Chamber wont close

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by smoak, Mar 29, 2003.

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  1. smoak

    smoak Active Member

    Mar 16, 2003
    I reloaded my first batch of 300 ultras and dicovered that they dont close easily in the chamber, it would be almost impossible to hunt with these and requires two hands to open the bolt. I find marks on the shoulder from somthing. I dont know what the problem is. I have 50 brass that were shot and resized, they also wont close in the chamber. So I pulled the bullet from a factory load, then resized it, this one fit! The bolt closed regularly. I did use a spray lube instead of the paste kind I used for the other 50 that do not fit. So is it the lube or the fact that I fired the cases? How can I make the 50 brass that wont fit, fit? [​IMG] [​IMG] [​IMG]
  2. Brent

    Brent Well-Known Member

    Jun 12, 2001
    My 300 Ultra did the same thing, keep adjusting the die down farther until they all just chamber. Mine was pretty ---- tight and camming over some before they chambered fine. Are you using a Redding die too?

    I just neck size with a type S bushing die now, works fine.

    My chamber has .005" runout on the neck at the 2 o'clock position so if I try to insert the case in opposite of that it binds and won't but barely close. Not worth fixing in this factory bbl. I had a big scratch on all my cases at the shoulder like you were saying, this scratch was in the same location relative to the point of maximum runout, that's how I found the exact position of the RO...

    I marked all the case heads on one edge and fired them with this line at the 3 o'clock position to keep track of the MAX RO location, I index them to the same spot from now on so I don't have to FL size them all the time, it works fine, flip one 180 degrees and at this point they won't chamber though.
    Good luck.

    PS: Factory chambers SUCK! [​IMG]

    [ 03-30-2003: Message edited by: Brent ]
  3. Steve Shelp

    Steve Shelp Well-Known Member

    May 3, 2001
    Brent is right and here's why. I think what you are seeing is the case "headspace" is growing when you sized them. These bigger cases will grow on you when only sized a little without true shoulder bumping.
    I've noticed this issue with my 338 Yogi. If you only FL size the case without bumping the shoulder, when the body gets squeezed in, that stress pushes the shoulder forward a little. This can be fixed by slowly screwing your FL die down at little at a time, relube/resize your case, chamber it and see if it's still sticky. If it is turn your die another thousands or so and keep trying until your bolt flops down easily. Lock your die's locking ring in place and you shouldn't have any problems in the future. Being that Brent doesn't see this problem when only neck sizing.... backs up this also, becasue the body isn't being squeezed in and the shoulder doesn't grow becasue of this.
    For the loaded rounds, if you use a bushing die.... removing the decapping pin assembly and the neck bushing and follow the above steps with the loaded rounds. If you aren't using a bushing die, the bullets will need to be pulled and then resize the cases. Becareful..... you are putting a primed and charged case inside a steel "chamber" with a small hole coming out the top. I've done this before without incident... just be aware of the possible problems.

    If you have a Stoney Point Bullet comparitor that will fit over the neck diameter of your RUM cases, you can easy see if this is the issue by measuring a datum point anywhere on a fired/sized and fired/not sized case. I believe you will find the shoulder is longer on the fired/sized case by a thousnads or more after sizing with your dies setup the way they are now.

    That would be my edumekated guess based on experience anyway [​IMG]


    [ 03-30-2003: Message edited by: Steve Shelp ]
  4. 4mesh063

    4mesh063 Well-Known Member

    Dec 8, 2002
    Hey Smoak,

    1-How hard did the bolt open the first time?
    2-Are you removing all the lube from your cases before firing them.
    3-Do you have a piece of tube to gage the brass with.

    If the bolt opened hard, you need to check either the load being too hot, or lube on the cases allowing too much stretch, or both. If you don't wipe your cases completely clean, and then clean your chamber so no oil is in there, you will be allowing the case to move rearward when firing and stretching the cases. If memory serves, a remington action will stretch a smidgen over 3thou. (that's your shoulder movement). The streach is done under great pressure (obviously) and is mostly not subject to rebound. Your cases WILL rebound when resizing so you have to go a bit too far in order to end up with a case that will fit in the gun. If you have a 22-250 case or similar, cut it off with a hacksaw about 1" long. Now trim it in a trimmer so you have a real nice face on it. Deburr it. Place it over the mouth of a case that fits nice in your gun and measure the length. This will give you a number to shoot for when resizing, and will be a datum on the 30deg angle (or whatever that thing has) which is the part that can't really be measured easily. Now set up your dies to give you a case that fits that dimension. Try to measure as close to the shoulder/body junction as possible as this is the hardest part to move without radiusing. The Neck/shoulder moves easy, but doesn't help your problem at all.

    If you begin having trouble with some cases not sizing the same as others, it's because they have work hardened and now are springier. (They rebound more) Anneal the neck and shoulder VERY SLIGHTLY and they will form beautifully with far less effort. I'd say not more than 2 sec spinning under the torch, and no water.

    Also keep in mind, resizing .001 is a lot harder than .010.

    If you oil your chamber, be sure to get ALL of it out of there before shooting.
  5. c east

    c east Well-Known Member

    Jan 2, 2002
    I have a p-14 enfield that does the same thing.No matter what I do Factory chambers and resizes nicely..I bought a bunch (500)of 300 RUM onced fired..none will chamber..I ground of the bottom of a RCBS die and moved the shoulder back ..Still no good...I blackened the case and there are scratches the entire lenght...Bought new dies still no good..It is either use all new brass and sell the 500 trimed and primed brass or polish the chamber to a larger size...Any thoughts?
  6. BountyHunter

    BountyHunter Well-Known Member

    Jun 13, 2007
    I have seen a similar problem and the problem was traced back to pushing the shoulder back too much. It seems you can push out the side of the shoulder case body junction. Gives hard closing and you think shoulder is not being pushed back, when in fact it is being pushed too much.

    Best way to find out and adjust is to carefully measure each case. Get a stoney point comparator tool with the shoulder comparators that measure the amount you push back. If you have a gun chambered, have your gunsmith take a barrel stub and make you a "shoulder bump gauge". Any good LR/ik BR gunsmith knows what it is.

    You should keep good records of shoulder location on virgin brass, once fired and just where it starts getting hard to close.

    Take cases that are hard to close (no need to load bullets, you will feel them)

    Take a candle and smoke shoulder and neck on a lubed case. for this I use Imperial size wax lube

    Back die way up, then start down. Watch marks on neck as you come down. Might have to refresh smoke occasionaly until you start hitting the shoulder.

    Keep coming down until you see smoke smudged on shoulder.

    Take another case, confirm hard to close in gun, measure location of shoulder. Smoke, resize, clean case and remeasure shoulder. Check in chamber to see if it closes.

    You want .002 shoulder bump back ideally to keep case close to max size for chamber and avoid overworking the brass.

    It works best if you remove the firing pin and spring in the bolt, to get a better "feel" on closing bolt.


    [ 04-04-2003: Message edited by: BountyHunter ]
  7. 4mesh063

    4mesh063 Well-Known Member

    Dec 8, 2002

    I'm really surprised, another RCBS Die user who cannot get thier cases in the gun! If there's 1 constant in the universe, I think that's it.