Re-Barreling a Factory .300 RUM

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Earnhardt, Aug 12, 2017.

  1. Earnhardt

    Earnhardt Well-Known Member

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    My questions are in regards to how to set up the barreling chambering.

    My factory .300 RUM barrel is in the average category when it comes to accuracy...3/4 to 1 MOA.

    I bought a Krieger barrel blank a while back, and the questions I have are in regards to setting up the chamber, and the jump to the lands.
    How do you guys know how to set up the free bore in the barrel?
    With the current factory 300 RUM barrel I have, the jump to the lands is so far, I'm wondering if I'm measuring it correctly. And with the minimal reloading experience I have, it's tough for me to figure out a load set up with the VLD bullets I'm using, when the jump to the lands on this factory barrel is so long.
    When you guys have a new barrel set up for your gun, do you have one or loads figured out from prior reloading experience, and base the chambering and jump based on that?
    Or do you have have barrels set up based on max. COAL, determined by a particular magazine you are using in that gun?
    When the load you have in mind, do you send your action, bolt and barrel blank out to a gunsmith to chamber and have them head space it? Or can you just send the barrel out, have the barrel chambered, and re-install it locally? The same as you would with a factory barrel exchange?
    Sorry for the newbie questions...

    Thanks, Josh
     
    Last edited: Aug 12, 2017
  2. jfseaman

    jfseaman Well-Known Member

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    I had a couple Remington 700 in 300 RUM.

    The throat on the factory chamber is immensely long.Sure, some will say it will be fine. FoGedAboudIt as far as loading goes.
    As I understand it, this is not a good idea. Others may comment different. Do what ever J.E. Custom says. :)

    I have an LR bench Rest R700 setup for VLD. I bought it used. As I understand it, it was built by Dave Bruno Rifles, Dayton, Pennsylvania 814-257-8089. He should have information on his reamer specifications.

    My data for this rifle is out in the shop not in QL. I shoot 210 VLD at about 3025. Seated .005 into the lands.
     
  3. J E Custom

    J E Custom Well-Known Member

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    I always recommend SAMMI chamber dimensions unless the person is an expert Reloader and understands the effects of some of these changes. SAMMI reamers determine freebore and aid in controlling pressure at high velocity. Seating a bullet against the lands, only increases pressure and is not necessary to get accuracy.

    Freebore is necessary on the big magnums if you want the advertised velocity without excessive pressures. freebore aids in obtaining max velocity at maximum pressures. If you decrease the freebore and load to maximum pressure normally powder charge will decrease and velocity will fall off.

    So I use the reamer to determine freebore and recommend loading to mag length minus 10 to 20 thousandths.

    J E CUSTOM
     
  4. Earnhardt

    Earnhardt Well-Known Member

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    Bear with me here...
    I am barely a novice at reloading, since I am more of a slug gun hunter.
    What I've read in regards to reloading is start at the lands and work your way back to a load or node that ends up the most accurate.
    So is this not the case with a big magnum such as the 300 RUM?
    So will the SAAMI reamer give me the exact same free bore in the Krieger barrel that I have with this factory 300 RUM barrel?

    jfseaman, was your barrel reamed to a load that you had data on?.. or what the shop had that reamed your barrel, and then you based your reloading build up on that?

    JE Custom, what you recommend is what I'm looking for right?
    Max mag length minus 10 to 20 thousandths.
    I could be reading this wrong, but what you recommend for my Krieger barrel will shorten up the free bore significantly over what I have now with the factory barrel, right?
    What after market DBMs/ mags give the longest COAL? And which brand are most guys using for the 300 RUM? Wyatt...Accuracy International...?

    Thanks
     
  5. AZShooter

    AZShooter Well-Known Member

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    I have been handloading since 1983. Back in the pre VLD days we seated hunting bullets to fit and feed from unaltered magazines. All my friends and I found accurate loads simply by trying different bullets and or powders till something worked. We factory rifles with SAMMI spec chambers and made the best loads we could.

    Only those crazy bench rest guys fooled with bullets seated close or into the lands. They even were so bold as to use "custom" reamers made to their specifications! My how things have changed.

    When the VLDs showed on the scene the BR and Long Range target shooters used them first. They kept using their custom reamers and discovered that VLDs shot the best kissing or in some instances many thousandths into the lands. This knowledge trickled down through a few magazines like Precision Shooting and even made it to Shooting Times with Rick Jamison talking about altering seating depth! Rick's article those many years ago sure shook up my handloading friends and me. Imagine altering the seating depth as the final accuracy tuning of a rifle!!! We figured he had too much time on his hands..... Then the internet with its many forums spread this information everywhere.

    I tried many VLDs and only a very few shot well. My 257 Weatherby which uses a custom reamer with .100" jump to lands is the only chambering that works well with VLDs. In fact 7 rifles used that reamer and ALL shot bugholes . Several years later Berger finally discussed how to get the VLDs to shoot.
    http://www.bergerbullets.com/vld-making-shoot/

    Many years later Berger began making Hybrid bullets and finally we don't have to play this crazy precise distance to lands game anymore.

    I have loaded for 5 300 Remington Ultra Mags and ALL responded with excellent accuracy with the use of the 230 gr Match target hybrid with seating depths that fit and feed from the magazine.

    Berger says you don't have to worry about seating depth with hybrid bullets. It is true. I have loaded quite a few Berger hybrids in many calibers and none required any more effort than seating to fit and feed from the magazine and working up a powder charge.


    Six 7 Rem mags 168 and 180 hybrids
    Five 300 RUMs 230 hybrid
    Two 6mm BR 105 hybrid
    Two 338 RCMs 300 gr Berger hybrid
    One 6mm-284 105 hybrid used as a repeater with .160" jump to lands
    Two 6mm-284 with 95 grain classic hunter hybrids
    One 300 WSM with a jump over .200" to lands
    One 300 RUM and the 215 hybrid
    One 308 and 215 hybrid

    Have a gunsmith install your barrel chambered with a SAMMI 300 win mag reamer and try one of the many 30 cal hybrids. You won't have to deal with the frustrating details of precise seating depth. Heck don't even worry about finding out the distance to the lands. It is like going back in history to an easier loading regime.
     
  6. J E Custom

    J E Custom Well-Known Member

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    Factory barrels have SAMMI chambers, so if your smith reams you Krieger barrel with a SAMMI reamer it will be the same depending on the quality of the factory chamber.

    SAMMI is the official guidelines for Reamer manufactures, factory rifles and Ammo and should be adhered to. Factory chambers are designed to handle factory ammo with safety and to prevent someone from seating the ammo/loads to long causing pressure problems, They limit the ammo length by using the magazine. The real reason someone needs a cartridge longer than the magazine is to get more powder in the case by seating the bullet longer increasing the COAL. This requires single loading or modifying the magazine to except the longer COAL.

    Seating the bullet against the lands should not be tried by a novice Reloader because of the many problems associated with this practice
    and only an experienced Reloader should try this in my opinion.

    Some of us have been shooting and reloading for many years and know what to expect and how to deal with changes in SAMMI chambers and ammo out of specifications. (I have been reloading 50 plus years and the experience has taught me never to recommend anything but a SAMMI chamber and ammo so people will stay out of trouble).

    I have used many SAMMI reamers And all Of my wildcat designs Have the same amount or more freebore for the reasons I have mentioned. 5 of my personal rifles have/will shoot under 1/10th of an MOA (Less than ,100 thousandth 5 shot groups and all loads are Mag length Minus 10 to 20 thousandths. The largest being group under 1/10th MOA. is .092 and the smallest group is .034 thousandths all with standard freebore or more. So I don't feel that I have to shoot anything but SAMMI specification chambers and ammo to get accuracy.

    Just My opinion

    J E CUSTOM
     
  7. jfseaman

    jfseaman Well-Known Member

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    No. The rifle was purchased second hand. I had to work up a load.
     
  8. Earnhardt

    Earnhardt Well-Known Member

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    Thanks for the info guys!
    I appreciate it!
     
  9. Buttermilk

    Buttermilk Well-Known Member

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    I had Jon Beanland take my factory Remington 700 LH LSS 300 RUM and work it over.

    The factory barrel had 1/2" throat...

    The reamer used on my Krieger bbl has 0.098" freebore, with a 0.343" neck diameter.

    This works really well with a Wyatt's extended box that allows 3.825" OAL. Should give plenty of room to chase the lands while the throat wears when using a Berger 210 VLD Hunting bullet.

    My gun has exhibited good accuracy 0.3 MOA - 0.4 MOA accuracy at 200 yards, with good speed (27" Krieger, B210VLDH pushed to 3144 FPS).

    Send your gun to Jon Beanland. He'll fix you up.

     
  10. .30US

    .30US Well-Known Member

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    I'm assuming you have cleaned thoroughly with a good copper solvent, since that is what I usually check first when accuracy really drops off, assuming a quality scope isn't the culprit.

    But, a factory 700 in .300 RUM was the worst example of setting headspace I've ever seen. The headspace was too tight, so they pulled the barrel and peened nubs to open up the headspace:
    10553465_10152151116022303_4807445379186709792_n.jpg