forming a false shoulder

jimbires · Feb 26, 2022

all this false shoulder talk got my interest up , I had to do it . I wasn't sure if it would be worth the effort . I found there is nothing to this .if you have the means do it , it can only help case life . I doubt I have I have 15 minutes in getting things measured , until I had 5 pieces with a false shoulder ready to fire .that includes taking a few pics . I have a 300 wby, and a bunch of bulk brass , so this is my guinea pig . I did a little measuring and found my rifle will stretch the brass about .011" from virgin brass to fully expanded . I started by running the brass through the 300 wby die to round out the necks . I then put a nice chamfer inside the neck with my VLD chamfer tool . I lubed inside the neck with RCBS case lube 2 . I then used my .334" expanding mandrel , and opened the case necks to that diameter . I'm sure this is way bigger than needed , but it's what I have . I'll say probably necking up .020 would be about right , but I don't have that size mandrel. I then used my 300 wby sizing die and started to size the case neck back down . this die is not a bushing die . I think if using a bushing die you would want to keep stepping the bushing down , not do it in one step . I backed the die out a couple turns and just worked it down , about a 1/4 turn at a time , until the bolt closed with some resistance . here is a few pics .

mandrel I used to over size the case neck.

mandrel in die . die has a viewing window to be able to watch the brass

bulk brass in back row . front row has necks opened up to .334 .

stages of sizing the neck back down to fit the chamber . the one on the right fits .

all finished .

TackDriver284 · Feb 26, 2022

Good stuff Jim, has the overall length of the virgin brass increased after the final step or did the length stay the same?
Now its time to go load them and fire them.
I will order the .323" mandrel later when I need other stuff to buy online, saves on shipping costs.

ShadeTree · Feb 26, 2022

Yes sir, you got it Jim. They aren't hard to make, just going through the exra steps is all. They usually shoot plenty good also. I've shot some pretty respectable groups comparatively to what a particular rifle normally shoots, when fire forming false shoulder'd brass.

jimbires · Feb 26, 2022

yea , there's nothing to it . I really thought it would be more goofing around , than it is . I'll start paying more attention to this now . as they say , I wasn't sure the juice would be worth the squeeze . it's so simple that if it gives even 1 or 2 more cycles , it's worth it .

Mark , I just ran down and made #6 ,. here are the measurements , using a caliper . the base to shoulder pretty much stayed the same . the OAL did change a couple thousandths .

out of the box ;
OAL , 2.8160
base to shoulder , 2.3890

false shoulder ;
OAL , 2.8135
base to shoulder , 2.390

SJB358 · Feb 28, 2022

Nice Jim.

trust me, I wouldn’t do it if it was tedious.

I almost fall asleep when folks talk about neck turning and pointing bullets….

jimbires · Mar 1, 2022

I've got away from some of the brass prep things I was doing . I started doing it when I was using common brass . I switched to top of the line brass and kept doing these things . had my head in a rut , I guess . I've now labeled a lot of it as unnecessary romance .

SJB358 · Mar 1, 2022

jimbires said:
I've got away from some of the brass prep things I was doing . I started doing it when I was using common brass . I switched to top of the line brass and kept doing these things . had my head in a rut , I guess . I've now labeled a lot of it as unnecessary romance .

Same here Jim. I don’t even mess with cleaning primer pockets anymore. I never saw the difference and have saved myself a few extra hours on my life.

ShadeTree · Mar 1, 2022

I uniform primer pockets and deburr flash holes on brass. Once and done . Can't see it as any sort of necessity for a rifle that's just capable of shooting an inch but not a tackdriver at 100, but it's hard for me to let them sit untouched. I never did do all the other stuff........turn necks or weigh brass. If I get an uncharacteristic flier in a rifle/load, I will mark that brass and check it against a couple others.

I like to keep it simple so I can keep shooting instead of working at shooting.

SJB358 · Mar 1, 2022

Same here ST. I’ve found most of the variation in my loads has to do with me.

TackDriver284 · Mar 1, 2022

Last night, I checked my 6.5 x 284 Lapua virgin brass headspace and its .004" less than the headspace of 2 X fired brass, so I won't mess with the 6.5 x 284 false shoulders. The 300 Magnum Lapua virgin brass is .013" shorter than fired brass, it is my mission soon to form false shoulders as Jim and Scotty described. That will give me something to do as soon as I get the mandrel I need .

SJB358 · Mar 1, 2022

TackDriver284 said:
Last night, I checked my 6.5 x 284 Lapua virgin brass headspace and its .004" less than the headspace of 2 X fired brass, so I won't mess with the 6.5 x 284 false shoulders. The 300 Magnum Lapua virgin brass is .013" shorter than fired brass, it is my mission soon to form false shoulders as Jim and Scotty described. That will give me something to do as soon as I get the mandrel I need .

Good luck and I’d likely not mess with the 6.5 either unless you just had a 277/284 expander.

I got em all when I bought them so it really isn’t more than an extra 20 minutes to do it. But with 4 thou it ain’t the end of the world either.

13, yup, it’ll be worth it.

ShadeTree · Mar 2, 2022

All this talk lately made me try something I was figuring on trying some day anyways. Forming to a 257 Roberts AI, with 6mm brass.

Cartridge drawings show a .048 difference between the datum line on the shoulder. Yikes. Just to not split the neck making a big jump, I went up to .257, then .264, then .277.

Set my false shoulder where I wanted, loaded up with a max charge of H4894 for a 257 Roberts and a 100 gr bullet.

Formed out nicely. But I'll admit I turned my head when I pulled the trigger.

I got a .050 difference base to shoulder measurement between the once fired 6MM brass, and the newly formed 257 Roberts AI. Aout like making a wildcat I suppose.

Only thing you need to do when going that big of a jump, plus taking the taper out of the case, is lightly lube the case. I didn't and got a noticeable stretch ring little more than 1/3 of the way up the case. That's from the rear of the case which is chamber measurements, grabbing the chamber, while the rest of the case is free and clear.

jimbires · Mar 3, 2022

I still clean my pockets . I have a prep station that takes the work out of some of the process . I use 3 stations all the time . primer pocket brush , VLD inside chamfer , bronze brush. I outside chamfer only after trimming .

TackDriver284 · Mar 3, 2022

jimbires said:
I still clean my pockets . I have a prep station that takes the work out of some of the process . I use 3 stations all the time . primer pocket brush , VLD inside chamfer , bronze brush. I outside chamfer only after trimming .

View attachment 16427

That reminded me that I have that VLD inside chamfer on my RCBS prep station that I haven't used lately. I have been doing it individually by hand with the regular chamfer tool, primer uniformer, and brush. Thanks for the reminder Jim, time to dust off my prep station to use it for the 6.5 x 284 virgin brass and try those Hot Cors again. I haven't been to the range yet to try the ones I prepped using the .263 mandrel / Hot Cors and those 147's. Looks like I have time tomorrow at the range.

jimbires · Mar 4, 2022

on the prep stations .
my primer pocket brush has a male thread . the empty spot on my station was also a male thread . I wanted all the tools mounted , to speed up the process . I went to two hardware stores to buy a connector nut that's used to couple two pieces of threaded rod , neither store had these in the size I needed . I forget the size, take a tool with you . I tried to drill both ends of an aluminum rod to make a long connector nut . I couldn't drill it straight enough to get it to run fairly true . I ended up using two round knurled brass nuts , of the proper thread size . my local True Value store had these brass nuts in the cardboard assortment drawers . I screwed one on the tool , the other on the prep station . I used a short piece of tight fitting rubber gas line to hold them together . I've been using it like this for a few years . it works fine for the primer pocket brush , no problems at all . I don't think it would have the grip to run a chamfer tool . it would probably pull apart on the neck brush operation .