Neck turning for a Factory chamber?

warrenb

warrenb

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I have 100 308 Lapua that has been once fired in my savage. I'm wondering if its worth neck turning. With the loose tolerances of a factory barrel is it pointless or even detrimental to accuracy?

BTW, After sizing with the lee collet die the runout is easy under 2 thou.

I have only neck turned for my 223 shilen barrel and even then I only cleaned up 30 percent of the necks. So not much personal experience to go on. :(

thanks.
 
Runout is not the reason you turn the necks. You turn the necks to uniform the thickness of the case neck. A round that is fired in a good rifle should show almost no runout regardless of the neck uniformity. If you find that your loaded rounds are no longer concentric, then during the loading process, it is good to check the runout after each stage to determine when the concentricity is lost, but all is for naught if your necks are not of a uniform thickness from the outset. If you can hold .002" for your loaded rounds, that is as good as you can hope for.
 
Neck turning

The biggest benefit of turning case necks for accuracy is that it tends to make the necks a uniform thickness. This allows for an even pressure on the bullet when it is seated into the cartridge, and a more even release of the bullet when fired.

Some manufacturers have generous specifications when it comes to brass thickness. I believe that Lapua holds theirs to closer tolerances.

You are already neck sizing using the Lee Collet dies. You might try about 10 cases or so with neck sizing, and run a bit of a test to see if it makes an appreciable difference in your targets. A two thousands of an inch runout is very good.

Another criteria is what level of accuracy do you expect. What distances are you shooting at, and what type of target (paper or game)? For really long distance targets it might help, but for Minute-of-Moose, then it is doubtful that an inch or so on the Moose will affect the outcome. In other words, for Hunting under 300 yards or so, you probably have enough accuracy now, but 600 to 1000 yard targets is another matter, and experimentation is something that can improve accuracy (or make it get worse.)
 
Thanks for the responses guys. Much appreciated. :)

Just to clarify.

The biggest benefit of turning case necks for accuracy is that it tends to make the necks a uniform thickness. This allows for an even pressure on the bullet when it is seated into the cartridge, and a more even release of the bullet when fired.
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I understand that, sorry I did not mean to emphasise runout in the question. However I did presume that neck turning would help with runout to some degree?

Some manufacturers have generous specifications when it comes to brass thickness. I believe that Lapua holds theirs to closer tolerances. A two thousands of an inch runout is very good.
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Thats good to know. I have another savage in 308, same dies and same press which gives me pretty much similar runout with winchester brass.

Another criteria is what level of accuracy do you expect. What distances are you shooting at, and what type of target (paper or game)?
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To be honest I am just trying to become as accurate as I can. No competition, just me shooting paper. So far to a max of 300 yards.

Sometimes I am quite dissapointed with my ability. Theres days when I can shoot 5 in the high .3s @ 100 and many times I'm in the .7s, .8, .9s, I'l stop there. :D.

I'm enjoying trying but the main point of my asking questions is to find some real advantages in the search for smaller groups. And So far I am the weakest link. :D

Thanks again guys.
 
Don't turn your necks.

Factory chambers have a SAAMI clearance of 5 thou in the neck. Turning will only increase that. It makes it more difficult to center the bullet with that much neck slop, and it works your brass far more.
 
In a match chamber, shooting most match bullets such as VLD's, The bullet tip sits in the lands. If you have little or no run out, and using fire-formed brass the case necks shouldn't be touching the chamber wall at all. If you are using non-jammed bullets, you want as little case clearance as possible to keep the bullet lined up with the bore. You also want the case to be uniform to ensure it sits true to the bore.

In a sloppy factory chamber, with a bullet not sitting in the lands, and with non fire-formed brass, the entire case sits on the bottom of the chamber, and the bullet will never point at the rifling with the same precise angle. Filling up as much space as possible with brass is a good thing. The bullet is long gone, before the effects of an irregular neck wall affect the tail end of the bullet.
 
I touch up the necks for all the rifles I shoot. The reason is to maintain concentricity during the sizing process. So little brass is removed, it would have little affect during the firing process.

I really doubt skim turning Lapua brass in a Savage is going to change anything on paper. As long as the ammo runout is around 2 thou, spend the time on tweaking the powder charge.

WAY more impact on accuracy.

Now if more runout is created, then check each step to identify where the runout is created. If in the seating process, better seaters like Forster or Redding will certainly help. Also, looking at neck turning can pay dividends.

Bedding is the most important thing to do with a factory rifle. The loading and proper powder tuning. Beyond that, its a crap shoot on what the barrel will do. If you can get 1/2 min average with any factory rifle, you are doing well.

Jerry
 
A bit of a hijack:

I'm waiting on a drop-in Shilen select match 223 barrel (20", 1 in 8) from mysticplayer for my Savage sporter. As it is, I can get the factory barrel to shoot 1 MOA. With the Shilen I'm hoping for 0.5 MOA, and I would be ecstatic with 0.3 MOA out to 300 yd. I shoot with Win and Lapua brass, and I want to make mag length 69 gr SMK loads. I have the Forster neck turner (with necessary accessories like a sinclair expander die) designed to be used with the Forster trimmer base, but I haven't set it up yet.

My question is this: How tight are the Shilen chambers, and would I appreciably benefit from turning the Lapua or especially the Win brass? From what I'm reading in this thread it seems like it would be worthwhile, but I'm hesitant because it's extra work. :redface:
 
Bughole accuracy is a culmination of many very small steps. Each on their own will not amount to a hill of beans but together, they can sure put a big smile on your face.

The Shilen will have a SAMMI spec chamber but the length is on a min side of spec. It shoots superbly as my rifles show. Personally, I would ditch the 69's and go straight to the 80's either Berger or Amax.

With the Savage factory center feed mag, there is no issue loading to mag length with the 80's over Varget, CCI 450, Win or Lapua brass and making them fly well. That is the setup I use on my 223 Tactical Savage and it rocks.

I would consider skim turning the necks for best performance AND I would suggest turning each time you need to trim. Brass flows in a 223 at elevated pressures and maintaining this can only help with small groups.

Annealing is also a great idea.

Best investment you can make is a quality digi scale with an error range UNDER 0.1gr. In a 223, 0.1gr is enough to be off tune.

Small things matter...

Jerry
 
agent_mango said:
How tight are the Shilen chambers
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Once you have the gun you can estimate it by carefully measuring the neck OD of a fired round then adding about .002" to accomodate springback. That's your chamber at the neck. If you want to be really sure, you can do a chamber cast with Cerrosafe ( http://www.brownells.com/.aspx/pid=384/Product/CERROSAFE_reg__CHAMBER_CASTING_ALLOY )
 
The use of minimum spec match chambers, minimum clearance necks and good fire-formed brass minimizes the amount of brass flow. These are the types of chambers where neck turning helps most, as it faclitates keeping the bullet centered in the bore BEFORE firing. Your bullet does not touch the neck at the moment of detonataion. If you can drop a bullet inside a fired case and it falls through without binding, turing necks makes no big difference.

I would personally not emphasize the need to neck turn with a SAAMI spec. neck or chamber. Use exceptional quality lapua brass and you won't need to do it. If you use cheap bulk brass, you need to pay more attention to making things consistent.

With your set-up, keep it simple and have fun.
 
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