350 Legend and Cast Boolits

[Texas by God]

I’m looking forward to a range report of this Abby Normal ammo you are loading. You’ve certainly put the work in on it- Rock on, FrankenSteen!

[Oldfeller]

Next, we may have to lap the throat in our AR to lengthen it just a smidge.

Lapping a throat isn't something you do casually, as the steel never grows back and any error you make is yours to keep forever.

Consider simply letting standard throat wear erode your throat naturally over time, as that will happen anyway.

Firelapping changes throat diameters and lengths fairly drastically, so if you ever do any firelapping you need to do a tap slug afterwards to see exactly what changed during the lapping process.

Having said this, making a throat lap involves the use of a lathe because you need to make a very precise lap form (size and length) in end of your aluminum lapping rod and you have to make a support sleeve that mates to your action to hold your lap rod precisely on the center of bore as you feed it forward oh so very very gently as it spins.

Using a drill to power the lap rod may be required to get the job done before you die of old age. But the drill makes the risk level go up as you can remove material faster (and screw up faster too).

At the back of the action where the installed support sleeve lives, you mark a start spot on the lap rod where it initially seats in the throat and you mark an end spot on the rod where you will stop lapping. These marks are not very far apart, now are they? Since you are just removing the rifling itself and just a tiny amount of bore material, the lapping job will move forward at a reasonable pace using 50 micron diamond paste to do the cutting.

You need a "ongoing progress monitor" that is readily visible or some sort of stop shoulder hitting the end of the chamber or you run the risk of lapping too too far (eek !!)

Why do I need to do this? I am using longer than normal bullets or bullets with a nose form that is non-standard to the 350 Legend general design from Winchester. I also want as much room for powder behind the triple aught buckshot string so I have to run the Luger types forward as much as the magazine will allow.

I am told that a Ruger already comes with a longer .357" diameter throat, so I suggest that a tap slug be made by anybody that thinks they have a "running out of throat" issue because you need to KNOW what you really have before changing anything.

[tomme boy]

Attachment 249853

Brass arrived today

It appears to be all Winchester I don't think its crimped.

Look over each piece. Over half of mine were crimped. It has the ring and the pocket is sharp from the crimp.

[Oldfeller]

Today we adjust the throat for both size and length by diamond paste lapping. This is rough diamond compound (50 micron size) in a heavy grease base and you can see I have my guide bushing in place on the back side of the action and the lap is charged and I am about half done with the lap job.

Rather than mess with a chain of bullets wearing out I cut the desired form into the end of the hard tough T-6 aluminum alloy rod that you see in the picture. This is a relatively durable lapping system and so far the lap is only worn .0005" at the end and I am about half done.



You can see the forward assist on the action in the picture to give you a spacial location of the bushing and yes, despite my own advice I am running a variable speed corded drill to make the lap rotate and using my thumbs to bump it up and down. I have both a stop mark and a stop shoulder on the lap rod to keep me from going too far into the barrel.

Goal is to have the throat taper to start to accept .357" jacketed bullets but have the narrower end of the taper go down to about .3565" which is what my sizer currently throws. This also allows a bit of wear growth in my powder coat sizer die, which is gonna happen whether I want it to or not.

It also splits the difference on any future full weight .358" rifle bullets after they go through my .3565" sizer and come out somewhere nearer to .357" due to spring back of the jackets.

Let's see how close I can come to the desired span of throat size and depth ......

[lar45]

Looking great Oldfeller. Have you shot any of the buckshot loads yet? I'm very interested in how they group.

[Oldfeller]

No, not yet Lar --- part of the reason for the throat lap job was to be able to run the front bullet in the Big Blue Train as far out of the case as the magazine would allow, making more room inside the case for MORE POWDER packed tight behind the caboose round ball.


You can see how much longer the throat is now by the lap discoloration.

All the throat lapping is all done now, the nose goes down to .3565" and the root by the case mouth is .3575" so I call it a success as by and large I got exactly what I was trying to get number-wise.

If I wanted it bigger later on, I can lap plate roll embed some larger grit lapping compound in the lap tip, but I think I am happy with what I have right now as it spans my push through sizing die and any commercial bullets that are run through that die. My powder coated bullets will load without sticking, hopefully anyway.

First loads will be a Big Blue Train of 3 Triple Aught buckshot string with a 124 grain Luger in front of them leading the way out of the magazine and into the 350 Legend's enlarged throat, making up a whopping HEAVY 335 grains worth of a FOUR (4) bullet load that I will then see just how fast I can get it to going.

Accuracy, we shall see ......

I have 300 factory stock fully supported Winchester brass coming in from Graf's and I will use that brass to make up these loads as they are somewhat on the wilder side of things pressure-wise.

[Oldfeller]

OK, I put a couple together to check on powder capacity and lump removal, two important parts of the puzzle.



There were lumps when I pushed the string of 3 round balls that deep into the case -- lumps that were .002" tall diameter-wise on the one that went deepest into the case. Pushing the finished round into the full length sizer die to crimp it takes care of the lumps while taper crimping the mouth into the powder coat (once again requiring practically no force on the press lever to do so).

Resulting lumps are less than .001" tall now and quickly doing the math that means the shot are compressed during crimp loading to right at (or a smidge just below) the standard print bullet diameter value of .355". This is in line with the final dimension they will finally take in the rifling, rifling which will displace some material that will once again join the inevitable bump up effects to make it all work out just fine.

Powder capacity is still quite low, I have room for 10-11 grains of either BLC-2 or WC820, with BLC-2 having a ton of time to burn completely and likely being a good bit more civilized about getting the train to rolling from a dead start than WC820 would be.

As said, these will be sub-sonic loads due to the limitations of powder capacity. They will likely be tough on the 5.56 reformed cases back at that unsupported web area, so if I fire them they will likely be a worst case test for the web area.

=============================================

New learning from loading and unloading the rounds that are capped with the lightly heel gripped Luger bullets several times over a couple of days now.

Powder coated bullets left under tension from powder compression and from case mouth compression that only grips part of the heel will move over time. The powder coat compresses and the grip tension gets relieved.

Once the case mouth compression is relieved, the bullets can tip and pull themselves right out of the case during slam loading and subsequent unloadings.

This is a development stopper, but it is one that Uncle Sam had bumped into and he built a thing called "bullet sealant" to stop it from screwing up his M1 carbine rounds and M14 rifle rounds. Same trick was used on Garand 30-06 rounds to keep the bullets where they belong in that particular autoloader too.

Civilians used to use a drop of clear fingernail polish to do the same thing, but I am fresh out until I can go to Walmart and buy me some more. My old bottle dried up over the years since I last used it.

Does finger nail polish even stick to powder coating material?

Answer is yes it does. Clear fingernail polish will act as an acceptable bullet sealant if the case mouth is parked partially over the edge of the crimp groove giving the clear stuff a protruding edge to grab some crimp and some "glue effect" upon both the bullet and the brass.

Looks good after the fingernail polish dries good. Appears solid to finger pressure, will now subject it to loading/unloading tests using the AR-15 action.

[Oldfeller]

It is Saturday afternoon and today we learned that the Ford Light Blue powder coating has extended curing requirements in order to be relatively size stable under compression forces from the case mouth.

It must be cured for over a half hour at at least 250 degrees F or else the coating isn't as strong and as stable as it need to be for a slow taper bullet case mouth crush seating job.

Next , I learned that my air dropped WW alloy is too soft to withstand large bullet seating forces without settling down and growing some in diameter.

Last learning is that I am simply having to crush things too hard and seating them too deep and I am basically causing myself issues because my net charge (powder and bullets together) is simply slightly too large for the case.

Winchester factory brass should have some extra CC's of case volume due to their construction and they will be here in a few days for me to try them out.

More later.

[cwlongshot]

BEFORE swage:


After swage:

Tommy,

I just wanted to say, You where spot on with the warning about primer crimp on there cases!! Thanks man!

Loaded up some RL7 & my 290 RD bullets cast in air cooled WW. W/alu GC. Shooting this afternoon. Tested to 26g @ 1650 fps no pressures. These loads are 26.5,27&27.5g

CW

[Oldfeller]

24" and 30" long lever arms, 5/8" high tensile aluminum rod stock

Well, the 2" diameter wooden balls trickled in from China, so I have completed the two longer "higher force levels available" lever arms for my very strongest single station cast iron press.

Us creaky old men have to cheat jest a little bit, don't cha know it?

[rockrat]

Just ordered some brass from Grafs!!!

[Oldfeller]

Errant thought for the day .......

My slow taper crimp trick using the full length sizing die has the ability to correct finished rounds at the case neck/bullet junction and even correct them up towards the head area (removing the bulges from the multi-ball loads).

Folks keep saying you can't put .358 Remington bullets into the Legend case without over-expanding that case neck junction to the point it won't load into the chamber.

I say "So what? You got a full length 350 Legend sizing die don't cha?" You can make whatever "minor releasing clearance" you need for that oversized finished round at will, dialing it in by the tenth of thousandths by turning in your full length sizing die in a little bit more from your standard slow taper crimp position.

Fair warning: You do reduce your bullet diameter where the case covers it down to close to .357" or thereabouts by doing this, but the bullet leaves the case mouth and immediately goes to .355" at the start of the rifling so your gun really doesn't care.

Remember to use some sizing case lube and to wipe your cases off good afterwards. Have some clear fingernail polish on hand, as you may find assembled rounds rotating the bullets on you sometimes as all fits were made smooth and "slip fitted" in a taper seated fashion by the compression seating trick.

Or, you can pre-size your jacketed lead slugs in your cast boolit sizing equipment ahead of time and do it that way. If your throat diameter is a stock .357" diameter and still at a print length you will have to seat the resized bullet more deeply into the case to get it all to work out even after resizing your heavy .358" jacketed rifle bullets to .357" diameter or less. This deep seating of the longer than stock bullet in a stock throat issue cuts down on your powder capacity accordingly.

But a trick is a trick is a trick --- you use them as needed.

Remember the lap rod trick, you could have a Legend throat that accepts .358" bullets at close to full length naturally if you wanted to go do that. Your magazine length becomes your limiter then ......

[Oldfeller]

Got my 300 pieces of Winchester range brass in from Graf & Sons today. It is a mess on the case length all right. I got .024" short to .027" beyond optimum trim length. This is more wildness that I have ever seen in a factory once fired case.

Taking the over length brass back down to optimum 1.70 trim length took some time as taking that much stock off was quite tedious.

Over 85% of my brass is primer crimped. Roughly 20% shows signs of excess pressure (most of these were the over length cases, btw). Chicken or the egg, which condition came first ????

I am going to tumble the cut cases for a couple of hours to de-burr the mouths good tomorrow AM then begin experiments to see if loading and unloading improve with a stock format bulge-less factory brass.

[bikerbeans]

Are going to pitch the short brass?

BB

[Oldfeller]

Heavens no, it is still perfectly usable in a standard "single boolit" Cast Boolit load. As will be all that weak headed Federal stuff you guys like to go and on about.

Funny that, my made from 5.56 Nato brass is .032" short of optimum trim length but I find that .032" short falls inside the tail end of the very broad Winchester natural trim length distribution (statistically speaking).

I think a portion of all the extreme high pressure signs seen in 350 Legend so far come from the grossly over length brass from the other end of that distribution that was way way too long and way way over crimped (duh) causing very high start pressures because Winchester uses a faster powder to get to their maximum speeds.

I will pick a "safe" cast boolit load with BLC-2 powder with enough pressure to completely form the case up at the head area, and then simply use the brass as it grows, then toss it when the neck cracks (which will eventually happen, I am pretty sure).

[Oldfeller]

Now here is a puzzlement question for the crew ---- what would I do if I get light primer strikes on the short brass because they can migrate forward in the chamber?

[Oldfeller]

Next mild puzzlement question .......

What the heck are these gizmos?

[cwlongshot]

Now here is a puzzlement question for the crew ---- what would I do if I get light primer strikes on the short brass because they can migrate forward in the chamber?

Kinda saw that coming...

As for Gizmos... dead link. No pic says to call admin.

CW

[Oldfeller]

Deleted and ran the pic through all over again, says it went through and I can see it just fine, but we all know they are working on the board as we speak ......

Heck, it said it was good the first time around, too. Looked great to me, too.

We all know that looking at the brass we just got in from Graf's that firing pin force and depth of strike is a variable item (just by looking at the primer strikes). Some primers got struck VERY hard and very deep.

I would choose to have mine to strike a bit deeper, that's all.


Here is that pic again just to see if it stays around better now.

[cwlongshot]

Case trimmers. The case length IS all Over the map!! I wont shoot factpry anylonger. But i still buy the FMJ.

I pull the bullets weigh the powder and set aside. Trim the brass to length and reload with a bit below average charge weight 21.5g IIRC was last amount. Then I size down a 140FTX bullet to 356 and seay just above cannalure and taper Crimp. When shooting these, I enjoy sub MOA accuracy and 2350 fps. I have posted a few pics of my ammo right outta a new sealed box you can see lengths differences naked eye.

CW