Mini doughnut with new barrel?

[jimbo88mm]

I rebarreled my stevens 200 for the first time. The old barrel was 243, the new one is in 260. I used a full length sized brass as a go gauge and two pieces of cellophane tape as the nogo gauge. Everything looks good except for a very slight bulge on the necks. I am not getting any other signs of pressure or headspace issues (ie no signs of stretched heads, flattened/cratered primers, stiff bolt lift, etc).

Using my dial calipers, I get the following measurements:

base if neck at shoulder: .295
apex of bulge: .299
top of neck: .293


My question is could this slight bulge be related to how I set the head space or is this more of an issue with the brass (RP)?

Is this even anything to worry about?

Can this be corrected by neck trimming?

Do I need to reset my headspace (hopefully not)?


In the photo below, the left case is from the old 243 barrel that I've inlcuded as a reference. The center and right case have the bulge in question.

http://i829.photobucket.com/albums/zz219/Jimbo88mm/mini-dounut.png

[thomae]

How long since the brass was annealed? As the brass toughens it tends to want to spring back when formed. Don't know if this is your problem, but it's what came to mind.

[Blue Avenger]

that about where your bullets end when seated?

[jimbo88mm]

This is new brass, never been fired before.

I was discussing this issue with one of my friends and he suggested that my H1000 loads were on the low side. Since this was a new barrel I worked up 10 loads at .5 grain increments with the max load of 47.5. This is still well below the max listed in my hornady manual of 49.something but I ran out of case space. I was seating the bullets to hornadys recommended length with the 140 Amax but the last three (46.5, 47, 47.5) were a little longer.

I took another look at my cases and the bulge defiantly seems more pronounced on the lower power charges and less on the higher power charges so maybe he's on to something. I'm going to get a drop tube and see if that helps.

[jimbo88mm]

that about where your bullets end when seated?


I'm 90% sure the bullet is going past the shoulder. The 140 Amaxs are pretty long.

[handirifle]

I would bet money on a bad chamber. If the cases are not bulged before you fire them,I say something is out of spec with the chamber.

[sharpshooter]

Nothing wrong with the chamber....the powder is too slow.

[1S1K]

Saw it before, they used a bad reamer.

[gotcha]

Jimbo, I'd go w/ sharpshooters advice....... 1st: SLOWLY, 1/2 grain at a time, increase powder chg to see if you can get nk to seal completely. Or switch to a faster burn rate. Note how soot goes down neck onto shoulder on the .260's as compared to the .243 case. Looks like not enough pressure to completely seal neck... or over sized chamber neck. Increasing the powder charge SLOWLY would be the cheapest starting point. BTW my fired 6.5mm case nks measure .292", loaded rounds meas. .2885"/.289".................. Is the case bulge 360* or to one side of the neck? Do you have a Ball micrometer to measure nk thickness at various depths on new & fired brass? Very remote chance but could be a brass issue. Just trying to think of all possibilities...............The H-1000 could work well in someone elses .260 but not in yours. Each firearm is a rule unto itself. ;)

[jimbo88mm]

Thanks for the replies.

The bulge appears to 360. Unfortunately I do not have a ball mic or anyway to check thickness.

I feel I have a good plan of action:

1) Work up the H1000 load a little more
2) Pick up some H4350 this week and see how that works
3) Get some factory ammo.

If I see the same doughnut with factory ammo then that confirms that I have a problem and I will contact the vendor.

[keeki]

looks like not enough pressure in the case before the bullet leaves it. Powder being too slow causes this or not enough neck tension on a compressed load.

[Blue Avenger]

H1000! there is your problem! Your playing base ball with a basket ball!

[jimbo88mm]

Got an update.

So I loaded up some more rounds. I went with three different loads: 47grs H1000, 41 & 41.5 grs of H4350.

I wanted to give the H1000 another chance because it shot well last time, despite the doughnuts. I seated the bullets out a little bit further so the load was as compressed as before. I could still hear the powder shake a little in the round once loaded.. the first time out I couldn't hear any powder move.

So it looks like I am still getting the doughnuts but its less pronounced then before. Using the dial calipers again I am getting the following numbers on a couple of cases:

41.5 H4350
base if neck at shoulder: .297
apex of bulge: .298
top of neck: .296

47 H1000
base if neck at shoulder: .293
apex of bulge: .295
top of neck: .294


http://i829.photobucket.com/albums/zz219/Jimbo88mm/mini-doughnut2.jpg


Incidentally, the H1000 load shot decent (5 shots @ 100 yards):

http://i829.photobucket.com/albums/zz219/Jimbo88mm/260_47H1000.jpg


Both loads are still a bit mild. I'll kick it up another notch and see how it looks.

[BradB]

I'd think the 260rem and H-1000 would not be a good match. ???