338 lapua improved/should I leave well enough alone

[njones125]

So I have a 338 lap improved 40 degree shoulder built on a mark v action. I have a load with 300gr Bergers and 97gr of Retumbo with a 0.050 jump that shoots clover leafs at 100. I see some guys on here with the same setup are around 100gr- 101gr of powder. I'm Getting an average of 2876fps with only an 8fps spread in velocities. Before I go see what this load does at extended ranges should I try to get a little more speed out of it? Part of me says leave it be 50-75 fps isn't a big deal, but am I really utilizing the extra case capacity gained with the improved version? What would you guys do? And although I am happy with how this load shoots I haven't tried a load yet this this rifle doesn't shoot sub MOA with.

 

[Wedgy]

As part of my load work up I always run it up to where I see pressure signs, that way I know where it is and I can stay far enough below it to account for temperature changes. If it is a hunting gun I will choose the highest node I can find as I am not worried about barrel and brass life, strictly performance. For target punching I want more longevity so I try not to go with the hottest loads. Single shot versus mag length is also something to think about. Everyone wants to hit that magic "3,000 FPS" ...but accuracy always beats velocity. 2,876 is no slouch, have you stretched it out yet ?
The big guns seem to make it really easy to shoot far....scary accurate.
My Edge ran the Bergers at 3,000 with Reloder 33 but was tough on brass so I think you have plenty of room to go faster if you want. If nothing else at least you will know where your ceiling is and you can still keep the load you have if you don't like what you find.

 

[RockyMtnMT]

As part of my load work up I always run it up to where I see pressure signs, that way I know where it is and I can stay far enough below it to account for temperature changes. If it is a hunting gun I will choose the highest node I can find as I am not worried about barrel and brass life, strictly performance. For target punching I want more longevity so I try not to go with the hottest loads. Single shot versus mag length is also something to think about. Everyone wants to hit that magic "3,000 FPS" ...but accuracy always beats velocity. 2,876 is no slouch, have you stretched it out yet ?
The big guns seem to make it really easy to shoot far....scary accurate.
My Edge ran the Bergers at 3,000 with Reloder 33 but was tough on brass so I think you have plenty of room to go faster if you want. If nothing else at least you will know where your ceiling is and you can still keep the load you have if you don't like what you find.

Well said.

If you want to see what it will do run up in 1g increments shooting over your chrono. I would not shoot more than 1 shot per increase. When you start to see pressure or velocity get too high back of a grain or two and load them to the same dimensions as the current load that is shooting lights out. Good chance it will shoot well too. You may have to make some minor seating depth adjustments to get it better.

Steve

 

[el matador]

I wouldn't mess with the Retumbo load if I were you. The velocity is already good and the accuracy it there, so I'd put that one in the books and be happy. If you want to experiment a little try RL33. That will give you a nice jump in velocity and you might find a node up around 3000 fps.

 

[codyadams]

Something else to think about is that the point of the Ackley cases is not just to improve performance, but also extend brass life and reduce the need to trim as much. Even if your performing similar to the standard .338 Lapua, that is still good performance, and your obviously going to be doing it at lower pressures due to the increased case capacity, which will make your rather expensive brass last longer.

However.

I have a .260 Ackley, and it was shooting very similar to your load with 140 Berger VLD's and h4831sc, single digit E.S., 1/4 MOA, extremely consistent, but it was only going 2930 fps, and it's a 30" barrel. That is doable with a 6.5 Creedmoor or a standard .260 if you run it hot. So I started experimenting, because hey, what else do I have a custom rifle for if not to have fun?

After some trial and error, I finally landed on a load with the 147 ELD-M going 3090 FPS with Reloder 26, and I validated trajectory today all the way out to 1233 yards, and at all the ranges I shot, 441, 743, 994, and 1233, I grouped right at half MOA. I will still play with this a little more, but the performance of this load FAR exceeds my previous.

What I'm trying to say is, you can play with other loads...the one you have now is not going to run away. So do some more load development, and have fun doing it.

 

[njones125]

Thanks for the info, I'm going to go up in .5 grain increments until I see pressure, I may stick with the load I have but at least that way I will know what my max is and what kind of velocity I can get, hopefully I can find some time this weekend to take the 97gr load out to at least 500 and see how it's shooting. I will post up the velocities with the new load charges just in case anyone is interested

 

[RockyMtnMT]

In a cartridge running ~100g of powder I would not mess with .5g increments. You should see a gain of about 25fps/g as you go up. Consistent increases in vel proportional to charge increase is another sign I look for indicating a consistent load.

My goal in load development is to use as few recourses as possible. Kinda like if it doesn't group well with two shots there is not much point in shooting a third.

Steve

 

[HARPERC]

.......So I started experimenting, because hey, what else do I have a custom rifle for if not to have fun?

..........So do some more load development, and have fun doing it.

Worth repeating.....

It's about education, and entertainment. If you're not learning something, and/or having fun doing it leave it alone.

 

[njones125]

That's probably a good point of going up in 1 gr increments unfortunately I loaded last night so I will be trying .5 Only loaded 5 rounds from 97.5-99.5 so we will see what happens. I'm guessing that the 98 or 98.5 should get me over 2900fps if my velocity/fps ratio increases as it has been. Realistically this rifle will outshoot my skill level, it is a hunting rifle first and I will
Be happy if it will hold MOA to 800.

 

[Wedgy]

You may see some small gains from Retumbo but if you are looking for a dramatic increase try some Reloder 33 as it and Reloder 26 seem to be miracle powders. Those to powders have caused more people to be called liars, purchase new chronographs, and clear out the bench shooting next to you than all others combined.

 

[RockyMtnMT]

You may see some small gains from Retumbo but if you are looking for a dramatic increase try some Reloder 33 as it and Reloder 26 seem to be miracle powders. Those to powders have caused more people to be called liars, purchase new chronographs, and clear out the bench shooting next to you than all others combined.

I am not a huge Retumbo fan but in this cartridge it sometimes truly shines. RL-33 and RL-26 are most always predictable and consistent.

Steve

 

[njones125]

Well I just got done shooting and was very surprised by the results.
97.5 gr Retumbo 2923fps
98. 2961fps
98.5. 2989fps
99. 3003fps
No signs of pressure but I was not expecting that much a velocity change. Does that seem kinda extreme. Nothing changed same cronograph same distance only difference was about a 40 deg temp change but Retumbo is supposed to be pretty stable?

 

[Good]

No pressure, load up a couple more at 100 and 101g and try those. If you see pressure drop a couple grains and see how she groups. Vicarious fun!

 

[codyadams]

Well I just got done shooting and was very surprised by the results.
97.5 gr Retumbo 2923fps
98. 2961fps
98.5. 2989fps
99. 3003fps
No signs of pressure but I was not expecting that much a velocity change. Does that seem kinda extreme. Nothing changed same cronograph same distance only difference was about a 40 deg temp change but Retumbo is supposed to be pretty stable?

That's a fair bit more velocity will be interesting to see if accuracy and consistency hold together!!