308, 30-06 at 1500 & 1760

[minute of elk]

I was inspired by questions raised in this thread: http://www.longrangehunting.com/forums/f19/308-bullet-weight-effects-past-1-000-yds-119183/

My basic premise- would i trust a 308 for man sized targets at 1500 yards? cold bore hits are priority, overall ability to make life difficult for a bad guy at 1500 secondary.



I'll start with conditions- about perfect. It was 40F, barometer said 30.15, 53% humidity, 2-5 mph winds, clear, sunny, cold- aka heaven.

I want to thank MontanaMarine for a few things- the load, the time, the preparation of the course (torture, right?), and for being an all around great guy to shoot with.

here are the rigs (and MontanaMarine's custom tactical shooting mat...)



front

my Tikka varmint 308 in a Mountain Tactical thumbhole tactical prototype, 20 moa rail, 10x SS, harris 6-9 swivels, duct tape & foam cheek. I modded the bolt stop & mag to feed 3.004" cases (still need to do something about the tilting follower, but Jason's on it- right Jason?). My loads are copied from MontanaMarine all the way- 48.5 gr R-17 under 208 amax's at 3.004" COAL

back

MontanaMarine's 30-06- i"ll let him fill in the details, because i'd likely get them wrong...

I recently switched triggers, so i took a 'zero check' shot at 100 & made my 3 clicks left to get it back to zero. Then i let it cool so i could honestly approach this from a cold bore perspective.

OK, we didn't have an actual 1500 yard target lined out, so MontanaMarine suggested that since he had a mile target already verified, why not just start there & work on the 1500 yard target after. Seemed like a good idea to me.

I'm a little sleep deprived (thanks to my 3 year old) & don't remember what MontanaMarine's first string looked like- sorry, man, you gotta fill that in, too. I do remember his first shot being low (and later realizing that his rifle was zeroed ~1"-1 1/2" low at 100), and we had some difficulty getting good splash to call hits & misses. We moved from the original .5 mil rock to a slightly smaller bush to its left & got good dust for spotting shots. Accuracy was better than I expected for a 30-06 at a mile.

Now we had a dependable target for spotting shots, so I slithered up to my 308 & consulted Shooter. My scope cap dope chart ends at 1500- which will be fixed soon , so i went with the app.
1) I dialed 24.6 mils, & held left edge. First shot, cold bore- missed 1 mil low & .5 mil right.
2) held 1 mil up & .3 left- missed .5 right of target- elevation was on target, but lowish
3) held 1.2 mil up & .5 left- missed .2 mil right, good elevation
4) held 1.2 mil up & .7 left- hit at 3 o'clock on the edge
5) held 1.2 mil up & 1 mil left- hit near center

You could say that i was encouraged...

Our solution to not having a 1500 yard target was to move 260 yards closer to the mile target. The light had changed enough that we weren't getting good spots on MontanaMarine's first string at the bush from the mile setup, so I gotta ask you to fill in the details again... I should have kept notes on both...

My dope card goes to 1500, and has been verified out to 1200, so i was more confident about the 1500 yard round.

Atmospherics: 4330ft, 45F, 30.12, 56% humidity

I dialed 19 mils & fired- the first string of 5 was difficult to spot- we both think i hit most of them, but decided to shoot the original .5 mil rock that wasn't showing splash earlier. It was all good now. Of course, he had to go & shoot a chunk off of the right edge & make it smaller for me, but I didn't mind.
second string- much better visibility for calling hits & misses
1) held .5 right- missed .3 off right edge at 3 o'clock
2) held top third- hit, center
3) held center- hit 7 o'clock edge
4) held center- hit 4 o'clock edge
5) held top center- hit 12 o'clock on the top edge of the rock (double splash)

My 2 cents- if I could take handloads (or Mexican match some 208's into the mix somehow on deployment), I would feel pretty darned cocky with my little 308 taking 1500 yard shots.

 

[MontanaMarine]

Rob, great day shooting for sure.

My first string at 1760 was about 1.5 mils low. I was shooting RL17, maybe it was runnig a little slower in the cooler morning, cooler air a little thicker, and my zero was about 1" low at 100 as I found out at the end of the day. I hadn't shot this rifle at paper in probably a year, and had pulled the scope off the Badger rail for cleaning at one point so that sorta opens the door to a zero shift.

The bush we shot at at 1760 we mil'd and estimated at roughly 20" tall, 30" wide.

At 1500 I was a tad low, adjusted, and went to hitting consistently on the rock that we estimated about 18"x 20".

Lighting was a little tricky in the overcast skies and shadows, but when the sun showed itself we were seeing very visible back-lit splashes, as we were shooting somewhat toward the sun (south).

We spent three or four hours working on targets. My data sheet was pretty much dead on out to 1200 yards or so, but was coming up a little short past that distance.

At the end of the day I wanted to verify my 100 yard zero, shot a three-shot group at 100 yards, it was .327", and about .75 moa low. That explained part of my low hits at distance.

 

[MontanaMarine]

I can tell you there is a significant difference between shooting 1760, and 1500, with the 308/30-08 and the 208 AMax. 1760 felt to me like we were really pushing it, even in conditions that were about as good as it ever gets.

Closing the distance to 1500 yards made everything seem a lot more responsive regarding corrections, and hit repeatability. for comparison, with my 30-06, I was dialing 58 moa at 1500 yards, and 80 moa at 1760 yards.

When we pulled it in to 1125 yards, it was like child's play. I was at 34 moa.

 

[Canadian Bushman]

Impressive shooting with the .308's guys. Congrats on a job well done and catching the conditions. What altitude were you fellas shooting in/at?

 

[MontanaMarine]

Our firing point was about 4330 ft. Target elevation was about 4890 ft.

 

[BrentM]

What speeds are you guys producing?

I have been thinking about digging my 06 out and installing my NF on it for some LR experience in this configuration. I have a friend who wants to build a LR rig but is gone for 6 weeks guiding. My thought is that he should use his 3006 and properly scope it. My rifle is currently shooting a 180 Nosler AB at 3/8 @100 and with a 3.5-10 I have shot several 1.25 to 1.5" groups at 300. I zero'd the rifle at 300. I have not chrono'd this load but I suspect it is around 2650 and the next best load is around 2750 and shoots 5/8th. I would probably take the higher speed load for LR. It is 2 grains stronger.

 

[MontanaMarine]

Brent,

My 30-06 has a 22.5" barrel (Douglas, #7, 1/10, stainless), and my load was 55gr RL17 in Norma brass, moly'd 208 AMax at 3.40" oal.

I chrono'd the load at 2720 fps in the summer temps about 80F. At that time I was hitting a mile at about 75 moa. On this outing the temp was about 40F and I needed 79 moa to hit. I suspect lower speeds, probabaly 2650-ish, and denser air were part of the equation.

Back when I was shooting a 26.5" bbl (same bbl before cut/brake) I was loading 60gr RL22 for 2800 fps in summer temps.

Shane

 

[minute of elk]

i'm seeing 2640 with tiny ES