enough recoil for me! I settled on 36 to 38 grs. BD and that is the only powder I used under the 0.735" RB. I have attached the Precision Rifle info:

    Piledriver_1.pdf
    PileDriver_2.pdf
    PileDriver_3.pdf

    There are also several threads on loading 0.735" RB's (in plastic hulls):

    https://castboolits.gunloads.com/sho...d-ball-loading
    https://castboolits.gunloads.com/sho...ound-ball-help
    https://castboolits.gunloads.com/sho...d-Ball-Results
    https://castboolits.gunloads.com/arc...p/t-37944.html
    https://castboolits.gunloads.com/sho...ULTRA-slug-gun
    https://castboolits.gunloads.com/arc.../t-276123.html
    https://castboolits.gunloads.com/sho...d-Ball-Results
    https://castboolits.gunloads.com/sho...highlight=ball

    That last link is Blood Trail's testing of some ACWW 0.735" RB's I sent him (they cast large).

    Hopefully there is some useful info in there... though not specifically for brass hulls.

    Longbow
    Last edited by longbow; 04-19-2023 at 02:03 PM. Reason: Spelling

  8. #8
    Boolit Buddy Radarsonwheels's Avatar
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    Killer info! Thanks!

    I just got back from the range. At 50 yards I was able to just about cloverleaf my groups with 27 and 28 grains of Longshot. At 100 yards I was still mostly hitting a silhouette but inconsistently- I suspect the “curveball” effect was at work. At 200 I only hit a door size target backer once out of five shots and 29 grains of Longshot was beginning to have a slightly sticky extraction which is plenty of pressure sign for me to back off of in future loadings.

    I still have a jug of blue dot to play with but I think 27 grains of Longshot under a thick card and 4 thick fiber wads is a winner at 50 yards. It sure smacked the 50 yard hanging steel pretty hard too, and letting friends shoot it (I had plenty of the proven mild 26gn cartridges loaded up) was great fun for everybody.

  9. #9
    Boolit Buddy Radarsonwheels's Avatar
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    Attachment 313160
    5 shots 50 yards- don’t mind the magazine of 7.62 that got emptied into there or the two touching neck shots from my buddy zeroing his new 338 scope
    Last edited by Radarsonwheels; 04-19-2023 at 05:36 PM.

  10. #10
    Boolit Buddy Radarsonwheels's Avatar
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    Attachment 313161
    8 shots aimed center head. Again, the two in the eye were sighters from the 338.

    Despite there being different amounts of powder- two ‘groups’ here- we have more of a pattern than a grouping. It did make hits but I wouldn’t call them accurate.

  11. #11
    Boolit Grand Master

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    Those links aren't opening for me.

    Something that just hit me... I was thinking this is a rifled gun but it is smoothbore, correct? Marlin 512?

    Regardless, if you get a good fitting bore size/over bore size RB you should be able to get smoothbore groups of around 4" at 50 yards. I found that both the cloth patched 0.662" RB's and 0.735" RB's over a hard card wad column both gave very good accuracy of <4" at 50 yards. By 100 yards, groups open up considerably to generally 8" to 12" and with some random flyers.

    Also, not round ball, but you may be interested in these links by Ranch Dog:

    https://castboolits.gunloads.com/sho...-Tail-Feathers
    https://castboolits.gunloads.com/sho...-Tail-Feathers

    You may find that the Lee slug in a shotgup with cushion leg cut off and hard card wad column suits the brass hulls. Again, there will likely be an increase in pressure with cushion leg removed so be careful there but Ranch Dog got good results using his load as illustrated. Just food for thought.

    Longbow

  12. #12
    Boolit Buddy Radarsonwheels's Avatar
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    Longbow- it’s a rifled gun

    Edit: more time to type now:

    The Lee slugs in wads of all permutations were super fun, but slightly less accurate at 50 than my current roundball load is at 100. I could hear them hiss through the air and I even believe I could sometimes see them corkscrewing on their way to the target. I could keep them on a door size target at 50 yards but that was about it.

    The 26-28 grain Longshot under full bore .730 round ball loads at 50 yards are either cloverleafing or darn near it.

    The same loads at 100 are more like 12” with flyers or an honest 18” but curiously not really centered below point of aim like I figured they’d be. At 200 yards with a 5’ hold over my spotter never figured out where they were going and only one hit the target backer. We have a generously tall berm, so my guesstimate was crude but safe.

    The 29 grain load of Longshot didn’t result in stuck brass, just slightly noticably stickier extraction, so despite the recoil not yet reaching any considerable violence I’m going to play it safe and call 28 grains of Longshot the max load for this combination of components. It does a great job at 50 yards and if I don’t find a better 100 yard load over blue dot I will still be happy.

    I do wish somebody had those green slugs in stock or a nice overgrown pistol bullet mold for sale!
    Last edited by Radarsonwheels; 04-19-2023 at 06:17 PM.

  13. #13
    Boolit Grand Master

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    If rifled I'd say the same comments apply.

    I used the same 38 gr. BD loads, hard card wad columns and 0.735" RB in my smoothbore giving consistent 3" to 4" groups at 50 yards and also in a borrowed rifled Remingtom 870 which gave 2" groups at 50 yards. I think the rifled gun could do better but I was getting pretty flinchy by that time having shot 30 or more rounds off the bench before shooting the rifled gun... plus that was with open sights.

    I should mention that I did not use COW or any filler under the RB's in these loads and a couple of recovered RB's showed skew on the "belt" around the equator indicating that the ball either hit the bore slightly off center or was rolling through the forcing cone. I think filler under the RB is a good idea both to provide a "seat" for the ball and to help support the card wads under it. The filler should help keep the RB centered and from rolling as it leaves the hull. A call carrier made from paper mache would likely be a good idea for the brass hulls as that would center the ball in the hull then squish down when it hit the forcing cone.

    I use COW under all RB's loaded into shotcups and if I go back to 0.735" RB's I would add a scoop of COW under the ball.

    With a rifled gun you shouldn't be seeing the "curve ball" effect unless the ball is not picking up the rifling spin... or not picking up full spin. It is possible the 0.730" RB's are skipping rifling. Have you recovered any balls to examine?

    Longbow

  14. #14
    Boolit Grand Master


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    I wouldn't say the stronger loads do not have their place. Sometimes they end up being more accurate than anything. My own pet load is 18gr Unique, which is right at 1000 fps. I've had no issues with accuracy with the faster loads though in a rifled barrel, it's actually been the most trouble free slug I've ever used. I'd doubt you are skipping the rifling unless your ball is less than groove diameter. If you happen to have a barrel with a groove closer to that .732", and your round balls are actually .727" or something (I'm pulling these numbers out of thin air), that right there can be your source of inaccuracy. Alloy does not matter that much at all. I've used from pure lead to heat treated COWW, and it just doesn't seem to matter to a round ball. What can be an issue with certain molds is getting a true round ball. Some of them don't vent very well, or overheat, or some issue where you end up with a ball that is .005" or more out of round.

    Some other general accuracy tips that have helped me is I like to weight sort my slugs. When I sort I find the one that is the heaviest (double check it isn't oversized from a non-closed mold or something), and then sort the rest to be within 1 grain of that. Lets say your heaviest one is 581 grains. I would toss any slug that is less than 580 grains. Second I load them so the sprue is always facing up. It appears you are already doing that, but I figured I'd double check. I also do as longbow does, and I use a scoop of buffer under the ball. Cream of wheat works good, as does any shotgun buffer. I use just enough to take up the dead space between the wad and ball. Something like a Lee 1.3cc scoop works good. I do lube my slugs, but I'm not certain it is needed. I've shot a bunch of bare slugs with no leading, but I don't think lube hurts. I do a single coat of Alox tumble lube.

    You see a lot of absolutely wild claims of slug gun accuracy, but in reality you are doing really good if you can average 4"-5" groups at 100 yards. You can do better, but that is not bad shooting at all. As of yet nobody has stepped up in person to prove they have a 2MOA or better slug gun, and growing up in the Minnesota shotgun zone, I've seen a LOT of rifled slug guns. At 200 yards if you can keep them inside 12" you are doing really good. There's more than just accuracy at play at that point, wind drift is going to mess with you no matter what.

    Anyway, check the things I've mentioned, and make sure your slug gun is working with a known good load first. If you move to Bluedot, 30 to 38 grains is a good range to be in for plastic hulls, but I'm not sure how it will work in a brass hull. I wouldn't expect a huge change, Bluedot is pretty forgiving stuff.

  15. #15
    Boolit Master Cap'n Morgan's Avatar
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    Have you checked for leading in the rifling? Like Longbow, I'm thinking maybe the ball is being sized down instead of spun? I have no experience with rifled shotguns, but I remember having to remove copious amount of lead from the forcing cone and the first inch or so of the bore. This was from shooting cheap shells with soft lead shot before the plastic wad came along.
    Cap'n Morgan

  16. #16
    Boolit Buddy Radarsonwheels's Avatar
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    Hey fellas

    I’m at work and haven’t done anything with the gun other than lock it up when I got home from the 2nd range trip when I tested 27/28/29 grain Longshot loads, but I really appreciate and enjoy the lively and intelligent discussion- thanks!

    I do run the balls nub up like I would in a frontstuffer. Before I made my first dummy round I pushed a ball through the bore and it wasn’t super hard to start which was my first worry. It engraved around 3/16” or so of circumferemce which gave me hope it would be enough to seal and with luck also twist without stripping the ball and leading. The slow (compared to smallbore rifles) twist also inspires confidence in that possibility.

    I haven’t checked the bore after this trip where I pushed the roundballs a little harder. After the last trip I was worried because the bore looked pretty gunky but it turned out to be just powder ash and lube. Honestly I didn’t even clean the gun (it was 5 or less shots) I just pushed a tight balled up paper towel through once and saw crisp rifling and shiny bore.

    I haven’t recovered a ball yet either. My club doesn’t want anything but paper shot and I think three trashcans full of water would be an expensive mess!

    I ordered 1000 count bags of unlubed wads by mistake from Dixie so the next 25 rounds I test will probably be only one lubed wad and three dry.

    Deapite the magtech primer charge being in a volcano shape inside the shell I’ve been successful running magnum Lp primers under the Longshot with no ignition issues.

    I will consider the cream of wheat idea- if I remember right it also scrubs the barrel nicely. I do think there is something about my compressed and heavily crimped load that is getting ignition and pressure to a reliable place.

    I’m thinking about how with this wad setup and repeatable load technique I had such a mousefart at 26 grains and started to feel a little touch of stickyness at 29 grains. While I’m sure I could probably shoot into the mid 30s grain charges all day without sending the bolt into my face the 27 &28 charges felt like a legitimate recoil just not punishing. I think I might have found the spot where pressures begin to curve rapidly upward with more Longshot.

    Next is more testing with the (27.5?) load and working up the Bluedot. I really need to get a chronograph too.
    Last edited by Radarsonwheels; 04-21-2023 at 02:09 PM. Reason: Typo

  17. #17
    Boolit Buddy Radarsonwheels's Avatar
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    Oh and Mega thanks I will spend more time assembling and checking the things you mentioned. I do all that with my own castings but am guilty of being lazy with storebought slugs unless I see a void or bad fill out.

  18. #18
    Boolit Grand Master
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    A .702 RB in a plastic shot cup exhibits an "equator" through the plastic hull, and is snug when loading into the chamber. The load runs out the no choke Hastings rifled barrel with great accuracy. A low load of 32 grs. Blue Dot works for me (I have never seen your gun, so only you can tell if it's safe for you). At above 33 grs. the petals start to tear and yield rotten accuracy. It's my hunting load and Wow, is it effective.
    Last edited by 725; 04-23-2023 at 12:55 AM.

  19. #19
    Boolit Grand Master

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    725... you are using soft lead for those 0.702" RB's aren't you?

    Which shotcups are you using? You probably told me before but my wrinkled old brain leaks a bit so I forgot!

    Are the RB's 0.702" as cast?

    I call my full bore RB's 0.735" but they actually cast closer to 0.740" in ACWW.

    Longbow

  20. #20
    Boolit Master
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    bump for tertle

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check