Fine Scratch on Land -how worried should I be?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Brown Dog, May 29, 2005.

  1. Brown Dog

    Brown Dog Writers Guild

    Messages:
    635
    Joined:
    Sep 26, 2003
    Just got my 308 back from having it threaded for a suppressor.

    Looking into the muzzle with a light I have spotted a fine scratch across the 12 o,clock land about 0.1in in from the muzzle.

    Even if it turns out to have no immediate effect on accuracy, will this now cause the top land to copper quickly?

    - this is quadruply frustrating since I won't be able to test the rifle for a couple of months due to an upcoming 'business' trip!

    How worried should I be?
     
  2. Len Backus

    Len Backus Administrator Staff Member

    Messages:
    6,357
    Joined:
    May 2, 2001
    I own a Hawkeye borescope and last year with its sharp edged tip I scratched the lands on my barrel rifle within its first 2 inches. Now I am much more careful with the borescope. /ubbthreads/images/graemlins/smile.gif

    These scratches were several in number and fairly long. This did affect coppering and accuracy and I cut off the end of the barrel and re-crowned to solve the problem. How long is this single "fine scratch" on your barrel?
     

  3. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    Brown Dog,

    Only real way to know is to shoot the rifle and see. I have seen some pretty scratched up bores shoot well while others that looked nearly perfect with the exception of a small scratch produce inconsistant grouping.

    Only way to know is to shoot the rifle.

    It is never a good idea to have a scratch near the muzzle as it will certainly increase the fouling to some degree.

    Since it is only .100" inside the crown it will be a simply task to shorten and recrown to remove the scratch, possible not even having to set the suppressor threads back any.

    Just shoot her and see what she does. At longer ranges, +200 yards will reveal more accurately how the rifle shoots so stretch things out a bit and see what happened.

    Good Shooting!!

    Kirby Allen(50)
     
  4. boomer

    boomer Active Member

    Messages:
    33
    Joined:
    Apr 20, 2005
    field testing is the only way to know for sure if it will effect the fouling and accuracy of your gun. But more then likely the suppressor will effect the accuracy of the weapon more then the scratch. I have suppressors on my
    M-16A1, and on a 30 whisper, as well as a Ruger 22 pistol and 10-22, I have different loads for shooting with suppressor and without, without is always more accurate. I would be more worried if the crown had a burr.
     
  5. Brown Dog

    Brown Dog Writers Guild

    Messages:
    635
    Joined:
    Sep 26, 2003
    Len, Kirby,

    Thanks for your rapid responses.

    I must say I was hoping for 'it'll be alright' type stuff but suspected it wouldn't be!

    Even if it shoots it'll now copper badly; thought so, but I needed to hear it from someone else!

    Two months until I can do anything about this -FRUSTRATING!

    Not a Happy Camper!
     
  6. Brown Dog

    Brown Dog Writers Guild

    Messages:
    635
    Joined:
    Sep 26, 2003
    Boomer,
    Apologies, busy typing while you posted. The suppressor I've had fitted is actually touted as improving accuracy -Reflex T8- but clearly that assumes unmarked rifling!
     
  7. jsali

    jsali Well-Known Member

    Messages:
    94
    Joined:
    Feb 15, 2005
    I don't know if this will comfort you but I bought a factory Sendero and after I got it home I noticed it had a cluster of what looked to be pin pricks inside the bore about 1/8", I thought it was done for sure but when I shot it it would hold 1/3 - 1/2 MOA groups w/handloads all day long. It did foul a fair bit but it wasn't horrible.
     
  8. Brown Dog

    Brown Dog Writers Guild

    Messages:
    635
    Joined:
    Sep 26, 2003
    Aaaaagh!:[​IMG]
     
  9. nowler

    nowler Well-Known Member

    Messages:
    174
    Joined:
    Mar 26, 2004
    hey matt

    what a pisser eh? gonna tell us who did it so i don't go near them with the proverbial?

    however, i wouldn't be overly concerned about it at the moment. i have had scratches inside the bores of some of my rifles and they all shoot like a dream imho /ubbthreads/images/graemlins/grin.gif

    don't believe everything you here about reflex's improving accuracy. i think you'll find that as the recoil and noise is reduced, people flinch less etc. etc and they perceive accuracy to get better. thats my thoughts on it all anyway. get yourself a neoprene sock for your can so the mirage doesn't blurr you after the first 4 or 5 shots.

    cheers

    d. /ubbthreads/images/graemlins/grin.gif
     
  10. Pete Lincoln

    Pete Lincoln Well-Known Member

    Messages:
    658
    Joined:
    Mar 17, 2004
    Matt, shoot it and see, if it don't shoot fetch it over here when we get a boar lined up for you, i'll chop the barrel back and re thread it for you.. that English channel is a pain aint it..
    I've not been hearing anything good about those reflex mods lately, mate of mine has just 150 rds through his(in 300wm) and its split/cracked. I was talking to a real nice bloke that does the PES mods in the UK, i'll be using either those, or Brugger and Thomet mods, ive got a B&amp;T on the way for testing. They cost 3x what the reflexs do, but the things are 10x the quality.
    whats about the markings for your BDC?
    Pete
     
  11. Brown Dog

    Brown Dog Writers Guild

    Messages:
    635
    Joined:
    Sep 26, 2003
    Derek,

    Best I don't name the fellow until I see how this all pans out. If the rifle does turn out to be spoilt I will be deeply unhappy....

    Will be up in your neck of the woods late Oct and mid-Nov at Stags then Hinds. I'll drop you a line when I'm back from the sunny place.

    Pete,

    Thanks, but no point in marking up the BDC until I find out if the barrel is OK. If it has to be replaced [note: 'replaced', I didn't pay this punter to turn my rifle into a pistol!] I'll have to do my comeups from scratch. Deep joy.

    Didn't mention that this genius also returned the rifle sans-bedding. Didn't occur to him to just unscrew the barrel. 'Ambulance for one please' /ubbthreads/images/graemlins/mad.gif.

    I have to get it reglued to the chassis before I can fire it again!

    Brize Norton tomorrow -pissed off that I can't get the AW sorted until I get back /ubbthreads/images/graemlins/mad.gif
     
  12. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

    Messages:
    6,848
    Joined:
    Jun 12, 2004
    Brown Dog,

    Looks like there was a burr or sharp edge on the pilot bushing used to crown the muzzle. This has happened to me as well in the past. Now whenever I get a set of pilot bushings in I polish and round both ends to ensure this does not happen.

    Did this to one of my 2000 yard rifles in 338-300 RUM and did not notice it until I shot the rifle and it was printing 1 moa groups at 500 yards. Gave the rifle a total look over and sure enough there was a little groove in the rifling just as you have in your picture.

    The problem is that it generally takes material off the lands so that it is undersized on that land and the bullet will release early and create a yaw in the bullet.

    This will be more appearant in a 3 or 4 groove barrel and as I can clearly see you have a 4 groove.

    As a rifle builder I will tell you things happen. Give the guy a chance to make it right before you do anything else. If a customer brough a rifle to me that I had worked on that had this problem, and it happened early on, I would fix the problem at no charge at all even if it ment a total rethreading of the muzzle. Shipping should also be covered to and from in my opinion.

    Give him a chance to make it right though. It sucks but things like a little burr on a pilot bushing happen and at times slip by visual inspection.

    Pointing this out to him will also help him prevent it in the future as well.

    Your barrel is certianly not ruined, just needs a bit taken off the end!!

    Good Shooting!!

    Kirby Allen(50)
     
  13. nowler

    nowler Well-Known Member

    Messages:
    174
    Joined:
    Mar 26, 2004
    hi matt

    good luck with the sun-tan vacation. i'll chat to you when you get back about the dsc II thingy.

    you may be stressing about nothing with your rifle. don't let it become a problem in your head before you find out that it my or may not be a problem at all....

    remember, your cup is half full and not half empty etc. etc

    d. /ubbthreads/images/graemlins/wink.gif
     
  14. Pete Lincoln

    Pete Lincoln Well-Known Member

    Messages:
    658
    Joined:
    Mar 17, 2004
    Matt, the AI's actions are generaly glued to the chassis, depending on the action wrench or clamp type, it might be nessecary to remove the action from the chassis. Give em a ring and have em sort the probs out whilst you are away. let me know what marks you want engraving on your BDC when you are ready
    Pete