Needing to turn necks after X amount of firings

[bsumoba]

I'm currently using no-turn 6.5x284 Lapua brass for a 284 Shehane. I have a .317 neck, and I am using bushing dies. I have about 10-12 firings on most/all the brass. Primer pockets are still good, although I suspect 3-4 firings more and they'll probably need to be retired.

I am starting to see a noticeable amount of "donut" on the shoulder/neck transition. It has slowly gotten more and more rounded in the shoulder/neck transition, but it wasn't a problem in the past, until about now as that donut is starting to migrate further up the neck. See picture below. The one on the left has a shoulder/transition that is rounded off and the one on the right is one that I just neck turned with a 35 degree shoulder cutter. I think with the round count getting high on the brass, that donut is getting more and more pronounced and now it is affecting my reloading because as I seat a bullet in, the bullet is pushing that material outward and it is affecting my bolt close.

Have anyone of you "non-neck turners" experienced this before and had to turn the necks down or are you retiring the brass well before then?

 

[dkhunt14]

I think mostly what you are seeing is the part the bushing die isn't sizing. If the bullets pressure ring is in front of that area, it shouldn't hurt you. That's also why I run an external mandrel in before seating the bullet. If it's there I want to push it outside. Matt

 

[chuckbuster243]

How far down thd neck do you size with your bushings? I am thinking the same thing as dkhunt14. I had the same thing happening on my 6.5-284 I brought my bushing up slightly and it went from fealing like I bottomed out on the floor to seating normally. Funny thing is on my non bushing dies I never have this issue. I may just have gotton lucky. My brass is in the 5-7 range and never got bad enough before the p pockets went south to have to break down and turn them. Matt

 

[Jason Boersma]

How's your accuracy with them? You could also try turning down into the shoulder a little farther also.
I have heard of guys modifying their die so the bushing goes farther down the neck to get rid of the problem also.

 

[Raythemanroe]

I turn so after so many firings or noticeable donut, I will just do a clean up turn..


Ray

 

[DHD]

Out of curiosity, did you just size with your bushing die before you turned into that shoulder, or did you use a F/L non bushing die?

 

[mysticplayer]

Brass flows with every firing... sharp shouldered cases will slow the migration a bit but it is going to move regardless.

Outside neck turn every firing or two and you will remove excess brass especially at the base....The turned neck looks great.

Standard shouldered cases like the 308 flow very fast... I remove material after every firing. Just a bit but it is there.

Keeps things consistent and no surprises... Annealing is a good idea too.

Jerry

 

[dkhunt14]

The thing with returning necks is you have to be really careful. I have seen more then one neck shot down a barrel on returned necks. It just plain down ruins a good barrel. Matt

 

[Changeling]

Why not just do it the way Matt said, push external mandrel in before you seat bullet. Simple, quick and effective.

 

[savagedasher]

The thing with returning necks is you have to be really careful. I have seen more then one neck shot down a barrel on returned necks. It just plain down ruins a good barrel. Matt

You nailed it . The donut is prone to have a fault line in it . Only takes one to ruen your day . Larry

 

[jnyfeler]

A mandrel pushing the donut out is no different than a seated bullet pushing the donut out; the donut remains a risk.

 

[BoydAllen]

There are several ways to deal with doughnuts after the fact. Turn necks on a lathe with a setup such that the mandrel turns with the case and is a press fit in the neck so that the entire doughnut is forced to the outside. Use a freebore lenght and bullet such that the shank of the bullet is not in the doughnut. Order a custom diameter reamer from Forster and ream them out. There may be one or two more but these should get you started. If you really wanted to deal with this from the beginning, at the risk of over working your brass, you could shorten a die so that you could push the shoulders of new cases back a considerable amount, turn to that new shoulder location (would not want to do this with a very thin neck); expand up to a larger caliber, and then neck down to precisely locate a false shoulder before fire forming. This would leave the brass at the top of the shoulder the same thickness as the neck.

 

[luckyshot52]

Have you been turning the cartridge lengths? The loaded non neck turned case looks like it has never been shortened. If so you could be forcing the neck area into causing the donut/ radius.

 

[dkhunt14]

It looks to me like your just turning brass off the shoulder, not off the neck. I don't see any shine on the neck where brass was removed. All cartridges have a small radius at the junction. It looks like you are turning it off. Matt

 

[bsumoba]

To answer a few people's questions...

I used a 7mm neck die without the button and sized the whole neck (including the region that is normally untouched with a bushing die), then I took my expanding mandrel and a lot of lube and sized the neck back up, moving all the "excess" material to the outside. I then proceeded to use my neck turner and turned them down to 0.014". I did cut into the shoulder a bit. Once thing I noticed when turning the necks is in the region where it is normally sized with the bushing, the cut was fairly light. As I went further down, I could see quite a bit of brass being cut. It wasn't huge where I got concerned, but it did tell me that there was a substantial amount of material in the donut region.

I am most likely beyond the "normal" life of this brass, having what I guess is 12+ firings on each of them (I am shooting a mild load, so primer pockets are still very good). The short answer is to probably retire the brass since neck turning them now would be a lot of work and in a few firings of each, will most likely need to be retired anyways.

My new lot of brass are all going to be neck turned going forward from the beginning and I cut into the shoulder a little bit more than the picture in the 1st post to ensure that as it grows, I am minimizing the donut.

The problem is that this donut was acting like a false shoulder in the chamber (because I am not sizing a portion of the bottom of neck due to a bushing die) so it required some force to close the bolt. I am jumping them 10K. My suspicion is that brass is all flowing back into the area that is untouched by the bushiing as I size down the brass from its fired diameter of .316 to 0.311. That brass has to go somewhere on the sizing portion of the stroke and I can only imagine it going down towards the donut region.

So, that being said...here are the results from the testing this AM at 100 yards.

Top two groups were all 5-shot groups, one is 10K out and one is 10K in, with 55.3 gr H4831SC and 180gr hybrids out of a 30" Brux barrel for the 284 Shehane. The 55.3 gr group was the one with all 5 brass turned, although this was the load I settled on from previous outings as being the best load so it might not be a fair comparison and the top right group for fun, shot a 5 shot group 10K in the lands to see if there was any change to the group size.

Now, the bottom 4 groups was a different barrel, 32" bartlein, same caliber, different gun. I shot a previous load work up all the way from 54.8-55.6, but saw some signs that I might be approaching a node beyond 55.6, so this week I loaded up 55.6, 55.9, 56.2, 56.5 and 56.8 gr of H4831SC, all 10K off the lands and 180gr hybrids. Sure enough, I was right and it looks like around 55.9-56.5, there seems to be a good node there. These were 3-shot groups. I will be going out tomorrow at 200 which is the farthest I have near me and see how this node does for 5-shot groups at 200. All bottom 4 groups were done with brass that require a little more effort to close the bolt, but not to the point where I was worried about it. Obviously, it doesn't look like it affected my groups all that much

Bottomline, here is what I got out of the feedback...I will proceed with caution on neckturning brass with a high round count and will most likely just retire the brass, I am considering actually getting a custom die with a neck honed to the exact dimension I want so it sizes all of the neck and not just a portion of the neck, neck turn the brass to begin with or start using something like the 284 Norma brass so I am not fighting donuts as much in the future, possibly switch to a two part process of finishing the necks with a mandrel to obtain more consistent neck tension, and most importantly.....sometimes we can do all this testing of theory and in the end, the shots on paper go against what you thought would happen prior to shooting it, just make us question more what the right answer is. LOL.

 

[bsumoba]

It looks to me like your just turning brass off the shoulder, not off the neck. I don't see any shine on the neck where brass was removed. All cartridges have a small radius at the junction. It looks like you are turning it off. Matt

The neck is fully turned. the lighting is only showing shine on the shoulder, but it did cut material off the whole neck and into the shoulder.

 

[savagedasher]

It looks to me like your just turning brass off the shoulder, not off the neck. I don't see any shine on the neck where brass was removed. All cartridges have a small radius at the junction. It looks like you are turning it off. Matt

Matt you were correct what you said first. I have reloaded brass 25 times but I don't use a bushing die. Larry

 

[savagedasher]

View attachment 974657 View attachment 974658

Top picture is a dasher ff + 2. With the plan to return once fully formed.

Bottom is an ancient dasher case, just for the sake of this thread. Notice the little "line" uncut in the lower portion.

From this experiment, I would be cautious of returning older brass. I don't like seeing that line myself.

Brass is gonna flow, especially initially, and on some cases more than others. Dasher for example goes through some serious changes early. But once formed fully, pretty much don't move. Unless you insist on annealing it all the darn time


Tom

I returned mine they went the trash pile just where I got them . Larry

 

[savagedasher]

That's to bad. What did you do wrong? I've always cleaned the dasher up once it's formed good.

Tom

Nothing they had been shot more then they need . Larry

 

[savagedasher]

That's to bad. What did you do wrong? I've always cleaned the dasher up once it's formed good.

Tom

I never do anything to my brass till after the seond fireing. Larry