My New Defensive Edge LRKM

[Broz]

Broz, shooting past 2000 yards do you have a spotter, or are you spotting your own shots from the scope?

I can usually spot my own shots. But the 2400 yrd shots last week my son was there spotting for me too. Depending on the type of rock sometimes a small dust cloud can be hard to see at 2K plus. But this rock was in the open and we had one miss and it was plain as day as dry as it is here.

Jeff

 

[MontanaRifleman]

Kirby,

Thanks for the thoughtful and informative reply. A lot of good info there for folks who are reading these threads and maybe looking at a project.

I knew there were variances in bores but I thought they were tenths of thou vs up to 2 thou. That's a big variance. And I know trying to build a rifle for just one bullet is a big gamble and I can see where a smith would not like to be put into that situation. would you see the same variances from the same barrel maker like Bartlien for instance? It seems the gain twists are the way to go with these long high BC bullets.

Watching Greg's videos has peaked my interest in something like a 375 CheyTac. It should be very interesting what happens in the ELR world in coming months and years.

 

[royinidaho]

Jeff,

I'm fairly certain that with the umph that you're impacting those rocks with that the national earthquake center in Colorado ought to be able to report your POIs within an inch or so.

Google 'em and see if they'll send you a report.

 

[meat head]

Still enjoying this thread ! JEFF you and KIRBY have had some good info maybe some of it will help BIGBUCK when he gets his 338 EDGE Barrel in & on he asked me what bullet's you were shooting so he already bought him some 300gr. otm's to try KEEP UP THE POST GUY'S IT'S GREAT.gun)gun)

 

[Fiftydriver]

I can usually spot my own shots. But the 2400 yrd shots last week my son was there spotting for me too. Depending on the type of rock sometimes a small dust cloud can be hard to see at 2K plus. But this rock was in the open and we had one miss and it was plain as day as dry as it is here.

Jeff

Lighting conditions and wind conditions also can dramatically help or hurt spotting impacts. Can be tricky in some conditions, the big 338s and larger really help kick up enough of an impact dust cloud to detect at long range...... SOMETIMES!!!

There are the occasional, WHERE THE HELL DID THAT ONE GO??? moments!!!

 

[Broz]

There are the occasional, WHERE THE HELL DID THAT ONE GO??? moments!!!

That usually is said right before I see the hit when the 4 or 5 second flight time seemed to be 5 minutes...

Jeff

 

[Broz]

Jeff,

I'm fairly certain that with the umph that you're impacting those rocks with that the national earthquake center in Colorado ought to be able to report your POIs within an inch or so.

Google 'em and see if they'll send you a report.

LOL, I don't know about that. Remember I have shot your 375, I see the difference in impact. But this 338 does hit harder than any other 338 I have owned.

Jeff

 

[Fiftydriver]

That usually is said right before I see the hit when the 4 or 5 second flight time seemed to be 5 minutes...

Jeff

Yep, or when your letting someone new shoot steel at long range, they shoot, you spot the hit and report it and then they wait for the sound, ususally just long enough to start talking right before the sound gets back to the shooting position!!

 

[fmajor]

Well hell, might as well throw a teaser out there. If things go as planned with my 300 and 338 Raptor projects, there will very likely be a 375 Raptor as well. In comparision with the 338 Lapua Improved chamberings, using Retumbo filled to the base of the neck, the Lapua Improved will hold 109.0 gr, the Raptor will hold 134 gr and the 338 AM will hold 158 gr.

basically the Raptor case will split the difference between the Improved Lapua and the Improved Cheytac and still function in a Lapua class receiver but will need to be a single shot.

That said, this is all dreams at this point. As long as it has taken to get this Raptor project off the ground, who knows how long it will be before the 300 and 338 Raptors are main stream and ready to start the next adventure. Many times in this project, over the past 10 months I have about said, screw it, the 338 Lapua Improved is plenty!!!

Your excitement about your new rifle is well justified, we are all excited to see you stretch her out!!!

Kirby I think your 338 Raptor project nestles perfectly btw the HUGE 338's (ie 338AM) and the big 338's (Lapua, Lapua AI, Edge, Edge +P, etc).

Launching the 300grn-ers, at muzzle, at 3,200fps minimum with room for a little more before pressure and/or speedy barrel-munching in a reasonably-sized rifle is for me the sweet spot. I'd not want to go bigger and good hunting bullets in 338 top out at 300grs .

A hunting cartridge that offers 3,200 fps with 300gr bullets provides excellent, flat-shooting trajectory, a HUGE freaking LR hammer and with reasonably high BC bullets wind consequence is minimized.

 

[Fiftydriver]

Kirby I think your 338 Raptor project nestles perfectly btw the HUGE 338's (ie 338AM) and the big 338's (Lapua, Lapua AI, Edge, Edge +P, etc).

Launching the 300grn-ers, at muzzle, at 3,200fps minimum with room for a little more before pressure and/or speedy barrel-munching in a reasonably-sized rifle is for me the sweet spot. I'd not want to go bigger and good hunting bullets in 338 top out at 300grs .

A hunting cartridge that offers 3,200 fps with 300gr bullets provides excellent, flat-shooting trajectory, a HUGE freaking LR hammer and with reasonably high BC bullets wind consequence is minimized.

With the results that Broz has posted on his LRKM, it also has to be included in this class of 338 magnum for sure as its obviously solidly in the 3100-3200 fps range with 300 gr bullet weights.

The 338 Terminator and the 338 Raptor are much different in design but should be very similar in performance. They are like comparing a super charged small block engine (terminator) to a big block naturally aspirated engine (Raptor). The Terminator gets its boost in performance by a special throat design with a smaller capacity. The Raptor gets its velocity simply with capacity allowing it to get the work down the conventional way. Which is better, probably neither could claim that title. Both have advantages and as time goes on, I am sure both will show their disadvantages as all wildcats do with more time in the field.

The 338 AM would be a supercharged BIG BLOCK!!! Remember that the 338-408CT will settle into that 3200 fps range very easily with slightly reduced charges and brass would last FOREVER!!! Carbon fouling may be a bit heavier then with higher pressures, would just have to keep on top of it cleaning every 30-40 rounds which is a good idea with these chamberings anyway.

The 338 ST, 338 Big Baer and my 338 Allen Mag do not do quite as well by dropping the chamber pressure down to the 3200 fps level as velocities can become a bit inconsistent. This is simply because of their larger case capacity over the standard 338-408 CT. With my 338 AM, 3250 fps is my recommended minimum velocity with the 300 gr bullet weights. In fact my accuracy load will generally produce 3250-3275 fps in most 32" barrel lengths. Again, brass lasts a LONG time at these levels and that's what I like more then getting the last FPS out of a given chambering.

Again, if your looking for that 3150-3200 fps, the Terminator +P and my Raptor should be very similar in performance and to my knowledge, at least at this time are about the only two games in town for this mid level of performance.

 

[Broz]

Just to be clear, we didn't have to "wring" the velocity out of the 338 Terminator +P to get it to 3200. And it has never shown sign of being done by dropping off or settling in on velocity. Both Shawn and my results in testing ran hand in hand with charge work up. We saw 3100+ easily 108 gr's. Then the advance of 30 fps per grain and we stopped with slightest sign of an ejector pin mark that showed up at 3195 to 3200 fps. There has not been one sign of even a firm bolt lift, and of all the brass I have fired you will not find the ejector shadow on all of them even when using a magnifying glass. There is room left in the case for a few more grains of powder and with the rate per grain we have documented I could see it going to 3250 if a guy wanted to push it as hard as he could. But I figured why? I was hopeful to get close to 3200 when we discussed this build. So when it came in easy I was very happy with these results.

The 338 Terminator +P wants to go. I dropped back 1 gr from the highest charge we tested and moved the seating depth out and the velocity came right back to 3200. I assume if I put that grain back in with this seating depth I would be at 3225 to 3230. I am not saying this is a mediocre load by any means, just that there is more there. Lets not forget my work up was done in our hottest ambient temps of the year too. I was shooting in 90+ degree days for load work up. I wanted data under worst conditions and also velocities / temp data at many temps for later dialing in.

Fully fire formed brass is still growing 3 grains of capacity with 570. So my next round of loading will be in slightly larger volume cases too. That may not change much, but surely is a plus for a little less pressure.

Later on down the road in some 20~40 degree days I just may rev this thing up and put her on the chip. Right now it is hard for me to think of it as a "Small Block" Since I still yet can't think of anything bigger I would trade her in for. So small block maybe, very efficient .338 case and chamber design, definitely.

Jeff

 

[Fiftydriver]

Just to be clear, we didn't have to "wring" the velocity out of the 338 Terminator +P to get it to 3200. And it has never shown sign of being done by dropping off or settling in on velocity. Both Shawn and my results in testing ran hand in hand with charge work up. We saw 3100+ easily 108 gr's. Then the advance of 30 fps per grain and we stopped with slightest sign of an ejector pin mark that showed up at 3195 to 3200 fps. There has not been one sign of even a firm bolt lift, and of all the brass I have fired you will not find the ejector shadow on all of them even when using a magnifying glass. There is room left in the case for a few more grains of powder and with the rate per grain we have documented I could see it going to 3250 if a guy wanted to push it as hard as he could. But I figured why? I was hopeful to get close to 3200 when we discussed this build. So when it came in easy I was very happy with these results.

The 338 Terminator +P wants to go. I dropped back 1 gr from the highest charge we tested and moved the seating depth out and the velocity came right back to 3200. I assume if I put that grain back in with this seating depth I would be at 3225 to 3230. I am not saying this is a mediocre load by any means, just that there is more there. Lets not forget my work up was done in our hottest ambient temps of the year too. I was shooting in 90+ degree days for load work up. I wanted data under worst conditions and also velocities / temp data at many temps for later dialing in.

Fully fire formed brass is still growing 3 grains of capacity with 570. So my next round of loading will be in slightly larger volume cases too. That may not change much, but surely is a plus for a little less pressure.

Later on down the road in some 20~40 degree days I just may rev this thing up and put her on the chip. Right now it is hard for me to think of it as a "Small Block" Since I still yet can't think of anything bigger I would trade her in for. So small block maybe, very efficient .338 case and chamber design, definitely.

Jeff

My comments about getting the last FPS out of a case design was in reference to my 338 Allen Magnum, not the Terminator +P or the Raptor. I should have been more clear about what I was referring to, my mistake.

Small block reference was only to make a visual comparision about how these two chamberings get the same work done in different ways.

You state that your cases are gaining 3 grains capacity after first firing?? that seems a bit strange to me. The cases must only be around 85 to 90% formed with your forming load. My wildcat cases I form for customers gain less them 1 grain capacity after the first full pressure firing. Maybe add a bit more powder to your fireforming load and your cases should form up more completely.

Have noticed that first firings with my formed cases will generally run around 1/2 moa low on impact at 1K compared to cases that have had at least one full pressure firing. Simply put this is from the energy that is robbed to form the cases to 100%.

Again, with a little tweaking with your fireforming load, you should get closer to 100% formed cases with no problems with undue stress on the case while forming. One other tip, I would recommend switching to a faster powder. I used to use unique and was fine with it until I realized that I was forming many thousands of cases a year for customers and wanted to see if I could use a faster burning powder which would allow me to get the forming done and use less powder. Switched to using Green Dot and dropped my fireforming charges by 30% which was a huge savings in powder cost. Plus the faster burning powder seemed to produce a sharper shoulder angle as well which was a additional benefit. May be something you want to try.

Your certainly not going to see the big $$ savings simply because the volume of brass formed will not be there.

One other thing that may be the reason why my formed brass is so close to high pressure formed brass is that I set my fireforming jigs up to run about 2-3 thou longer then my chambering guage. As such, after forming, I have to run the cases through a FL sizer to JUST bump the shoulder a bit for proper chambering. THis helps to sharpen that shoulder up ever so slightly as well and also allows a kind of custom fit of the virgin brass to the rifles chamber, works pretty well. If Shawn set up your fireforming barrel the same length as your rifles chamber, I can see why your seeing what you are which makes no real difference, just needs that first high pressure fireforming to get fully formed cases. I wanted to try to develop a method that would eliminate the need for a second firing to get full case forming so when the customers get the brass, their first loads will be within reasonable margins for shot placement on that first high pressure loading.

Again, want to stress that my comments about getting the LAST FPS out of a chambering were directed toward my 338 Allen Magnum and not your Terminator or my Raptor chamberings. Should have made that more clear. I have many customers pushing right to or slightly over 3400 fps with my XHS in my 338 AM. They are seeing 4-5 firings per case and are happy with that. This is plenty safe as well from a pressure stand point and with the new Bertram brass its much easier to do then with the old Jamison brass. Still, I like around 3300 fps for my all around load in the 338 AM and do not load it to these 3400 fps levels just for added brass life. That was what I was referring to, noting more or less and not directed toward your Terminator and want to stress that I DO NOT believe you or Shawn are pushing things overly hard with this project in any way.

 

[Broz]

Thanks Kirby, we are on the same page.

The problem with my fire formed brass was me. I could not find Unique like Shawn used so I had a pound of Universal clays and used it. My load with cornmeal was probably on the conservative side too. So this is why I think the first firing with a "real" load and a 300 gr bullet is sharpening the shoulders and gaining those 3 gr.

I had heard before that 85% formed from the corn meal method was on par, so I was not concerned. But I will learn for future forming from the info you just offered Thanks.

 

[Fiftydriver]

What are you using for a plug in your fireformed cases?

Pretty much any fast handgun powder will work great for the cornmeal forming method, some just need a bit more powder, some a bit less depending on their burn rate so you may just want to add 1/2 grain at a time until you get good case forming. You never want to see any ejector rings while forming and bolt life should always be easy of course.

The faster handgun powders seem to slam the corn meal into the shoulder area with more authority which seems to sharpen up the shoulder a bit better. It all works though!!