fire forming brass

[ishootaRUM300]

Here is a picture of some brass I am fire forming. I think am using a 129gr hornady sp with remington 9.5 primers and 44gr IMR4831 I don't know for sure because my load data is at my buddies house where we have our reloading bench.

These are four of the first five shot. The first one is at my buddies house and they are fifth shot, fourth shot, third shot, second shot from right to left. They are all loaded with the same load, but I think I can see a difference in the shape of the case when you look at the shoulder. Is this something I need to worry about or will it be ok because I don't think they are forming the same what do you guys think?

 

[just_a_hunter]

I can't tell any differnce? What do the primers look like?

Is it a 6.5x284?

Todd

 

[ishootaRUM300]

It is a 260Rem AI and the primers look good nice rounded edges.

 

[TOPGUN]

How many total rounds have been down the pipe and are you the only owner?

 

[ishootaRUM300]

I am the only owner. It is a brand new barrel just got it from the smith on Thursday. I have a total of five down and I can see a difference in the brass. When they are right next to each other the first have nice sharp shoulders and the last three the corner seems to be more rounded.

 

[TOPGUN]

LAST EDITED ON Mar-18-12 AT 09:11PM (MST)[p]The little bit I know about fire forming is that you're supposed to use the lightest recommended powder load with the bullet you're shooting to do it properly and that it takes some experimentation to get it right. Could it be that you were well over that load and the pressure was too much to fireform the case properly, but not excessive enough to show any case damage? That would be my only guess.

 

[RELH]

It appears that you are on the very edge of getting good resizing. I would up your powder load by 1 grain and go from there. If several cases does not have full sharp fillout on the shoulder, a 1 grain increase should do it or 1.5 gr.

My reloading manuels do not show IMR-4831 powder for that caliber. It does show H4831 and you are just below the min. starting charge for H4831.

RELH

 

[sageadvice]

+1 RELH

I suspect that you could continue with the reloading of these cases but i would also recommend a slightly hotter round in fire forming the remainder. In many cases, one can shoot Factory ammo down the tube to conform to the AL chamber. Most of these Factory rounds are substantially hotter than some of the recommended Fire forming loads that i see here and there.

Not familiar with the .260AI but suspect that it will prove out to be a outstanding multipurpose cartridge once the minor bugs are worked out. Can you simply shoot factory .260 ammo to fire form if one were to choose to go that way?

Joey


"It's all about knowing what your firearms practical limitations are and combining that with your own personal limitations!"

 

[BuckSnort]

I agree with RELH and sage... You should be able to shoot the max charge of a .260 and not be over pressured in an AI...

It's just weird to me that all 4 are the same powder charge..Maybe the pressure increased (bbl temp)just a bit with each round fired?

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[ishootaRUM300]

Here is the load data from Hodgdon max load of IMR 4831 44.0gr for a 120gr bullet 44.0gr for a 140gr bullet. Hornady has a range of 37.6 to 45.7gr of IMR 4831 for the 129gr bullet. Nolser has 42 to 46gr of IMR 4831. Barnes has 39.5 to 43.5gr for the 130gr bullet. I have both Hornady 129gr sp loaded and a few nosler partitions.

 

[sageadvice]

RE: fire forming brassing

I found this article very informative. In it, he claims using 47gr H4831 to fire-form. Nice piece! Good luck with your project, i like it!!

http://www.6mmbr.com/gunweek046.html

Joey


"It's all about knowing what your firearms practical limitations are and combining that with your own personal limitations!"

 

[Cahunter805]

LAST EDITED ON Mar-19-12 AT 04:17PM (MST)[p]
You could add another .05 to 1gr of powder and it would help with a little more pressure.

Are you feeling a slight resistance when closing the bolt almost at the end of bolt throw? A correctly set up AI chamber has just a slight amount of "crush fit" at the top of the shoulder of the case. On new brass there's a slight radius there that holds the case well against the blow of the firing pin.

Another thing you can do is seat the bullet to around .001 off the lands or just kissing them. This will also keep the firing pin from moving the case during forming.

 

[D13er]

....hold your finger over the end of the barrel....



JB

 

[ShowThemToMe]

Here's what you do:

Start out with REDDOGS recomended Load!

Back the Load down in 5 Grain Increments!

When the Primer Quits Blowing out of the Shell you're gettin close!






[font color=red size=redsize=18"face"]SHOW THEM TO ME![/font]
If You Love Your Country,SHOW THEM TO ME!




Hot Dog,Hot Damn,I love this Ameri-can

 

[RELH]

The reason your shoulder edge is not fully filling out is because you lack enough pressure to fully fire form that paticular brand of cases. Increase your load by 1-1.5 grains and you should fill it out and still be within safe pressure levels.

The Hodgon reloading manuel is noted for being conservative on their reloading specs. Also when you blow that case out to AI specs, you are going to lose pressure and velocity due to larger case interior space. If you use the reloading specs for a STANDARD case, your pressure and velocity will be less then given for the standard case. You can safely increase the powder charge to gain the advantage that the AI case will give you.

It would pay to have a chony to develope your loads for the newer size case.

RELH