My New Defensive Edge LRKM

[Fiftydriver]

Kirby, What do you use to fill the case with corn meal? Another powder powder measurer?

Use a powder funnel that's as large as your case mouth will allow without spilling. The larger the funnel hole, the less chance you have of corn meal packing up and stopping which happens from time to time anyway but the larger the funnel hole, the less stoppages you will have.

I pour right out of the corn meal can. Does not take long until you figure out how fast you can pour the corn meal before you get a stoppage in the funnel. I usually fill the funnel up about 1/3 up and then tamp the case with funnel and extra corn meal on top to settle in the corn meal, then level the funnel across the case mouth, over the corn meal container so excess just falls back into the container.

A powder thrower will not work with corn meal, believe me, I have tried everything to speed up the process by making it as automated as possible. I even set up my progressive RBCS press to see if I could make it work. The only problem turned out to be inconsistent corn meal levels in the case which without the tamping, you just do not get consistant amounts and your pressure on the wad varies. Its important that you keep the pressure on the wad as consistant as possible. Within reason. No need to be exact but close to get uniformly formed cases. Just gives more consistant results when you shoot the cases for the first time with live loads.

 

[ChrisAtl]

Thanks Kirby. Now I have learned something today!
Have a great day.

 

[clemens]

I have learned something new as well. Thanks for all the information you all put into this site. No wonder I lose a hour or more sleep I just keep reading.

 

[meat head]

Thanks BROZ,and KIRBY, for the info had heard of it but didn't know how to do it.gun)

 

[CA48]

+1 Thanks for sharing.

 

[Fiftydriver]

Thanks BROZ,and KIRBY, for the info had heard of it but didn't know how to do it.gun)

You can use pretty much any handgun powder that has a burn rate of Unique or faster. The faster the burn rate, the more careful you have to be to make sure your not producing to sharp of a pressure spike. A proper fireforming load should literally fall out of a chamber when fired in a clean chamber. If you have any resistance, your either far over pressured or the chamber is dirty.

Again, the more consistant you can get in compressing the powder/cornmeal column, the more consistant your forming will be.

Also, you HAVE to have at the most zero headspace and preferably a chamber set up for around 0.004" crush fit. If the headspace is much over zero, the firing pin will drive the case forward in the chamber until the chamber shoulder stops the case and then on ignition the shoulder will blow out but there will not be enough pressure to force the head of the case back against the bolt to properly fill the fireformed case to fill the chamber.

When this happens, you will not get really good consistency until you fireform the load again under high pressure live fire loads.

As long as the chamber is set up correctly, the chamber will hold the case solidly against the bolt while firing so you will fill the chamber properly and should get excellent results from the start with your newly formed brass.

If you see any primer set back out of the case head, that tells you that your headspace is not set up in the chamber OR in the brass your necking down. There are ways to correct this. If your necking down a case, for example in my 7mm AM, you take a 338 Lapua and neck it down to 7mm so you can position your secondary case shoulder wherever you want to get that perfect 4 thou crush fit.

With a round like the Improved 338 Lapua, I have seen a few lots of even Lapua brand brass that were a bit short in headspace. There is a simple fix. the Lapua brass has a very good anneal on their necks and shoulders. Get a 35 cal expander, neck your brass up to 35 cal and then neck back down repositioning the shoulder for the correct crush fit. This will eliminate any case wall thinning which is generally not a problem with the Lapua case but other cases are not nearly as strong and it can be critical to get the fireforming correct or you will give up some brass life.

 

[NZ Longranger]

Kirby, Jeff,
Have you guys ever tried using cleaning patch material without the cornmeal? While not as many as you Kirby, we also fireform thousands of our wildcat cases a year for customers. We use similar powders to you, the fastest burning powders we can get our hands on for little cost. Years ago shotgun reloading was very popular here in NZ, but with the price of clay target ammo so cheap now, everyone has long since given up loading it. We are often able to pick up large drums of fast burners like 700x, N320 or Red Dot for nothing. We use from 25gns in the smaller cases like the Fatso up to 45gns in the P-Chey based Lunatic, then cut a 4x2 cleaning patch in half and stuff it in and tamp it down on top of the powder. We use any primers we can get cheapest, to save our good match primers. Again like Kirby, we have made special fireforming barrels to save our customers good barrels. We've worked out all our fireforming loads across the Oehler 43 ballistic laboratory and re-iterate what Kirby says. The pressure spike with these fast burning powders is so quick that the usual pressure signs on the case often don't show until well past max. Soft primers are a better indicator.
Anyway, the half a 4x2 patch works well for us and is a lot less messy than cornmeal!
Greg

 

[MontanaRifleman]

I have heard of guys stuffing cotton, as in cotton balls, into the cases

 

[NZ Longranger]

Yep, I'm sure that would work too, as the 4x2 cleaning patch material is just cotton. But half a 4x2 is easier to keep consistent size and weight wise than a pinch of cotton wool I'd guess.

 

[seidersjoden]

Jeff,

May I get your number, maybe PM me if you'd like. Have talked to Shawn a little about this rifle, would like to get your feedback.

Thanks
Joden

 

[graybullet]

what king of trigger is used?

 

[alcesgigas]

Is there anyplace I can buy fire-formed Lapua AI brass? I'm real leery about learning how to fire-form cases on a spanking new LRKM. However, Broz's results do temp me to jump up to the Terminator + P instead of the Edge + P.

 

[Elk Hunter 338]

alcesgigas,
Shawn's LRKM is whicked platform and I'm extremely positive that once the LRKM is in your hands Shawn can give you step by step simple instructions to make your brass.

 

[NZ Longranger]

Is there anyplace I can buy fire-formed Lapua AI brass? I'm real leery about learning how to fire-form cases on a spanking new LRKM. However, Broz's results do temp me to jump up to the Terminator + P instead of the Edge + P.

We'll happily form you some brass but it might be a bit expensive sending it all the way from New Zealand! And we'd need to know just what your head space measurement is, but I'm sure I could get that of Broz and Shawn. We have fireform barrels in both 35 and 40 degree versions.
If you get stuck, we'll certainly help you out!