custom rifle showing funky groups,.....HELP GUYS!!!!

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by sakofan, May 26, 2003.

  1. sakofan

    sakofan Well-Known Member

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    Bullet runout????Has your ammo been checked using a runout guage??.sakofan....

    [ 05-26-2003: Message edited by: sakofan ]
     
  2. Guest

    Guest Guest

    Is there a pattern to the shot thrown out of the group? Vertically out or horizontally out, or random to all 4 quadrants?
     
  3. Dusty

    Dusty Active Member

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    Have you bedded the HS stock? They claim they don't need to be bedded, but they will shift POI if not bedded. especially in a Mag.
     
  4. Mysticplayer

    Mysticplayer Writers Guild

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    Any consistency to where the flyer goes or do your composite groups look like a pattern with a central group?

    Consider: Bedding, rolling during recoil, powder and pressure spikes, concentricity of ammo, over sized throat/freebore, scope and mount looseness, flinching?

    For the first while, I like to shoot over a chronie so that I can see if any flyers are due to vel/pressure spikes or drops. That way i can mark the case and refire. If the flyer persists, then the case gets pitched. Do your load development with fireformed/neck sized brass only. Measure runout and correct if necessary.

    Measure the fired brass before sizing and bullet seating to track down any problems you may have during the loading process.

    The rest is straight forward. Good luck with your quest.

    Jerry
     
  5. JustC

    JustC Well-Known Member

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    Gentlemen, the cases are sized neck only in a wilson die that has a .334 bushing. The brass, remington of course, is running at around .013-.014" neck thickness (as I havn't cleaned the necks up yet) but they are within .001" case-to-case. The bushing seems to be maybe .0005" in variance around it's internal surface (as measured with the rear of the caliper and keeping tension while rotatng the bushing) Could this variance be something?

    The barrel is NOT bedded with a pad, which as I stated, I am thinking is incorrect. The stock is the Tactical HS model, so it is nice and wide at the front, but that may not mean much.

    There is bedding along the sides of the action, but without removing the stock, I am betting there is none under the action (which it would need if there were a barrel pad)

    The primer pockets are done with a drill and sinclairs uniformer, and they shine like a mirror. The cases are deburred and chamfered. Runout is no more than .002" max, with only an occasional .003" on the RCBS casemaster.

    [ 05-26-2003: Message edited by: JustC ]
     
  6. Mysticplayer

    Mysticplayer Writers Guild

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    I would look at the bedding and redo. Even if there is bedding under the action, it may not have been done properly and not actually touching the action. Try loosening the action screws and see if the action springs back. Also check to see that the action screws have not been he-man tightened. Firm hand pressure is all that is needed.

    Are the bullets touching the lands? Can you get a chamber cast made? What type of powder are you using? Primer? Try shooting over a chronie.

    your gear sounds top drawer and should not be causing these flyers. Check the volume of the brass to ensure that there isn't a few that is overly large or small. Just pour in some very fine powder like H870- tap the case to settle and then dump into the next one. If the volumes are the same, the powder will settle very nicely at the top of the neck. Haven't found a problem with my factory brass yet.

    Finally, do you have a scope with a proven track record. Sometimes even the best fail internally. Ensure that all mounts are nice, tight and straight.

    Have you tried shooting the rifle without the muzzle brake. Not pleasant but if the brake is not concentric with the bore, will cause flyers. Also check the diameter of the "muzzle" on the brake. The bullet should not touch the sides/bore.

    I have had a brake that was so tightly machined that you could see traces of copper on the edges of the brake. Good thing this one was on straight. A little opening up and voila, end of problem.

    Jerry
     
  7. Brent

    Brent Well-Known Member

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    When you say "pad", if you're talking about a point on the forend that would contact the barrel for support... it would more than likely cause worse problems than help anything, even with a heavy barrel. It could help "maybe" with a very light contour bbl if freefloated it's inconsistant vertically. The action needs to be bedded full length front to rear IMHO. Bedding should not contact sides or front of the recoil lug... bbl either.

    Were you cleaning the bbl between shots while breaking it in?
    How many go into one hole before you get a flier?
    Does the bbl get up to the same temp when it throws a flier?

    Sounds like it's too early to tell really.
    If you had shot 20 rounds or so through it, two or three times, and it always threw fliers without considering cleaning effects, charge wt changes, etc, then you could narrow it down a bit easier.

    Maybe you already broke in the barrel and cleaning and charge wt changes weren't entered into the equasion at all...
     
  8. JustC

    JustC Well-Known Member

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    I am really hoping it is just a loading issue.

    Brent, the barrel pad I refered to is the area of epoxy that is often placed under the first 2 inches of the barrel, out from the action. That is a lot of barrel hanging from the action face. It may just be superstition,...but it seems that it would provide more ridgidity.

    The barrel never was heated up. I ran a patch through it each round, and then a dry patch. I never shot it twice in a row for the first 30rnds. I was even using light loads just to do the first break-in session.

    I may be totaly off,...but my way of thinking is that if one bullet hole touches another,....they all should. (with the exception of operator error)

    Thanks to everyone so far,...your help combined is far greater than any trial and error session that one man can pull off.

    keep any suggestions you have coming.

    [ 05-26-2003: Message edited by: JustC ]
     
  9. Brent

    Brent Well-Known Member

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    I'm with you on the "pad" now. I relieved that area on my Ultra, as it was bedded for two inched down the bbl too. IMHO it can only affect consistancy in a negative way when the bbl temp, or gaurd screw torque changes. One more variable I don't like to deal with, same with the forend touching too.

    I'd get to the point you can shoot it steadily for twenty-thirty rounds and NOT clean during this time, to me that's the only way you can rule out it's affect, which IMHO is and will wreck your groups.... If you can get 40-50 rounds out of it without groups opening up, I'd go with it! Cleaning will only make you stop and start over untill it settles down again, that might be 1,2,3,4,5 rounds later... the gun will tell you how many. Cleaning it is likely just twistin your brain at this point, if the problem persists "after" you're in a groove and when know how many shots the gun will take before accuracy falls off, then you may want to take a closer look again. It should go away when you've let it settle in though.
    Good luck, sounds like you're off to the races with this one though! [​IMG]
     
  10. Steve Shelp

    Steve Shelp Well-Known Member

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    JustC,
    Not sure of your actual barrel dimensions, but I've seen to many floated 30" tapered barrels hanging off from any action without any bedding at all that shot very good.
    My 1K BR LG rifle is a Kelbly action with a 30" 1.25 tapered to .940" at the muzzle without ANYTHING touching that barrel and it shoots really good along with 75% of the other LG class rifles I shoot against.

    Don't get your yourself backed into a corner in thinking that if 2 touch the other is the "flyer". There's nothing to say that the 2 farthest bullets holes are the normal group and the one that touched a previous bullet hole isn't the flyer. If you've tried this load a couple of times and your bedding/scope/mounts/screws/etc check out as being good to go...... move on to another load and quit running into that brick wall. Without getting my hands on your rifle it's hard to really tell, but I've seen certain loads do this before.

    bottom line: if everything mechanical checks out from all the good info above..... change that load. I've got a saying that I have to remind myself of once in awhile. "if you keep doing what your doing... you will keep gettin' what you got" Sounds simple and obvious, but it's true.

    Also FYI: when you get 3/4" flyers (I assume we are talking 100yds here) it isn't cases, velocity variations, flash holes, or anything small like that. Those things are for tweaking a load down to that final ragged hole (again assuming 100yds +-).
    When you are measuring flyers with a tape measure the problem isn't fixed by measuring your cases, bullets, loaded ammo with a micrometer and/or calipers. It's something mechanical in your rifle, the shooter, or the wrong load. That's what I would be looking at if this were my rifle.

    Good luck and let us know.

    Steve
     
  11. JustC

    JustC Well-Known Member

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    Thanks Steve,...I am glad to hear that about this barrel and others it's size.

    One more thing guys,...(for tonight anyway)

    I went to check the stock/action screw torque, and the foreward action screw is rounded out. I can probably beat the wrench into it (lightly with a small mallet) and get it loose, but it is toast for anything else.

    This has me wondering if the smith tightened it too much, and couldn't get it back out. If it is overtight,...will this cause any significant grouping issue?

    I will be placing a call tomorrow and trying to find a delicate way of saying,...."it was like this and, I need another one". It seems funny when I look at it, that I may have a harminics issue and it just so happens to be just this shy of rounded out.

    [ 05-26-2003: Message edited by: JustC ]
     
  12. JustC

    JustC Well-Known Member

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    My 700 action has been trued, my lugs are lapped, I had a sako extractor installed due to the bolt thrust from the 300RUM with 220-240gr pills. The barrel is a 30" pacnor 1:10 finished at 1" and then a Vais break. The trigger is set at 8oz with a consistent break, the stock is an HS Precision (I wanted to shoot it before the MBR was due to arrive) and the recoil lug is hardened stainless at 2x factory thickness. The mounts and rings are Talley with 8x40 screws. the scope is a brand new NXS 8-32x56. All through break-in and even now, it will shoot anything from 169gr lapua to 200gr matchking and even partitions into one hole with varying powder measures,.....BUT the groups are erratic [​IMG]

    It shoots,..lets say in one place, then the next bullet will place 3/4" away, then the next one or two bullets will cut the first hole. I can't find a correspondence in the cases,...and they have been benchrest prepped, by a benchrest competitor.

    What do I check for, or what do I tell the gunsmith to look for? He stated he doesn't think it needs a barrel pad,......but I am thinking it does. The long heavy barrel will sink fairly easily into the barrel channel if given some pressure (not much) I know being that heavy, it probably isn't jumping enough to hit the channel, but I am wondering if it is somehow,.....harmonicaly challenged due to it's weight hanging from the receiver.

    Please pick your brains gentlemen,..I am starting to become diseartened and really upset with it's performance for amount invested. I have only fired 40rnds, but the one hole groups shows me it is not the loads,...it is having some randomly occuring issue.