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Thread: Testing different ammo types for a 308 at 25m?

  1. #11
    CGN Ultra frequent flyer Blackcats's Avatar
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    Quote Originally Posted by Potashminer View Post
    It has been my practice for a number of years to always start with a new-to-me rifle and scope at 25 yards. You can peer down the bore at home (if you can remove the bolt) and get the crosshairs on the same point, but I like to start at 25 yards with at least 2 foot x 2 foot cardboard with a vertical line and a horizontal line. Aim for the intersection and fire pairs - you should get two bullet holes very close or overlapping. Then adjust scope turrets and repeat - walk your pairs of holes until they are exactly on the vertical line, and dead on or a bit low of the horizontal line. At that point, ready to move a target to 100 yard line and sight in as you wish. Many people will call 2" high at 100 yards "good enough" for hunting.
    Many rifles change the point of impact as the bore fouls or the barrel warms up. You need to discover what your rifle does. So, start with a clean cold barrel, on another day's session. Mark or note the order of the bullet holes, to see if a drift occurs as you fire 5 rounds. If you are going to go hunting with a clean cold bore, that is what you need sighted in for. A "clean cold bore" is a once a day shot, so "sighting in" can involve many trips to your shooting place. And then you want to know if your rifle will start to drift as the barrel fouls, or as it heats up. If your first shot did not do the job, you are rapidly getting into an undesirable situation - your game may be wounded, likely moving, if not running, and it has become much more difficult to put it down. So, put all your marbles on that first shot - know where it goes.
    Been shooting and hunting for over 50 years . Same method I use and works well !

  2. #12
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    Back to OP's question #1 - again , no one can really predict what your rifle will do with different weight or brand ammo. When my Dad passed on, his M1917 30-06 came to me with an assortment of loads he had been hoarding - Dominion, Winchester, Federal; 150, 165, 180 and 220 grain. With that mixed lot of ammo, I have a target at 100 yards that you cover all the bullet holes with palm of your hand - certainly "close enough", and he took literal truck loads of deer, moose and elk with that rifle. Next rifle that you try will put a particular brand or weight into nice groups, and then spray the next combo all over the target. You have to get out and shoot your rifle to know.

    Question #2 - Certainly, 25 yards is not going to prepare you for 500 yard shooting, but a 3" 3 or 5 shot "group" at 25 yards is telling you that there is something wrong with your set-up - you, the rifle, the barrel, the scope, the scope mounts, the particular ammunition. Even a 3 MOA combo should be putting bullet holes within 3/4" or less of each other at 25 yards. And the fabled "1 MOA" hunting rifle should have pairs of bullet holes touching at 25 yards.

    At short range, you will have parallax sighting error to deal with. One common technique is to replicate your cheek weld, perfectly, for each shot - whatever error is present, you will be repeating it. The error will be much less at 100 yards - most hunting scopes that I am familiar with are set from factory about 150 yards parallax free - so your bigger error is always the further that you get from that set distance.
    Last edited by Potashminer; 05-28-2020 at 12:57 PM.

  3. #13
    CGN frequent flyer billbmcleod's Avatar
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    [QUOTE=Potashminer;17103243]I have more than once spent time with someone trying to "sight in", but not actually wanting to "waste cartridges". Fires one shot, spins the sight adjustment - next hole is the wrong way, or completely off the target, etc. until box of shells is gone - not sighted in and does not know anything about what the rifle or scope is capable of.

    So, I learned to start at short range, where for sure I will hit the cardboard. Shooting pairs at that range indicates whether the system has capability, or something wrong. Usually can see the holes from shooting bench, so saves walking, too! I have minimal experience with sighting in a handgun, but above is my practice for all my rifles - scope, iron sights, aperture sight, rimfire or centerfires. Can not "sight in" unless you have some notion of the capability.

    If you and your 30-30 can do 3 or 5 rounds into 3" circle at 100 yards, then get that "circle" centered about 2" high and go hunting. Knowing that you are going to be shooting into a 6" circle at 200 yards - perfectly adequate for the 8" to 10" kill zone on most big game.

    Drifting - I have a Parker Hale No. 1 in 303 British - in the course of firing about 25 rounds - trying to "sight in" - it walked an easy 18" between first and last shot - not all due to heating, I am sure - something was moving somewhere - scope mount? scope? bedding? - I still have not chased that down, but I do not take that one hunting. How much can it drift? No one can answer that for your rifle - you have to take it out and shoot it, and then tell us what you and your rifle achieved.[/QUOTE)

    I have had the same experience with a guy I was hunting with a few years ago. We were 1000 km from home and stopped at a gravel pit to try his rifle as he had not shot it for years. After many single shots and adjustments he still couldn't put it on paper at 50 yds.
    He used up all the ammo he had (1 box) so I got some of mine and tried it and with luck got it lined up. I tried it for 100 yds and adjusted it for elevation and back in the truck we get to go find a moose.
    We didn't, see any moose and a few years later he brought his rifle to try on my range. The same thing was going to start again when I insisted he shoot 3 round strings. I had a large paper behind the target and he was all over it. It finally occurred to me that I had never seen him shoot anything with any kind of accuracy. I told him that his scope must be screwed and I had another available that I could put on. He left the rifle and I went back and tried it myself and it grouped fine. I sighted it for 100 yds and told him that I found a loose mount. The truth being he was a terrible shot. I have hunted with him since and I am just glad he hasn't seen a moose as I was afraid of him wounding one.
    A long story and kind of got off track but I don,t have much else to do.

  4. #14
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    billbmcleoad: I always wonder about "average" guy in the bush - I have definitely met your partner's close relative!! So much malarky in marketing and internet that one can somehow "buy" a gizmo that will take a shooter into Carlos Hathcock's league. In my 40 years of prairie hunting - by far, most unwounded game taken by me or partners is 250 yards or less - big majority of that a lot less - like inside 150 yards. Yet I have seen shooters completely miss a standing whitetail at 100 yards. That is not the gear - that shot is doable with a 6 MOA rifle. That is the shooter. The shooter owns everything - the loads used, the scope, the installation, the practice to hit what he shot at. Can't buy anything to offset the lack of "ownership" for the shot.

  5. #15
    CGN Regular Sniper_485's Avatar
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    Quote Originally Posted by Potashminer View Post
    Ha! We were thinking the same! But a 7mm bullet seated in a 270 win case will not chamber - gets stuck in the neck area / "throat" - no explanation for that barrel, except it has the perfect dimensions for a P13 in .276 Enfield cartridge, but apparently a correct 270 Win reamer was used to chamber it. Getting way out in wild guesses, perhaps BSA had a .276 Enfield barrel blank mixed up in their stock of 270 Win barrel blanks? Oversize groove explains why it passed the proofing, no doubt easily! As close as I can measure, the bore is .270"
    My "plan", if I ever get one of those "roundtuits", is to try some Nosler Partitions - I have some 140 and 150 grain on hand - thinking / hoping that the exposed lead base might "obturate" and fill the grooves? Pure conjecture, but definitely running out of things to try. No clue how former owner(s), before the CGN guy who discovered the problem, were able to do anything effective with that rifle.
    I think I'd be tempted to get it chambered and the bore reamed to .280 Remington if thats where you're at.

  6. #16
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    A 280 Rem reamer may not completely clean out a 270 Win chamber (the 280 Rem is a longer cartridge, but the 270 Win shoulder is smidgeon larger diameter as per SAAMI chamber drawings) so moving barrel shoulder forward may be required; as well, a normal 280 Rem reamer will not go into that .270" bore - I have a reamer here, but the nose is .276"-ish diameter. I have no idea how to have a rifled bore changed from .270" bore with .282" grooves into a .277" bore with .284" grooves?? A re-bore will not clean out the grooves, so would require recutting to exactly match existing grooves - I do not think that is possible? It is a BSA "sporter", probably a Model E, built on a WWI M1917 - I have several take off M1917 30-06 barrels here that would no doubt simply screw right on, but no fun in that!!!
    I suppose I could have the throat portion only opened up with a throating reamer? And then hope a 270/7mm Wildcat cartridge never gets chambered into a regular 270 Win chamber?
    Last edited by Potashminer; 05-28-2020 at 03:39 PM.

  7. #17
    CGN Regular Sniper_485's Avatar
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    Quote Originally Posted by Potashminer View Post
    A 280 Rem reamer may not completely clean out a 270 Win chamber (the 280 Rem is a longer cartridge, but the 270 Win shoulder is smidgeon larger diameter as per SAAMI chamber drawings) so moving barrel shoulder forward may be required; as well, a normal 280 Rem reamer will not go into that .270" bore - I have a reamer here, but the nose is .276"-ish diameter. I have no idea how to have a rifled bore changed from .270" bore with .282" grooves into a .277" bore with .284" grooves?? A re-bore will not clean out the grooves, so would require recutting to exactly match existing grooves - I do not think that is possible? It is a BSA "sporter", probably a Model E, built on a WWI M1917 - I have several take off M1917 30-06 barrels here that would no doubt simply screw right on, but no fun in that!!!
    I suppose I could have the throat portion only opened up with a throating reamer? And then hope a 270/7mm Wildcat cartridge never gets chambered into a regular 270 Win chamber?
    I would think a 7mm.270 would not chamber in a .270 Win.

  8. #18
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    I agree - in this case, I took a 270 Win case, then used expander set up from a 7x57 Mauser die and got the case neck "opened up" - seated a 7mm bullet - would not chamber in this 270 Win chamber. Then I read that was the reason the 280 Rem was made a bit longer that 270 Win - so that it could not be chambered into a 270 chamber - maybe there are "sloppy" ones out there?? Besides a longer headspace dimension (2.105" vs 2.054" +/- .005"), SAAMI drawings show 280 Rem neck area is supposed to be about .005" larger than a 270 Win neck, bullets are .007" difference, so neck walls on 280 Rem actually a smidgeon thinner than for 270 Win. I could sacrifice this reamer - get the nose ground down to .2695" and ream out a 280 Rem chamber. Quite certain I could "make it work" with handholds - not sure at all if that would be a good idea with factory cartridges that would chamber??

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