I have used wax, and cream of wheat as a filler, with no bullet and cotton. Terribly nasty and pain in the rear. You can use bullseye and start at 5gr and see if its forming to your chamber using a head and shoulder gauge. If not, keep raising the bullseye. Be careful with bullseye however. You have to have a piece of fireformed brass to compare it to however and need some head gauges

I guess I should have added that I want to use the fire forming process during break in. Starting from scratch with a new barrel ya see. Trying to kill two birds with one stone. I just threw out all of my old brass and I have a shiny new bag of win brass (100 count) to load. I was kind of figuring on fire forming all at the same time and get the break in done as well. Am I just spinning my wheels?

mello

Nice

If you want to follow any number of break-in procedures, fine, Seems like everyone has some of their own, and that's another story. Personally, I shoot a series of one shot, clean, 5 times. Three shots, clean, 5 times. Then on to 5-shot groups, clean. Maybe excessive but it's what I do. As far as fire-forming, as has been stated here before, if you have some unwanted bullets and a reasonable amount of a powder that did not shoot as you had hoped, use them for your fire-forming. I have not had trouble with new brass that I've run thru my resize die, checked for trim length, load as normal, and just go shoot them. Oftentimes, they shoot just as well as the older previous casings. Chamber dimensions can play a role here, but for most intents and purposes, it just isn't going to matter that much, if at all for your intent.

yep it happens , my 730 waters is like that . just neck down load and shoot a 3030 case like it was all readyfire formed case, saved a whole step

RR- I didn't laugh at the notion of a 1/4" group, I laughed at the huge understatement attached to it.

I would say that just shooting to fireform standard brass to a standard chamber is a bit of a waste of time. If it were me, I'd just FL size the new brass (although, all the new Winchester brass I've ever used never really needed it, it doesn't hurt to be sure), load them with your load workup and shoot them. If a particular load seems promising, refine it with the now fireformed brass. Once you've got the load dialed in, load up the remaining cases with that load and use them for practice or even hunting rounds, since accuracy is likely to be quite acceptable.

Why waste barrel life and components when the difference between the FL and neck sized brass isn't likely to be that great.

Mike

Previously I posted a question about fire forming brass. I wanted to minimize case stretching in the process, especially in the head region. I good explanation of what happens is detailed at the Hornady web site (good read). This is the load I ended up with.

Fire forming load for my 25-06 Ruger M77 Varmint
Hornady 117grn btsp .257 20 thousands into lands
cci 250 LRM primer
54.5grn Ramshot Magnum powder. starting load for safety

By seating the bullet into the lands I hoped to eliminate movement of the brass forward buy the firing pin.

Pic1 is of brass from my old barrel. The ring on the brass is large enough to be felt as well as seen. This is why it was sent back to Ruger. It actually left a micro ridge around the head region. I am unsure whether it was due to a slightly large chamber or slightly large headspace. I figured I would let them figure it out. Of note: when I cut open the brass no thinning was evident.

Pic2 is from the new barrel with factory ammo. Notice I still have a ring but no noticeable ridge. I have been told the shiny ring is from the brass stretch in that region.

Pic3 is from my fire form loads. NO ring is visible or measured!






Results: It worked. Of special consideration is brass length of the fire formed loads. In all previous loads (hand or factory) I have had to trim after the first firing. The brass length actually shrank in the forming load. From starting at 2.489 trimmed it ended up at any where from 2.487 to 2.480 with an average of 2.484. Factory round’s brass ended up at 2.492. This was a surprise to say the least and leads me to believe that the case formed to the chamber without positive stretching along its axis. I expect this to give me a better more consistent case with a longer life, but only time will tell.

mello

RR
I was/am counting on the magnum primer combined with having the bullet seated into the lands to drive up pressure. That combination should have significantly raised the peak pressure, especially the seating depth. Hopefully the raised pressure will still be with in specs by limiting the powder charge to the starting load. By seating into the lands I was trying to duplicate the effect of a tight chamber by limiting case movement forward as the primer was struck. Curiously my forming loads were also fairly accurate. I was only firing at 25 yards but I still was getting 5 shot groups of 0.25 or less, plenty enough for hunting. I will still have to see what they do at 100 to tell. I left the range when several young men showed up with sks’s and their brass was literally flying from bench to bench.

mello