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fireforming/full length resizing

Started by swampthang, September 27, 2012, 05:20:18 AM

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swampthang

correct me if im wrong but fireforming brass swells the neck to the EXACT size of you chamber. so if you use a f/l resizer to size brass isnt the fireforming useless. me and a buddy have an argument going. i say "yes" once you fireform and then f/l resize it fireforming does no good.
"kill em all"

MZ5

I usually use, and hear used, the term 'fire form' in connection with re-forming other brass (say 250 Savage) to your desired cartridge (say 250 Ackley Improved).  However, it is also used just to talk about firing correctly-headstamped brass to form it to your specific chamber.  In that case, _I_ believe that yes, a F-L sizer die negates whatever advantage fire-forming gives you.  I think that, if you want 'fire-formed' brass, you should be using a neck sizer.  I have a neck-sizer for all but I think 1 of my rifle cartridges.  I've even had Lee custom-make me collet neck sizers for my 25 WSSM and my Creedmoor, because I personally think that indexing off the _inside_ neck diameter is the only sensible thing to do.  I don't personally care for outside neck sizers, though they certainly can work acceptably, and are common.

Trent

I think generally speaking, fireforming refers to firing a cartridge case that was re-formed from one case to another. Like making a wildcat or using .308 brass to create 6.5 Creedmoor brass.

In your example though, yes to a certain degree you are loosing a little of your chamber specific dimensions depending on HOW you FL resize.
1) 3/4 neck FL resizing. Some people refer to this as "neck sizing with a FL die".
You're only screwing the FL die down far enough to resize 3/4 of the neck and very minimal, if any, body sizing takes place.

2) Shoulder bumping with a FL Die.
In this case you are screwing the FL die down far enough to only bump the shoulder back about 0.001" to 0.002" from it's fired size. This is almost a full FL resize where in the body is resized, but not completely.

3) True FL resizing. Screwing the die down to contact the shell holder and then an additional 1/8 to 1/4 turn down. This is what is in most directions that come with dies from the maker.
This is a full resize and the brass at this point should fit in any chamber of that particular type of cartridge. At this point, unless there is an anomaly, you will have removed any "fireforming" dimensions from your chamber.

That's my two cents. Cheers brutha!

swampthang

a man (or woman) that doesnt appreciate the knowledge found on our forum or the willingness to help each other is "just plain crazy as hell"
 although ive shot along time . one can never get to many tips or too much knowledge.you men are great!! once again : THANK YOU ALL. i bump the shoulders back on a 300wsm i have and use neck bushings on a 308 bench gun. but dont know how to use my die to neck sz. like trent does. if mr.white still has his 3 die set he will sell me im gonna go ahead and get them they are the f/l set plus neck sizer in creedmoor. may ask some more questions later.
"kill em all"

MDM

Weigh the water volume of an unfired factory piece of brass, fire it and then FL size however you plan on doing it and check the water volume on that sized case.  I bet it increases a few tenths of a grain.  I've got a tight custom chamber and I saw an increase in .2-.3 grains of capacity from factory unfired brass to FL sized brass with a .001-.002 shoulder bump.  So, fireforming does have some merit and does do "something", and I suspect the increases in capacity may be greater in a factory chamber.  What does all of this mean? Probably nothing in the end results but it is what I found.

FL sizing does not always bring all brass back into spec for each chamber.  My buddy's factory chamber will in no way chamber in my custom chamber with any amount of FL sizing.  I had another buddy buy 600 pieces of once fired Creed brass and he could not get it to chamber in his custom chamber either, and his was cut with the same reamer as mine.

ibgp3

Quote from: MDM on September 28, 2012, 07:06:12 AMFL sizing does not always bring all brass back into spec for each chamber.  My buddy's factory chamber will in no way chamber in my custom chamber with any amount of FL sizing.  I had another buddy buy 600 pieces of once fired Creed brass and he could not get it to chamber in his custom chamber either, and his was cut with the same reamer as mine.

I'm seeing something similar in my DPMS LR6.5,
...No FTF, but FL sizing only marks the neck.
If I got your buddy's 600 pieces, they would probably be too large for my chamber.
...In which case I would take .2" off of the bottom of the dies and try again.

MZ5

I'm not completely certain that my FL die is giving me any room inside my mass-production factory chamber, either.  I'm not trying to use it to squeeze the brass that much, but I now have a few pieces that are a few-times fired, and even with that die down touching the shellholder, I have noticed that the bolt doesn't close as easily as I would expect on _really_ F-L sized brass.  It's only a couple/few pieces, though, so there are many things that could be driving this observation at this point.

MDM

For what its worth, I found that with following the Hornady die instructions of just touching the shellholder was not moving my shoulder at all.  I had to go a little further to get a .001 bump.  The Hornady bump gauge set really helps set your dies up correctly.

swampthang

so whats causing this-: my buddy wanted me to reload him some 300wsm. i loaded to his specs. ( he has a diffrent load than me another guy worked up). they were perfrectly loaded. when i sent them to him he cannot chamber them and close the bolt. whats the problem and how to fix it. i FULL LENGTH resized them. rcbs die and redding micrometer seater die. they have been shot and loaded 6or 7 times .
"kill em all"

Trent

How hard was your cam-over on the handle? It's either the body, the shoulder or the bullet that is touching. I generally go with a HARD cam-over when loading old brass for another chamber. It just depends on a few things that can cause this. Chamber differences, dies, and how work hardened the brass is.

My two Creedmoors have nearly identical chambers (one Savage factory and the other cut by Shilen). I have a pair of factory 7-08s that the fired cases from one will fit in the other... but not the other way around. A hard cam-over on the FL sizing will get those cases to fit in the other 7-08 though.  In the 7-08 scenario it is the headspace that is the culprit.

If you have a 300wsm body die you can try resizing them without taking them apart and see if you can get them to fit.

ibgp3

Quote from: Trent on September 28, 2012, 03:35:10 PMIf you have a 300wsm body die you can try resizing them without taking them apart and see if you can get them to fit.
just make sure there is nobody upstairs ;D ;D ;D

giterdone

#11
Regarding those .300WSM cases that have been shot 6-7 times resized and would not re-chamber.  Time to anneal those cases.  A body die will resize the case without touching the neck dimensions.  It can/will set the shoulder back if adjusted to do so.  Resizing loaded rounds in a body die is not recommended by the manufacturer; I have done it with some success, but I would not hover over the suspect loaded round when operating the press handle.   YMMV
The latest caliber or gear is no substitute for experience and skill.  Rifles and cartridges don't make hits-----shooters do.

Trent

It's no more dangerous than seating a bullet on top of a primer and powder which we all do thousands and thousands of times. There's nothing contacting the primer. In fact, there is a void under the primer.

FORD4X4

I've got a weird full length/neck sizing story. I've got two Model 70 .270's. Had one forever and acquired the other recently. When shooting the new one with reloads 'neck' sized (die not touching shellholder) from the other rifle's fired brass, the bolt was firm to close. No problem for half the box, but rifle stopped firing the rounds. After checking headspace and case dimensions, blah blah blah, found out I had to full length size (all the way, too) cases to fire primers. Chamber dimensions on the new rifle is very tight and other rifle is looser. I understand the stiff bolt closure, and its not excessive, but why won't the firing pin fire the primer?

swampthang

pretty sure the problem is overworked brass. dont know bout his neighbor that reloaded for him. he said they have been shot and loaded SEVERAL times which was why i bumped the shoulder back on them to accomodate for some of this. i set my die up with a solid ,but not extreme rollover. and when i complete the down stroke ,it bottoms out on the bottom of the brass,which in therory sizes the entire case and bumps back the shoulder .1-.2 thou. these brass however were trimmed shory of the recommended 2.090 some were as much as 2.085 and as long as 2.094. i trimmed long ones to 2.090. this is why i hate working behind others, but he's a best friend and hate to turn him down and not do it for him.
"kill em all"