How much change in POI if bullet weight change 150-165gr

[IdahoSkies]

How much of a change in drop (velocity/powder amounts, rifle, etc being equal) would a change from 165gr to 150 gr or vice versa make in a 30-06 load.

I know the only solidly safe answer is do it and see, each rifle is different, but I was wondering if anyone had any general ideas of how much of a difference does it make.

I ran some numbers in a few programs and I can't really tell much of a difference at least out to 300-400 yards. (which is well at the far end of my ability).

 

[jmr40]

Not all that much.

The problem is that 30-06 loads are all over the place. You can find factory loads that start a 150 gr bullet as slow as 2700 fps or as fast as 3100 fps. The 165's can be almost as bad, so it makes it hard to compare apples to apples. Different bullets have different aerodynamics too. Shoot 165 gr Speers and they will dorp a lot more than 168 gr Bergers even when started at the same speed.

Trying to make things as equal as possible there will only be about 3" more drop at 300 yards with good quality 200 gr bullets than 150's, less than 1" difference between 150's and 165's.

This is with handloads. With factory loads you can't control the variables so it is harder to say.

 

[sage5907]

jmr40 has a good explanation. I have found that if I load a 150 grain Speer boattail with 57 grains of IMR 4350 and compare the point of impact at 200 yards with a 165 grain Speer boattail loaded with 57 grains of IMR 4350 the point of impact for all practical purposes is identical. No change in hunting zero for this one particular rifle. I haven't tried it with Sierra Gameking boattails but I would think the results would be similar.

 

[Art Eatman]

I went messing around on my 500 yard range one day and was rather startled:

'06 Max loads. 150-grain Sierra SPBT. 165-grain Sierra HPBT. 180-grain Sierra SPBT.

All groups impacted within three inches of each other.

 

[natman]

How much of a change in drop (velocity/powder amounts, rifle, etc being equal) would a change from 165gr to 150 gr or vice versa make in a 30-06 load.

There will be a modest change in trajectory once you get the gun rezeroed for the different load.

POI on the other hand is a complete crap shoot. Some guns will shoot two different loads to more or less the same POI, but I've had POI change more than a foot because I changed to a different bullet of the same weight.

Try it and see is the only way to tell.

 

[cluttonfred]

Yes, you do have to try it, but if you can find the ballistic coeffiecient of the specific bullets in question you can at least run the trajectory numbers and get a ballpark idea of where to start. You'll need to know at what distance your rifle is zeroed with the current load to start.

 

[Hardtarget]

And that is why its fun to reload and get out there and shoot! After reading what you guys have posted its easy to see why the .30-06 has long been a hunter favorite!

Mark

 

[Sheepdog1968]

Not that I measured it formally but it seemed to change by about an inch at 100 yards.

 

[Sheepdog1968]

And that is why its fun to reload and get out there and shoot! After reading what you guys have posted its easy to see why the .30-06 has long been a hunter favorite!

Mark

Though I take my 30-30 out most often, my Rem 700 XCR II in 30-06 with a 4x scope is my go to general hunting rifle and was bought for that purpose.

 

[BCRider]

We're only talking about a 10% change in bullet weight. On top of that the heavier bullet is likely, or should, have a better BC. So it's not much of a surprise that there's very little difference in POI.

 

[cluttonfred]

Here are some numbers from http://gundata.org/ballistic-calculator/ for two similar 150 and 165 gr .30-06 loads zeroed at 250 yards:

A .30-06 Springfield, Federal Sierra GameKing BTSP, 150gr
B .30-06 Springfield, Federal Sierra GameKing BTSP, 165gr

Range Drop (in)
A B
0 -1.4890 -1.4883
50 1.2707 1.4443
100 2.9097 3.1712
150 3.3249 3.5863
200 2.4011 2.5721
250 0.0100 -0.0025
300 -3.9923 -4.2830
350 -9.7673 -10.4326
400 -17.4967 -18.6333
450 -27.3853 -29.0893
500 -39.6644 -42.0293

As you can see, the differences are really negligible.

 

[Captcurt]

Depends on the gun.

I had a Ruger 77 in 270 that didn't care what you put in it. It would shoot 130gr and 150gr to the same POI. Brand of bullet did not matter. I must confess that I didn't try round nose though.

On the other hand, there was a Rem. 742 Carbine that shot 4" or 5" off if you even changed brands of bullets, and this was at 100 yards. That one didn't stay around very long.

 

[bhk]

It is not the trajectory changes that will mess you up, it is the change in point of impact (sight in) that can. Some of my guns seem to shoot to the same point of aim at 100 yards when I change bullets weights, others shoot to wildly different points of aim. Only one way to find out.

 

[H&Hhunter]

I've found that some rifles don't change much with different weight bullets and some do. So verifying on paper is the best way to be sure. Don't ever count on a paper chart to give accurate velocity or trajectory information. It might be right on, it might not be.

 

[cougar1717]

Remington's data sheets used to be approximately 1/2" difference at 300 yds and 1-1/2" at 400 yds with a 200 yd zero. Programs, data sheets, and rules of thumb don't really make a difference at the range.