Scratch the .338-375 Ruger, make room for the 6.5mm-06AI

[Coyote Hunter]

Well, my intent to build a 700-800 yard elk rifle in .338-375 Ruger custom has fallen by the wayside for a number of reasons.

The first is practicality.  I don’t really NEED such as rifle, as I already have a perfectly good .300 Win Mag that will suffice.  Another is that the Interarms Mark X action I have is made for a .30-06 size cartridge and I’d have to get the bolt face and feed rails modified – no big deal in the greater scheme of things but unnecessary if I go with a .30-06 or one of its many siblings.  Then there is the cost of shooting – the cost of .338 plinking bullets would be about double that for a .30 or under, brass costs would be more and the .338-375 Ruger would consume more powder. Then there is the issue of forming brass.  While none of these were show-stoppers, there was another and more important issue  - l decided to build a rifle my daughters would be comfortable shooting, which meant a .30-06 or smaller.  Since there are already multiple .30-06’s in the safe I decided a sub-.30 would be the way to go.

The goal was still to have a rifle capable of 700-800 yard shots on deer and antelope if needed but more importantly be capable of 500-600 yard shots at the range.  Specifically, I was looking for the best balance of trajectory, retained energy, recoil and powder efficiency.  The ballistics for a number of cartridges were investigated with a variety of bullet weights and types in each cartridge.  The cartridges studied included the .257 Roberts, .25-06, .257 Weatherby Magnum, 6.5mm-06, 6.5mm-06AI .264 Winchester Magnum, .270 Winchester, .280 Remington, .280 Remington AI, 7mm Remington Magnum, .300 Win Magnum and the previously intended .338-.375 Ruger (using .340 Weatherby data).  Since I already have a .257 Roberts, 7mm Remington Magnum and .30 Winchester Magnum they were used for comparison purposes only but were not candidates for the new rifle.

What I found was the 6.5mm-06 and 6.5mm-06AI with 120 Ballistic Tip and 130g Scirocco bullets did very well.  They shot nearly as flat as the .257 Weatherby 110 AccuBond and  flatter than the .257 Weatherby with 120g Partitions but offered more downrange energy, burned less powder and generated less recoil. The 130g Scirocco was just behind the 7mm Remington Magnum in terms of trajectory and energy, but again burned less powder and generated less recoil.  Estimates for the 6.5mm-06 Ackley Improved, using up to 10% more powder and generating 3% more velocity, are even more impressive in terms of trajectory and energy and still provide better powder economy and generate less less recoil than the other loads.  (The 6.5mm-06 AI/130g Scirocco actually beats the 7mm Rem Mag 140g AB load at 800 yards in terms of both trajectory and energy – at least on paper.)

For a couple of reasons, I am leaning toward the 6.5mm-06 Ackley rather than the standard version.  The primary reason for this is that I could use inexpensive .25-06 brass without fear that someone might chamber a loaded cartridge in a .25-06 rifle.  The additional velocity provided by the AI version is tempting but I might find myself loading to standard 6.5mm-06 velocities and reaping the benefits of lower pressure and longer barrel life.

Below are some of the comparisons I ran using “Point Blank” ballistic calculator (available free at www.huntingnut.com).
A few notes on the data:
1. Most velocity data is from Nosler 6th Edition.  Some are estimates or are from other sources.
2. In some cases bullets have been changed from that in the data books – notably for the Scirocco, but also for the TTSX.
3. Manufacturer Ballistic coefficients have been used when available.  In some cases they are estimated.
4. Recoil data is calculated for a 8.3 pound rifle and scope combo.
5. MPBR (Maximum Point Blank Range) is calculated for a maximum rise or drop of 3” from Line Of Sight (6” diameter target).
 

Code: [Select]

=============================================================

Name: .257 Roberts, 100g TTSX
Ballistic Coeff: 0.418 (estimated)
Bullet Weight: 100
Velocity: 3250
Target Distance: 270
Powder charge: 48g
MPBR: 317
Recoil: 12.2fpe @ 9.7fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3250 fps  2345 fpe    0.00 in
300 yds   -1.81 in  2591 fps  1491 fpe    5.91 in
400 yds  -11.26 in  2392 fps  1270 fpe   10.80 in
500 yds  -26.94 in  2201 fps  1076 fpe   17.64 in
600 yds  -49.70 in  2019 fps   906 fpe   26.40 in
700 yds  -80.85 in  1846 fps   757 fpe   37.35 in
800 yds -123.07 in  1685 fps   631 fpe   51.30 in


=============================================================

Name: .257 WBY 110g AB
Ballistic Coeff: 0.418
Bullet Weight: 110
Velocity: 3480
Target Distance: 289
Powder charge: 71.0g
MPBR: 338
Recoil: 19.6fpe @ 12.3fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3480 fps  2958 fpe    0.00 in
300 yds   -0.58 in  2787 fps  1898 fpe    5.38 in
400 yds   -8.46 in  2579 fps  1625 fpe    9.93 in
500 yds  -21.46 in  2380 fps  1384 fpe   15.99 in
600 yds  -40.79 in  2191 fps  1172 fpe   24.03 in
700 yds  -67.23 in  2009 fps   986 fpe   33.97 in
800 yds -102.25 in  1837 fps   824 fpe   46.15 in


=============================================================

Name: .257 Weatherby 120g Partition
Ballistic Coeff: 0.391
Bullet Weight: 120
Velocity: 3427
Target Distance: 250
Powder charge: 70.0 (estimated)
MPBR: 330
Recoil: 20.9 @ 12.7fps

Scope Height: 1.500
Temperature: 70
Altitude: 500

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3427 fps  3129 fpe   -0.00 in
300 yds  -2.70 in  2699 fps  1941 fpe    5.94 in
400 yds  -11.73 in  2481 fps  1640 fpe   10.94 in
500 yds  -26.40 in  2273 fps  1377 fpe   17.73 in
600 yds  -47.92 in  2076 fps  1148 fpe   26.69 in
700 yds  -77.22 in  1888 fps   950 fpe   37.76 in
800 yds -117.09 in  1713 fps   782 fpe   51.91 in



=============================================================

Name: 6.5mm-06 120g BT
Ballistic Coeff: 0.458
Bullet Weight: 120
Velocity: 3294
Target Distance: 276
Powder charge: 55.5g
MPBR: 324
Recoil: 16.4fpe @ 11.3fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3294 fps  2891 fpe    0.00 in
300 yds   -1.38 in  2683 fps  1918 fpe    5.26 in
400 yds  -10.21 in  2497 fps  1661 fpe    9.65 in
500 yds  -24.52 in  2318 fps  1432 fpe   15.48 in
600 yds  -45.51 in  2147 fps  1229 fpe   23.22 in
700 yds  -73.96 in  1984 fps  1048 fpe   32.76 in
800 yds -110.98 in  1827 fps   889 fpe   44.27 in



=============================================================

Name: 6.5mm-06 130g Scirocco
Ballistic Coeff: 0.571
Bullet Weight: 130
Velocity: 3151
Target Distance: 270
Powder Charge: 55.3g
MPBR: 318
Recoil: 16.6fpe @ 11.3fps


Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy   10mph Wind Deflect
  0 yds   -1.50 in  3151 fps  2866 fpe   0.00 in
300 yds   -1.79 in  2670 fps  2057 fpe   4.37 in
400 yds  -10.94 in  2520 fps  1833 fpe   7.94 in
500 yds  -25.51 in  2376 fps  1629 fpe  12.69 in
600 yds  -46.41 in  2236 fps  1443 fpe  18.92 in
700 yds  -74.29 in  2101 fps  1274 fpe  26.59 in
800 yds -109.83 in  1971 fps  1121 fpe  35.70 in



=============================================================

Name: 6.5mm-06 Ackley Improved 130g Scirocco
Ballistic Coeff: 0.571
Bullet Weight: 130
Velocity: 3245
Target Distance: 278
Powder Charge: 60.8g
MPBR: 327
Recoil: 19.2

Scope Height: 1.500
Temperature: 70
Altitude: 500

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy   10mph Wind Deflect
  0 yds   -1.50 in  3245 fps  3039 fpe   0.00 in
300 yds   -1.24 in  2754 fps  2189 fpe   4.20 in
400 yds   -9.73 in  2601 fps  1953 fpe   7.69 in
500 yds  -23.27 in  2454 fps  1739 fpe  12.25 in
600 yds  -42.59 in  2312 fps  1543 fpe  18.12 in
700 yds  -68.62 in  2174 fps  1365 fpe  25.51 in
800 yds -101.83 in  2041 fps  1203 fpe  34.27 in


=============================================================

Name: 7mm RM 140g AB
Ballistic Coeff: 0.485
Bullet Weight: 140
Velocity: 3340
Target Distance: 282
Powder charge: 67.5g
MPBR: 331
Recoil: 23.5fpw @ 13.5fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3340 fps  3468 fpe    0.00 in
300 yds   -0.99 in  2755 fps  2359 fpe    4.84 in
400 yds   -9.29 in  2576 fps  2063 fpe    8.88 in
500 yds  -22.72 in  2404 fps  1797 fpe   14.20 in
600 yds  -42.31 in  2239 fps  1559 fpe   21.21 in
700 yds  -68.88 in  2081 fps  1346 fpe   29.91 in
800 yds -103.11 in  1928 fps  1156 fpe   40.27 in


=============================================================

Name: .300WM 165g AB
Ballistic Coeff: 0.475
Bullet Weight: 165
Velocity: 3290
Target Distance: 277
Powder charge: 79.0g
MPBR: 325
Recoil: 31.9fpe @ 15.7fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3290 fps  3965 fpe    0.00 in
300 yds   -1.31 in  2700 fps  2671 fpe    5.06 in
400 yds  -10.01 in  2520 fps  2326 fpe    9.23 in
500 yds  -24.13 in  2347 fps  2017 fpe   14.84 in
600 yds  -44.75 in  2181 fps  1742 fpe   22.24 in
700 yds  -72.53 in  2021 fps  1496 fpe   31.29 in
800 yds -108.63 in  1868 fps  1278 fpe   42.24 in


=============================================================

Name: 300WM 180g AB
Ballistic Coeff: 0.507
Bullet Weight: 180
Velocity: 3160
Target Distance: 268
Powder charge: 73.0g
MPBR: 315
Recoil: 31.8fpe @ 15.7fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3160 fps  3991 fpe    0.00 in
300 yds   -1.94 in  2620 fps  2744 fpe    4.96 in
400 yds  -11.39 in  2454 fps  2407 fpe    9.01 in
500 yds  -26.63 in  2294 fps  2104 fpe   14.54 in
600 yds  -48.64 in  2140 fps  1831 fpe   21.76 in
700 yds  -78.20 in  1993 fps  1587 fpe   30.66 in
800 yds -115.98 in  1850 fps  1368 fpe   41.16 in


=============================================================

Name: .338-375 210g TTSX
Ballistic Coeff: 0.482
Bullet Weight: 210
Velocity: 3223
Target Distance: 272
Powder charge: 83.5g
MPBR: 319
Recoil: 43.6fpe @ 18.4fps

Ballistic Data
~~~~~~~~~~~~~~~
  Range  Elevation  Velocity   Energy  10mph Wind Deflect
  0 yds   -1.50 in  3223 fps  4843 fpe    0.00 in
300 yds   -1.66 in  2649 fps  3273 fpe    5.11 in
400 yds  -10.80 in  2474 fps  2853 fpe    9.33 in
500 yds  -25.60 in  2305 fps  2477 fpe   15.01 in
600 yds  -47.13 in  2143 fps  2141 fpe   22.49 in
700 yds  -76.15 in  1987 fps  1841 fpe   31.71 in
800 yds -113.60 in  1838 fps  1575 fpe   42.72 in
=============================================================
 

[Siskiyou]

I have to agree with you choice of a 6.5-06AI.  The .264 bullet falling in the 140-grain range is a favorite with the 1000-yard, high tech paper punchers. (I write that in respect.)  Do to my limited skill I draw the line at 400-yards in a rare pinch.  Brother has a 6.5-284 Winchester, which is in favor with the long-range shooters striving for accuracy.  A quick look at the Sierra Manual 5th edition shows to achieve velocities of 2900 to 2950 at maximum a 26-inch barrel is employed.

I like your standard of 6-inch point blank range because that is my general guideline for clean kills.  To achieve your standard you need a rifle of the highest quality to meet that standard at 500-600 yards and beyond. 

My brother’s 6.5-284 has a 25-inch barrel, I do not know the barrel length of his .256 Newton, which in reality is a form of 6.5-06.  I guess the 6.5-284 fans like it for the short fat powder column, and being able to build it on a shorter action and still have the case capacity of the 30-06 case.  The downfall of the 6.5-.284 Winchester appears with longer bullets being loaded because they intrude on the case capacity, and the shortage of new cases at times.

It is reported barrel life of 6.5-284 is on the short side, but that is a price that you maybe willing to pay.  For most people a barrel that holds extreme accuracy for seven hundred rounds is acceptable.  While 700 rounds maybe bench rest accuracy, hunting accuracy should run longer.  I rather doubt there would be much difference between the 6.5-284 and the 6.5-06.  Will the additional powder capacity of the 6.5-06AI burn out barrels faster.

I like the ideal of a 6.5-06AI but have some concerns about a .270 Winchester round become jammed into it.  Kind of a look from beyond the grave.  This would be avoided with the 6.5-284.

I ran a number of 6.5 bullet comparisons with my favorite Hornady .270 Winchester, 140 grain SPBT.  My load comes from a Hornady manual and I have fire it across the Chrony.  The .270 bullet held up very well and exceeded the other `140-grain .264 bullets out to five hundred yards when they took the lead.  The 130-grain .264 Swift Scirocco smokes them all and appears to be an outstanding choice.  I was using the Sierra Infinity Six ballistics program to run the comparisons.

I believe a couple of other items are needed to complete the package.  A scope that does an acceptable job at 400-yards may not be up to the 500-yards and beyond task.  When you get out to those ranges a highly adjustable scope will be required.

A top of the line rangefinder that will work on antelope and deer at long range is a must when a few yards amount to bullet drop out of the kill zone.  You may already have this tool with your top-flight group of rifles.

Anyway I like your program, my brother gave me a sportier 6.5 Swede as a retirement gift.  The 140-grain Nosler PT has proven deadly out of it at modest velocity.  Many of times the thoughts of a 6.5 pushing a bullet two or three hundred feet faster per second has crossed my mind.   

When my brother had his 6.5-284 built I did a bunch of load research for him.  I have inherited a bit of 6.5 mania from him. 

[Coyote Hunter]

Siskiyou –

Thank you for the comments and information.  As I mentioned, one reason I’m leaning toward the 6.5mm-06AI is to prevent loading a round into a .25-06.  (I don’t have a .25-06 but might get one someday.) 

By the same token, I don’t have to worry too much about loading a .270 Win round in any form of 6.5mm-06 as I don’t own a .270 and will avoid getting one for this very reason.  There are currently three .30-06’s in the safe but I’m not sure I could close the 6.5mm-06AI’s bolt on a .30-06 round without a hammer as I’d have to beat the bullet into the case against the resistance of the powder column.  I shudder to think what the result would be, though...

Nosler’s 6th lists 3294fps for the 6.5mm-06 and a 120g BT, 3151fps for a 130g AB.  I would plan on using the 120g BT for plinking and the 130g  AB or Scirocco II for hunting.

I shoot a lot at 500 and 600 yards and find the Burris Fullfield II 3-9x with Ballistic Plex reticles pretty good for that purpose, but not as good as big glass and twisting knobs.  Cheaper, though.  But you are right – when I go further I will have to look at other options.  I have a Leupold RX-IV rangefinder which works pretty good but isn’t as reliable as I’d like at 700-800 yard on soft targets.

[cwlongshot]

I built a custom 6.5-06 on an Argentine Mauser action and a Shillen barrel, some 12 years back. My favorite bolt caliber!! I wanted something different, that would work for long range deer and antilope.

 The 120BT has proved a good bullet for long range broadside shots. Very accurate and good penetration as long as no big bones are hit. The 125Partition has worked  very well altho not as accurate as any of the others. (Still shots a loose inch/inch and a quarter @ 100) 140 Speer BT is another good bullet as is the Hornady SST. I haven't tried the Scirocco but have also herd good things about it.

 Good luck with your project!!

 CW

[nomosendero]

Very good choice, I thought about the same thing for awhile, but always other fish to fry. If for some reason the Swift doesn't shoot the 140A-Max with a .550 BC would be a fine wind bucking bullet for Deer
& down.

[john keyes]

6.5mm-06



YES!

been dying for some info on this round.




(carry on  )

[Coyote Hunter]

6.5mm-06

YES!

been dying for some info on this round.

(carry on  )

Nosler 6th has the best load data I've seen from a manufacturer.  I plan to form brass by running .25-06 or .270 through a 6.5mm-06 sizing die, then trimming.  (I do both steps to all my new brass anyway, so no additional work will be needed unless I go with the Ackley version.)

[cwlongshot]

6.5mm-06

YES!

been dying for some info on this round.

(carry on  )

Nosler 6th has the best load data I've seen from a manufacturer.  I plan to form brass by running .25-06 or .270 through a 6.5mm-06 sizing die, then trimming.  (I do both steps to all my new brass anyway, so no additional work will be needed unless I go with the Ackley version.)

 Using the 270 to form from requires an additional step as its case is longer and shoulder is different then the intended parent case. One other reason for NOT using it (or the 25-06) is if you have either of these calibers. It will be very easy to mistake one for the other. IE there isn't enough difference between the 25, 26 and 27 diameter bullets that a casual glance can detect.  I prefer to make them form 30-06 as intended. back when I built mine I actually form LOADED 150 gr Win SilverTips CHEAPER than virgin win 30-06 brass. So I bought 5 boxes of the loaded ammo and pulled the bullets, tossed the powder and primers.

 Another excellent book is P.O. Ackley Handbook Volumes I & II. I'm not even sure if its in print anylonger. My volume I is 1966 and VII is 1971 and the third printing.

CW

[john keyes]

I hope this is somewhat relevant: is the 6.5/284 a throat eroding round..?  and will the same occur with a 6.5/06?

[Siskiyou]

Here is a link to the 6.5-284 and it discusses throat erosion.

http://www.6mmbr.com/SixFive284.html

I think you will find a couple of sweet spots with the .264 dia. Bullet

The first is the high ballistic efficiency of certain bullets that start showing up around the 500-yard mark.  The story is the .284 case is a short neck, fat case designed to give 30-06 case velocities in a short action rifle.    When comparing 140-grain loads it looks like the 30-06-parent case requires two or three more grains of powder to achieve the same maximum velocity

Second is the long, thin bullet offer excellent penetration on game.

The step up from this sweet spot is the .264 Winchester Magnum.  It had a reputation of burning out barrels rather quickly.  I came very close to buying one, but baby needed shoes.  In fact I think manufactures went to stainless steel barrels for the round because of throat erosion.

I cannot help but think that similar the 6.5-284 and the 6.5-06 will show similar eroison issues within a few rounds.

I think the erosion issue is more critical to the competitive shooter who fires the same rifle all the time.  I just got off the phone with a shooter that fires a few hundred rounds a year.  He was not concerned with barrel erosion because he fires a number of rifles during the year.  In fact the only reason some rifles get out of the safe is for an annual cleaning a lube.

Now you got me worrying about a couple of .270 Winchesters I have had for many years.  I am getting higher velocities then the two 6.5 rounds we are discussing and I have fired close to 700 rounds in each rifle.   

[nomosendero]

Coyote Hunter has the same incurable disease that I possess, too many shooting toys, or at least some would think so!  When you have other rounds for volume shooting like the 308 & various varmit rounds, it won't be a problem. All he has to do is choose 2-3 of the better bullets & the top couple of powders. It won't take long for an experienced reloader to figure out which bullet the rifle likes & in less than a couple of hundred rounds you can not only have the load, but know what it will do at ALL yardages you want to shoot, that is if your rifle & optics are right. Since he has other rifles to volume shoot he can shoot this one a small amt. a year & be good to go!!

Like I said before I have thought of doing the same & I am not worried about barrel life for reasons stated.

However, this would not be a good choice for an allround one rifle guy that also wants to volume shoot, but I doubt that anyone thought it would be. 

[Coyote Hunter]

I hope this is somewhat relevant: is the 6.5/284 a throat eroding round..?  and will the same occur with a 6.5/06?

Competitive shooters claim the .6.5-284 and 6.5mmm-06 burn barrels out at 700-900 rounds.  I've also read that cutting an inch off the receiver end and rethreading/rechambering a shot-out barrel often results in a barrel that shoots better than when it was new.

But that is for competitive purposes and hunting accuracy lasts much longer.  Frankly, I am no more concerned about a 6.5mm-06 than I would be about a .25-06 or .270 Win.

[shotgun31]

I have a 6.5-06 barrel on an Encore that I have used this season, and have had great success with the 140 gr Berger VLD bullet.  Shot a nice Montana antelope, and a South Dakota whitetail with it.  Nothing impressive as to range, 240-250 yards, but the bullet sure worked!  Neither animal moved following the hit.  It's about a 1" rifle at a 100 so far;  I haven't found the right load yet.
Shotgun

[sasu]

In the past few weeks I have studied a long range moose caliber, too.

I found out that the best trajectory in a commercial cartridge comes from 7 mm Remington Ultra Magnum, 30-378 and 338-378. They have the same trajectory, only the size and weight of the bullet delivered differs.

These three calibers extend the maximum point blank range by about 100 yards even when compared to other magnum cartridges.

As I understand these three powerful calibers eat the throat fast, maybe just in a thousand shots, and they cannot be downloaded effectively. Very special purpose cartridges.

When choosing between these three, the only question remains if the heavier bullets are worth the additional recoil and heavier gun.

[FW Conch]

  Not to me !