Powder Charge and Windage?


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Malfader13
January 6, 2006, 02:29 AM
I have been reloading for a while to save money but now am getting more serious about gaining more accuracy. I don't think it should but am wondering if a powder charge, all other things being equal, will effect your windage. I was on at 100yds with one charge but would be off to the left with two other charges. Any ideas what might be going on here? It could be me I suppose as I have only taken this particular gun out three time had have about 800 rounds through it.

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AnthonyRSS
January 6, 2006, 02:34 AM
I noticed this yesterday as I experimented with my first .30-06 loads. I zeroed my gun at 100 yards with a 165gr SST on top of 54gr of H4350. I moved up to 56gr and it shot 5 inches left. Not a big deal, really, and I am going tomorrow to try 57 grains. I shot a 1.1" group with the 54gr, but didn't shoot the 56grain load.

dmftoy1
January 6, 2006, 07:14 AM
I'm curious about this too . . . .I'm trying to duplicate XM193 ammo for my .223 and I've got it close in terms of FPS and it hits at the same elevation but it shoots to the right of the POI of the XM193. I tried both rounds in the same session alternating and it was pretty consistently 2 inches different. I was attributing it to a different COL, but I don't know if that has anything to do with it or ? Looking forward to what people who have experience with rifle rounds has to say.

Have a good one,
Dave

dakotasin
January 6, 2006, 07:28 AM
i have noticed powder charge does indeed affect windage. probably has everything to do w/ the elliptical vibration of the barrel on firing, and where the bullet is leaving during that vibration.

i have also noticed that merely switching powders can change poi significantly from a different powder, even if velocities are similiar. i have no explanation for that, except to say that is part of the fun in being a rifle crank and handloading addict.

Steve in PA
January 6, 2006, 08:43 AM
Different powder charge = different velocity = different downrange ballistics

Malfader13
January 6, 2006, 11:41 AM
Ok I will have started keeping a more accurate log book on my reloads and go shooting just about every week with a friend of mine. I will post my findings. It dose sound like the charge dose effect windage, and the different charges I used were out of the Hornady book and each charge should have been 100fps greater then the last though I don't yet have a chronograph to test this yet. Any findings from others I would be greatly interested in.

~z
January 6, 2006, 12:20 PM
Malfader, you have discovered barel harminics. I have been baffeled by this for years. Same bullet, same case, same primer, same velocity, same conditions, different powder...different POI. That is just how it works. Fight it all you want, if you win, let me know how you did it.
~z

Ol` Joe
January 6, 2006, 12:33 PM
Malfader, you have discovered barel harminics. I have been baffeled by this for years. Same bullet, same case, same primer, same velocity, same conditions, different powder...different POI. That is just how it works. Fight it all you want, if you win, let me know how you did it.
~z

I agree! Any change in the load even a slight change in charge weight will often cause a change in the barrels vibration. The POI will vary depending on where in the barrels vibration it`s pointing when the bullet exits. Barrels don`t just jump up and down when fired they move all over the place. Here`s a site with some barrels under fireing stress being put to motion in a engineering study.

http://www.varmintal.com/amode.htm

P-32
January 6, 2006, 09:21 PM
It's just like taking a box of every manf.'s bullet out and trying them all at once. No two will shoot the same.

I find a load I like then stick with it. Don't have to move the scope/sights around so much that way.

MNgoldenbear
January 6, 2006, 10:00 PM
+1 on barrel vibration. Pretty sure that would be the cause. Another thing to beware of is firing conditions. Be aware of wind, temp., humidity, lighting, etc. Wind and temp. are obvious. Humidity is probably only a big issue at longer ranges. As for light, I was a beginning shooter and was firing PPC competitions. Couldn't figure out why my windage was consistent for 7, 15, and 25 yards, then shifted significantly at 50 yards. It was later pointed out to me that the 50 yard firing points were covered, so the sights were shaded. The sunlight striking the sights at an angle had made me favor one side slightly (side the light is coming from IIRC) and that effect was no longer present under covers.

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