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Thread: Powder coated 300 blackout bullet sizing

  1. #1
    Boolit Buddy thumbs's Avatar
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    Powder coated 300 blackout bullet sizing

    Been power coating for years but never to rifle. I want to start casting and powder coating for the 300 blackout. What should the final sizing be for loading? The mold I will be using is a 155gr .311. What sizer do I need or do I need any?

    thanks for the help

  2. #2
    Boolit Man
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    Slug your barrel, I would size it to. 311 if nothing else. You want consistency if nothing else.

    Sent from my SM-G965U1 using Tapatalk

  3. #3
    Boolit Buddy thumbs's Avatar
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    Thanks. I wonder how much you can size a bullet down. If the cast bullet is .312 and PC it. Can I size it down to .309?

    The reason is I can get a sizers for .309, .311 and .312. I was wondering I if I could size the .312 down to .309? The reason I ask is if that can be down without much trouble I could buy the .309 and increase the size to say .310 or so. I know the jacketed bullets are supposed to be .308 and cast should be .001 to .002 over jacketed. I can't get a .310 and I am afraid maybe the .311 may be a bit large.

    Oh I don't have the barrel yet.

  4. #4
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    The more you size a bullet down the more material you are moving around, Since your PC losing lube groove space is not a problem alloy is also a factor the harder the alloy the harder to size. So you may have to size down some then size down again not doing it in one step.
    But the first thing to do is slug your barrel and size should be based off of that.
    Reloading to save money I am sure the saving is going to start soon

  5. #5
    Boolit Master gpidaho's Avatar
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    My 300 BO AR upper will tolerate .310 but likes .309 better. I have the Lee .311 155gr. and it works ok sized down, powder coated and then resized. Mine prefers the Noe 311-214-FN-CA5 with its tapered nose they feed real slick. Best of luck. the Blackout is a fun round. Gp

  6. #6
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    I played with cast in five different black outs. In AR Bolt and single
    Shot actions. I bought a couple molds borrowed a few others. Cast them hard 100% lino and real soft (10bhn) Most all where powder coated. Loaded both sub and super sonic.

    I found in most guns using LC brass, I needed to neck ream for bullets over 311. (Of coarse all guns are different) Across the board better accuracy after reaming. Most all where better with 311 until the hardest bullets where loaded and these where more accurate when sized smaller but never under 309.

    By and large 130-165 bullets where most accurate NONE where stellar. But two of same rifles would shoot 1/2 MOA with J Bullets.

    I pretty much gave up with cast in the lil BO. I do very much like the round, but these five at least aint very cast friendly.

    Ooh one mold was the LEE 230... ABYSMAL accuracy My Savage 24V in 30/30 shoots them better than the BO ever did!! And it surely shouldn't with its rifling twist. But at least I can and have a way to shoot up what I cast!!

    Hope you have better luck!! I think your good starting with a middle weight My best accuracy was almost 1” @ 50yards with a 165g Spitzer Lyman mold GC’d @ about 1200 fps.

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  7. #7
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    In most cases yes you can size down from 312 to 309 with no real issues.
    If you see any coat flaking at all you have a adhesion issue which needs to be solved first
    Also watch that the bases stay flat a true. Otherwise you should be good
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  8. #8
    Boolit Buddy
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    Slug the barrel then go from there. I have tried every kind 30cal bullet I could get. Lee's 312-155-2r worked best. I sized mine at .310 with 10bhn lead. Most blackout won't chamber anything with a nose much over .305. Powder coating often brings the nose thickness, up to much. We should get a group buy for blk only bullet about 165gr PC only going. Something like this a little shorter with a thinner nose should be great in the blk. http://castboolits.gunloads.com/show...me-Cast-Boolit
    Last edited by Ramson222; 07-07-2019 at 07:07 PM.

  9. #9
    Boolit Buddy
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    [QUOTEOoh one mold was the LEE 230... ABYSMAL accuracy][/QUOTE]
    In my FrankenAR, I shoot this boolit, PC in Eastwood Light Blue and sized .309, over imr 4227. It shoots grapefruit sized groups, subsonic, at 200m all day.

  10. #10
    Boolit Buddy thumbs's Avatar
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    After much playing around getting magazines that work I had some pretty good results with the 300BO. Very very long story but so far the pmag gen 3 seem to work without mods. The gen1 with mods works pretty good but not 100%. Of course the Lancers work great.
    I am using the Lee 155gn mold dropping at 165 and powder coated over 4227 starting load. With the red dot I "can" get one ragged hole at 50yards. Not all the time but pretty much. At 100yards I will have to check again but about 2" with the red dot. The dot takes up the entire target at 100 years, at least a 4" square. Now that's with my 72 year old eyes. LOL Still doing some work with the irons. Haven't gotten them sighted in yet but groups are a little larger than the red dot but still moment of ground hog. Sure is a great little pistol to shoot. Quite a bit of fun. Sure glad I can keep the cost down with the cast boolits 600 rounds at 75 cents to a dollar ain't cheap. Under 15 is doable.

  11. #11
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    I use the Lee 312-155-2R PC'd, sized down to .309 over h110 and get 10 shot 1 hole groups out of an AR pistol

  12. #12
    Boolit Buddy thumbs's Avatar
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    Quote Originally Posted by Conditor22 View Post
    I use the Lee 312-155-2R PC'd, sized down to .309 over h110 and get 10 shot 1 hole groups out of an AR pistol
    Ill try that one also. Have a bunch of 296 around.

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    I bought a lee 309 and its shoots good enough that I never bothered to try anything else. Keep in mind that they can be persnickety in feeding cast and going bigger can cause feeding issues. Ive got 3 300bos I shoot the rcbs 130 in at 309 and id bet any of the three would do 2moa at a 100 yards with scope on it. the two shortys do that at 50 with a red dot and the 16 inch gun with a 1x4 does less then 2 inches at a 100 yards. Keep in mind this is with NO load development at all. First load I tried with wc297. Only other powder ive tried with that bullet is wc820 and it seems to do about the same. 110 I save for my hunting loads using barnes x bullets and that load is scary accurate.

  14. #14
    Boolit Grand Master popper's Avatar
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    Click image for larger version. 

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    New 31-142D Bll coated. Got to wait for the ac 50/50 alloy to set up before loading. Comes out 140gr GCd. Yea, in a hurry and humidity is terrible so no PC yet. Should be able to push them 2200 or so with the right alloy. Looking for 1800 with these soft ones. They drop 309ish & sized to 308. Nose fits fine. Soft alloy through the Lee sizer comes out smaller, no alloy springback.
    Whatever!

  15. #15
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    Quote Originally Posted by Lloyd Smale View Post
    I bought a lee 309 and its shoots good enough that I never bothered to try anything else. Keep in mind that they can be persnickety in feeding cast and going bigger can cause feeding issues. Ive got 3 300bos I shoot the rcbs 130 in at 309 and id bet any of the three would do 2moa at a 100 yards with scope on it. the two shortys do that at 50 with a red dot and the 16 inch gun with a 1x4 does less then 2 inches at a 100 yards. Keep in mind this is with NO load development at all. First load I tried with wc297. Only other powder ive tried with that bullet is wc820 and it seems to do about the same. 110 I save for my hunting loads using barnes x bullets and that load is scary accurate.
    This is exactly the advice you gave me via pm when I went down the 300 blk rabbit hole, worked very well and hoping for same results with the pistol I’m building now.

  16. #16
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    heck back in the 70s and 80s we sized down 460 bullets to 452. Some were very accurate. .003 is nothing.
    Quote Originally Posted by Smoke4320 View Post
    In most cases yes you can size down from 312 to 309 with no real issues.
    If you see any coat flaking at all you have a adhesion issue which needs to be solved first
    Also watch that the bases stay flat a true. Otherwise you should be good

  17. #17
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    hope those are going in a bolt gun because I would about bet my house they wont run in an AR
    Quote Originally Posted by popper View Post
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    New 31-142D Bll coated. Got to wait for the ac 50/50 alloy to set up before loading. Comes out 140gr GCd. Yea, in a hurry and humidity is terrible so no PC yet. Should be able to push them 2200 or so with the right alloy. Looking for 1800 with these soft ones. They drop 309ish & sized to 308. Nose fits fine. Soft alloy through the Lee sizer comes out smaller, no alloy springback.

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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