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300 Win Mag Inaccurate After Cleaning

tatasta
Hello,

Just a quick question. I have a Model 70 300 Win Mag Laredo. If I clean the bore well, it shoots about 2 MOA. Once I have fired about 5 rounds after cleaning, it will tighten up to 1-1.25 MOA.
Is it just me or does this make sense?

Thank you!
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Comments

10 comments

Date Votes
  • ruger41
    Yes it does--lots of rifles do that--Your first shot or so are what as known as fouling shots. After a good cleaning your rifle just likes 5 and then gets down to business. Of course there will come a point when the rifle needs to be cleaned again when the accuracy starts to suffer, but what is going on with yours is totally normal.

    http://www.gunwerks.com/Resources/Videos/Learning-Videos/Fouling-for-first-shot-accuracy.aspx

    here is a video on it.
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  • tatasta
    Thank you!!

    That helps a bunch. I feel better now.

    tatasta
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  • Sig220_Ruger77
    +1 to what ruger41 said.

    I never take my hunting rifle, carry gun, etc. with me RIGHT after cleaning the bore. Leftover oil in the bore makes the bullet traveling though it a little more unpredictable.

    Jon
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  • gunnut505
    I always use a dry patch prior to shooting a "cold" shot; it removes any dust or any oil I might have left in the bore and makes me that much more confident that it will hit point of aim.
    I also use heavier barrels than most hunting rifles come with because I can have them mag-na-port ed and not have to worry about a banana peel happening.
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  • coledigger4
    quote:Originally posted by Sig220_Ruger77
    +1 to what ruger41 said.

    I never take my hunting rifle, carry gun, etc. with me RIGHT after cleaning the bore. Leftover oil in the bore makes the bullet traveling though it a little more unpredictable.

    Jon


    Same here. I always take my hunting rifle, no matter which one, and shoot 3 or more shots. I then take it to hunting camp dirty.
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  • cussedemgun
    tatasta,

    With due respect to the previous posters, 5 shots for fowling is not normal nor acceptable with me.

    The condition you describe is indicative of a metal fowled barrel. Is it possible the rifle was fired with moly (molybdnum sulfide) coated bullets in the past? The moly coating will build up in the bore & can be VERRY dificult to remove completely. Copper fowling can also cause similar problems but is usually easier to see.

    To evaluate the bore, you need to seek the help of a gunsmith with a bore scope. The naked eye just can not see close enough for this kind of inspection.

    Jim
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  • midnightrunpaintballer
    quote:Originally posted by tatasta
    Hello,

    Just a quick question. I have a Model 70 300 Win Mag Laredo. If I clean the bore well, it shoots about 2 MOA. Once I have fired about 5 rounds after cleaning, it will tighten up to 1-1.25 MOA.
    Is it just me or does this make sense?

    Thank you!


    Ok, you're shooting a 300 win mag and consider 1-1.25 moa "tightened up" Nothing wrong with that but it tells me you're hunting and not bench rest shooting. Therefore, you're probably not using moly bullets. I'm going to assume that you're using copper jacketed bullets and yes, the others are correct. 3-5 rounds to foul in a clean barrel is perfectly normal. And also consider, the first couple are also warming up the barrel which also changes things. When it's cold, it's called a cold bore shot and can still be a little outside your normal groups. Nothing wrong with this either but pay attention to where it goes. As mentioned before, Foul in your barrel before you head to camp and know where that cold bore shot is going to hit. If you're shooting long range, it'll be the difference between a good hit or a miss. Or even just a bad hit.
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  • Kenneth Stuart
    If a rifle can not be depended on to put the last shot where the first shot hit with a clean barrel, something is wrong. And I do something about it. The barrel is free floated, the action recoil lug and the support part of the chamber are glass bedded, and the barrel is thoroughly cleaned, wiped clean, and flizted with a ox-yoke butterfly patch coated with Flitz and cleaned again. The rifle taken to the range and sighted in with a series of three shots starting with a clean barrel each time. Usually the rifle is now consistently accurate from first shot to last shot. Then I clean the rifle and wipe a patch lightly coated with synthetic motor oil through the barrel and put it away. When I go hunting, I wipe the oil out with a clean patch. I don't worry about the rifle because I know I can depend on it and after hunting with it I clean it. This works for me.
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  • Bergtreffer
    There is something else to consider. You said that after cleaning, the first and succeeding shots up to five tighten up. Tightening up is also "drifting". It is possibly that there is stress in the barrel that the warming of five shot causes the barrel to warp, thereby drifting the shot.

    In the steel production plant, gun barrels begin life as a rolled sheet of steel that has a gradiant of heat from the center out to the edges of the sheet. The center of the hot sheet of steel is the most stable and has the least variation of heat internally across its section (cross-section). While hot, the sheet of steel is sliced into individual, solid barrel billets that cool. Subsequently the cooled bar stock that ultimately will be used for gun barrels is gathered and placed on racks for inventory and later shipment. There is no effort at the steel plant to differentiate amoung the bar stock as to whether one was cut directly out of the center of the sheet of steel, or it another one came from the very edge of the sheet. The location within a sheet of steel, from which a gun barrel billet is taken has a lot to do with how accurate the finished barrel will be.

    I have a pre-64 Winchester Model-88 in .308 caliber. The rifle has a glass bedded Bishop stock and it is very accurate for the first two shots from a cold barrel. However, with successive shots the barrel drifts seriously toward 10 o'clock; meaning that it drifts left as well as up. It is a beautiful rifle, and is great for a couple of cold barrel shots, but it then goes to heck in a hand basket. One time on a bench I decided to methodically burn a 20-round box of old loads through the rifle, just to see how bad the drift would become. After 20 methodically fired rounds, the point of impact had moved approximately 8 inches left and 3 to 4 inches up. My conclusion at the end of the test strongly suggested that Winchester put a barrel on my rifle that probably came from one of the outer edges of the rolled steel sheet.

    Because my barrel drifts the bullet impact point left and up, I further conclude that the barrel billet that became my barrel was not finished out and mounted to the action in a pure left-right horizontal attitude. The heat stress of firing causes the warping of the barrel and drifting of the impact point left and up. Therefore the barrel billet to finished barrel product became rotated off axis from its original placement in the sheet of steel. Probably if my barrel billet had been rifled on a rotary forge much of the differential stress would have been worked out of it in the heat soaking and hammering operations.

    I understand that my reply perhaps has been a little long winded, but I just wished to interject a point of order here. It does sound to me that you have more going on with your barrel than oils and cleaning patches. Normally we all deal with external ballistics, but there is an entire other world of internal ballistics that needs to be considered.
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  • Herschel
    Lots of good suggestions in this thread but one to one and a half minute groups in a hunting rifle is more than adequate. What you want to know is where the lst round from a cold, uncleaned barrel goes. We are not talking about bench rest shooting or rapid fire strings in hipower shooting.

    I would say shoot some fouling shots and leave the bore uncleaned.
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