A.I. Fire Forming Tip of the Day

[Howland]

I successfully fireformed .270 Winchester into .30-06 Springfield using no lube at all.

I had mistakenly grabbed them off the LGS shelf where they sat right next to the .30-06. I fired eight rounds before I figured out why the report and recoil were so light and I wasn't on paper at 50 yards.

 

[Pdvdh]

Hah! I've seen some of those after-the-fact fireformed cases at the local gun shop. Can produce some interesting discussions. Like guess what happened here?

Fireforming belted cases can result in some ugly looking casings, since the case head is held in contact with the bolt face by the belt, no matter what lies ahead of the bullet. The bullet don't know or care what lies ahead of it... Neither does the casing...

 

[TwoMore]

I know it apples and oranges, but I have been using hydro dies on the two AI's I load for. I lube them in the die but run full loads to hunt with after. I hydro them just to stiff bolt and then size just to where the bolt frees up. I bump -.001 of fired cases. i have never tried the COW method, before the hydro dies I just backed down about 15% and jammed the lands, I can see where a deep chambered barrel would give some probs

 

[Rich Coyle]

I know it apples and oranges, but I have been using hydro dies on the two AI's I load for. I lube them in the die but run full loads to hunt with after. I hydro them just to stiff bolt and then size just to where the bolt frees up. I bump -.001 of fired cases.

Same here. Mine is not A I but total wildcat.

 

[Pdvdh]

Hydroforming dies are appealing. I've never used or purchased one. But I like the idea.

I have too many wildcats to purchase hydroforming dies for all. Sometimes I wildcat my wildcats!

 

[TwoMore]

both of mine I will have limited barrel life so the hydro dies were a must

 

[TwoMore]

Here is a pic of my process the far right case is a bertram 338 edge necked to 308 then 284 , the middle is after the hydroforming and the left is ran thru my sizer bumped .001 under

 

[Bravo 4]

Phorwath,
Any other observations or updates you'd like to add to this thread?

 

[Pdvdh]

One additional update. The burn rate of the powder used to fire form the parent cases seems to play a role in the resulting case shrinkage. I use SR7625. Elkaholic was using a faster burn rate powder and having a less successful result. We discussed it and suspected the powder burn rate could be a factor. So he then switched to a fire forming powder with a burn rate similar to SR7625, and then had good results.
I think the faster burn rate powders don't hold their peak pressure long enough to cause permanent case expansion.

I continue to have positive results using SR7625 as my case fire forming powder.

You could PM 'elkaholic' and ask him which powder he ended up using. I don't remember which one he used.

 

[shawnb]

I tried this morning fireforming a couple more 300 win to 30-375 ruger. I used the exact same method except one had lube, the other dry. You can see the case on the left (dry) had more case stretch after the belt. More than i like. And the lubed case on the right looks way better above the belt but the whole case shrunk and the neck is to short now.

This was done with using the jam a bullet into lands method. I think i need to use the COW methos with crush fit, and leave the casing neck longer to accommodate for the shrinkage.

 

[shawnb]

Heres another photo of the cases

 

[Pdvdh]

I tried this morning fireforming a couple more 300 win to 30-375 ruger. I used the exact same method except one had lube, the other dry. You can see the case on the left (dry) had more case stretch after the belt. More than i like. And the lubed case on the right looks way better above the belt but the whole case shrunk and the neck is to short now.

This was done with using the jam a bullet into lands method. I think i need to use the COW methos with crush fit, and leave the casing neck longer to accommodate for the shrinkage.

Were you headspacing off the shoulder of the 300WM cases prior to fire forming with bullets? I only used the lube on COW fire formed cases, and the case length shrinkage was reduced, and the shoulders were completely blown forward for proper headspacing off the shoulder for my next firings with bullets.

If you COW fire form, you'll want to set the shoulder of the 300WM case back for a friction crush fit when closing the bolt. Prime, powder charge and compact cream of wheat over the gun powder. Seal the COW in the case neck with some tissue. Then lube the case. If you want to go overkill, also clean and lube the chamber. Boom!

Let us know how much case length shrinkage you end up with. Shouldn't be much.

What are you using for case lube?

 

[shawnb]

I pushed the shoulder back enough that the neck/shoulder junction was a little farther back than needed with a 338rcm die. Then sized down with my sizing die to 30cal. Seated the bullets with lots of jam, lubed with sizing wax and fired them. The one without lube stretched a lot at the base above belt and grew to 2.605" from 2.590".

The lubed case didnt stretch at the base and shrunk to 2.565" from 2.590". My guess is its because the case was able to expand all the way it needed to withouth stretching and ended up shrinking because of that.

 

[shawnb]

So what youre saying is size so the neck/shoulder junction is a crush fit. Do i lube the casing this way? I just received my gunwerks 300 win mag brass for testing. I wanna get a system before i try that and ruin good casings.

Ill probably just load bullets. I have lots of cheap bullets but no pistol powder and cream of wheat