6mm or 6.5mm - Yes. This again. But with Data!

[Cold_Bore_88]

So I am specing out a new rifle. I will primarily use this rifle for PRS matches but don't have any plans to compete on a national level...yet. It seems like everyone is telling me to go 6mm (6 Creed to be exact). I always hear that the "real" competitors shoot 6mm. However, I am struggling with 6 Creed or 6.5 Creed because of the data I am getting out of AB. The data below is based on Hornady Match factory with ELDM bullets. Velocity is what is advertised.

From my limited experience in local matches, WIND IS EVERYTHING! I don't see the real advantage to a 6mm in regards to wind. Am I missing something? I can handle the trajectory but want to eliminate wind as much as possible. Our local matches go out to 1100 yards.

Drop (MRAD)
6.5 Creed w/ 140 gr @ 2700 - 1200 Yards = 12.3
6mm Creed w/ 108 @ 2950 - 1200 Yards = 11

Windage (MRAD) - 15 mph @ 3 o'clock
6.5 Creed w/ 140 gr @ 2700 - 1200 Yards = 3.8
6mm Creed w/ 108 @ 2950 - 1200 Yards = 4.2

Note: I don't want to be forced to load so 6 or 6.5x47L, Dasher, etc. are not for me.

Can someone tell me what may be flawed in my thinking? No matter what I do to the velocity, 6.5 always performs better in the wind. In fact the % delta between the 2 is greater in the wind variance which favors the 6.5.

 

[Blowby]

Not sure where you're planning on shooting but E8.6 / W2.1 at my elevation on a typical day using my 6 creedmoor / DTAC 115 @1200 yards, 2947mv.

I calculate E9.9 and W3.0 at 500 ft elevation.

 

[Cold_Bore_88]

Maybe it is something I am doing wrong in my calculator. With your numbers above I get 10.7 and 3.8.

 

[morganlamprecht]

the answer is recoil...the less there is the easier it is to handle...wind between a 6 and 6.5 from 300-800 yds is basically a wash, and thats where matches are won...a 6.5 is competitive...ive ran 6mm but, ive run 6.5 the last 2 yrs...i rarely free recoil anything like a lot of guys do though

 

[tomcfc11]

morgan nailed it. If you can spot your impact on target then you have a better idea of wind for farther targets.

 

[Cold_Bore_88]

Why so slow on the 6mm? I get 3070fps with 110gr SMK's without breaking a sweat. The 6mm has more than enough horsepower to easily break 3k. if you're going to run it slow, then I agree, there isn't much advantage over the 6.5.

At 500 feet elevation and 15mph FV wind from 3 o'clock, my holds would be 9 mils elevation, and 3 mils wind at 1200 yards.

I am assuming advertised factory load velocity from Hornady. Don’t want to screw with loading. Takes a lot of time for small payback.

 

[6point5CM]

I wonder if there is a calculator for weight/felt recoil. I bet you could add a longer/heavier contour barrel to a 6.5 increasing a pound or two (think Rem Heavy Varmint) and have the same recoil with a 6.5 as a 6 with a Heavy Palma or Marksman style contour.

I personally run a 6.5 creed but with 130's at 2900. Easy recoil, in between your two examples for elevation, and bucks the wind well. That could be a viable option for you as Prime runs 130's and shot great out my rifle while I was building up a once fired brass supply for reloading.

For my personal trued dope, at 1200 yards at 2,000 DA and 50 degrees and 15mph wind, I get 10.5 Elevation and 3.3 Wind.

 

[Sheldon N]

Looking at wind, instead of looking just at total wind drift look at how much you miss by when your wind call is off by 2 or 3 mph. Once you are more than 0.3 mil off you are likely missing a typical size PRS target. The difference between calibers is not as dramatic as your numbers above might suggest. Spotting your misses or hits and making better corrections can easily offset the difference in ballistics.

 

[rookie7]

morganlamprect said it - recoil management.

However, if you aren't going to reload the only answer when all variables are considered is 6.5 creedmoor.

There are more on-the-shelf options in ammo.

Plus, if you dig deep enough you will find that the 6mm can be very finicky. Shooters report adjusting loads at 400 rounds give or take - maybe less, maybe more. If you are shooting factory ammo, there aren't any adjustments to be made to seating depth, powder, etc.

Equip your rifle so it is heavy - 17 pounds or so - buy the best brake you can - go shooting.

 

[Cold_Bore_88]

Looking at wind, instead of looking just at total wind drift look at how much you miss by when your wind call is off by 2 or 3 mph. Once you are more than 0.3 mil off you are likely missing a typical size PRS target. The difference between calibers is not as dramatic as your numbers above might suggest. Spotting your misses or hits and making better corrections can easily offset the difference in ballistics.

I find myself coming to this conclusion a lot. It’s the Indian. Not the arrow.

Can I still say Indian?

 

[260284]

Not sure where you're planning on shooting but E8.6 / W2.1 at my elevation on a typical day using my 6 creedmoor / DTAC 115 @1200 yards, 2947mv.

I calculate E9.9 and W3.0 at 500 ft elevation.

The DTAC is flatter than the 108 ELDM.

 

[Sheldon N]

I find myself coming to this conclusion a lot. It’s the Indian. Not the arrow.

Unless the arrow is a 308. In that case the Indian is screwed.