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257 Roberts Improved...fire-forming...Powder...Fast or slow ?

Another option would be to neck down 7X57 cases (PPU, cheap) to .25 using a .257 R F/L set back for a crush fit without an expander ball in the die and FF with COW. I make 6mm AI's that way but use a .243 W die, no expander. backed off, the .243 die with it's 20* shoulder makes for an easier neck down. New brass, anneal after neck down.
 
Another option would be to neck down 7X57 cases (PPU, cheap) to .25 using a .257 R F/L set back for a crush fit without an expander ball in the die and FF with COW. I make 6mm AI's that way but use a .243 W die, no expander. backed off, the .243 die with it's 20* shoulder makes for an easier neck down. New brass, anneal after neck down.
That sounds like a great option . I would for sure be able to obtain my crush fit right from the start. Thanks
 
Upon a neckdown from .28 to .25 the neck brass will thicken meaning neck turning might be needed. How much depends on your chamber neck dimensions as measured by a FF neck, allowing for .001 brass spring back.

Not to go into a big production, bullets should easily slip fit into a fired case. If not, the sized necks need to be turned down until an easy slip fit can be obtained. Excessive turning will result in inadequate neck tension. While not as accurate as a micrometer, a high quality caliper will suffice for measuring neck diameters. Like load up 5 rounds with successive .001 neck diameter reductions fire each, then test for slip fit for each. Go for the one with the biggest diameter yet allowing a slip fit. Seating bullets should require some force.

Just about every wildcat loader/shooter needs a neck turner.

Ideally the neck walls should be from .0125 to .015 thick and there has to be enough neck tension to hold the bullet. My 6mm AI loaded rounds = .268 - .028 - .243 = -.003, or .003 neck tension. .014 neck wall thickness. Upon resetting the neck turner cutting blade just barely contacts a sized previously fired and sized neck. This will allow for +- .001 duplication. Ideally, numerous neck turners could be used for a variety of ammo leaving each in a fixed setting but that would be spendy.

Upon FF by COW, a guess would be that 20 thou psi is sufficient to give sharp shoulder angles. I use pistol powder and any ole primer. Start by measuring the entire weight capacity of the case then only use 10% of that charge to start. Be real cautious. After fire forming be sure to remove any COW debris inside of the case as it will affect capacity for future loadings. I use a piece of rebar binding wire fashioned into a 100* or so angle on one end and straight on the other. Probe and scrape just under the shoulder and then poke the wire thru the spit hole and probe and scrape again. I FF in my garage using a 5 foot long piece of 4" diameter PVC pipe capped at one end. I insert about 18"inches of barrel into the pipe then fire. I clean the chamber after each 10 rounds. A dull thud can be heard outside the garage. I use 9 grains of HP38 to FF the 6mm AI.

I shot 85 grain Nosler BT bullets out of my .257 AI with H4350 @ over 3400.
 
Upon a neckdown from .28 to .25 the neck brass will thicken meaning neck turning might be needed. How much depends on your chamber neck dimensions as measured by a FF neck, allowing for .001 brass spring back.

Not to go into a big production, bullets should easily slip fit into a fired case. If not, the sized necks need to be turned down until an easy slip fit can be obtained. Excessive turning will result in inadequate neck tension. While not as accurate as a micrometer, a high quality caliper will suffice for measuring neck diameters. Like load up 5 rounds with successive .001 neck diameter reductions fire each, then test for slip fit for each. Go for the one with the biggest diameter yet allowing a slip fit. Seating bullets should require some force.

Just about every wildcat loader/shooter needs a neck turner.

Ideally the neck walls should be from .0125 to .015 thick and there has to be enough neck tension to hold the bullet. My 6mm AI loaded rounds = .268 - .028 - .243 = -.003, or .003 neck tension. .014 neck wall thickness. Upon resetting the neck turner cutting blade just barely contacts a sized previously fired and sized neck. This will allow for +- .001 duplication. Ideally, numerous neck turners could be used for a variety of ammo leaving each in a fixed setting but that would be spendy.

Upon FF by COW, a guess would be that 20 thou psi is sufficient to give sharp shoulder angles. I use pistol powder and any ole primer. Start by measuring the entire weight capacity of the case then only use 10% of that charge to start. Be real cautious. After fire forming be sure to remove any COW debris inside of the case as it will affect capacity for future loadings. I use a piece of rebar binding wire fashioned into a 100* or so angle on one end and straight on the other. Probe and scrape just under the shoulder and then poke the wire thru the spit hole and probe and scrape again. I FF in my garage using a 5 foot long piece of 4" diameter PVC pipe capped at one end. I insert about 18"inches of barrel into the pipe then fire. I clean the chamber after each 10 rounds. A dull thud can be heard outside the garage. I use 9 grains of HP38 to FF the 6mm AI.

I shot 85 grain Nosler BT bullets out of my .257 AI with H4350 @ over 3400.
Thank you for the step by step instructions,I appreciate you taking the time . Your process sounds like a winner to me . This is new territory for me,I wish I would have waited and learned about the COW method before using hot loads with bullet jammed .
 
Here are some pics - on the left a 90% or so fireformed case needing just .5 grain more HP38 pistol powder - on the right a completed 6mm AI round with nice sharp shoulders and the neck turned down to .268. The bullet is a 87 VMax. Not intended for FYNE bench rest shooting but does ok. I turn my necks with a RCBS neck turner and periodically sharpen the cutter blade on a diamond knife hone. The cases are chucked into my DeWalt cordless and turned at some slow speed. I don't remove more than .004 at one session. I like to anneal after neck turning. P9090035.JPG
 
Here are some pics - on the left a 90% or so fireformed case needing just .5 grain more HP38 pistol powder - on the right a completed 6mm AI round with nice sharp shoulders and the neck turned down to .268. The bullet is a 87 VMax. Not intended for FYNE bench rest shooting but does ok. I turn my necks with a RCBS neck turner and periodically sharpen the cutter blade on a diamond knife hone. The cases are chucked into my DeWalt cordless and turned at some slow speed. I don't remove more than .004 at one session. I like to anneal after neck turning. View attachment 1125433
That .5 grain of pistol powder makes a huge difference . Looks like I will buy some new brass and start over . I loaded up the brass that grew enough for a crush fit,they were the Hot H4895 rounds . Hope to shoot them today,I am hoping they survive the second firing OK .

Thanks again for all the info.
 
Next batch will get a false shoulder . I have fired my first attempts 2 times,with one third of them being fired 3 times . All are holding up just fine with nice sharp shoulders . The next 100 will get the false shoulder and COW treatment . Hoping to find a recipe calling for Red Dot ,if need be I will pick up what powder will work best.
 
Hi Dale, sorry for the wait. Been hectic around here with some family illnesses. Its pretty simply, much like the COW method except I used coffee. COW would burn and big chunks of carbon would get packed into the corner of the shoulders when I did 257 and 243 ackleys. I went with coffee because it is already burn/roasted and it smelled better. I added 14 grains of IMR Red which formed them pretty well but I would start lower and work up until your shoulders are nicely formed, filled with coffee to the base of the neck and then stuffed a small piece of tissue into the neck to hold it all in place. I thought the coffee was easier to clean out of the barrel too.
 
Yea, but would the bad stuff in the primers & powder screw up the coffee making it taste bad? We drink Starbuck's @ $12 plus per pound but I guess a cheaper brand would suffice. I think the carbs & sugar in the COW makes for the carbonized black stuff. This changes my FF protocol.
 
I have no experience fire forming, but I have a Kimber 25-06 at the smith being rebarreled to 25-06AI, so I am closely watching this thread.

What about hydro-forming to get a case close to final size, then fire forming as a last step? Seems that would minimize the number of times a case would have to loaded, fired, and cleaned, to get to final AI dimensions?
 
I have a hydro forming die for my 22-250 AI and still prefer to fire form. It takes a good set up to use the hydro die to its fullest. I was getting good fill out to probably 90%, but it's hard on a press and messy.

I use a crush fit and a max load of RL15 for the parent case, and the fired case looks perfect. Doesn't hurt that the fire forming load is half MOA every time I form. I usually form after cleaning and right before a deep scrub cleaning. When the barrel is toast I'm going to form hundreds of pieces of brass before putting a new barrel on it.
 
The IMR Red/coffee sounds interesting . Can you give some info on your method and powder charge please ?
Dale, I simply used 15 gr Imr red, coffe, topped with tissue, 257 brass, load and shoot. 95-98% formed. Clean and load them for load tests. I like simple
 
Dale, I simply used 15 gr Imr red, coffe, topped with tissue, 257 brass, load and shoot. 95-98% formed. Clean and load them for load tests. I like simple
Thanks Ken, I will have to give that a try . I have some cheap coffee that's perfect for something besides drinking. Thanks for the info .
 
You have to experiment a little. Coffe can work and so does cream of wheat. Be sparing with the tissue, just enough to hold the powder and COW in the case, maybe 1/6 sheet (again experiment). Don’t expect a full fill out. That will come the next firing. Then anneal and enjoy.
 

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