Neck turning for SAMMI spec chamber?

[johnnyi]

Is there a measurable gained value in neck turning match quality brass, like Lapua, for a sammi spec chamber?

 

[CatShooter]

Is there a measurable gained value in neck turning match quality brass, like Lapua, for a sammi spec chamber?

No... you gain nothing, and will loose some neck thickness.

 

[brxbrad]

The way I understand it is neck tension is neck tension reguardless. Neck turning results in even tension for consistant release.

 

[CatShooter]

The way I understand it is neck tension is neck tension reguardless. Neck turning results in even tension for consistant release.

There are many times that efforts like turning are a total waste, and a factory chamber is one of them... he said "Is there a measurable gained value ", not theoretical.

If you skim 1/2 a thou off of one side of a Lapua case neck - you will NOT see a "a measurable gained value".

 

[fdshuster]

I agree. I'm using Lapua 308 brass right out of the box for my 1000 yard rifle, factory chamber & have never outside neck turned the Lapua brass. I find a maximum variation in case neck wall thickness, measured with my tubing mic., of .001", the majority being less.

Outside neck turn them & you will be working the brass even more than it gets with the usual sloppy factory chamber. Less neck wall thickness means the case necks expand more during firing to fill the chamber neck, so a more likely chance of getting case neck splits sooner than if the necks were not turned. Of course, if you are willing to get involved in annealing your brass, then it would be a moot point.

Not something I enjoy doing, so am happy to limit it to where it is really needed.

I save the neck turning for my tight, fitted necks that I have on my 6ppc's & 6BR's.

 

[amlevin]

If you absolutely feel the need to turn, only do so enough to "knock off the bumps".

If you're using premium brass it may be a waste of time. For lesser quality brass it might well make a difference, having uniform neck thicknesses from case to case. One of my "mentors" who can shoot the testicles off a gnat at 300 yards ??? tells me to limit neck turning to only one side of the case neck. Just go deep enough to get a cut 180 to 270 degrees around the case.

Lastly, the term "Factory Chamber" doesn't really describe all rifles well. Some chambers can be tighter than others, depending on whether they were cut with a new reamer or a worn one. All can be within the SAMMI specs. Most "No Turn Match Reamers" just tend to be at the low end of the tolerance.

 

[artbosco]

Is there a measurable gained value in neck turning match quality brass, like Lapua, for a sammi spec chamber?

No! Lapua brass is the most consistent brass on the market. Turning for a SAMMI chamber would be counterproductive. Use your time more wisely.

 

[CatShooter]

I agree. I'm using Lapua 308 brass right out of the box for my 1000 yard rifle, factory chamber & have never outside neck turned the Lapua brass. I find a maximum variation in case neck wall thickness, measured with my tubing mic., of .001", the majority being less.

Outside neck turn them & you will be working the brass even more than it gets with the usual sloppy factory chamber. Less neck wall thickness means the case necks expand more during firing to fill the chamber neck, so a more likely chance of getting case neck splits sooner than if the necks were not turned. Of course, if you are willing to get involved in annealing your brass, then it would be a moot point.

Not something I enjoy doing, so am happy to limit it to where it is really needed.

I save the neck turning for my tight, fitted necks that I have on my 6ppc's & 6BR's.

Very well said...

 

[johnnyi]

Thanks guys! I will look else where to fill the need to make tiny brass shavings! ;D

 

[Jeff Von Rosenberg]

Johnny I'm no expert like Catshooter and some others but sometimes that" measure able gain" although theoretical may be realized in your confidence. If you feel more confident that your neck pressure is more consistent, then that might overshadow other variables. That said other than my AR's I have no SAAMI chambers so I am left turning necks for 8 guns! I guess it is a "labor of love" JVON

 

[jlow]

The answer is it depends. If you are shooting close range i.e. below 300 yards, probably not. If you are shooting longer distance i.e. 600 yards or greater, it is IMHO useful.

Part of the problem here is as brxbrad already said, neck tension consistency. LaPua brass can have as little as 1 thousands difference in neck thickness. Sounds very little but keep in mind that the neck of LaPua brass is only around 14 thousands. So if it is 14 on one side and 15 on the other, the difference can be as much as 7% difference. In my book (of reloading), that is quite a bit if it is going to affect your neck tension consistency, which can translate to MV differences, which in turn can translate to vertical stringing at 600 + yards.