How many rounds can you shoot before accuracy fades?

Discussion in 'Reloading' started by 204tcAK, Mar 24, 2014.

  1. 204tcAK

    204tcAK Active Member

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    Well folks with my new 375 jdj barrel, it can hold good groups until the 7th or 8th round. Then it started to open up. I'm hoping as a few more rounds are run through it, it will start settling down.
    I used re-15 48.0 gr's with sierra 250 gr slugs.
    How many rounds can you shoot before you see accuracy fade?
     
  2. RT2506

    RT2506 Well-Known Member

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    Each individual barrel is a different critter so round count will be different. Are you talking about total round count down the barrel or shots fired in a string?
     

  3. backwoods83

    backwoods83 Well-Known Member

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    This is a loaded question, to many variables to give a true estimate. On the other hand a 375 bore using <50grns of RL15 should last a couple thousand rounds more than a 308win, and the 308 can go 3K to 8K rounds depending on the barrel and how its treated. So theorectically you could get 10K rounds with the right barrel and treatment. On the other hand if you're talking about a shot string, sounds about like 7 or 8 rnds has heated it to the point that its starting to walk, not really much you can do about it.
     
  4. 204tcAK

    204tcAK Active Member

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    Just firing strings in a day. Not the total life cycle of the barrel. Also, these are virgin brass. I won't use any fire formed ones till I'm done with the new cases. Time at the range is useful information if you pay attention to what the accuracy is doing from a clean bore to where things walk around. I think I'll be punching 10 rd strings in a day when i take it out then clean out the crud till my virgin cases are fire formed.
     
  5. RT2506

    RT2506 Well-Known Member

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    If you are shooting 10 shot strings without letting the barrel cool between shots your groups will open up because of the heat in the barrel not because of fouling. I would shoot no more than 5 shots and let the barrel completely cool down then shoot again and see what your accuracy is.
     
  6. Marble

    Marble Well-Known Member

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    My rifles fade with heat too. I actually started bringing a small electric fan with me to the range to put air on the gun between rounds. I found a way to get the barrel pointed directly at the fan and with the bolt removed, it is completely cool in 5 minutes or so in 80 degree weather.

    I have a Ruger 10/22 that I built 12 years ago. Everything is Volquartsen except for the bolt assembly and receiver. The carbon fiber wrapped barrel never gets hot, accuracy drops after10-15 shots. I can shoot .25-.30 groups at 50 yards with quality ammo on a clean barrel. At about 15 rounds, the group open up to .4 or so, then .5. Just a quick brush through the barrel and powder solvent and it back to tight groups.
     
  7. 204tcAK

    204tcAK Active Member

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    I will reduce the number of shots in a string after I have fire formed the new cases. I will clean out the bore after each session and take note how the groupings hold together during each outting. I have a few cans of gunslick foam boar cleaner that I can use to eliminate most if not all copper fowling. The first time I used it in the 375 jdj barrel, the foam was squirting out from the breach. It got pretty messy. But, I do have a casing that I crushed when I was first adjusting my die to form the 375 from its parent 444 marlin case. I can drill a hole thru the base where the primer seats into so the tube from the boar cleaner fits snug and cut the top half off the cartridge and toss it away. Now, mind you that I'm not reccomending anyone attempt this procedure. If any of you are familiar with the Thompson center, you know it's a break open action where you can remove the barrel completely and I presume that this modified case will work for which it is intended in my bore cleaning efforts.
    That being said, I will also increase the time between shots to minimize the heat distortion. Elimination of many variables which can give false accuracy tests is the goal in the production of a quality load.
     
  8. lloydsmale

    lloydsmale Well-Known Member

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    ive got a 22250 that will go 40 rounds without opening up if i take it slow. I also owned a weatherby vangruard 257wby that would open up after 5 shots.
     
  9. jfseaman

    jfseaman Well-Known Member

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    To many variables left out.

    If you are asking so you can find out what is "normal" and learn great. What your rifle does in the intended use is what is important.

    As I Understand It: Benchrest group shooters need to do there 5 sometimes as fast as they can load and shoot so for them 5 is the only important number.

    If I leave at least 1 minute between some of mine can go high double digits, others with large powder volumes and thin barrels can go 3. Since those are hunting rifles it doesn't matter.

    If I leave 2 minutes or more, the target rifles can to all day regardless of caliber.
     
  10. 204tcAK

    204tcAK Active Member

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    The 375 jdj will primarily be used for hunting but, I will take it out from time to time and pop a few rounds. I normally reload meat bangers a grain or two under pressure signs from the initial pressure string tests. I settle for 2" or 3" groups at 100 yds. But this time around my observation with the 48.0 and 48.5 charge weights stacked on top of each other. Then opted to load some 48.0 to see how they would preform. The first 4 rounds with this setup were spent on dialing in impacts on top of crosshairs. Then shot 5 and 6 made a ragged hole followed by 7 which was 1" right and slightly lower than the ragged hole. I think I found a sweet spot for my barrel using re-15 @ 48.0 gr and sierra 250 gr slugs.