Please help

[jjhuep]

Hello,

I am having this issue I would like answered if possible. I shot 20 rounds of Federal Premium Vital Shok 150 grain Nosler Partition in .270 caliber and then shot Winchesters 150 grain Partition Gold's in .270 caliber. I had the gun sighted in with the federal and at 100 yards the federal was all grouped about 1.5" above bullseye. NOw with the Winchester all the shots were grouped about 4-5 inches high at 100 yards. At 200 yards the Federal was about dead on while the Winchester was about 3 inches high. I also seemed to get tighter groups with the federal. Anyways, why is this. The bullets Velocity tables are about identical. The only visible difference is that the federal has a copper like casing while the Winchester seems to just have a normal metal look to the bullet. Anyways, has anyone else seen this? Do you find that federal or Winchester is a better ammo.

jjhuep

[Phil Dunlop]

Sorry I can't tell you why that happens, but it is very common for different loads to behave like that.

My own 308 Winchester Featherweight groups several sporting 150gn loads to roughly the same point of impact, but throws Aussie F4 ball over a foot away at 100yds.

P.D.

[Chriss Grube]

Different Powder and primers. Federal Factory ammo will generally out shoot all the other brands. I gave up on the partitions because they wouldn't group worth crap in any gun/load combo I tried.

[jjhuep]

Thanks for the quick response. I probably would not shoot the partitions but I am practicing for a moose hunt in about 4 weeks. I know, a .270 is on the small side, but I am comfortable with this gun from deer hunting. I am just resighting the gun with the larger 150 grain bullets. I figured that I should use the nosler partition for a moose. Anyways, I guess I will just use the Federal 150 grain Nosler Partition instead of the Winchesters for obvious reasons. If anyone has something else to say in defense of the Winchesters I am all ears.

[warpspeed]

I have had very good luck with Federal ammo in 270 Win. I like the Nosler Partition bullets for hunting. I've also had good luck with PMC ammo that is loaded with Barnes bulltes. 130's I think they were.

Good luck on the hunt!

[jkelly]

I'll try to explain what I believe to be true, but I could be wrong.

External ballistics is what happens to the bullet in flight after leaving the barrel.

Internal ballistics is what happens to the bullet before it leaves the barrel.

When we see two different types of ammunition printing to different spots and having different sized groups we tend to think it's related to external ballistics. At short range, 100 to 200 yards, in this case, external ballistics has little to with group size and placement (we are speaking of hunting rifle accuracy at short range).

Internal ballistics, that is primer, powder, seating depth, bullet shape, and bullet jump ect. have more to do with group size then External ballistics.

So why is one ammo type more accurate (smaller groups) then another of similar velocity?

Well, the more accurate round (Federal) is likely to be closer to the ideal for your gun. The same may not be true for the same model gun produced on another day, where the Winchester round may be more accurate. It is also possible that the Federal ammo is more similar to each other then the Winchester.

Why does one ammo print to a different place then another of similar velocity? Again at short ranges this difference is due to Internal ballistics. While the bullets may leave the barrel at the same velocity, the time it takes to leave the barrel and the effect of slightly different recoil place the barrel in different positions. For a three inch difference at 200 yards this is about .015 inches (I think).

Although I have a rifle in 270 Winchester, I haven't shot factory ammo in it for 15 years, so I couldn't comment on the new factory loads. I do know that my 270 likes 130 grain bullets more then the 150 grains. And I'll agree that Partions are not it's favorite, but I shoot them any way (sometimes in 150 gr).

Respectfully,

jkelly