Ppc blow back issue

[Sleepyhollow]

Let me first say I don't have a fire forming barrel. Just my comp barrel. Yesterday I decided to form some new brass. Filled to the neck base with pistol powder and plugged with soap. Fires them then turn my necks to .259.5 at bullet ring. This barrel is .262 neck but seems to like a tighter tolerance.
Shot that brass today and had a ton of powder blow back and noticed necks only swelled to .261. Fired several times with the same results. First time I've form like this but didn't wanna waste bullets and ware and tare on my barrel.

 

[Ccrider]

That sounds about right. 262 neck you expect spring back to 2615 or maybe .261. You may have to shoot them one more time to get them fully formed. The blow back is likely from the shoulders being pushed back a bit more than you are used to seeing. No big deal.

Why the soap? Does it fireform and clean at the same time?

 

[Sleepyhollow]

The soap was what I had on hand to plug them. I'll keep shooting them and see if it improves.

 

[Ccrider]

The soap was what I had on hand to plug them. I'll keep shooting them and see if it improves.

Just yankin your chain a little. I don’t use a filler, just keep my barrel tilted up. Tissue or paper towel work fine.

 

[spike-55]

sounds like a lot of powder??? depends on what pistol powder you use to fireform, some are better than others- generally a faster burning seemed better
Load with 12 gr Red Dot then filled with COW (cream of wheat) up to the bottom of the neck all held in place with an old cleaning patch or paper towel stuffed into the neck. No bullet. in any case be sure to put a very thin coat of bullet lube on the case to help.
stan