fire forming, dry or wet chamber

H

Hal

New member
When fire forming, what gets the best results, a dry chamber or lightly lubed cases ?

This is for the 6MM Dasher, a 6BR case with the shoulder moved forward .100 and a 40° shoulder with a case length of 1.555".

I'm thinking about chambering up a fire forming barrel.

When some guys fire form they end up with short cases. What is a good method to end up with longer cases.

Hal
 
Hal,
I talked to Jim Borden about the same thing and he said no lube on the brass.I bet some people will disagree so, just give him a call and he can explain it to you.
 
Tony Boyer and many others recommend a light lube to the outside of the case. Go figure. Let the case decide what length it will end up on its own. My cases have always shortened after necking up, and after fire forming. :)
 
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Lubing your chamber is a completely goofy "fix" for a problem generated by TOO MUCH HEADSPACE.

Fix the headspace, problem goes away.

Do what'chew gotta' do to promote a crush-fit on your fireform cases and you will get straight cases.

Jim B is a wonderful source of information, a wise man and free with his knowledge. Also very busy, and he does this for a living.
Please consider some form of recompense if calling for info only :)

JMO

al
 
I would guess the reason that a Dasher shooter would be concerned about short cases after fire forming, would be the issue of having too much space between the ends of cases and the end of the neck portion of the chamber. In a worst case situation, how much gap are we talking about? On the lube for fire forming thing, successful shooters have done it both ways forming PPCs, but I would not recommend it when firing a full pressure load when the "fire forming" is something like firing a new 6BR case in a 6BR chamber. Because the term also gets used for this sort of thing, I think it important to make the distinction.
 
alinwa said:
Lubing your chamber is a completely goofy "fix" for a problem generated by TOO MUCH HEADSPACE.

Fix the headspace, problem goes away.

Do what'chew gotta' do to promote a crush-fit on your fireform cases and you will get straight cases.

AL

I'm thinkin crush fit is good/ straight cases is good/ lubing the case when ff-ing 220 Russian with full cases of N133 gives the brass a chance to stretch more in places than at just the web/ giving the case more life.............maybe. If your chamber is straight and your die makes straight brass when it comes out, and your bullet seater does it's job, why wouldn't 50k# pressure make straight brass/with long life?? Mine does.:cool:

Later
Dave
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Dave Coots said:
alinwa said:
Lubing your chamber is a completely goofy "fix" for a problem generated by TOO MUCH HEADSPACE.

Fix the headspace, problem goes away.

Do what'chew gotta' do to promote a crush-fit on your fireform cases and you will get straight cases.

AL

I'm thinkin crush fit is good/ straight cases is good/ lubing the case when ff-ing 220 Russian with full cases of N133 gives the brass a chance to stretch more in places than at just the web/ giving the case more life.............maybe. If your chamber is straight and your die makes straight brass when it comes out, and your bullet seater does it's job, why wouldn't 50k# pressure make straight brass/with long life?? Mine does.:cool:

Later
Dave
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yours does, because your headspace is set at a thou or so ;)

With a "DAsher" or any of the other cases with truly excessive headspace (ie, in the excess of .003) lubing WILL NOT yield consistent cases. It will make cases that look and fire OK but if you have the means to measure them up you'll see that they're not straight.


As far as "more life"....... I mean, I fire cases up to and including blown out 338Lapua, HOT, as many firings as I care to get..... 50?.....100?? ......All doable.
Click to expand...
 
Two different animals between a PPC and a Dasher and fire forming. The PPC is like an Ackley chamber, it's grabbing onto the neck/shoulder. Sometimes you even have to bump a 220 case to close the bolt to FF.

The Dasher case is hanging in "mid air", held only by the neck. I think a combo of sizing up the neck, then necking down for a false shoulder, and then a long seated bullet should do the trick nicely.
 
I shoot two cartridges that are f-formed with excessive headspace, the 30BRX (30BR +.100) and the 30 WolfPup (30BR+.240). I've f-formed them all sorts of ways, and lightly lubing has given the best results.

30 BRX:
brx.jpg


30 WolfPup:
unfiredpup.jpg


Good shootin'. -Al
 
The 6 dasher is tricky. I just fireformed 100 cases. lost two to split shoulders. all of them are short. 1.525-1.530
but i have a short freebore. and a 1.555 OAL chamber length so i think a trim lenght .015 short of the chamber is normal. so im not too worried about being .015 short of that. It shoots well and i have not done much shooting with it yet or any tuneing. I just make sure to clean the freebore every time i clean.

Now alot of guy's would consider a 1.525 case junk. but they are running a 1.570 chamber and a .155 FB for the hybird bullets.

Now How to get a dasher case to blow long. I have been told by one of the best dasher guy's out there. it's a long process.
you can go to accurate shooter, it has been discussed alot. But NO lube on the case. clean dry cases, clean dry chamber. is one of the must .
 
Thanks for the replies and different point of views.

.025-.030 difference in case blow length depending how the case was fired formed is interesting.
I have to do more research.

Al: That Wolfpup is unique.



Hal
 
Crush fit

Like Wayne and Al said.

Use a crush fit to control headspace and you will have consistent size cases. Lubing case bodies creates bolt thrust and you can end up with various headspace on cases and some that will always be hard getting in and out of rifle. I create a crush fit for any case I ever fire form. When I neck turn, I set the shoulder back at least .005 from what chamber will be and neck turn to that shoulder/neck junction. Then I expand neck up one caliber from the desired caliber. After that I set die up off shell holder and size part of the neck to result in a case that has headspace about .004 to .006 longer than chamber headspace. For me this helps get consistent headspace cases and maximizes the length of the cases adn I DO NOT GET case thinning at the head to body joint

Jim
 
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