Point of impact change

[ebby]

Hey guys, I'm leaving in a few weeks for a Mtn Goat hunt and was wondering y'all could help me. I'm taking my 6.5 PRC. Currently I'm shooting a load with the 124 hammers but the factory 143 ELDX shoots great too and I'm leaning towards the heavier bullet. My question is what kind of point of impact shift should I expect on the hunt?

I'm in TN and about 700ft elevation. Temps in the 80's around here while I'm setting my turret. I'll set my marks out to 600 which will be the farthest shot I'll take on the trip. Temps should be 30-50F or so on my hunt with elevations from 3500-7000ft or so. What should I expect? Will there be a big difference if I choose one bullet over the other? Thanks guys!

Lee

 

[Rick Richard]

Why don't you run the data through a ballistic app. It can tell you probably better info than the guesses you will receive. Just an idea.

 

[ebby]

Yeah. I will do that. I was just curious more about generalities than the exact numbers.

Will the altitude and temp cause my impact to be low or high? I'll play around with my Ballistic app and figure it out.

Thanks

 

[Hugnot]

About zippo if max range is less than 600, this is assuming same bullet. I would be more confident with the 124 solid copper bullet; a diagonal shot thru some beast might be required. Most apps would come up with about 1 inch which is about zippo. Actual barometric pressure would be a bigger concern than altitude. Less air pressure due to higher elevation & a fallling barometer & more humidity would make bullets fly higher.
Much more important is angle of fire - like mountains, up & down. Many range finders can provide firing solutions with determined angle of target, or use cosine table.

 

[ebby]

Thanks! That's what I'm looking for. Sounds like it won't be much difference and not enough to worry about. Good to know it will be slightly high if anything. I will prob try to find time to load up some more Hammers and take them instead of the eldx. Drift is only 2.5" more at 500 with a 10mph crosswind.

 

[LVJ76]

Different bullets with different bearing surfaces will have a different POI.

Example, when my is 7mm-08 sighted with 139gr SST, if I shoot a 120gr BT, it impacts 7" to the left and about 1" low.

It's a lot I know, but I've tried it 5 times, or more, and it does it every time. And this is just one example, there are more but not as drastic.

So if possible, I recommend you check before you leave.

 

[ebby]

I'll be checking. I'm going to settle on one bullet for the trip. I am aware that different bullets will hit differently. I was questioning how much impact shift should I expect from the higher altitude and lower temps not from the two different bullets. I'll have one bullet decided on and the turret set before I leave. Thanks.

 

[RidgeTop]

Hey guys, I'm leaving in a few weeks for a Mtn Goat hunt and was wondering y'all could help me. I'm taking my 6.5 PRC. Currently I'm shooting a load with the 124 hammers but the factory 143 ELDX shoots great too and I'm leaning towards the heavier bullet. My question is what kind of point of impact shift should I expect on the hunt?

I'm in TN and about 700ft elevation. Temps in the 80's around here while I'm setting my turret. I'll set my marks out to 600 which will be the farthest shot I'll take on the trip. Temps should be 30-50F or so on my hunt with elevations from 3500-7000ft or so. What should I expect? Will there be a big difference if I choose one bullet over the other? Thanks guys!

Lee

Probably have to shoot it to find out.

 

[Rick Richard]

I'll be checking. I'm going to settle on one bullet for the trip. I am aware that different bullets will hit differently. I was questioning how much impact shift should I expect from the higher altitude and lower temps not from the two different bullets. I'll have one bullet decided on and the turret set before I leave. Thanks.

You won't see that much of a difference between environmental conditions, however as you know the further out you go it could mean the difference between a kill or miss…or worse. By the way, good luck on that hunt.

 

[LVJ76]

I'll be checking. I'm going to settle on one bullet for the trip. I am aware that different bullets will hit differently. I was questioning how much impact shift should I expect from the higher altitude and lower temps not from the two different bullets. I'll have one bullet decided on and the turret set before I leave. Thanks.

My bad, got it wrong.

 

[Varmint Hunter]

Funny that you should ask. A few days ago I was shooting the 124 Hammers at 417yds. The velocity was 3,200 ft/sec. I eventually got around to shooting some 143 ELD-X bullets at 3,027 ft/sec with an SD of 6. I was surprised to see that they grouped right next to the Hammers. The drop was the same but the 143s grouped 1.75" to the right.

I'm not sure how this relates to a similar test in any other rifle but it is interesting that both bullets (at different velocities) grouped so close together.

BTW - I did not clean the barrel between shooting the two different bulletss. The 143's shot into a tidy 1.38" at the 417yd line.

 

[Dean2]

Under hunting conditions most guys cannot hold the small difference elevation and temp will create under 600 yards. The one thing I would suggest is work up your loads with a temp stable powder. I have seen some very large changes in trajectory caused by going from 70F to -20 using some of the Reloader powders, as in 300 FPS drop in velocity. WAY more than I have ever seen with any other powder. I repeated the test a couple of times because I originally didn't believe that large a jump was possible. It makes them unusable in this part of the world as we hunt down to -45.