.6.5 MM X 284 Build?

Discussion in 'Gunsmithing' started by kc, Sep 29, 2010.

  1. kc

    kc Well-Known Member

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    My youngest brother got his hands on a .3006 action from a Remington 700 and wonts to build a 6.5x284 and will be shooting a 140gr Bullet or as light as a 120gr. When he builds this rifle
    on a long action what should the OAL be? he read in a Magazine that its better to use a long action if you are making your own loads. and if you are shooting a 140gr Bullets.
    kase
     
  2. Derek M.

    Derek M. Well-Known Member

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    6.5-284 Cartridge Guide
     

  3. kc

    kc Well-Known Member

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    After reading about this calibre I think he should just stay with the 06.
    Hell I shoot around 500 rounds with my .308 in one day. And I have a 7MM Magnum that needs to be re-bareled. And I dont need the head ake changing or shortening barrels every 700 to 1200 rounds I am not in the buisness of doing every ones work.
     
  4. shortgrass

    shortgrass Well-Known Member

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    Go to "Rifles, Bullets, Barrels, and Ballistics" and read the thread on over- bore cartridges by fiftydriver. I wouldn't make any choice on what one artical in a magazine or one post on the interdnet says. It's opinion,,,, not fact. Do more research, then make up your own mind.
     
  5. Derek M.

    Derek M. Well-Known Member

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    I'm assuming that is a bit of embellishment? If you happened to be shooting for 12 hours, that's one shot every minute and a half to minute 45 seconds nonstop. No time for bbl cooling.

    Depending on what your brother wants to do, the 6.5x284 may be a better caliber for his purposes, or it may not be. JB at Accuflite has stated that his custom Sako 6.5s go 8000 rounds or more with his LW barrels. The key is to not overheat the bbl.
     
  6. NesikaChad

    NesikaChad Well-Known Member

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    I build quite a few 6.5's for folks. Long actions definitely make life easier and better facilitate the "lawn dart" 140+ grain bullets.

    Great cartridge, great accuracy, easy to load, reasonably good barrel life, and easy on the shooter's shoulder. Your going to get between 1200 and 1500 rounds out of your barrel. You may be able to stretch this out a bit if its a hunting gun as the accuracy requirement isn't as critical as it would be in a full effort target gun. Dont' expect much past 1500 though. The throat in the barrel takes a lickin. Anything that has to deal with exposure to 50+ thousand pounds and flash temperatures of over 6000F isn't going to tolerate it forever. One has to appreciate that powder is abrasive also.

    If your a shooter (I mean a REAL shooter) then you've already accepted that barrels are consumables. They are no different than tires on a race car. Increases in performance mean something has to give somewhere else. In this case its the barrel. If it costs 500 a year to shoot a gun capable of the performance a 6.5/284 can deliver I personally think it's acceptable. It's 42 bucks a month. . . (300 barrel and 200 to chamber it)

    To put it in perspective I own a 300-338 Lapua Magnum set up to shoot 125 grain Nosler ballistic tips. 4375fps is my muzzle velocity on a 34" barrel with a 12 twist. I don't shoot the gun often but I don't expect the barrel to last beyond about 700 rounds. It costs money to play hard. . .

    I still think its great choice.

    Regarding your question:

    With a long action you have some room to enjoy the benefits this cartridge offers. For anything less than a dedicated bench/F class gun I think it best that a guy minimizes the drama at the reloading bench. That being said if at all possible you build the gun around the cartridge. The whole point of a 6.5 is to use a bullet with a .6+ BC in most instances. This means 140+ grain bullets which are quite long. Taking advantage of the 284 case capacity means having the bullet's boat tail/bearing surface intersection set just above the neck/shoulder junction. This maximizes the powder charge and avoids the added task of having to potentially deal with (meaning ream out) the "doughnut" that's common at the base of the neck in a lot of cartridges. (Meaning the ID of the neck decreases slightly due to how the brass is made)

    If the tooling (chambering reamer) is made accordingly it'll time everything up so that the ogive/bearing surface tangent on the bullet is at the appropriate distance (whether it be in or out slightly from the lead in chamber) to promote good accuracy and good overall function of the gun. (I don't encourage jamming a bullet deep in the lands in a working gun as I've seen in too many instances that if the neck tension isn't sufficient the bullet has a nasty habit of staying put and making a real mess out of the gun with powder going everywhere when the case is extracted)

    Basically, use the long action, load the bullet so that the boat tail stays just above the base of the neck and get to shooting. Target velocity out of a 28" barrel will hover around 3100fps with 140's. Any faster with thin jacket hunting/target bullets will often result in jackets going one way and bullet cores going another. One has to remember RPM is a function of velocity and twist rate. With this cartridge the bullet is spinning at 279,000 rpm when it leaves the barrel (at 3100fps) That seems to be the threshold from my experience.

    In some instances it is possible to slow the twist down and make up the difference with velocity to get the rpm back up so that it'll stabilize to get good accuracy, but then things become a bit more "moody" and the reloading practice has to be diligent and careful.

    8 ROT to 8.5 ROT is typically most popular for the heavy 6.5 bullets.

    Another opinion held by some is to shy away from a single point cut rifle barrel as sometimes the geometry inside the bore is invasive on the jacket. A polygonal, R-5, or other variant may work better as it'll "nibble" on the jacket rather than "bite" and avoid the potential stress point along the jacket that may encourage a bullet to disembowel itself. I personally haven't seen this but it doesn't mean it isn't viable. The last two I did were both on cut barrels (Mark Chanlynn and a Kreiger) and both shoot exceptional. I however didn't try pushing the velocity so who knows?

    A good starting load:

    140 grain Lapua, Sierra, or Berger
    55 grains of 4831 SC
    Federal 210 primer
    Lapua case


    Good luck on your project.

    C
     
    Last edited: Sep 30, 2010
  7. Kevin Cram

    Kevin Cram <b>SPONSOR</b>

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    I've had the pleasure of working with the 6.5 - .284 cartridge in my own personal guns for over 10 years now. For 1000 yard target accuracy it's good for 600-800 rounds. Now that's shooting 10 shot sub 5" groups at 1000 yards with about 6 sighter shots prior. The barrel gets pretty hot. For hunting accuracy I'll let it go for up to 1200 rounds. Set the barrel back an inch or so and get another 600 rounds out of the barrel. I've never been able to get any sort of accuracy out of pushing the 140g class bullets much over 3000 fps. Chad's a little hot on his load and a little high on velocity especially for a starting spot from my experience. 51g - 53g of H4831SC, a Fed 210, a 140g A-Max or SMK, in Lapua brass will get you between 2950 and maybe a tinge over 3000 fps. The 6.5 - .284 is an exceptional round for accuracy. As for your original question about OAL. I run a 140g A-Max with the boat tail junction seated at the neck/shoulder junction and my measurement from tip of bullet to base of case is 3.125" I've shot the 6.5 - .284 in Kreiger, Brux, Shilen, Hart, Obermeyer, Broughton, Bartlein barrels. I've used 1-9 and 1-8 twist and could make the gun shoot under 1/2" at 200 yards all day in any of these barrels. The Obermeyer barrel is the unique one. Boots runs a tighter bore than any other .254" He's getting 2000 plus rounds out of his 6.5 - .284 and still staying competitive at 1000 yards with it. The only oddity I've found is that they all liked to shoot dirty. It normally would take 10-15 fouler shots for the accuracy to settle down, but then I could get close to 100 rounds of shooting with out cleaning before the accuracy went away. A good cleaning, some fouling shots and I was good to go again. I know it goes against everything I've learned about keeping them clean but hey it worked. I shot 1000 yard benchrest with the Hoovers (kings of the 6.5) and learned quite a bit about how good and versatile the 6.5 - .284 really can be. I wouldn't over look the 6.5 - .284 for long range hunting wood chucks and varmints out to 1000 + yards and deer size game out to 800 yards. The right chamber, good brass prep and loading technique is the key to top performance in this round.
     
  8. NesikaChad

    NesikaChad Well-Known Member

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    I've received a note or two from folks suggesting that the load data I posted for this cartridge is a bit on the hot side.

    I've not experienced this, but in the interest of safety I would agree that it is better to initially tone things down. This load was given to me during a conversation with Middelton Tompkins almost ten years ago. Anyone involved with NRA match rifle/1k shooting almost certainly knows that name. I've known Mid since I was 19 years old and trust him completely. I never questioned his advise and in my experience the data he provided me has never steered me wrong.

    My personal rifle chambered in this is on a Kreiger 4 groove. The reamer is nothing special, just a minimal spec chamber with a throat length appropriate for the bullet weight. The velocities I quoted are real. I stand behind that. I live at 3500ft elevation. Maybe that has something to do with it. All the test groups and subsequent load development work were shot inside COR BON ammunition's fully instrumented test tunnel about 5 years ago. I would have to think their instrumentation didn't give me bad #'s.

    Hope this helps.

    C
     
  9. JUDD

    JUDD Well-Known Member

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    I personally shot 3 of Kevin's 6.5-284's he had. They all shot lights out and saying he knows this cartridge an uderstatement.

    His heavy gun shoots better then any gun I EVER had the privilege of shooting.

    You need help with a 6.5 or want one built Kevin knows his stuff.
     
  10. Derek M.

    Derek M. Well-Known Member

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    Regarding Kevin's comment and Obermeyer bbls, I have one on a 308. I seem to recall Boots telling me that there is 10 thousandths height with his lands. I don't know a lot about barrels but that alone coupled with the canted or Russian style land seems like it would be of benefit and make the barrel last longer, especially if you had it long enough to where you could set it back if needed.

    The first 5 shots out of my 308 were with 210 Bergers (for break-in purposes) with a mild charge of IMR4064. The group was barely larger than a dime. This is with cleaning after every shot of course. I kept going and got to about 18 rounds when I stopped the cleaning after every shot process.

    I've emailed him a couple of times asking about getting a couple of 6.5 barrels if possible. I think right now it is still impossible. I was lucky to obtain 2 thirty cal barrels!
     
  11. Kevin Cram

    Kevin Cram <b>SPONSOR</b>

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    Obermeyer barrels are sometimes hard to get. I have a supplier that usually can get me Obermeyer barrels when asked nicely. Chad your 3500 ft. elevation is probably why your getting faster velocities than most of us.