Do I need to neck turn?

PinesAndProjectiles

PinesAndProjectiles

Formerly MinnesotaMulisha
Full Member
Minuteman
    • Jul 30, 2013
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    #1
    I have a 6mm Creedmoor. I do not know what the neck diameter in my chamber is, but a fired piece of brass is .274" - .2745" outside at the neck. So I'm leaning toward it being .275" to .2755"

    Initially, I am sizing down Peterson 6.5 Creed brass, using a Forster FL sizing die, which after sizing, measures .272"

    A loaded round measures .2735 to .274 inches at the neck, leaving me .0015 to .002 thousandths of neck tension.

    This leaves almost nothing for clearance in the chamber.

    Do I need to neck turn my brass?
     
    #4
    Are you not pushing the shoulder back or not back enough and its a case headspace issue? Have you marked the bullet, case neck and shoulder with a sharpie? Where is it hitting.....Your neck diameter with a loaded bullet is pretty consistent. If its only happening on 1 every 20 then it sounds like a case headspace or COAL issue hitting the lands.
     
    #5
    No, I purchased 300 pcs of new 6.5 brass, then FL sized them to 6 Creed and in doing so, I made sure I didn't bump the shoulders at all. I plan on making up some dummy rounds tonight so I can sharpie them and look for witness marks.

    I'm loading 105 Berger hybrids .020" off the lands. I would hope that one lot of Bergers wouldn't vary .020".

    I did not outside chamfer the case mouths, and am wondering if some of them may have a ding in them and it is what is catching in the chamber.

    Thanks for the help, @padom. I appreciate it.
     
    #6
    Do you have a once fired piece of brass that you measured case headspace before you converted this brass? Did you ensure the shoulders on the converted brass were 0.0015"-0.002" back from your fired case headspace?
     
    #7
    I do now. The barrel is new and I started off with new brass so I had nothing to gauge off of. I measured the new brass with a headspace comparator before I FL sized it and made sure the shoulder didn't move. I will measure my fired brass and compare it to the new brass after work and post up my findings.
     
    #10
    MinnesotaMulisha said:
    I cannot slide a bullet into a fired case.
    Click to expand...

    I don't think this is a headspace issue, or something that you should be going by bolt close feel on since the neck is such a small area that you would not feel interference in the same way that you would with shoulder bump.

    With your loaded round neck OD measuring within a half a thou of fired brass neck OD, combined with the fact that you can't easily slide a bullet into a fired case, I would be neck turning if I were in your shoes.

    You might not be hitting pressure issues now, but if there was any additional interference from dirt or carbon build up you are starting to get into dangerous territory where the case cannot easily release the bullet.

    I'd probably skim the necks down to the point where you were at roughly .272- .2725 for loaded round neck OD. That would give you 0.001 clearance per side all the way around the neck.
     
    #11
    The other step I would take is reach out to your gunsmith and ask them what your actual chamber dimension at the neck is. They should have that from the reamer specs. That might give guidance too as to whether neck turning is really needed.
     
    #14
    It depends, other 6mm cartridges run chamber neck OD in the .272-273 range so it's not unheard of. For example my 6BR based cases are loaded neck OD of around .2685 with Lapua brass. I'm sure there are larger chambers out there though, from a quick google search of 6 Creed reamer prints. Larger chambers likely were done to accommodate people sizing down 6.5 creed brass but not wanting to neck turn.

    Knowing your chamber dimension at .2735 I would definitely neck turn. Not safe to shoot as you've got it currently set up with brass larger than your chamber neck.
     
    #17
    padom said:
    Really? I can't slip a bullet in by hand in multiple different bolt guns of mine..
    Click to expand...

    I guess that depends on whether it's a condition of the brass resiliance/springback vs clearance in the chamber. If you've got the chamber clearance then no problems. I've had brass come out of a .272 neck chamber on the first firing at .269 fired case with a tight fit trying to slide in the bullet. That's a brass issue and not a chamber issue, but I knew my chamber reamer neck OD so I wasn't concerned.
     
    #18
    Correct, I know my clearance which is .003 -.005 on those rifles and bullet is a hard press fit on fired brass. I'm just saying just because you can't press a bullet into fired brass doesn't mean there's a neck diameter issue.
     
    #21
    MinnesotaMulisha said:
    I was hoping to avoid neck turning as I’ve never done it before. Thanks for the help!
    Click to expand...
    Get your gunsmith to run a finish reamer into the chamber, to bring the neck up to specs, so you don't have to neck-turn. A tight neck should only be present when the owner requests it, not by accident, or due to a worn reamer. I think it is worth the effort to learn how to turn necks, but it changes your sizing die requirement. Your standard sizing die may not compress the neck of a neck-turned case enough to hold a bullet. This is not an issue for those who use the Lee collet/mandrel die, but it's frustrating if it happens, and you don't have the Lee collet die, or a smaller bushing for your bushing set-up, if that's the way you size necks.
    Padom obviously (based on his previous posts and shooting skills) knows what he's doing; the rest of us need to turn our necks if a bullet will not fit in a fired case. Get your chamber properly reamed. It may have been cut with a worn reamer, or with a tight-neck reamer, which you did not request. Some gunsmith shops use tight reamers, then tell their customers to ONLY fire factory ammo. That's because reloaded ammo may run into an issue such as you are describing.
     
    #22
    You might request the loaded diameter of Hornady 6 creed brass from a fellow member if you're not keen on neck turning, just to see how it measures out.
    Unless the reamer was specifically designed as a no turn with necked down brass, having to turn is not unusual at all. A Forster handheld and the appropriate pilot aren't horribly expensive. I like a minimum of .002, but preferably .003 total clearance for a gun that gets used.
     
    #25
    padom said:
    Correct, I know my clearance which is .003 -.005 on those rifles and bullet is a hard press fit on fired brass. I'm just saying just because you can't press a bullet into fired brass doesn't mean there's a neck diameter issue.
    Click to expand...

    +1. At .003 clearance or less you may not be able to slip a bullet in so that's not really a reliable method. Extreme pressure, popped primers, expanded case heads, deep ejector marks, heavy bolt lift, vertical stringing, etc at minimal loads is pretty reliable though lol.
     
    #26
    Without starting a whole new thread but asking the same question of whether I need to neck turn or not. Custom 7mm STW, bullet will not slide into fired case. Fired case neck measures .315. Considering brass spring back I would consider the chamber neck to be .316. Loaded round measures .314. My other custom STW has a fired case neck that measures .318 and of course a bullet slips into a fired case easily. I must say I've had a little issue with consistant accuracy in the first gun and I wonder if it's been due to neck tension. What do you guys think? Neck turn for the tight gun or not? What is the ideal neck clearance .003-.005? Thanks
     
    #27
    doc88 said:
    Without starting a whole new thread but asking the same question of whether I need to neck turn or not. Custom 7mm STW, bullet will not slide into fired case. Fired case neck measures .315. Considering brass spring back I would consider the chamber neck to be .316. Loaded round measures .314. My other custom STW has a fired case neck that measures .318 and of course a bullet slips into a fired case easily. I must say I've had a little issue with consistant accuracy in the first gun and I wonder if it's been due to neck tension. What do you guys think? Neck turn for the tight gun or not? What is the ideal neck clearance .003-.005? Thanks
    Click to expand...
    Pulling 5 pieces of brass out of your batch and turning them for 3 or 4 thou clearance should tell you if not getting a clean release is the issue. The only round I shoot that compares with your STW is a 300WM, and I think my clearance in that gun is 4-5 thou. Still shoots like a mofo, just works the brass a bit more.
     
    #28
    doc88 said:
    Without starting a whole new thread but asking the same question of whether I need to neck turn or not. Custom 7mm STW, bullet will not slide into fired case. Fired case neck measures .315. Considering brass spring back I would consider the chamber neck to be .316. Loaded round measures .314. My other custom STW has a fired case neck that measures .318 and of course a bullet slips into a fired case easily. I must say I've had a little issue with consistant accuracy in the first gun and I wonder if it's been due to neck tension. What do you guys think? Neck turn for the tight gun or not? What is the ideal neck clearance .003-.005? Thanks
    Click to expand...

    If it’s custom then your smith should be able to supply you with a print or measure the reamer and eliminate any speculation which is absolutely the avenue you should take.
     
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