Bullet-VS-False shoulder fire forming

[Hal]

What are the pros and cons of each method?
Does one method produce straighter cases than the other?

Hal

 

[Waskawood]

I just finished forming 300 BRX with the jammed bullet method. I had three cracked shoulders out of them all. Very pleased with the results. Best of all was the accuracy.

Pro's: Load and shoot.
Con's: Needed a little tighter neck tension so I had to purchase an extra bushing for the die.

 

[Terry]

I have done both. It depends on the use. In a Varmint gun load and shoot. In a BR gun I like the cream of wheat method.

 

[Phil]

The "Jamb" method requires more neck tension,it is best suited for thicker necks,as they hold tension better than thinner necks.
Also, with the jamb method you should remove your ejector as the spring will push the round forward in the chamber.

The "False Shoulder" method requires you to neck up the brass(.25cal.) then neck a portion of it back to 6mm,creating the false shoulder.
Some people believe it overworks the brass,others don`t......

I personally do both,create a false shoulder and jamb the lands.

I asked a member of this board his opinion and the above method was his reply,i believe he mentioned something about a belt and suspenders approach......

As to which method is better,that is for the individual to decide.

My 2 cents....For what it`s worth.

Phil.

 

[4xforfun]

I have tried them all. And now I use them all.....together. I bump up to 25 and then make a false sholder using lots of neck tention PLUS I jam the bullet hard. My brass comes out perfect....I loose about one in a hundred due to sholder splits.

As far as overworking the brass....My win a the IBS nats last year was with brass formed this way, fired 4 times, and was never annealed. This has been HOTLY debated over at BR central. Suposedly, no matter how much neck tension you can muster and how hard of a jam you can get, the firing pin WILL push the shell forward in the chamber causing irratic brass measurments. I figured that since I always iron out the kinks in my new brass before the first firing anyway, I may as well just add one more step...iron them out to 25 instead of 24, and then the added step of reducing back to 24 cal., making the false sholder in the process. I take my bolt apart (for feel purposes) and set the false sholder so that the bolt closes fairly hard.

It takes me an extra 15 min per 100 brass. A small price to pay for perfect brass!!!

FWIW, I have since baught a Bench Sorce machine...When I get 3 firings on my brass I will do the final trim to length, uniform the primer pockets, and start to anneal every time.

Anyway, this is just my .02 worth....take it as just that, my opinion.

Thaks,
Tod

 

[BoydAllen]

I think that the point about how much neck tension is available is a good one.

 

[bozo699]

I have use all three methods mentioned plus I have turned to create a false shoulder on tight neck chambers and combinations of all of them, they all worked but I think once all the smoke cleared, the method that has worked the best for me in the 6BRX is I turn the 6br brass .030 or so past the shoulder/neck junction of what the 6BRX will be, the brass absolutley need to be fired a second time before it's match ready so I see no reason to beat it up with a hot load on the first firing, 29.0-30.0 of Varget is plenty, 28.0-29.0 grains of H-4895 or RL-15 is plenty, I use non-mollied flat base bullets, 80-105 grain, I prefer 105 fb speer bullets, I use .004-.005 neck tension. There not accurate enough past 500 or 600 yards so I ring the gongs and break clays at 400-600, usually do this on a windy nasty day to practice wind reading, I did 300 cases here a while back and lost three cases in the initial f.f process and two more were discovered after the second firing, I have 4 firings on it now and haven't lost another case. I know several world champs that use COW method so I know it must work but I felt my cases were never completely concentric after this method, I did 300 of them in February and I am going to have to use them for varmint rounds, as they didn't meet my criteria for match cases. At one point I thought it was the cats meow but I am not so sure now, I may revisit it someday.
Wayne.

 

[johara1]

I turn necks to .0104 on the first turn and where i stop is my shoulder plus jam the bullet. Blow length is between 1.550 to 1.553,if the chamber is dry and the cases are free of any lube. I mostly use Varget if i use the fire form barrel. if i'm using a good barrel i use the powder that i'm shooting for the fowlers. Adjust the powder charge for your length. I finish turn and trim for the second firing.......jim

 

[bozo699]

I turn necks to .0104 on the first turn and where i stop is my shoulder plus jam the bullet. Blow length is between 1.550 to 1.553,if the chamber is dry and the cases are free of any lube. I mostly use Varget if i use the fire form barrel. if i'm using a good barrel i use the powder that i'm shooting for the fowlers. Adjust the powder charge for your length. I finish turn and trim for the second firing.......jim

Wow that's a lot what chamber do you have Jim?
Wayne.

 

[johara1]

Wayne, I have a .266 neck, do your math. .0208 + .2433 = .2641. Just under.002 clearance,i want the neck to hold in chamber when ff. Then i take a finish cut and trim.........jim

 

[lloydx2]

I think Wayne is talking about blow length? You are referring to oal case length @ 1550. When I measure blow length I do it off datum on case shoulder.

 

[bozo699]

Wayne, I have a .266 neck, do your math. .0208 + .2433 = .2641. Just under.002 clearance,i want the neck to hold in chamber when ff. Then i take a finish cut and trim.........jim

Jim,
I wasn't being a smart alic I was just curious what chamber you had as I run a .269 so I knew yours had to be much less, that's all, sorry if I came off other then that, I really enjoy your posts and have learned a lot from them.

So when your all done what do you leave yourself for clearance, about .003 when your all done turning?
Wayne.

I see you just posted before I did Lloyd, no Jim had it right, that is just more then the average guy's have been turning them as the .268 and .269 are very popular, but as the old saying goes
"turn thin to win"

 

[johara1]

Wayne, I didn't take bad in any way ,sometimes i don't paint a good pic. But the best part i sold a reamer with a .136 FB. and a .269 neck because of the blue box brass. I only use a little over .002 clearance and no way can you clean up the neck with out going smaller so i can have uniform neck tension. Blow length is the total length of the case,i trim to 1.550 after fire forming and my chamber is 1.560 in length........jim

 

[Scott Harris]

I turned my cases to .0115, ran a 6.5mm mandrel through them for a false shoulder and then used 28.5gr of H4895 with a 105 gr bullet for the fireform/match load. Shot a 587 at the match and most lost points were wind related. Lost 4 cases out of 160 to split shoulders. The fireform load was really accurate, can't wait to see what the formed case will do.

 

[pawpaw77]

what primers are you using with the h4895

 

[lloydx2]

What are the pros and cons of each method?
Does one method produce straighter cases than the other?


As long as your chamber is straight. Cases will be good once fired. I do not think jamb produces as consistant blow lengths as false shoulder. There is no doubt the firing pin striker moves the case forward on impact. Even with 205m. The false shoulder also has it flaws. Loaded round run out can suck .005. And some say your overworking brass. One way to improve this is to turn a 25 manrel down to give yourself .004 OD over neck DOA. There is no need to go more this is plenty. Don't use a forester fl die. I use a Wilson neck die with appropriate neck bushing. I have a shim I use to push the case into the die farther. This shim establishes placement of false shoulder. Using this method produces rounds with great loaded runout under 002. Another benefit is minimal working of the brass if your concerned with that. Lloyd

 

[Scott Harris]

what primers are you using with the h4895

CCI 400s: no problems there.

 

[bozo699]

Wayne, I didn't take bad in any way ,sometimes i don't paint a good pic. But the best part i sold a reamer with a .136 FB. and a .269 neck because of the blue box brass. I only use a little over .002 clearance and no way can you clean up the neck with out going smaller so i can have uniform neck tension. Blow length is the total length of the case,i trim to 1.550 after fire forming and my chamber is 1.560 in length........jim

Thank's Jim I appreciate that, I am not running a Dasher anymore but I can't keep my blow length as precise as I would like and it's usually under 1.550 by quite a bit, I am going to change my next reamer to reflect on my blow length, I was just talking to my Smith and shooting partner about this just the other day because of the carbon issues.
Wayne.

Lloyd,
As I said I have used at least four different methods including the false shoulder, I did not notice the blow length was more constant but probably never paid attention in a comparison minded way, I haven't tried turning a .257 mandrel down as you mentioned, I do like that idea,..thanks
Wayne.

 

[johara1]

Wayne, a friend has a reamer that has a chamber length of 1.555, he doesn't have to worry about the case moving, there is no where to go.......jim

 

[BoydAllen]

Wayne,
A long time back, I asked Tony Boyer if having his chambers set for a 1.500 max case length (to minimize the gap at the end of case necks) had yielded any advantage. He said that it had not. Much later, after listening to Jack Neary talk about the importance of frequent trimming, and that he sees no reduction in accuracy with a .035 gap at the end of the case neck, I have abandoned another tighter/closer is better position. Back in the corner, where the neck part of the chamber ends, is that hardest place to reach and keep clean with normal cleaning methods. On the other hand, as we get closer to the middle of the neck, routine cleaning is more likely to keep up with the rate of fouling. If the gap doesn't matter, and farther back is cleaner, if we trim very often so as not to have cases grow to a length that overlaps fouling laid down when shorter cases were fired, I think that we are good to go, and better off than if we are closer to the corner, with a narrower gap. As always, opinions are probably worth what they cost.

Boyd