My New Defensive Edge LRKM

[CB11WYO]

Yeah, also Mr. Carlock has his "2751 yard practice" video on here as well. You can see the impacts pretty well...

Sorry, didn't mean to get off subject...

 

[Needtohunt]

I agree about the sacrifice, but not sure I do about the other. Back when I was tuning Blown Nitro and Blown Alky engines, it was the taller thin parts we ground off the pistons in the valve relief. If they were lower they could wick the heat out before they liquified. Leave a taller thin part and it was gone by 1/2 track. Kinda like torching steel. The taller this part will start the cut earlier.

We will see, all speculation at this point. But what I do know is this Mo-fo is an ELR HAMMER!!

Jeff

Jeff
you are the reason I am making my first post. Years ago you recommended H1000 for the 210VLD in a 30-378. I shot that combo for a round count of 700 rounds with no throat damage at all. Accuracy with that combo was fantastic, terminal performance not so good. Then I tried a load with RL25 and 150gr just for fun to see what velocity it would run and did severe damage to the throat. End of 150 test. Still wanting more speed as I was having inconsistant terminal expansion with the 210s I tried WC872, H50BMG, US869 all with no success. Then I tried Vv N570 and found a load for the 210s and have been using it ever since. I picked up over 300fps and terminal ballistic issues went away. My round count with Vv N570 is at 400 now. I am running them as hot as the weatherby brass will stand and the throat is showing mud cracking now. I too hunt in all temperatures so temperature stability in a powder is important. I developed my load at 95*F and shot 760 yd groups as cool as 27*F with only minimal trajectory variation. I also believe you will like the pressure stability of N570. Some powders work fine till you start trying to crank up the boost and the pressure spikes unexpectedly. The N570 lets you decide how much pressure you want to use without spikes. Yes it will burn the barrel but not as bad as some and I dont know of any single base powder that will give you the velocity you want. I think you will be pleased with the overall performance of this powder considering the goal.
Thanks for the H1000 info years ago - 5.125" groups at 1000 yds with an Accumark
Love your new rifle right out of my dreams!

 

[Fiftydriver]

Kirby,
So your saying that by mixing old and new, or even once fired brass for that matter. The result could be poor long range accuracy?

You will see a difference if you shoot a case that has been formed with corn meal next to a case that has one high pressure loading fired in it. The results are generally not dramatic and you will likely need to shoot them at 1K minimum to really be able to tell its the cases that's causing the variation but yes you will see a difference at long range.

 

[mmaher]

I just shot Shawn's LRKM today...2250 yds. Like I was launching a SCUD at the rock. THAT, my freinds, is an amazing rifle.

 

[Fiftydriver]

Broz,

Have you guys ever used Norma brass with your current loads as a check for your pressures? The reason I ask is because when I was developing my 7mm AM, 300 AX and 338 AX, using the Lapua brass made it very difficult to read pressures. In the early days of the AMs and AXs, I was chambering them in modified Rem 700s and this made me a bit uncomfortable as I knew from load development that the Lapua case would take well over 70,000 psi and just smile and show no sign at all of high pressures.

THis made me very nervous knowing that the rifles based on the Rem 700s would be going out and someone would be running the Lapua case to its limits and be WELL over what the Rem 700 should be subjected to long term.

Now, this is not the concern with your project or any other custom receiver based project, I only bring this up because for me, when I was doing load development, I knew that I was unable to read any pressure sign on the Lapua case. As such, when doing load development, I only used Norma brass because while its very high quality, its also relatively soft compared to the Lapua brass.

In my testing, a 338 Lapua with Norma brass will loosen its primer pockets at nearly exactly the same load and velocity as the Remington RUM brass when used in same barrel lengths with same bullets. The Rem RUM brass has been reported to have permanent case head deformation at around 65,000 psi. Which means simply the primer pockets start to expand at this pressure. So is the same for the Norma brass.

Using this information, I was able to develop loads for my 7mm AM, 300 AX and 338 AX in the Norma cases and load them up to roughly the point where primer pockets would loosen to the point of not being usible in roughly 4 firings. With this load data, I knew that my wildcats were being loaded to roughly 65,000 psi. Then I could simply switch over to the Lapua brand brass and never see a single pressure sign EVER!!!

Just curious if you or Shawn has done any testing in this manor to check the pressures your running at.

I am not saying your running over 70K, just curious if you have done any pressure testing like this?

 

[Broz]

Kirby I am very comfortable reading pressure in Lapua brass. I have lots of experience with the 300 gr bullets and the 338 LM. My last one I ran full house loads and got 15 firings from the brass and all primer pockets were still tight, all 100. That rifle is still going strong holding 1/2 mos to 1500 yrards plus.

The first signs of pressure in Lapua brass will show up with a flat face of the CCI 250 primer. Next will be a slightly muffin topped primer and at this time the faint shadow of the ejector pin bore on the head stamp. This first sign of stamping we see with the use of a magnifying glass. Then if you keep pushing the pressure up the pin stamp will become more evident along with a slight firmness of bolt lift on the second or 3rd shot.

To answer your question directly, no I have not used Norma brass. Shawn, however did the initial testing of this rifle with Hornaday brass. The Hornaday is equal in case volume to Lapua and I believe it to be softer. I am not sure who makes it for Hornaday? Norma? Not sure?

If I were not completely comfortable with the level of pressure being safe I sure would have not let several member from this forum shoot the rifle at the last Townsend shoot. They all seen my ammo box of fired brass, they all felt the smooth bolt lift even after a couple shots. They also watched and spotted for me while I took a few rounds from the same box and whacked a rock 1/2 moa tall at 2272 yards. My dial up was on with an inputted MV of 3198 fps in Bryan Litz AB program. This velocity was also verified by my Oehler 35 and my magneto speed as well as Shawns magneto speed.

Thank you for your concern, and info., it is appreciated.

Now Kirby, I am going to rib you a bit.

DUDE!! It's the patented +P chambering. lightbulb

Shawn and I did the math before Shawn ever agreed to build this chambering for me. We were counting on 3150 fro a 30" tube and hopeful for a little more. The addition of the 32" tube and N-570 pushed it to the max velocity we hoped for, 3200 fps.

Jeff

 

[MontanaRifleman]

If I were not completely comfortable with the level of pressure being safe I sure would have not let several member from this forum shoot the rifle at the last Townsend shoot. They all seen my ammo box of fired brass, they all felt the smooth bolt lift even after a couple shots. They also watched and spotted for me while I took a few rounds from the same box and whacked a rock 1/2 moa tall at 2272 yards. My dial up was on with an inputted MV of 3198 fps in Bryan Litz AB program. This velocity was also verified by my Oehler 35 and my magneto speed as well as Shawns magneto speed.


Jeff

I will testify the bolt came up smooth as butter... also inspected the brass and it looked good.

 

[Fiftydriver]

Hornady brass is similar to Norma in strength. I am also not sure who makes it or if they make it in house but its on the same lines as RUM, Norma and the like. Good brass to develop loads with.

I am in no way saying your running dangerous pressures, sorry if I implied that, I was just curious if Shawn had done any pressure testing like this to get an idea where his wildcat runs pressure wise is all.

Sorry if I offended, was just curious. Will just read your results from now on to stop jacking the post. Again, if I offended I apologize. Was not my intent.

 

[Broz]

No offense at all Kirby and I welcome any post you have, any time. The things you and Shawn do are what keeps my blood lively, I like big long range calibers.
What I was trying to show with my explanation was a full report to demonstrate to you what I do and that I was confident in how I do it. I do not claim to be the rifle builder you and Shawn are, so when one of you ask me a question I will do my best to offer what I know in an attempt to prove my methods.

I like to joke at times so I was just kidding around with the joking part. If it offended I also apologize.

You have probably answered for me why Shawn did the load charge and first chronograph testing with the Hornaday brass. He was looking for early signs of pressure in softer brass. A lower amperage fuse if you will. I wondered about that but hadn't asked.

In Shawn's notes with the rifle he supplied me with the load work up in 1 gr increments.

At 112 gr of N-570 he noted the first sign of a faint ejector mark he could see using a magnifying glass. This charge averaged in Hornaday brass a velocity of 3192 with a high of 3198.

I ran my loads to 112 also, then backed off to 111 gr. and moved the bullet closer to the lands. With the bullet closer the velocity came back up and like I said I am running 3198 for and average MV, and in my app for drops. The highest MV's I have recorded were 3205, 3207, 3209 during load development.

Jeff

 

[MontanaRifleman]

Kirby, I sure didn't see any offense on your part and I hope you don't think I was "taking sides". I just wanted to confirm that there were zero indications of excess pressure. What you bring up about the Lapua brass maybe "hiding" excess pressure seems like a valid point and your technique of using Norma brass for pressure testing sounds good to me. But looking at Jeff's brass, the primers, there was not a hint of over pressure and the bolt was very smooth. I guess that's what we go by if we don't have pressure equipment.

Anyway, when you speak/type, I always listen

 

[Fiftydriver]

I am sure that is what Shawn was doing with the Hornady brass.

 

[barnesuser28]

Jeff, what is the first animal you will be hunting for with the LRKM? When does the season open? Is antelope on the list?

 

[Broz]

Jeff, what is the first animal you will be hunting for with the LRKM? When does the season open? Is antelope on the list?

Yes, Antelope, in OCT. I feel it is the perfect antelope rifle at any distance. Poor lil suckers...

Jeff

 

[Fiftydriver]

Where will you be hunting speed goats this fall?