View Full Version : Followup to fire forming
04-13-2010, 08:24 AM
As a followup to fire forming brass, all seem to be in basic agreement that some type of fiber (be it cotton, cream of wheat, crackers, etc.) be used to occupy space if using light powder loads when fire forming brass.
If having worked up an accuracy load and the load is just under a load that show signs of excessive pressure, and there is still a slight portion of the case that is unfilled with powder, can you think of any reason that cotton could not (or should not) be used to help keep the powder in full contact the flash hole? In other words, is there any advantage or disadvantage to filling the remaining space with "fiber" on all target or hunting loads?
04-13-2010, 08:33 AM
I have heard that you can ring your barrel using a filler.
You could always use some cast bullets with slow powder if you wanted to have a caseful of powder.
04-13-2010, 08:38 AM
Cant answer experientialy on your question but do know that accuracy loads are seldom maximum loads so space is usually left, personally knew a guy that did finish fill his cases with filler when shooting matches.
It would seem that there could be some benefit to having every charge with the same form internally upon ignition, but again, I do not know and this is just thinking out loud..
For hunting accuracy purposes it would seem to be an unneeded step.
Just want to clarify, you are using smokeless powder correct? Also should you use anything below you do so at your own risk. I am not sure how much reloading experience you have &/or how much of this has been in the area of wildcat cartridges so I hope you don't take offense to any of the following as I am basing my response assuming you have limited experience. If this is not the case I apologize.
With Black powder you want a compressed load, with smokeless not so much, although I know some loads are slightly compressed this is "typically" not the case when reloading.
Now on to your question. I have reloaded for over 40 years, off and on, now and it is my understanding (I am not an expert) that pressure is a result of Bullet weight, bullet style, powder charge, powder type, case capacity, air space, temperature and primer. Change any one of the above and pressures can go up or down.
You have a slight air gap in the cartridge now and are loading just under a load that shows excess pressure signs. Adding a "filler" may put you into that excess pressure area again. Personally if you want to add filler I would do two things:
First talk to the powder manufacturer. In some cases they do not recommend using a filler with certain powdes as it can cause high pressure, unpredictable results or other conditions deemed hazardous.
Second, drop my load 10-15% and slowly work back up using filler if they say it is OK.
Be very careful with the powder bullet combination and temperature changes. Significant changes in temperature can take a load that shows not pressure signs and appears to be perfectly safe (pressure wise) and create a severe high pressure situation to a point where it is dangerous to shoot. I have presonally witnessed that in the area I have lived for 50 years. We load in the winter, test rounds in the spring and shoot matches thru the heat (sometimes 90+ degrees) of the summer, sometimes with no shade. Certain powders will exhibit large swings in pressure from the nice 50 & 60 degree temps to 80 degree temps as evidenced by 1 moa groupls opening to 5 or 6 moa groups.
In your last post we were talking about fire forming cases without projectiles (or I was anyway), now you are talking about loading with a projectiles and this can cause a big difference in pressure. Tread lightly...
04-13-2010, 09:02 AM
.........do know that accuracy loads are seldom maximum loads so space is usually left.................
Yes, I was aware of that.
It would seem that there could be some benefit to having every charge with the same form internally upon ignition, but again, I do not know and this is just thinking out loud...
I think there may be some benefit but nothing I can substantiate. I used to be seriously into BR competition and we would either use stacked, compressed loads or use a filler depending on type of powder. Most of us used H322 or T322 (a hotter powder) when shooting 6PPC.
Naturally, the 50BMG is a wee bit different and we are using H869, likely the slowest powder available.
04-13-2010, 02:46 PM
I have seen many recommendations on fire forming. Some use bullets, some only use a wad or wad and filler. I think all ways can work when used properly. If using a bullet, the load should probably be a starting load from a load manual, with a powder that is OK at low load densities. If using a wad or filler and wad, fast powders are used in very small amounts. How to choose?
For bulleted loads, use a load that would be a starting load in the parent cartridge if the case has not been shortened. If case capacity is going to be less that the parent cartridge then more care will be needed. For example, if forming 357 Herret from 30/30 cases you might use a light 357 Herret load or a starting 357 S&W load without damaging your gun. DO NOT TAKE THIS AS RECOMMENDED PRACTICE, only as conjecture based on limited experience and reading.
To use a wad or wad and filler, you need to work with fast powder and try to find recommended loads through extensive research. Non-bullet loads should be restricted mainly to rimmed cases or cases that have a shoulder to support the case in the chamber.
04-14-2010, 06:52 AM
Thanks for your replies. If "things" become eventful, I will post the results.