New .338 lanches a 300gr Sierra MK at 3500fps?

[Steve Shelp]

Brent,
I just laid out my 338 Lapua case from a sectioned case I have out of my chamber. Moved the shoulder foward another .015", left the taper alone as they extract very nicely even when hot load are fired. Depending on whether you want a 35 degree or go to the 40 degree shoulder you could end up between 123-125gr of H2O approx.

So to review what is already known: My current case holds 120.5gr of H2O. Has produced 3165fps in a 45" barrel with R25 (in one rifle!!) with a 96gr load accurately. This 45" barreled rifle and mine have both fired up to 98gr of R25 but it was on the hot side in summer time temps. Don't have the chrono numbers for the 98gr load though.

So if you use slower burning powders with the current case or any amount of case capacity increase you should be able to get 3200fps easily in a long barrel. How much over 3200fps would be guessing.
But Darryl has a point about 5-7 firings of 100 cases. Are you going to be able to push 3300fps with the Lapua case, I'd say that's probably stretching it, but you never know. You've got my curiousity up. Wish I was in the position to do this myself just to see.

Steve

 

[Darryl Cassel]

Brent and Steve

Marck Chapic has a 338/416 Imp with a BAT action and 40" barrel and I was there the day he took it to 3350 FPS using the 300 gr bullet with NO pressure signs what so ever.

I even opened the bolt on one of the fired cases to see if there was any sticking----None was present. He could have pushed it faster but, stopped there.

I doubt if a lessor volumn case would be able to do it. If he would have had a 44" barrel he could possibly have added another 100 to 125 fps to that velocity.
He was using an Oehler chronagraph for his printouts that day.

As I have stated before ---I have run mine to 3310 FPS at the expense of brass and that's in a 37" barrel. Had I had a 44" instead, my velocity would be WAY up there---Probably 3400 or more?

Just added information.
Darryl

 

[922]

... and a case of Darryls 338/416 Imp that was 134gr water.

You can show the photos of this cartridge ?

 

[MudRunner2005]

You do realize that this thread is over 11 years old right?

 

[922]

You do realize that this thread is over 11 years old right?

I'm sorry Оthers can help me ?

 

[MudRunner2005]

I'm sorry Оthers can help me ?

It's ok, no need to appologise, I was just letting you know this was a really old thread and might not be of much help. I should have worded my post different earlier.

I'm sure there's plenty of others on here who can help you, if you are looking for something like in the original post.

If you are looking for large magnum calibers, contact Kirby Allen.

 

[Fiftydriver]

The 338-416 wildcats were pushed VERY hard back in the late 90s, early 00's to get some impressive numbers. Unfortunately, by their own admission, their brass life was only 1 or 2 firings at this level. To me that is not practical or even SAFE!!!

Since then, there have been a host of 338 magnums based on the 408 Cheytac parent case ranging from the standard 338-408 CT up to my 338 Allen Magnum with several in between. With a 300 gr SMK, these wildcats produce 3200 fps to 3450 fps depending on chambering and barrel length with good chamber pressures. By that I mean getting AT LEAST 6 firings per case.

3500 fps with a 300 gr SMK, that's pushing it off a Cheytac based wildcat. The 300 gr Berger is abit faster and would get you closer but in reality, there is no need. When you can get +3300 fps with a 338 cal 300 gr berger, that shoots lights out and hits like a mac truck, there is not a lot better out there in a system that is consistant over a wide range of bore diameters and barrel lengths.

This combo will do MUCH more then most of us will ever use in the field and offers us reach that again, most of us SHOULD never attempt on live game but we are already there and have been for many years.

The next step up in performance will likely not come in 338 caliber but in 375 cal when we get new, better bullets on the market to exploit the advantages of the slightly larger caliber. Get better barrel life with same ballistic performance now. With better bullets, I believe the 375 will become the ultimate bore diameter in the cheytac class case capacity range.

 

[royinidaho]

I believe the 375 will become the ultimate bore diameter in the cheytac class case capacity range.

Well whatdathinkaboutthat?

I may have for once in my life guessed right. I'm liking my 375 AM.

Kirby, if you look at this. . .

With 142.2 grains of Retumbo and seating depth exactly as you set it, from the loaded rounds I received, I'm getting slight extractor marks on about 50% of the cases with 1 case giving just a titch of bolt lift pressure.

Also last summer one primer blew. Haven't reloaded that case yet so I have no idea of primer pocket expansion. However, the ejector mark is solid. I can easily feel it with a finger nail.

I'm backing her down a grain as I don't think effectiveness of that big sucker will suffer much.

Temps were summer time temps for the bit heavier extractor mark. Temp lately has been around 30 and getting a few shiny marks on only some cases.

You definitely done good on this one!

 

[Fiftydriver]

Well whatdathinkaboutthat?

I may have for once in my life guessed right. I'm liking my 375 AM.

Kirby, if you look at this. . .

With 142.2 grains of Retumbo and seating depth exactly as you set it, from the loaded rounds I received, I'm getting slight extractor marks on about 50% of the cases with 1 case giving just a titch of bolt lift pressure.

Also last summer one primer blew. Haven't reloaded that case yet so I have no idea of primer pocket expansion. However, the ejector mark is solid. I can easily feel it with a finger nail.

I'm backing her down a grain as I don't think effectiveness of that big sucker will suffer much.

Temps were summer time temps for the bit heavier extractor mark. Temp lately has been around 30 and getting a few shiny marks on only some cases.

You definitely done good on this one!

A lot of what your seeing is likely a result of that Jamison brass. The reason is because my reamers are speced around the old TTI brass which has slightly thinner necks then the Jamison brass. It works but its a snug fit. This results in some slight pressure increases as brass life increases. Very common from what I am seeing as brass ages.

I would recommend use up this brass and then switch to some new Bertram 408 CT brass formed into the 375 AM. This brass is pretty much identical to the original TTI brass and is a bit stronger then the Jamison brass. Generally offering 50-75 fps more velocity with same brass life or same performance with even longer brass life. Plus, with the better neck to chamber fit, we see a less finicky combination overall.

 

[royinidaho]

Kirby,

Thanks for the info.

She sure is fun to drive but needs to be handled with a bit of a "touch". She doesn't like to be ham fisted around the dance floor.

Oh, and magpie accurate to 350.

 

[Fiftydriver]

Kirby,

Thanks for the info.

She sure is fun to drive but needs to be handled with a bit of a "touch". She doesn't like to be ham fisted around the dance floor.

Oh, and magpie accurate to 350.

They are all like women, they all like to be handled differently to be happy!! Also, as with women, you better listen to what they like to make them happy a well!!!

 

[922]

The 338-416 wildcats were pushed VERY hard back in the late 90s, early 00's to get some impressive numbers. Unfortunately, by their own admission, their brass life was only 1 or 2 firings at this level. To me that is not practical or even SAFE!!!

What do you think about 338 Kahn and 338 Raptor ?

 

[Fiftydriver]

What do you think about 338 Kahn and 338 Raptor ?

The 338 Kahn is simply a 338-378 Wby with a conventional 35 degree shoulder angle. This does not really increase case capacity at all, just a different shoulder design. When loaded to pressures that result in good case life with the Wby or Norma brass, you will top out at around 3050-3100 fps max in a 30" barrel length.

The 338 Raptor is still in its infant stages but it is a clear step above the Kahn. It will easily get into the 3150-3200 fps range with 30" barrel length. Again, these velocity levels I am referring to are loaded to very responsible chamber pressures. I can get 10 firings per case out of my 338 Raptor loaded with the 300 gr berger at 3140 fps. I would call that very comfortable loads.

 

[Kiwi Greg]

I believe the 375 will become the ultimate bore diameter in the cheytac class case capacity range.

I couldn't agree more from what I've seen with the 375s.

With new projectiles being developed, things are looking good for the .375