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Thread: My 300 blackout doesn't like cast

  1. #1
    Boolit Buddy thumbs's Avatar
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    My 300 blackout doesn't like cast

    I started loading my powder coated lee mold 155gr (actually dropped at 165) only loaded five and tried to cycle the in the rifle. Nope got one or two to function but that was it. Checked the brass with my case checker it worked out fine. I then measured length and the neck diameter of the brass and again to spec or a touch under. After quite a bit of fiddling around trying to figure it out I decided to load a few dummy 135gr Hornady SP bullets. Loaded them to spec and they ran fine. The I put the two bullets together and of course the ogive on the cast it a bit longer. The Hornady tapers pretty fast while the cast is more or a pencil kinda thing. Of course its longer being 35grains heavier. Anyway I checked and rechecked everything I can figure and can't seem to figure it out. The cast won't go into battery but when I check the bullets I don't see any rifling marks on the bullet. Any ideas??

    thanks

  2. #2
    Boolit Master
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    try sizing them down as cast dia runs about .312-.314 vs 308 or 310 dia Js

  3. #3
    Boolit Bub
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    I haven't had time to do any accuracy testing yet but did work up a load over the chrono of Lee 230 grain cast and coated. I sized to .309 and they have ran in several different guns

    Sent from my moto e5 cruise using Tapatalk

  4. #4
    Boolit Master
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    I’ve always read that Lee 155’s run in everything. I just got a .300 bo so I don’t know first hand yet...


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  5. #5
    Boolit Buddy thumbs's Avatar
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    turtles

    Thanks. They are sized to .309. Long story but the short of it is "chamber length" LOL Who would have thunk it. Anyway I was taking my lead from Elvis Ammo. Nothing wrong with him but his chamber is a bit longer than mine apparently. My chamber runs 1.975. He set his OACL to around 2.335? I think. I was using his numbers and it wouldn't work. Anyway made up a case for my chamber gauge and found the problem. For my chamber I was way to long. I made up some dummy rounds with my cast and set the OACL to 1.965 and they ran perfectly. Even in my mags. I only dummy loaded 5 but they ran smooth. Didn't do that last time with the cast.

    Thanks for the help its been a long day LOL

  6. #6
    Boolit Master
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    So I had an issue with the neck/throat junction on one of my barrels...the brass was inside spec but still short enough that the pressure was causing the lead to "flow" into the tiny space between the case mouth and the chamber throat causing little lead rings that...after a round or two would cause the rounds to not go into battery. Give that throat a good scrub with a bronze brush and see if you find lead inside the throat.

    It caused the rounds to not go into battery and leading until I trimmed up a batch of brass a bit longer that bridged that gap and no longer allowed lead to flow into that area just ahead of the case mouth. If you have some casting flux or cerrosafe , making a chamber cast will help you know where that neck/throat junction is on your rifle. Be careful not to leave brass too long or you get some issues with pressure or not going into battery for other reasons

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  7. #7
    Boolit Buddy thumbs's Avatar
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    One more question. I never loaded cast for rifle before so I know not of what I speak. For these bullets to function in the action of my upper I have to set the bullet about .0100 below the bottom of the neck for the case. In other words the base of the bullet is about .0100 below the neck into the case. Is this safe? Is there any reason the bullet cant extend into the case a bit. That is the only way I can get the proper COAL.

    John this is a brand new upper not one round through her. When I put the case on the chamber gauge I can hear a metallic tap when I use the gauge up and down with only the case on the gauge not bullet. The case appears to be sitting the same way as the brass in my 5.56 chamber. The action seems to function properly, just manually running the action. Before the round would not go into battery. That problem may rear it ugly head once I get to the range and run some rounds through her. LOl

    thanks
    Last edited by thumbs; 07-18-2019 at 06:34 PM.

  8. #8
    Boolit Master Boolit_Head's Avatar
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    If it's brand new don't even worry about function until you get at least 100 rounds through it. The parts have to get a bit of function to them to loosen up a tad and work right.
    On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning may be squeezed out of the text or invented against it, conform to the probable one in which it was passed.

    Thomas Jefferson, letter to William Johnson, June 12, 1823

  9. #9
    Boolit Buddy thumbs's Avatar
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    That was the problem I couldn't get it to go into battery from the get go. I couldn't fire one round if my life depended on it. I was checking to make sure it would at least cycle the rounds when I got a chance to take it to the range. The way it was I would have turned around an gone home with no rounds fires. LOL

  10. #10
    Boolit Master Boolit_Head's Avatar
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    Check it with factory rounds for a sanity check for the first time. Cuts out the errors you could have made on the reloads.
    On every question of construction let us carry ourselves back to the time when the Constitution was adopted, recollect the spirit manifested in the debates, and instead of trying what meaning may be squeezed out of the text or invented against it, conform to the probable one in which it was passed.

    Thomas Jefferson, letter to William Johnson, June 12, 1823

  11. #11
    Boolit Buddy thumbs's Avatar
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    Actually I was going to buy a box this afternoon but none to be found. Didn't have time to look very hard. I'll probably get to the range before I can find factory ammo. Always good to have around though.

  12. #12
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    Load them to 2.25" OAL and see if it works. That is a standard ar15 mag length to feed from the mag. You are limited by what the inside of the mag allows.

    If it does not chamber then start seating deeper till it does.

  13. #13
    Boolit Master

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    I suspect the nose diameter, in front of the driving bands is to big to go into the rifling. Had that problem with mine, the barrel had very little leade. I switched to a 152 SP cast and it works like a dream!

  14. #14
    Boolit Buddy thumbs's Avatar
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    Quote Originally Posted by tomme boy View Post
    Load them to 2.25" OAL and see if it works. That is a standard ar15 mag length to feed from the mag. You are limited by what the inside of the mag allows.

    If it does not chamber then start seating deeper till it does.
    When I measured the chamber with the chamber gauge it was 1.975" now that was as far as I could get the 165gn Lee cast into the chamber. I cant get 2.25" COAL to even come close to going into the chamber with those bullets. Unless I am doing something wrong and I really don't know what it is. The 130 gn Hornady's will seat deeper but they aren't as long.
    Last edited by thumbs; 07-18-2019 at 09:58 PM.

  15. #15
    Boolit Buddy thumbs's Avatar
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    Quote Originally Posted by mattw View Post
    I suspect the nose diameter, in front of the driving bands is to big to go into the rifling. Had that problem with mine, the barrel had very little leade. I switched to a 152 SP cast and it works like a dream!
    Actually that is exactly the problem. I can get it to cycle but I have to seat the boolit so about .0100 of the boolit base is below the neck. Is that a problem??

  16. #16
    Boolit Grand Master popper's Avatar
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    Neck on bo isn't really a neck. No problem.
    Whatever!

  17. #17
    Boolit Buddy thumbs's Avatar
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    Quote Originally Posted by popper View Post
    Neck on bo isn't really a neck. No problem.
    Popper are you saying the boolit extending into the powder area below the, "neck"or whatever it is, isn't a problem?

  18. #18
    Boolit Master

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    Quote Originally Posted by thumbs View Post
    Actually that is exactly the problem. I can get it to cycle but I have to seat the boolit so about .0100 of the boolit base is below the neck. Is that a problem??
    With the 300BO, I have not seen an issue with the base of the bullet below the minimal neck. I am using the NOE 152 (on the left) the others are a light Lyman designed for the 30 M1 carbine. I really suspect that the diameter of the nose, just ahead of the case mouth is where your problem is. The NOE design has a reduced neck starting at the end of the top driving band, memory may be wrong but I think the diameter of the nose is .301 or .302. The Lyman 311414 would also work well, same nose design.

    Click image for larger version. 

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  19. #19
    Boolit Buddy thumbs's Avatar
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    Yes the Lee 155gn is a bit cylendricial and has a rounded nose rather than a pointed one. I think this doesn't allow the bullet to push as far forward as a pointed bullet may. In other words the ogive is very much forward. In my case I have to seat the bullet back far enough for the round to cycle in the rifle but because of the oal for the bullet it necessitates the base to extend into the powder chamber. My factory bought bullets, although lighter, chamber fine using publish load data. The 155 Lee because of its shape extends into the powder chamber. I hope I am making myself clear. thanks My bullets are .313 sized at .309
    Last edited by thumbs; 07-18-2019 at 11:55 PM.

  20. #20
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    It is not ideal that the base is in the case body. But, it will not hurt anything. Load some up and go shoot them.

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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