.260 neck bushing, help please

[Mikecr]

OK, we were all taking the context of your issue as being about neck tension resulting from various bushings. That is, too little.
This is likely unrelated to your ACTUAL problems, and so far a waste of discussion.

 

[Limbic]

OK, we were all taking the context of your issue as being about neck tension resulting from various bushings. That is, too little.
This is likely unrelated to your ACTUAL problems, and so far a waste of discussion.

agreed

4-5" at 500 yards is one thing. If you are getting that at 100-200 yards then you have other problems. Scope reticle or scope is bad, actions screws are loose, ect. Your problems are much larger than neck tension.

 

[Milligan]

Ok, a bit more context is probably required here. I am appreciating the input so please stay with me on this long post.

Setup is a Sako 75 action in a mcmillan stock with a 23" 1:8 twist border barrel (UK make). Scope is a Zeiss Duralyt 3-12x50 sat in 1 piece Sako optilocks. It also has an Atec Cmm4 Aluminum moderator (suppressor) on the end of it.

Everything has been tightened up, checked, rechecked etc.

I live in the south of England, so ranges are unlikely to be above 200yds on live game. Bullets have to be soft point or ballistic tip (expanding) and reach certain velocity/energy levels to be legal - so no Scenars or SMK's for hunting.

I have both Nosler and Lapua brass, both headstamped .260 so nothing's been stepped up or down.

The powder I've been using is Viht N160 - on the advice of the smith who built the rifle. Primers are CCI large rifle.

Dies are a redding seater, type S neck sizer and a Hornady FL sizer.
Powder is thrown with a Hornady Auto thrower.

I started with a standard Redding die and the Nosler brass.
The nosler brass loaded with a 123gr Scenar gives an OD .288".
The std Redding neck sizer only sizes to .288"

Outcome here was that accuracy was erratic, particularly using the magazine.

Lapua brass then made an entry so I bought some; the first loading from new produced very accurate results, 1/4 moa at 100yds. At roughly the same time I got a bushing sizer.

Still with the Lapua brass, on second firing of the brass I used the .291 without the button or the .292 with the button. The former producing reasonable results with 140gr Gamekings. The latter, again, very erratic.

So, my next outing - which I am hoping will be tomorrow - I am intending to try some FL sized lapua brass through the Hornady which gives .292 and some neck sized through the .291. All other variables held constant.

Part of the issue is that range time here is neither convenient or cheap and with all the regulations, you have to buy expanding bullets, powders and primers over the counter, and produce your licence - PITA.

 

[Limbic]

I found my .260 Lapua brass to be a bit thick walled. I had kept the same .001-.002 neck tension but used a larger bushing. .293 maybe. Make sure you measure your loaded rounds so as not to use too much neck tension. I don't use any expander balls/buttons just bushings. I FL, bump shoulder, and neck size every time.

I don't know much about your powder thrower but make sure it is accurate and precise.

Your powder should be ok. I've use H4831SC with good all be it slow results.

Is the gun bedded?

 

[Milligan]

No, gun isn't bedded. I believe the 75's are difficult to bed, something to do with the lug's proximity to the stock screw.???

I have measured the OD of the loaded round. Will give it a try when I'm able and see how I go.

Thanks for all the input, genuinely useful to have a knowledgeable sounding board!