Stumped

[nvbroncrider]

Okay guys I'm stumped and totally confused. On my 6.5X55 I had made up some rounds last year to do some testing with some 125PT I have been using Nosler brass once fired neck sized some chamber nice and smooth others very stiff. All rounds were loaded shorter than the lands after an accuracy test nothing popped out. I fired the last that would chamber this week. So tonight I went through the whole lot of brass and tried chambering each piece of brass most wouldn't chamber and some would with quite a bit of force. Borderline beat the bolt shut. So I got out a new box of brass and chambered one smooth as silk. So I set up my FL die and adjusted it per the manual and tried it in the rifle no joy I continued cranking down on my die until it chambered like the factory new unfired brass. I had two unfired rounds left that wouldn't chamber they were COAL of 3.025" if I recall correctly which was the Nosler #7 recommended seating depth. So I pulled the bullets and powder figured I'd try to fire the primers they chambered and fired. So now I'm totally confused. Overall length of the brass is well under SAMMI max. I took a ton of measurements before sizing and there is only one thing I noted that raised flags as to why I couldn't chamber smoothly. At the shoulder SAMMI max diameter is .435" I consistently was measuring .440-.442" on the brass before sizing, each round that I could chamber a shiny ring was appearing at the body shoulder junction, factory new brass is .436". At the case head SAMMI is .480" factory and fired rounds were .477-.478" as was factory new. Now looking at the drawings this case as a fair amount of taper over the length of the cartridge .045" from the case head to the shoulder. My big question is why did the last two rounds that I pulled chamber without an issue but was shooting 3.100" fine on factory new brass but these at 3.025" wouldn't chamber with a bullet but chambered fine with no bullet? I'm totally confused and have my ears open looking for answers or suggestions.

 

[Guy Miner]

I'm having some trouble following everything you typed, but:

Full length re-size all your brass. Size the heck out of it, all the way down to the base. See if that helps.

I think that's likely the problem, not the overall length.

Dunno.

 

[nvbroncrider]

That's what I did Guy. The part that troubles me is I did all that and the two loaded rounds that wouldn't chamber after I pulled the bullets they chambered fine and they were both way short of the lands I'm just asking why.

 

[RiverRider]

That's all a bit difficult to follow, Jake...but as I read it you're saying that two loaded rounds would not chamber but then after you pulled the bullets, then those cases would chamber. Based on that understanding I have to wonder if the case shoulders are work hardened. If that guess is correct then maybe annealing will fix it.

 

[SJB358]

Jake, it is a little hard to track your post, but are you sure you were short of the lands?

I would fire the same piece of brass a few times. Don't mess with the rest of them. Just load and shoot the same case a few times. Get your resizing down with that case. Make sure the bullet is far away from the lands.

Fire it, try and put it back in the chamber, if it is tight, bump the shoulder .002 try to rechamber, you may feel a little something turning into final lockup. A little is okay, alot means you need more.

I'd work with the same piece of brass till you get it worked out perfectly. That way your working with the same piece each time.

 

[ElmerThud]

It sounds to me like there are a couple of possibilities here worth investigating.

1. The case shoulder hasn't been bumped back quite far enough in F/L resizing (assuming the die set per manufacturers instructions)
If you take a round that has chambered smoothly and then been fired in your rifle and measure the case shoulder at midway shoulder (or just use a Hornady Headspace guage) and set your resizing die to ensure the resized cases at that measurement, the problem should be resolved.

My own Sauer 202 SE has a headspace dimension of 1.770" and that's what I resize to. The dia. attached shows SM 6.5x55 a SAAMI dimension of 1.779", but clearly different manufacturers have other more custom chamberings.

2. It's possible the shell holder thickness at the rim may have interfered with the resizing of the case base (at the web) try using a different manufacturers shell holder in your press.

Having a fired and resized empty case chamber in your breech is a good test and what SJB says is most certainly worth doing. It'll give you a good indication of whether your brass is resized correctly or not before you go to the trouble of loading the rounds. ATB

 

[Partisan]

What are the neck OD measurements with/without bullets? Especially at the shoulder neck junction.

 

[JD338]

Jake,

A few thoughts....
Is the shoulder bumped?
Is the shoulder bulged from over sizing?
Do the cases need to be trimmed?

JD338

 

[OU812]

That's what I did Guy. The part that troubles me is I did all that and the two loaded rounds that wouldn't chamber after I pulled the bullets they chambered fine and they were both way short of the lands I'm just asking why.

Wonder if the necks on those pieces of brass are a little thick for so reason? If you have not done so I would measure the outside necks of the brass in question wo a bullet then seat a bullet and re measure. Do the same to a known good case that chambers fine with a bullet and compare the cases.

Bill

 

[IdahoCTD]

Most of the Nosler brass I've used has had really thick necks. There is a good possibility that the case necks are too thick with the bullets seated.

 

[nvbroncrider]

Guys thanks for your responses.

RiverRider,

I don't think this is the case as I bought the brass new. Loaded fired neck sized and about 30 rounds have been fired twice.

Bill, Partisan and Nathan,

I have not looked into that but that is a possibility I've not yet run down.

Elmer, Guy, and Scotty,

After I had these initial issues I've taken my F/L die and kept cranking it down until the brass will chamber like a new factory piece which I have some more of.

Jim,

All had been neck sized. No shoulder bulge and all cases are well under SAMMI length in fact all are under Hornady recommended trim length. The diameter of the shoulder though appears to be .001-.007" larger than SAMMI spec as close as I can tell by measuring. New cases are also larger measuring at .436" versus SAMMI .435"


The two things that came to mind for be is expansion at the shoulder since this case has quite a bit of taper. Or as you gentleman have suggested case necks being too thick.

Does anyone here have a bolt action rifle that they can't just neck size?

 

[257 Ackley]

I would get a bump gauge to make sure you are setting the shoulder back. You may have a chamber that is slightly out of spec that will not allow you to only neck size. As others have said, if the bolt will close on the case without the bullet, it may be a tight throat that will require you to turn the necks after a couple firings. Do a chamber cast so you have the exact dimensions to use as reference points.

 

[nvbroncrider]

Thanks Joel. I measured a couple necks tonight .292 and .293 loaded so I guess I'll have to fire a few to get some more data. Book spec is .297

 

[RiverRider]

Jake, you mentioned a bright ring showing up after trying to chamber a loaded round and I understood this to be at the shoulder/body junction. Is that correct?

 

[Elkman]

Does anyone here have a bolt action rifle that they can't just neck size?

With of the ones I shoot frequently (3) I neck size only, until they need set back. I think you are on the right track Jake.

 

[nvbroncrider]

Jake, you mentioned a bright ring showing up after trying to chamber a loaded round and I understood this to be at the shoulder/body junction. Is that correct?

Yes I did and those rings would appear on fired cases after I tried to rechamber in the rifle. and according to my caliper it measured from .438"-.444" book and SAMMI claim .435" my new brass that has no problems chambering measured .436" I did FL size everything until it chambered nice and easy. I've just never experienced this and want to know why.

 

[baltz526]

I have a Match sizing Die in another case, that causes the same problem with some brass. I came to the conclusion that the brass was springing back too much. When I sized the same brass in a standard RCBS die it chambered fine. But a percentage of the brass in the match die would just not size down enough to over come the spring back. Tried 3 different case holders with no success. If I did not have the RCBS die, my next step would have been to machine the shell holder. Some batches of brass are just junk, no matter who's brand is stamped on the base.