fireforming by jam... no false shoulder ?

[queen_stick]

I read this - http://www.6mmbr.com/6improvedform.html

Now I'm curious if anyone is forming 6mmDasher cases by jamming the bullets hard, rather than creating a false shoulder (by turning or sizing).

If this works, then it would save a lot of time creating false shoulders. I'd like to try this method, but I'd rather not split cases and find out later that I should have skipped the 'jam method' and went straight to the 'stepped neck method.'

Walt

 

[TheBlueEyedBear]

I have formed 300 pieces of Lapua brass with the same method that Leo Anderson told me about. Used a 105gr A-Max (Jammed) pushed by 30gr. of H4895 with a 450 primer. I think I too may have split a neck or two, but by far this was easy and an accurate load for fire-forming.

 

[jr600yd]

Can't say anything about the Dasher but I fireformed 300 6BRX cases using the "Jam" method. Like the other guy's I used 105 Hornady's, Lapua 6BR brass and 29.5 grs of Varget. Haven't split a neck yet.

Good shooting, Jim

 

[queen_stick]

Thanks for the replies. I'll try jamming and shooting (nos stepped neck). It may be a couple weeks until I can try it, but I'll try to post here with my results.

 

[Clark]

I have not done 6mmDasher, but I have experimented with 100 ways to fire form 257 Roberts Ackley Improved in a chamber that is too long.

The best way is with 10 gr pistol powder, and then cream of wheat cereal, and then shoot it straight up or put Ivory soap in the mouth and shoot horizontally. Putting high pressure lube on the case helps it slide back in the chamber. I use Lyman moly bore cream, but many lubes will do. Even if the shoulder does not then look fully formed, it already very accurate and the shoulder will be formed on the next firing with a bullet.

I have jammed into the lands, but that is pitting firing pin against seating force or jamming force, and the firing pin can win.
Jamming into the lands gives better accuracy, as it centers one end of the bullet, but not great for fire forming.

 

[queen_stick]

Thanks for the input Clark.

This is my first run at fireforming, so maybe I'll try all 3 methods and see what works for me. (COW, stepped necks w/full loads, and jamming).

I'm not using a new match barrel, so sending some rounds down the tube isn't of major concern. I'd still like to take it easy on the barrel if possible, so the COW method may get chance here. Like mentioned above, I'll update this post with whatever I come up with.

Anyone else with some advise or suggestions ? I'm new to this, so I'll accept any assistance I can get.

 

[savageboy]

I use the cow method tomy satisfaction.

 

[tightneck]

Think I'd worry about HEAD SEPARATIONS, not split necks. A tenth of an inch worth of headspace, and a jammed bullet to make up the difference? No thanks...

 

[queen_stick]

tightneck:

That's the main reason I posted this question. It seems dangerous! The more I asked, and more I researched, the more I found out that case head separation doesn't really happen; worst case seems to be split necks, which occurs with stepped necks as well. I think if you were to seat the bullet to normal length (not jammed), then tried to fireform the dasher, it would pose more of a threat? I don't know that for sure, just seems kind of logical. (Again, that's based what I think, not what I know from experience or science.) As long as your not using a "stupidly high" powder charge, the pressure should remain at a safe level.

I like playing with this stuff, but I think fireforming could be the most dangerous part of "wildcatting." tightneck and I are on the same page, in questioning the "jam method." For that reason, I may not try it. I like my fingers attached to my hand, and full functioning eyeballs!

Anyone ever have a "serious" failure when fireforming? Case head separations, hang-fires, or worst case scenario - blow the gun apart?

 

[queen_stick]

Curiosity killed the cat...

I should really be doing a paper for school right now (going for my Master degree!), but I just couldn't help myself.
(If this wasn't successfully done in the past by experienced people, I would never have tried this.)

I loaded 30.0grns of Varget with a Fed 205 primer, and a 105 AMax Jammed really hard. (jammed to the point I felt comfortable closing the bolt with pressure - I read the article on hard bolt closures, and the dangers associated with it.) I set it so it was a tight fit, but I still felt comfortable closing the bolt... basically used some common sense.

I left the picture as big as I could get it, so you can get good look at the shoulder. (If interested, I can email the original picture, which is huge, and very clear - it fills up my 28" monitor plus some ) I felt the inside of the case with a small wire and feel no separations at the former shoulder/body junction, or in the webbing.

(LEFT = New 6BR; MIDDLE = fireform by jam only; RIGHT, case already formed and shot a few times (a dummy round that came with my barrel))

 

[queen_stick]

Cropped the huge image for a close-up...

 

[MarkS]

queen_stick,

I have shot 6 Br IMP for 9 years, and have tried all methods. I think the jammed works best and is more accurate. COW is very messy. I find a FF load that works, load everything up and use them as sighter and fowler, as I work up loads with the fired cases.

Mark Schronce

 

[jerrschmitt]

I've got a .243 Ackley Improved that was chambered a little long so that it won't fire factory 243 rounds. I tried jamming some long bullets and it just pushed about half of them back in the case. Then I formed a false neck with a 6.5 MM expander and loaded 10 gr. Unique / COW and fiber filling.

After about 20 rounds of this I just loaded the false neck cases with a standard load of 40/R15 and a 60 Burger. They shot quite well actually.

 

[queen_stick]

jerrschmitt...
You're saying that the jam method just shoved the bullets into the case, in such a manner that they did not fire? (Case pushed forward in the chamber). Sounds like you needed more neck tension?


Makr S...
That's a great plan! You're going to need to shoot fowling shots anyway, so why not get 2 birds with one stone and fireform while fowling. Thanks for that pointer - that's an awesome idea.

I have another question... Do you have trouble with flattened primers when fireforming? I only tried that one case pictured above... the case head shows some signs of pressure (flattened primer, machine marks, and ejector mark, which I believe are from the case head flying back into the bolt face, rather than excessive pressure. Am I correct in thinking that way?

Do you remove the ejector when fireforming? It seems logical to think that the case head would stay tighter to the bolt face if that bugger was removed from the equation?

 

[blawton]

Ok you pulled the leo card.....

I have formed 300 pieces of Lapua brass with the same method that Leo Anderson told me about. Used a 105gr A-Max (Jammed) pushed by 30gr. of H4895 with a 450 primer. I think I too may have split a neck or two, but by far this was easy and an accurate load for fire-forming.

 

[blawton]

Now over the years we have tried many many way of fire forming cases. Time and time again after using corn meal and jamming bullets we figured out that using a false shoulder formed the cases better on the first try without near the hassle or problems of any other way. I would never suggest doing it any other way. I have gone as far as setting up all my new reamers on wild cats a few thou short of the virgin brass just so i can create a false shoulder and i have way less headaches....

Another consideration is this. You are taking this brass and pushing it near it limits while moving the shoulders this far. In turn this is going to create splits in the neck and shoulders no matter which way you form the brass. Its something thats just going to happen every once in a while.