Gunsmithing 7mm RSUM Barrel Burn out 570 Rounds

Unsichtbar

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May 19, 2008
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A friend of mine burned his 7 mm RSUM barrel out in 570 rounds the bore scoped photos look like a 6.5 x 284 barrel after 1000 rounds, stress cracking etc. He is thinking about a coating. Salt-bath nitrocarburizing by Melonite, nitride coating or it has been suggested by several metallurgists around here that a process by Sub one www.sub-one.com they have used in industry. It is not known if they have ever done barrels. Any one have direct experience with these coating and recomendations?


573 rounds down the tube
Break-in was: shoot one/clean x10;
shoot two clean x 10, (no copper)
shoot three clean x 10 (was doing first ocw test with groups here)
shoot five clean x 10 (testing different primers, then seating depth testing here)

I’ve tested Berger 180 VLDs with Reloader powders 25, 22 and 17
with velocities ranging from 2750 to 3150 fps and am changing
powders to 4831sc (received 10 lbs yesterday).
I also ordered a new barrel from Brux. OCW testing says 3050,
2940, 2870 and 2760 are the fps nodes to shoot across all RL powders (+/-
20fps), so I tried seating depths from 20 jammed to 120 jumped in 30 incs per
Berger’s instructions. My best groups at all velocities have been
with 8 jammed and 28 jumped, but again, can't get less-than-1MOA
consistency -- even in no-wind conditions at Bayou at 6:00 am at
100, 300 or 600 yards.
 

jasonk

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Feb 23, 2007
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Re: 7mm RSUM Barrel Burn out 570 Rounds

It seems like NotAGuru here has some experience with the Nitride coating, might pm him.

Honestly it sounds like he might have got a hard/bad barrel, I'd just rebarrel it with the Brux and shoot away, chances are the next one will last much much longer. I wouldn't spend the money and take the chance of coating the new barrel, the 7 Rsaum isn't that hot of a round compared to many other.

By the way, was it a factory barrel or a custom tube (if custom, who made it)?
 

Jerry m

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Feb 15, 2003
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Re: 7mm RSUM Barrel Burn out 570 Rounds

Did the barrel ever shoot 'good'? Interior of the barrel is not 100% correlation to a bad shooter. Some can look like crap and still shoot fairly well. Have you tried another bullet? Don't throw it out yet.

Good luck

Jerry
 

Unsichtbar

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May 19, 2008
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Re: 7mm RSUM Barrel Burn out 570 Rounds

The barrel is gone, no question about trying to recover. Its looking for a solution for furture barrels, to extend round count if he stays with that round. Nitride?
 

BLAWTON

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www.lawtonriflebarrels.com
Re: 7mm RSUM Barrel Burn out 570 Rounds

Sounds like you got a bad barrel. Barrel makers cant control every piece of steel that goes through the place. It happens to the best of um..... Give them a call, good chance they will work with you on it.
 

USMCj

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May 1, 2008
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Re: 7mm RSUM Barrel Burn out 570 Rounds

Why not try sending it to Brux? they might replace it for you.
 

BLAWTON

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Re: 7mm RSUM Barrel Burn out 570 Rounds

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Clark</div><div class="ubbcode-body"> Bart Bobbits barrel wear formula

That is a formula for how many rounds for a 1/4 moa rifle to open up by 50%. </div></div>

Doesnt do much good if the barrel is already toast. Every barrel is different. We have ran 6.5x284 barrels for 3k rounds. Just sounds like there was a problem with the steel.
 

300WSM

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Apr 29, 2004
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Re: 7mm RSUM Barrel Burn out 570 Rounds

move to 300wsm next time
laugh.gif
 

264win

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    just built my 7 saum target rifle 28" benchmark barrel + badger thruster . my acc is amazing everything i ve tried with 162s has been near .5 moa . velocity from 2900-3200 h1000 seem to give the best fps for me but cant get the sd. below 30 . going to try some remington primers ... sorry to hear someone having problems with this great round . hope the new barrel performs better . adam
     

    BLAWTON

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Robert Gradous</div><div class="ubbcode-body"> Nitride can be a coating,but it also can be chemical electrical process which can be up to .015 deep. One might say that the rifling might shatter because it is only .003 to .004 tall. </div></div>

    Not quite.
     

    1shot2kill

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    6mmbr.com did a thing on that melonite a while back the do barrels but not actions and there is a minimum order amount
     

    wnroscoe

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    I'm really not surprised it's gone after just 570 rounds but, you'd think it would have lasted a little longer. There have been several 1k BR guys complaining about their 7wsm's burning out quicker than expected, 700+ rounds.

    Strings of fire, barrel heat and powder choices all play a role in a barrels life. Like I've always said, there's trade offs for everything. With high BC bullets at respectable velocities (2,900+ fps) barrel wear is the trade off. I burnt a 6mmBR barrel up at 2000 rounds with 30.8 grains of RL-15. Even the small ones can go. When were shooting 62+ grains of powder in a 7mm anything, I don’t think they'll last too long. My 7/300 is feed 69.0 grains of H1000 with the 180 Bergers. If it makes it to 1000 rounds, I'll be surprised.
     

    Jim See

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    110 rounds and you cleaned the barrel 40 times!!!

    Shoot 1 and clean 3 times
    Shoot 3 and clean twice and most Brux barrels are broke in.
    Shoot strings of 50-100 before you need to clean again.

    By the time I clean a barrel 40 times their is over 2000 rounds thru it.
     

    Robert Gradous

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    (Nitriding),Nitrided:
    Nitriding process methods are as follows.
    Gas (Box furnace or fluidized bed).
    Liquid (salt bath).
    Plasma (ion) nitriding.
    The advantages and disadvantages of these techniques are similar to those of carburizing. However times for gas nitriding can be quite long,that is,from 10 to 130 h depending on the application,and the case depths are relatively shallow,usually less than 0.5 mm. Plasma nitriding allows faster times,and the quickly attained surface saturation of the plasma process results in faster diffusion.
    When I was a kid and ran a rail I used to get the crank shaft nitrided to make the junerls harder so it would not gauld.
    If you were to look around there is a very good action company,one like we use on our rifles that their bolt uses this.
     

    Wild_Bill

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    Stay away from double based powders they are harder on barrels the extra energy they give comes at a cost.

    For the 7mm SAUM H1000 is awsome with heavy projectiles i am using 67.5gr retumbo with 175gr MatchKings DONT LOAD THIS i have a long throat but retumbo is the coldest powder ADI make it is caller AR2225 here then re packaged there for you as `Retumbo.

    It will usualy give a higher velocity in a 7mm mag than H1000 with the same charge weight and also have less pressure with less heat. This also applies to using a 6.5-284.

    i know people are trying to get massive velocities with RE17 but it will toast your barrel and it is fairly unstable at the higher pressures people are running it at.

    Stick with the single based stick powders like the Hodgdon Extreme or the VV 100 series they are also single based and cooler as well as being more temp stable like the Extreme series powders.
     

    nesikabay

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    Re: 7mm RSUM Barrel Burn out 570 Rounds

    Your problem is the brass that you have. I know this probly wont go over to well here. Buti have done a little testing just for fun. But a factoy 284 with 180 gr bullets will easly get you to 2925 with Hodgen 4831sc and even faster with RL 17. Then the 284 Shahane will get to 3100fps. Accuracy with both are great. And barrel life is much better<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Unsichtbar</div><div class="ubbcode-body">A friend of mine burned his 7 mm RSUM barrel out in 570 rounds the bore scoped photos look like a 6.5 x 284 barrel after 1000 rounds, stress cracking etc. He is thinking about a coating. Salt-bath nitrocarburizing by Melonite, nitride coating or it has been suggested by several metallurgists around here that a process by Sub one www.sub-one.com they have used in industry. It is not known if they have ever done barrels. Any one have direct experience with these coating and recomendations?


    573 rounds down the tube
    Break-in was: shoot one/clean x10;
    shoot two clean x 10, (no copper)
    shoot three clean x 10 (was doing first ocw test with groups here)
    shoot five clean x 10 (testing different primers, then seating depth testing here)

    I’ve tested Berger 180 VLDs with Reloader powders 25, 22 and 17
    with velocities ranging from 2750 to 3150 fps and am changing
    powders to 4831sc (received 10 lbs yesterday).
    I also ordered a new barrel from Brux. OCW testing says 3050,
    2940, 2870 and 2760 are the fps nodes to shoot across all RL powders (+/-
    20fps), so I tried seating depths from 20 jammed to 120 jumped in 30 incs per
    Berger’s instructions. My best groups at all velocities have been
    with 8 jammed and 28 jumped, but again, can't get less-than-1MOA
    consistency -- even in no-wind conditions at Bayou at 6:00 am at
    100, 300 or 600 yards.
    </div></div>