FF sizing eye opener

[rangeball]

Since I have my rempac here at work with me with the plug out, I thought I'd push a couple of the 310 APBs I FF last fall through to gauge their loading resistance, as I didn't take notes and can't remember exactly.

When I sized them I put a line on the ogive to line up with the die, and ran them through 3 times. My bore definitely gives a different loading experience depending on alignment so I index and have my muzzle marked.

First one I had to really work to get it seated. I don't remember it being this difficult. Even with proper alignment it was a bear to get the base started, but once I did it pushed down with about 20# of resistance, which seemed like I remember it being last fall as I was thinking I could tighten it up just a tad to get better accuracy (I'm hoping the .040 bushing and large PFC give me more complete ignition and solve this but time will tell). Until I came to the part of the barrel where the charge sits and ignites. Could not push through by hand, had to resort to a rubber mallet and had to whack it pretty good. Bullet came through but the base looked like it was expanded a bit. I blame the resistance on carbon build up where the load ignites, but never imagined it would be that substantial. Also the base of the bullet now looked flared out a bit, and I can't imagine why it would be. Would NOT fit back into muzzle, so I swapped it and sent it through base last, and had a hammer down the entire way. It seems to have reset the base but it's still very hard to get it to re-start.

Not sure what is at work here. Any ideas?

[10ga]

Even with 3 passes that jacket and core want to expand some. More time more expansion. There can be a considerable difference size between freshly sized and year ago sized bullets. "Spring back" can vary with how much sizing, jacket and core alloy etc... lead alloy bullets without jackets spring back the least and jacketed the most. I have no experience with all copper bullets as purchased or annealed so can't comment on how they react to sizing over time. 10

I would think a pass through the die just a day or so before shooting would get them back to what you need. this should be a good thing to check on how bullets might differ when sized in August and then trying to load them in December while hunting. Could end up FUBAR in the field. 10

[hunter]

I think you are getting a carbon buildup or crud at the end of the plug where the powder ignites.
It is hard to get it cleaned out and it is hard to push a bullet past it.
With the base stuck on the crud ring and hitting it with a mallet probably shortened it and swelled it up.

[Deleted]

clean you barrel well and start over. if the fouling has been there a while it gets hard and crusty...

[Deleted]

I've noticed flare back on the 310 also but I've only got ten (1st and only ten I've bought, sample) so I wasn't concerned about it. Wasn't sure why it did that either.

[rangeball]

All great points, thanks. It is eye opening to see the spring back after almost a year. I wasn't expecting that and don't recall reading about it.

I'll get the bore spotless and start over. Looking back other than running a brass brush through it I haven't thoroughly cleaned it in a couple of years. I guess its time.

[Deleted]

What powder are you shooting...maybe different residue different crusting...?

[rangeball]

Nothing but H4198 ever in this barrel.

[cowhunter]

I have the same thing and I thought it happens with all barrels. I thought it had to do with a little lip created by the breach plug. I guess I don't clean any my barrels very well if it is carbon. Mine are not much problem. I just have to hit the rod hard a few times withy palm or a hammer.

[dannoboone]

Oct 23, 2014 12:25:43 GMT -5 cowhunter said:

I have the same thing and I thought it happens with all barrels. I thought it had to do with a little lip created by the breach plug.

Methinks you're on to something, but is it created
by the BP, or the machining?
A properly sized bullet going all the way down a
brand new .451 barrel stopped where the end of the
BP would be when installed. They have to then be
tapped to go through that one place.

[rangeball]

Oct 23, 2014 16:54:22 GMT -5 dannoboone said:

Oct 23, 2014 12:25:43 GMT -5 cowhunter said:

I have the same thing and I thought it happens with all barrels. I thought it had to do with a little lip created by the breach plug.

Methinks you're on to something, but is it created
by the BP, or the machining?
A properly sized bullet going all the way down a
brand new .451 barrel stopped where the end of the
BP would be when installed. They have to then be
tapped to go through that one place.

Hadn't considered that but in my recent case it was the last two to three inches before the face of the plug.

I plugged my plug and an soaking the barrel overnight in hoppes #9.

Smells wonderful