Just out of curiosity, I went to the "game lands" range near where I live. The range has permanently installed benches with no room in between, but this worked for the purposes of my experiment. I took my M1A and found that South African surplus FMJ, Winchester white box 7.62 FMJ, and Federal XM762D all shot to same point of impact at 100 yards. I think the XM762D has a boat tail, but they are all about the same 150 grains or so. I would have liked to confirm at longer ranges, but 100 yards is max at that location. Has anyone else tried this or something similar at longer ranges? If so, what have you found?
(I know that ideally, you should re-zero every time you switch brands, lots bullet weights, bullet styles or whatever, but some odd future situation might preclude doing so right when you need ammo and somebody hands you a box or mag of something different.)
puff, for the 4 MOA rifleman, it all shoots good, and to the same POA.
Since the rifleman 'fires every shot like it's a sighter', anything to that varies is quickly noticed, and accounted for in following shots...
Now, it's Arpil 19th - what are you planning to do for the Cause this day? :) (At least, get out and take friend shooting, and talk to him about the Heritage...)
As I write this, my printer is pushing out copies of the Appleseed flyer. I will be taking them to a steel plate shoot tomorrow. I seem to be not very persuasive since Appleseed discussions always seem to land on deaf ears. They say however, that every once in a while, even a blind squirrel finds a nut.
I'd say you have an exceptional rifle. In my experience different rifles shoot different loads to different points of impact with the same point of aim.
My father in law had a Browning BAR GD II (that's the 30.06 semi auto deer rifle, not the BAR most folks think of when they here the name) that he kept because it was the only rifle he'd ever had that shot 180 and 220 grn. Remington CorLokts into the same 5" circle at 300 yds.
It would be really interesting to see how the different shells group in your rifle at 300 yds. or farther.
One time while I was in the Army we were issued 7.62 Nato ammo for our M14's from a Canadian manufacturer (Valcartier Industries I believe it was). That ammo did not "fly" like the 7.62 Nato ammo we used at any other time. We always zeroed our M14's the same way on the same targets (called the Canadian Half Bull) everytime we qualified so this was not due to a change in POI at 25 meters. I distinctly remember having to aim low (near the bottom of the target) rather than at the head to the target, to knock the 250 and 300 yard pop ups down. Based on POA to knock the pop ups down from 50 to 300 meters it seemed like the bullets were almost flying level rather than arcing. We didn't fire on paper past 25 meters so I have no recollection of the difference in POI in inches vs. previous lots of ammo we were issues.
Certain ctgs are known for keeping different brands of ammo in the group. The 375 H&H, 38 special, and 308 Winchester lead this this short list, and will even keep different bullet weights in the group. Don't get your knickers in a knot, but temp (for every 20 degrees at 200, or 10 degrees at 600), sunlight (light up? sight up!), and other conditions beyond your control will reset your zero. NEVER MARRY A ZERO! By all means separate your ammo as best you can, but when the hard war starts, you will be too busy to worry about such things. Cheers, dave
Sorta hate to ruffle feathers, but cartridge has little bearing on flight path of the bullet. Given a 150gr. FMJBT exiting a M1A at 2600fps v.s. a 150 gr. FMJBT exiting a M1Garand at 2600fps. the cartridge has no further control of this projo after leaving the barrel. All that can and has been done in done before this exit. Control falls into several catagories. Barrel twist and dimensions, velocity and bullet design. If the same bullet leaves numerous barrels at the same velocity and stablized the same then the results will be the same. When things are done differently, never expect the same results.
My experience with M1's is that different brands of milsurp ammo will, more often than not, shoot to widely differening points of aim. In part it is the cartridge, at least how it's loaded. Different powders can cause different vibration characteristics in the barrel. I see this with handloads as well, and in my bolt guns too. In the case of the .308 ammo in my M1, there can be as much as 3 MOA in both windage and elevation changes from one brand to the next.
Maybe my M1's are just twitchy - heck, all my rifles are extremely twitchy and sensitive to differences in bullets and powder. I have taken to filling out an index card with all the zero info for each type of ammo I've bought and tested and sticking on the buttstock.
Good point, different ammo will shoot different. As will different velocities. My point was using consistant cartridges of same design and using same loadings should yield very similar results provided the cases are of good quality. If the cases are not made to react, upon firing, consistantly, than your results will not be consistant. That being said, the final point is finding the sweet spot for your rifle. Having fired several thousand rounds thru my 22-250, it didn't take long to realize 1" groups were relative easy, but just as easy to lose. Maintaining the fodder that a rifle likes to digest insures reasonable groups in the future. Once you have this magical recipe, KEEP IT. That holds true to every rifle I've owned.
I have found that a primer can make a difference too. I loaded some 7.62x39 with a CCI primer and also with a Winchester primer (two each). Both had 123 grn FMJ bullets with Winchester brass and Reloader 7 powder (can't remember the powder charge off the top of my head). The CCI primed rounds printed appx 1" higher at about 50 yards.
This is very believable! Ignition factors change from primer to primer. However all this difference in bullet affect occurred inside the barrel. Once it left nothing else has an effect on the projo except wind. Still if the exit speed is the same out of the same barrel using the same bullets, the results will be the same. Now to correct myself to a degree. Pressure curves can allow a bullet to exit the barrel at the same speed as another bullet with a different pressure curve and yield different results. A difference in what the barrel was doing upon the release. Barrel heating is another factor that will change strike point on your bullet, being as the barrel heats it loses as tight -a-control on the projo thus allowing less stabilization of the round. Still, all things done the same including maintaining temp. of barrel should result with same or very similar results. Experimentation usually yield the best results somewhere. Just keep pressures in the safe zone!