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Sighting in rifle....bullet issue.

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Sighting in rifle....bullet issue.

Old 10-30-2014, 06:42 PM
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Default Sighting in rifle....bullet issue.

today I was sighting in 2 - .308 Savage bolt action rifles at 100 yards using a vice.

I was using 149 grain bulk ammo, cheap stuff. both guns sighted in well and shot consistent.

then I pulled out a box of federal gold ammo, 165 grain. it did have a very small hollow point tip. In both guns was not even on the 12"x12" target with this ammo. put the other in..dead on...put the other in...miss again. I have heard hollow point can wobble off aim...but man that is a lot. anyone had this happen before or she some light on why?
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Old 10-30-2014, 07:00 PM
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Different ammo from different manufacturers will have a different point of aim even with the same grain bullet.
Did you clean the barrel before going to the different lot of ammo?
Did the barrel have time to cool between lots?
It is quite possible that your barrel does not like the 164 grain JHP.

Its best that you sight your rifle in with the ammo you intend to hunt/plink with in order to stay consistent.
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Old 10-30-2014, 07:00 PM
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Point of impact will differ significantly with a change in ammo. Different velocity's, bullet weights, trajectories, etc.
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Old 10-30-2014, 07:21 PM
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I have shot all my life and usually just buy whatever is on sale and I have never seen this much fluctuation. I have seen an inch here or there, but we are talking a sighted rifle in a vice. change ammo and is greater than 12" off target.
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Old 10-30-2014, 07:22 PM
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Originally Posted by WildLines View Post
today I was sighting in 2 - .308 Savage bolt action rifles at 100 yards using a vice.

I was using 149 grain bulk ammo, cheap stuff. both guns sighted in well and shot consistent.

then I pulled out a box of federal gold ammo, 165 grain. it did have a very small hollow point tip. In both guns was not even on the 12"x12" target with this ammo. put the other in..dead on...put the other in...miss again. I have heard hollow point can wobble off aim...but man that is a lot. anyone had this happen before or she some light on why?
The difference between surplus ammo and premium ammos ballistics are/can be notable, not to mention the 147gr vs 165 will have a differed POI. Since your on paper with the surplus I'd suggest moving your sight in target to 50 yards to get on paper, make your adjustments then go to your 100 yard zero or what ever zero you are needing.
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Old 10-30-2014, 07:27 PM
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My 300 weatherby does the same thing with higher grain ammo. I'd go with vertigo's advice. Good hunting
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Old 10-30-2014, 07:27 PM
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Different powder ... probably higher velocities ... thus different point of impact. No different than working up a hand load on any gun. Heck, 2 grains can make a few inches of difference. Your bulk ammo is cheap for a reason.

All of the .308s I have LOVE the SIERRA GAME KINGS! Sight in your guns for your intended hunting/defense ammo. Then compensate forthe plinking ammo.
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Old 10-30-2014, 07:43 PM
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That is a lot of variation considering you are shooting at 100 yards. I think vertigo is correct in saying that maybe the rifles don't like the 164 grain JHP. I also agree with sighting in your rifle with the ammunition that you plan on using for hunting.

Also, here is a link to the Federal ballistics calculator online.

http://www.federalpremium.com/ballistics_calculator/
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Old 10-30-2014, 07:55 PM
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Originally Posted by WildLines View Post
I have shot all my life and usually just buy whatever is on sale and I have never seen this much fluctuation. I have seen an inch here or there, but we are talking a sighted rifle in a vice. change ammo and is greater than 12" off target.
I'm of the same opinion based on experience. However, I have never used a vice to hold the stock. Use sandbags and tell us what you did, because a rifle's "jump" upon ignition is part of the trip.
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Old 10-30-2014, 07:56 PM
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The combination of the different grain bullet and probably different powder, brass and primer all contribute. The main reason is the weight of the bullet. Move to 50 yards next time. The hollow point has nothing to do with it, otherwise nobody would shoot hollow point.
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Old 10-30-2014, 08:43 PM
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Originally Posted by WildLines View Post
I have shot all my life and usually just buy whatever is on sale and I have never seen this much fluctuation. I have seen an inch here or there, but we are talking a sighted rifle in a vice. change ammo and is greater than 12" off target.
Not 12", but at least 6" minus the size of your group. So if your shooting a 2" group then it may only be off as little as 4" to miss a 12"x12" target completely.

I would not expect cheap ammo shoot to the same POI as match grade fodder. Sighting in a rifle is part of changing ammo, it needs done every time. Once in a while you get lucky and they are close enough to work though.
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Old 10-31-2014, 07:16 AM
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As many have said, sight in with the ammo you will hunt or compete with. When I buy my .308 Win rounds for deer hunting, I buy 3 boxes at a time. I have enough to sight in and hunt the season without shooting different rounds.
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Old 10-31-2014, 07:29 AM
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Total BS about Hollow Points throwing off aim. Much of the match grade bullets the competitive rifle shooters use is Hollow Point.

Powder Type, Burn Rate, Brass, Primer, Barrel all have to do with it with bullet weight being the most likely cause.
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Old 10-31-2014, 07:29 AM
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Is it possible the scope mount on the second rifle came loose?

Seems odd that nominally identical rifles would behave so differently with a change in bullet weight. As far as bullet weight effect on POI, the heavier bullet usually results on a higher POI, but 6" at 100 yards is a bigger effect than I've seen with other .30 caliber rifles. Usual differences I see with a 10-20% change in bullet weight is 0-4", 2" being the most typical, but these are all rifles fired from sandbags.
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Old 10-31-2014, 07:33 AM
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Originally Posted by Fish Hunter IV View Post
Total BS about Hollow Points throwing off aim.
Tru dat. WildLines, were the 165's boat tails? Open tips (hollow points) along with the boat tail are considered by many pros to be the most accurate bullets.
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Old 10-31-2014, 10:31 AM
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Scopes are tight with locktite, confirmed before sighting in.

This is 2 separate .308, both having the same issue with these bullets.

I am shooting at an outdoor range, so a flat angle in a vice. I expected it to be off....but not the difference between being sighted in and not even on a 12" target. Seems excessive to me. I don't expect a .308 shell has any lob in it at 100 yrds with any load.

I am hunting tomorrow....and will be shooting the 149gr .308 bulk ammo. It will do fine and will look at it again later. I will probably leave it sighted on the cheaper ammo so I can shoot it more for fun.
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Old 10-31-2014, 10:57 AM
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What size are the groups you're shooting, and is the vice something like a Lead Sled, or a device that clamps around the stock?
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Old 10-31-2014, 11:46 AM
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What's the barrel twist rate on those rifles?
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Old 10-31-2014, 12:46 PM
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Originally Posted by NCummins View Post
Point of impact will differ significantly with a change in ammo. Different velocity's, bullet weights, trajectories, etc.
x2

Last edited by Garett; 11-14-2014 at 01:21 PM.
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Old 10-31-2014, 01:24 PM
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You have been given good advice. Bottom line different rifles perform better with different ammunition. In the case of my WWII Springfield it prefers 180 grain Noslers.
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