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    • #24665
      Fishman
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      My 300 blackout has a tight throat. So tight that every bullet design I’ve tried, and that is several, needs to be deep seated to chamber. PC is a no go because it fattens up the nose too much.

      Now I’m no gunsmith, but I have done some minor things and can follow directions. I “think” I need a .308 throat reamer to open it up a bit. If someone could point me toward the correct tool as well as a source of directions on how to use the tool correctly, I would appreciate it. I suspect a few others have had this issue so coming up with a solution would help others. I realize I could just buy another barrel but it might have the same issue.

      If I’m barking up the wrong tree, just tell me. I’m listening.

    • #24666
      Goodsteel
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      You’re not barking up the wrong tree.
      Look here for a place to rent a throating reamer:
      http://www.reamerrentals.com/searchresults.asp?cat=25

      Educate yourself on how to use this tool. It takes a certain amount of feel and a deft hand. It’s all good unless you really don’t care what it feels like and you ream your throat too deep. The barrel may still group for you, but you’ll never touch the throat if you go too far.

    • #24675
      Fishman
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      Thanks for the link and the advice, Goodsteel. A dummy round or three sounds like a good idea on this, maybe with 2 or 3 chosen designs. That rental cost isn’t bad, even with the insurance. I’m going to try and get to this in early March and update this thread.

    • #24684
      Artful
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      Have you done a chamber cast or any other tests to determine where the interference is?

      Cerrosafe Chamber Casting Alloy

      http://ads.midwayusa.com/product/462291/cerrosafe-chamber-casting-alloy-1-2-lb?cm_mmc=pf_ci_ebay-_-Gunsmithing+-+Tools%2C+Jigs+%26+Fixtures-_-Cerrosafe-_-462291&sdc_id=eBay

      http://www.300blktalk.com/forum/viewtopic.php?t=96887


      One thing to keep in mind is that various reamers have been used in the past (300 Whisper, .30/221, 300-221, etc)

      Here is a site all about 300 blackout

      http://www.300blktalk.com/forum/view…87d691361bb2ac

    • #24688
      Fishman
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      Artful, I have not but that’s a good idea. If I’m going to modify the throat, it would be best to know exactly what I have first

    • #24692
      Anonymous
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      Do you have Bullet issues or Brass issues
      I am using converted brass and when I measure the 223 brass neck if larger than .010/.0105- 0.011 I DO NOT CONVERT IT
      If I am checking the brass I might form 1 or 2 and measure the shortened brass
      I did do about 20 that 223 neck thickness was .012 and when it was made in to blackout neck measures 0.015-.016– > not gona work with cast and still not sure on the jacket loads (brass is set aside)

      Using the RCBS 165 sil / 180 sil and a copy of the lee 155g sizes to 0.30105

      I find it is quicker to sort neck thickness by lots/ headstamp than by turning necks for thickness

      I do segerate the thicker neck stuff to jacketed loads only

    • #24695
      Harter
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      Your barrel finish will make a difference here also . If you got a white barrel no problem but if it is chrome lined yu have a jacketed only .Melonite presents a similar situation it amounts to a nitride finish which is corrosion resistant but also a medium temperature case hard9. . It might not hurt anything to change the cut but I will almost certainly result in weird wear.

    • #24703
      Fishman
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      It is definitely a bullet issue, as their is damage from the throat transferred onto the bullet. Also I have had bullets pulled from loaded rounds that would not chamber all the way. These are designs that are not bore riding (think lee 155 and similar) so I’m thinking the throat is pretty well non-existent. I purchased my brass from Grumpa and it is first rate.

      I don’t know if the inside of the barrel is melonited, but I know it isn’t chromed. I bought one of the very first Diamondback 300 blk rifles on the market. My communication with Diamondback was less than satisfactory. Their CS guy was unhelpful and a smart — to boot. But that is a good thing to check and I’ll do some research.

    • #24711
      Harter
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      Does the barrel have e black Matt finish that wears to a flat polish like black chrome tools ? That would be Melonite. If it is just black parkerizing you should be ok to ream.

    • #24715
      Smoke4320
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      Fishman I would suggest you contact goodsteel about him fixing your barrel..
      he does this for a living will do it right and if damaged will make it right .. and probably at not much more cost than the reamer rental and return
      Just a thought for you

    • #24800
      popper
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      7.62x40WT – not BO. Case is longer and neck is shorter. I use range pickup & once fired factory BO brass. I neck turn all as even factory BO is too big for cast. I use Lee dies, 0.307 (?) stock plug. My first upper was Diamondback – was supposed to be 1:9 but is 1:7. Shoots OK but not what I wanted – it’s chamber is loose. replaced with 1:10 and it’s tight. The SAAMI chamber spec is, well, not very detailed. You don’t say what weight boolit you want to shoot – but I would recommend NOT throating it. Get a mould that has a smaller dia. nose to accommodate the PC or use some high temp epoxy paint in the nose portion of the mould, it works & cheap to try. I try for a 0.330ish neck dia. for LOADED rnds but found that even the Lee FCD can buckle the neck – so I mic the neck after crimping now. You also need to make sure your seater doesn’t bulge your boolits when loading. IMHO, only ream the NECK if the groove/throat is large and neck is samll. – which needs a custom reamer. I turn the necks with the case in my drill chuck and handheld turning tool. Doesn’t take much time and only do it once – so far.
      Tim – please increase default font size and darkness for us older folks?

    • #24802
      Fishman
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      Smoke, I have contacted Goodsteel and will see what he says. Thanks for the suggestion

      Popper, I tested a bunch of different moulds and the NOE 309413 (I believe) looked like the ticket, although with the pointy nose it wouldn’t be much of a hunting bullet. 150 grains with a bore riding portion of .300-.301. I loaded about 40 and they worked ok. So I cast up about 500 and loaded 300 rounds. Imagine my dismay when most of them didn’t work. Turns out the nose on the second batch ran large enough that it would jam in the throat and stay there. I tried PC on the lee 155 in a fit of unbridled enthusiasm soon after I started casting for this gun and as you can imagine that was a no go as the already fat nose got fatter.

      I really do appreciate all of the suggestions and apologize if my frustration with this barrel is coming through in my posts.

    • #24815
      popper
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      I started with the 31-165A for the AR10, worked great, then to the 165C for PC. I borrowed the nose shape for the 142C but made the ogive radii longer to fit the BO + shrank the nose dia. for PC. It isn’t a bore rider but the front band goes in ~0.1″. Every once in a while I get that band scuffed when chambering. A long bore-rider would be a problem. For the money, Accurate gave me a custom Al. mould with fast delivery. Nothing against NOE, their turn around for custom was just too long. BO chambers/barrels seem to be all over the place – I did a 145C that worked fine in the 1:7 barrel. I figure it’s cheaper to get a custom mould than rework the gun.

    • #24831
      Fishman
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      That would have made sense before I loaded up 300 rounds thar won’t chamber 🙂 To be fair, I did test it and the design doesn’t have a long bore riding design, rather it is a spitzer. This barrel is just a tough one.

      Part of me wonders if I shouldn’t just sell the barrel to a guy who likes to shoot jacketed 125’s ( it works great for that) and get a barrel of known quality with a slower twist since I want to shoot designs 160 gr and lighter. I’ve gotten a lot of info and have to guard against analysis paralysis.

    • #25224
      popper
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      I got Mcgowen to make me a barrel for this, 18″ 1:10. Works great when my reloads are right – to 2100 fps so far. Got to try it with HiTek this week. If I did it again I might pull the front band into the ogive or make the angle a bit less sharp. longer/heavier GC version works great in 308W, 2700 fps in 24″ 1:10. Stepped base is self aligning for seating, like a bevel base but accurate bevel. Left a tad of GC shank else there would be a sharp edge in the mould that probably wouldn’t last long.. I actually spec’d the dia. smaller than the 0.312 shown as my bore is tight. The groove is ot a L.G. but I did load a couple with Mazzola oil and it shot fine, same load.

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