Necking down .308 to .260 problem

Nov 14, 2012
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#1
I'm having issues necking down .308 brass to .260 in that it's really tough to close the bolt when I've put a piece of brass in the chamber.

Rifle: Remington 700, Remage barrel headspaced with PTG gauges
Reloading setup: Redding FL sizing die, Hornady Lock 'n Load Press
Brass: Lake City and Federal Match once fired brass
I've tried both the spray lube and the waxy stuff in the shoe polish-like can

The Hornady OAL gauge dummy brass chambers with no issue

I've run the die all the way up and down the die bushing but for whatever reason, I really have to muscle the bolt closed. I haven't charged a round yet as I don't want to be fighting the bolt on a live round.

Thoughts? Thanks for any advice you have.
 

BearNaked

Beer Saved The World
Feb 13, 2017
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#8
I use the same brass and you have to use a small base die then turn the necks. ive found that LC military brass necks range from about .013-.018" thick.

if you have doubts what is causing this, take a black permanent marker and color the top half of a case. then run it through the action and it will show you were its hitting with scratch marks. I would bet $100 its the case necks being too thick.
 
Likes: McCrazy
Nov 24, 2013
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Dallas
#9
Methinks that spife, itwillis, and BearNaked are on the right track.

When I first "made" .260 cases from .308 cases, I was pleasantly surprised how easy it was... one pass through the .260 resizing die, and TAHDAH!!! .260 cases were made. No longer would I have to buy expensive .260 cases, I was going to simply buy .308 cases and resize them and show 'em how it's done. It was glorious. It was beautiful. It was amazing. It was problematic as soon as I tried to chamber one in my rifle. Shit.

After a bit of measuring, I determined that sho' nuff, the OD of the neck was too thick, and I was left with a choice... either I could spend the cash on a neck turning setup (realizing that the cost of such would pay for a lot of .260 cases), or I could give up on my dream of being able to utilize .308 Win brass in my .260-chambered rifle. What to do, what to do...

I really like my 21st Century neck turning setup.
 
Likes: BearNaked
Feb 13, 2014
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#10
I've come to the same conclusion... I think I'm going to get the neck turner. I have a few thousand 308 cases that I can start with (still shoot 308, so I'll keep a half 308, and resize the others).

After I shot the necked down cases the first time, they seem to seat better now after fire-forming. Still a little tight, but not nearly as bad.
 

WyoWindCall

#youknowmorethanme
Feb 22, 2013
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#11
Well, I think that this has been figured out but here is my 2 cents. I used to convert 308 brass and yes, in fact, your necks are too thick, that solved it for me. But I will say that I have had better luck converting 243 brass ( still need to neck turn it for better concentricity), and now I just said screw it and I buy 260 starline brass. not as good as the Lapua but I don't cry as loud when I lose a piece in a match.
 
Likes: Badfinger
Feb 17, 2017
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#13
You can buy .243 cases and size up to 6.5. Case length is the same for .243, .260, and 7mm-08. Before neck turning, you need to run an expander mandrel through the case neck, and use a turning mandrel in the neck turning cutter. Otherwise, the necks will be too tight to turn on the neck turning mandrel. Once it's all set up (and it is a royal pain!), it's quick and easy; and once a case is neck turned, it won't ever need it again, most likely.
 
Apr 12, 2017
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#14
I neck down LC LR brass for my bolt 260, as well as gas 260. I found i had to bump the shoulder back a bit because of the little donut bump that’s formed from the resizing, and i was golden. I don’t fireform, just load and go. Bolt gun has ES/SD of 2/0 and gas gun gas ES/SD of 10/4.4. I never had to neck turn a single piece of brass, and I’ve fired over 5000 rounds Combined out of both guns. Zero issues
 

BearNaked

Beer Saved The World
Feb 13, 2017
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Texas
#15
I neck down LC LR brass for my bolt 260, as well as gas 260. I found i had to bump the shoulder back a bit because of the little donut bump that’s formed from the resizing, and i was golden. I don’t fireform, just load and go. Bolt gun has ES/SD of 2/0 and gas gun gas ES/SD of 10/4.4. I never had to neck turn a single piece of brass, and I’ve fired over 5000 rounds Combined out of both guns. Zero issues
i would love to see a 10 shot string over a chrono showing an ES of 2 with an SD of 0. I'm not saying its impossible, just highly unlikely.

curious to how many shots you chrono'd for this result.
 

Greg Langelius *

Resident Elder Fart
Aug 10, 2001
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Arizona, good place for me...
#17
I neck down Hornady 7mm-08 brass, but I only neck down the end half of the neck, leaving the aft half at the original diameter. The necked brass measures .987" and is .989 with the Hornady 143 ELD-X seated.

My barrel is a Lothar-Walther, ordered with a SAAMI chamber in the early 2000's. Fired cases measure a very consistent .998" at the rear, wider portion, and .991" at the mouth, and have a very narrow carbon ring just where the narrow portion transitions into the wider. I am running a bit hot, (43.5gr of H-4350) and the primers exhibit significant flattening, but till retain some roundness at the edge. No swipes or other alarming pressure signs are evident.

The logic behind only necking down the end is twofold. First, the wider portion of the neck may be centering the cartridge better in the chamber. Second, the neck portion is shorter, and may be providing lighter neck tension.

In any case, no issues have developed that I can notice offhand, and the technique is one that was passed down from my Elder Brother Bill. He learned it from BR shooters in the 1960's, when BR type dies were not yet available, and they were trying out different strategies to manage neck tension.

Since I single feed all my 260 cartridges, neck tension can be lighter, and I can get by with a basic 2-die F/L reloading die set using this strategy.

Greg
 
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shoot4fun

Gunny Sergeant
Oct 27, 2003
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#19
I tried reading all the posts so if I missed the suggestion I apologize.
Measure the neck OD at the mouth, the mid-point and just above the juncture of the neck/shoulder.
My theory is that your bushing die isn't sizing all the way down the neck and you have a bulge at the bottom of the neck.
If that is the issue my suggestion would be to use a Hornady Neck Die in 6.5 caliber to size the full neck down to the desired diameter.
Also, I found that I needed to neck turn just about .001 or .0015 to make everything smoother.
 
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