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Posted: 4/17/2009 1:29:08 PM EDT
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I'm about to start reloading for .308 and am going to be fireforming some new win brass using some left over Tac and 150gr fmj bullets. The question I have is should I be seating these things out to the lands for fire forming. I've read that this technique is often used to increase the concentricity of fire-formed cases. I know seating to the lands can increase pressures so I'd have to use starting loads. Any input would be appreciated.
DOC |
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I would, personally, load the bullet with the intention of using it for other purposes than to fire form the case. The only gun that I have to fire form the cases in, is my .22-6mm Ackley Improved. The process that I use for it is to seat the bullet to magazine length and have at her. I use Redding Competition bushing dies for all of my varmint rifles, and you will not notice HUGE gains in accuracy by using a bushing die, but it is easier on the brass and does help some. I can visualize the process you mentioned working, seating closely (and safely) to the lands, and how it would help concentricity, but I am not well versed in the actual physics of it...so I can only respond with, "It sounds good".
I guess I am reading you as stating that you are wasting good bullets, primers and powder to fire form the case? My advice is to load up some really good loads for your rifle, and neck size the brass after the fact. In other words, I would treat the fire forming as a secondary benefit as opposed to the primary goal. If you are not bumping the shoulder forwards, such as in an Ackley Improved case, I would not think that the case alteration would be so radical that it would offer great benefits in accuracy. |
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Quoted:
I would, personally, load the bullet with the intention of using it for other purposes than to fire form the case. The only gun that I have to fire form the cases in, is my .22-6mm Ackley Improved. The process that I use for it is to seat the bullet to magazine length and have at her. I use Redding Competition bushing dies for all of my varmint rifles, and you will not notice HUGE gains in accuracy by using a bushing die, but it is easier on the brass and does help some. I can visualize the process you mentioned working, seating closely (and safely) to the lands, and how it would help concentricity, but I am not well versed in the actual physics of it...so I can only respond with, "It sounds good". I guess I am reading you as stating that you are wasting good bullets, primers and powder to fire form the case? My advice is to load up some really good loads for your rifle, and neck size the brass after the fact. In other words, I would treat the fire forming as a secondary benefit as opposed to the primary goal. If you are not bumping the shoulder forwards, such as in an Ackley Improved case, I would not think that the case alteration would be so radical that it would offer great benefits in accuracy. Basically, my train of thought here (and it may be wrong), is that by firing the brass in my chamber first before working up a load I will have more reliable results when trying to find the right load. The new WW has 0.006-0.007" more headspace than my chamber and a few of the cases have as much as 0.007" of runout. Some of the out of round cases are sure to have less runout after I fire them. I'm just thinking that since I'm working up a load that will only rarely be used with new brass in my rifle, I'd be better off not testing loads with new brass. I'd hate to waste all those SMKs only to find out my chosen load performs differently in new brass than in reloaded brass. I'll be using the remnants of a pound of TAC that lost out to Varget in load development for my .223 and the bullets I'm using are just some cheap fmjs that my local shop had in stock. Don't get me wrong though, I'm not going to just be dumping these rounds into the backstop just to get it over with. I've got a peice of AR500 plate that needs a good ringing.  All that said, I'm just gonna seat them to 2.800" and have at it. I'm not all that comfortable seating to the lands at this point anyway.
Thanks, DOC |
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I will never berate a fellow loader for trying something safe.
Honestly, I think that you will notice very minimal results. I neck size for two .220 Swifts, a .22-250, .204 Ruger and my .22-6mm AI, and, although I notice groups shrink past 250-300 yards, it isn't anything to write home about, and the Prairie Dogs, Coyotes and other varmints can never tell the difference. Be sure to test and post the results for us, if you would. |
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Fire form the cases with a full power load and bullet seated to normal length. This will blow the case out sufficiently for that rifle.
Don't over think this too much. Unless you mark the cases so they are inserted into the chamber in the same orientation every time, they are unlikely to go back into the chamber the same every time they're shot. Believe or not, this is common enough amongst BPCR shooters who mark each case with a small notch filed in to the rim. Then, it's chambered up, or down, or pointing in what ever direction the shooter had decided is best. The chamber, quality of barrel, the crown, and the bullet quality will be have the greatest influences on accuracy. A good rifle will shoot fire forming loads well enough to shoot in Highpower matches; I've seen that very thing happen. There was no point in burning up components just to form cases. |
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