.264WM/140 VLD Load Development (M70)

[barefooter56]

I just shot those rounds across the chrono. I wasn't shooting for groups, so there aren't any targets or pics to be had. I am expecting the node to appear in the vicinity of 3150. If that is correct, I believe the ES and SD numbers may reflect that. It will be a few days before I can test further.

Thats cool. Pay more attention to the SD and the velocity than the ES. You may want to add a target in the mix so you can see whats happening on paper. The target is always the final judge. The chrony and everything else is just a "suggestion" of what may work. IMHO.

 

[tbrice23]

I completed load development with Berger 140 VLD's and Retumbo in my .264 Winchester Magnum. The rifle is a South Carolina-produced Winchester Model 70 sporter in factory trim. The first target is the seating depth test. The second target is the powder charge workup. I still need to chrono the final load (69.9 grains) and verify it at longer range.

I am also working with RL-33 and will post the final results when I have them.

I am interested in rechambering my 6.5 284 to 264wm.
Question 1. Is this a sproter weight barrel and what make barrel is it ?

Question 2. Whats the barrel length ?

Question 3. Did you do powder charge before seating depth ?

Question 4. How far off the lands is your final load with 140 vlds ?

Question 5. What brass did you use ? I have winchester 7mm RM brass I plan to neck down and neck turn.

Sorry for the interrogation.

 

[benchracer]

I am interested in rechambering my 6.5 284 to 264wm.
Question 1. Is this a sproter weight barrel and what make barrel is it ?

Question 2. Whats the barrel length ?

Question 3. Did you do powder charge before seating depth ?

Question 4. How far off the lands is your final load with 140 vlds ?

Question 5. What brass did you use ? I have winchester 7mm RM brass I plan to neck down and neck turn.

Sorry for the interrogation.

1, 2. This is a Winchester factory, 9 twist, sporter weight, 26", barrel.

3. For various reasons, I prefer to test seating depth first, then do the powder charge workup. Once the seating depth is established, I have found that I can change components without re-testing for seating depth.

4. My final load is approximately .040" off the lands.

5. I am using Nosler Custom .264 WM brass with no special prep.

No worries on the interrogation. I am glad to answer questions.

I have a 6.5-284 being re-chambered to .264 WM, too. It has an 8 twist, 5R, #4 contour, 26" Krieger barrel on it. Since it has enough twist, I want to try the Matrix 150's and 160's. I suspect RL-33 may do better with heavier bullets. If not, I will stick with Retumbo.

 

[tbrice23]

Thank you for the reply. My buddy has a 26 nosler reamer and was trying to get me to go that way but there are many reasons I'd rather go with a much more practical approach and rechamber to the 264 WM.
Also I am getting pretty good at building lee collet neck dies , which I love to use in addition to partial full length sizing on belted magnums.

 

[65WSM]

I have long experience with Model 70s in .264 Win Mag. Several barrels worth.

Retumbo is hard to beat as a powder. Most of the load data published was developed long ago. Develop your own loads and do not pay much attention to published data. I always laugh at Nosler and Hodgdon data that may date from the 1960s. I am hording a supply of VV N-570 and it will outdo the Retumbo with 140 gr bullets. I would also be looking for the IMR 7977. As I heard from the Blackhawk staff at the Sportsman's Show, ADI had a fire and Hodgdon has gone back to the Canadians to get the new powders with anti-copper fouling additives made. There is likely to be a 'pre-fire" and "after-fire" Retumbo at the very best.

Copper fouling, especially with eroded factory barrels is always an issue with the .264. I would recommend HBN coating and the new IMR 7977 may help. I could never get a full box between cleanings without the groups opening up.

I have found that there is a wide range of brass thickness, hardness and head designs with the .264 Win Mag headstamp. That explains the Quickload underestimate of the volume. I tend to use brass with the 7mm Mag headstamp because it is cheaper. I also anneal frequently. I would not fool with anything but Norma or Nosler cases because of the primer pockets.

 

[benchracer]

I loaded five rounds with the 69.9 grain charge of Retumbo and fired them over my chronograph. Average velocity came in a hair over 3200, with a min of 3184 and a max of 3225. ES was 41 and SD was 15. This load ended up being about 50 fps faster than I had expected. I think I am going to back down to 69.3 and re-test.

I have attached the QL predictions that I have been using during the load development process. The relevant OBT node appears at 1.330ms.

The powder charge discrepancy for this set of predictions vs actual is the largest I have seen since I began using QL, which reinforces the need to reconcile predicted to actual before proceeding with load development.

I also learned the importance of using once fired brass when doing the initial min-max tests (to align predicted data to actual data). I used unfired brass in my initial workup and obtained the following results:

66.0 2918
67.0 2983
68.0 3056
69.0 3099
70.0 3156

The 70 grain load yielded a velocity very close to the predicted node @ 1.330ms, so I backed down from there and worked back up, with the results I posted earlier. The 69.9 grain load appeared to be the one I was after, so I loaded up five more rounds @ 69.9 and chronoed them to determine muzzle velocity, ES, and SD. These were the results:

Shot 1 3194
Shot 2 3209
Shot 3 3184
Shot 4 3225
Shot 5 3207

AVG 3203
ES 41
SD 15


Using fireformed, neck-sized brass, the muzzle velocity climbed by about 50fps vs unfired brass, which leaves the 69.9 grain load just outside the predicted OBT node. For this reason, I intend to back down and re-test the 69.3 and 69.6 grain loads for accuracy, velocity, ES, and SD to verify whether or not 69.9 is still the winner.

It will, unfortunately, be a few months before I can do anymore testing. Will post updates when I have them...

 

[benchracer]

RL-33 did not perform well in my rifle. It was shooting 2"+ groups @ 100 yards. I didn't bother to keep any targets or photograph them. I suppose I could experiment with different primers, but I have a very good load using Retumbo and don't want to waste any more barrel life chasing a load with another powder.

For this rifle, my load development will end here.

For reference purposes, I am posting the QL predictions for RL-33, along with the velocity runup I performed to verify the QL data. The discrepancy between predicted and actual was much smaller for RL-33 than for Retumbo. I performed this velocity runup with new brass, as well, so I would expect actual velocities in fireformed brass to be somewhat higher. During load development, I encountered ejector marks just below 79 grains with once-fired brass.

QL information regarding load density with RL-33 is way off. QL shows RL-33 as having a lower load density than Retumbo, when it is, in fact, much coarser grained and takes up a LOT more room in the case than Retumbo does.

Again, the relevant OBT node appears at 1.330ms.

At any rate, this combination shot very poorly in my rifle. I suspect that RL-33 may need a hotter primer or heavier bullets to come into its own. When my 8 twist .264 WM is ready, I intend to explore RL-33 further.

66.0 2663
67.0 2686
68.0 2705
69.0 2765
70.0 2783
71.0 2826
72.0 2925
73.0 2948
74.0 3004
75.0 3059
76.0 3103
77.0 3134
78.0 3223

 

[barefooter56]

I have attached the QL predictions that I have been using during the load development process. The relevant OBT node appears at 1.330ms.

The powder charge discrepancy for this set of predictions vs actual is the largest I have seen since I began using QL, which reinforces the need to reconcile predicted to actual before proceeding with load development.

I also learned the importance of using once fired brass when doing the initial min-max tests (to align predicted data to actual data). I used unfired brass in my initial workup and obtained the following results:

66.0 2918
67.0 2983
68.0 3056
69.0 3099
70.0 3156

The 70 grain load yielded a velocity very close to the predicted node @ 1.330ms, so I backed down from there and worked back up, with the results I posted earlier. The 69.9 grain load appeared to be the one I was after, so I loaded up five more rounds @ 69.9 and chronoed them to determine muzzle velocity, ES, and SD. These were the results:

Shot 1 3194
Shot 2 3209
Shot 3 3184
Shot 4 3225
Shot 5 3207

AVG 3203
ES 41
SD 15


Using fireformed, neck-sized brass, the muzzle velocity climbed by about 50fps vs unfired brass, which leaves the 69.9 grain load just outside the predicted OBT node. For this reason, I intend to back down and re-test the 69.3 and 69.6 grain loads for accuracy, velocity, ES, and SD to verify whether or not 69.9 is still the winner.

It will, unfortunately, be a few months before I can do anymore testing. Will post updates when I have them...

benchracer,
Looks like you are close. Let us know what you get from your next test session and lets try to get that SD down some more if you can.

 

[benchracer]

benchracer,
Looks like you are close. Let us know what you get from your next test session and lets try to get that SD down some more if you can.

I expect both ES and SD to drop somewhat when a load is found that is actually in the OBT node. The only way to know is to burn some powder!

 

[barefooter56]

I expect both ES and SD to drop somewhat when a load is found that is actually in the OBT node. The only way to know is to burn some powder!

Yep. Look for a flat or almost flat " waterline" on the target to confirm the improvement. Good luck!

 

[benchracer]

I finally had the opportunity to re-test my loads with once fired brass, though at 200 yards instead of 100. The 69.3 grain load was the winner. ES tightened to 34, while SD climbed slightly to 17. AVG for three shots was 3160.

The three shot group measured 1.315" outside-to-outside. Corrected for bullet diameter, the center-to-center measurement comes to 1.051, which is right at .5 MOA. Not bad for a factory sporter!

 

[benchracer]

The 69.6 and 69.9 groups impacted higher on the target and overlapped slightly. If you look closely, you can see that the leftmost impact, about half way up, is actually two impacts. The second impact is the overlapping one from the 69.9 group. Both groups hovered around MOA, having very similar ES and SD numbers to the 69.3 group.

 

[benchracer]

It looks to me like the 69.3 group is very near the top of the node. I am going to do one more round of testing. I will shoot 15 rounds, 5 each @ 68.7, 69.0, and 69.3 to confirm my node and see if the ES and SD numbers tighten any further, before settling on a final load.

 

[barefooter56]

It looks to me like the 69.3 group is very near the top of the node. I am going to do one more round of testing. I will shoot 15 rounds, 5 each @ 68.7, 69.0, and 69.3 to confirm my node and see if the ES and SD numbers tighten any further, before settling on a final load.

benchracer,
Lets try 68.8, 68.9, 69, 69.1, 69.2 grains and see if we can get that SD below 10.