Arbor Press Newbie Question

[Legionnaire]

Last night I had my first experience with a K&M arbor press and LE Wilson chamber type bullet seater. I was loading .264 caliber 140 grain Nosler Partitions into new .260 Remington Lapua cases over a charge of IMR 4350. In a number of instances, the bullets would begin to seat easily enough, then hang up almost as if they hit an obstruction; with a bit more pressure they would then seat fully. Seating the long partitions to a COAL of 2.800 puts the base of the bullet well below the bottom of the case neck. What is happening here? Thanks.

 

[#40Fan]

 

[Legionnaire]

Right. In virgin brass?

 

[ballisticdaddy]

It sounds like you are feeling the bullet passing either the neck to shoulder junction. If you seat the bullet so it does not pass the neck to shoulder area does it still feel the same? If this is an established load you just probably could not feel the resistance with a standard press and seating die.

 

[Legionnaire]

It's a new load to me, but a standard "book" load. I was actually loading a range of powder charges to find an accuracy node. I am tempted to load a few on my bench press to see if I can still feel the constriction. Just did a search on "donut" and that is indeed what I seem to be feeling--at the junction between the neck and shoulder. Just surprised to find it in new Lapua brass.

Neck tension seems fine on these rounds, as does the concentricity. These are hunting rather than target loads, so I am not seeking the ultimate in precision. I assume this is more of an annoyance than a significant problem?

 

[ballisticdaddy]

It's a new load to me, but a standard "book" load. I was actually loading a range of powder charges to find an accuracy node. I am tempted to load a few on my bench press to see if I can still feel the constriction. Just did a search on "donut" and that is indeed what I seem to be feeling--at the junction between the neck and shoulder. Just surprised to find it in new Lapua brass.

Neck tension seems fine on these rounds, as does the concentricity. These are hunting rather than target loads, so I am not seeking the ultimate in precision. I assume this is more of an annoyance than a significant problem?

On virgin brass the neck tension is usually all over the place even with Lapua brass. I use an expanding mandrel to ensure consistency prior to loading especially when using virgin brass.

 

[sdean]

Does your press have a washer pack? Mine does and if you have a lot of neck tension it gets squirrelly at the bottom.

 

[Legionnaire]

Does your press have a washer pack? Mine does and if you have a lot of neck tension it gets squirrelly at the bottom.

It does not. Starting out simply.

The expanding mandrel sounds like a good idea.

 

[#40Fan]

Did you FL size the cases with the expander ball still in the die?

 

[Legionnaire]

No. The virgin brass slipped into the chamber easily, so I didn't size it at all. Perhaps that was my mistake.

 

[earlcurtis67]

Compressed load?
140 RDFs and 42(?) gns. of 4831sc in new Peterson brass is compressed for mine,

 

[Legionnaire]

No. While a max load of 43.0 grains of IMR 4350 does fill part way up the shoulder, it's easy to vibrate it down to where there is no "crunch" when seating the bullet. And I experienced the constriction with lesser charges as well.

 

[earlcurtis67]

No. While a max load of 43.0 grains of IMR 4350 does fill part way up the shoulder, it's easy to vibrate it down to where there is no "crunch" when seating the bullet. And I experienced the constriction with lesser charges as well.

I also vibated the cases. And now that I think about it I used an expander mandrel first and then FL sized with Widden non bushing die. E

 

[Legionnaire]

Thanks, all. You've given me enough to plan my next reloading session. I'll prep the remaining virgin brass differently (size with a mandrel) and see what difference that makes. Not really sure it's a donut problem in the traditional sense; it may be a pressure ring formed by the bullet itself that "peaks" as it were when it hits the neck/shoulder juncture. In any event, it sounds like (1) this is not an unusual experience, (2) I should run the necks (at least) through a die in the future, and (3) I should not experience pressure problems with these rounds; of course, given varying neck tension, they may not be as accurate as they might have been had I prepped and uniformed the necks. Thanks for the feedback.

 

[joshb]

It's normal. Pushing the bullet thru the neck/ shoulder junction is always harder. The shoulder acts like a buttress.

 

[Legionnaire]

Makes sense; thanks.