neck size question.

Longshot

Longshot

CGN Ultra frequent flyer
Rating - 100%
55   0   0
Location
Complete Denial
Here's one for you fellas. I have a 6xc that shoots between .5 and .75 moa. I think it should do better with the 105 hybrids.
The reamer that was used says .273 neck. My fired cases come out at .272. The bushing I have been using is .268. I am shooting bn coated bullets. I'm wondering if I should move down to a .266 neck bushing an give it a little more tension or is this enough already? Inquiring minds want to know what your experiences are.
 
Neck clearance

If chamber reamer was .273", you should have at least .0015" clearance on each side. That would give you a neck of diameter of .270" with bullet seated to start with. That would be a safe place to start. It would be a mistake to neck turn all your brass before you see what the rifle likes. I have loaded and shot PPC ammo that was very close to zero clearance.
 
Longshot said:
I'm not turning necks at all. Should i be?
Click to expand...


yes, if the neck isnt consitant all the way around, when sized and when the bullet is seated the thinest part of the brass with be the part that will stretch out whil eht thick part stays more or less inplace, this leads to bullet run out issues, which can lead to inconsistant accuracy. while already haveing .004 neck tension on there alreay you have more then enough and i wouldnt be goin to a tighter bushing.

IIRC - turn your necks to unifor thickness, size, seat a bullet, messure the outside of the neck and subtract .002" and that should be the size of the bushing to use, unless you have a reason for wanting more neck tension then that
 
The only way to know for sure if you should neck-turn, is to neck-turn and see if there are any improvements.
I've never owned a tight-necked rifle, so when I turn, I'm really only looking to improve the uniformity of the brass. So I set-up the cutter to cut about 75% of the neck on 75% of the brass.
And I never turn new brass, only fired. Then fully prep the brass, and the last step (for me) is the neck turning. I select a random piece of brass, and set the cutter so it just touches the high points on the neck, taking a cut on about 1/4 of the circumference, leaving the other 3/4 untouched. Then I randomly select another piece of brass and turn it, to see how much of the neck it cuts and make any adjustments from there, always re-cutting the early cases if I decide to thin the neck more.
This means that you will sometimes over-cut some brass, I usually mark it and keep it separate, tho' you could choose not to, or toss it.
 
How does it feel when you're seating the bullet? Do they seat easy/hard, can you move
the bullet by hand after? Personally I would think you should be fine but you may want
to try one on either side of .268. What twist are you shooting? I agree that you should
have tighter groups but I think I'd look at bullet weight or seating depth before neck
tension.
 
Well I've tried 105 hybrids, 115 Dtacs, 115 vlds. I'm shooting a bartlein 5r in 1/7.8. Bullets seat just fine and I don't think I can move the bullets after however I've never really tried. I've gone from 38-40 grains of H4350 and it seems the node is around 39.5. I've gone all over seating depth as well and got it down to 1/2 minute but not consistantly. So I figure I've weeded out most of the usual causes so I'm wondering about neck tension as a possibility.
 
Even if you don't turn down the neck I made a habit of turning to uniform so there was no inconsistancy. To go from not turning to simply uniforming solved a big issue I had with flyers that ruin groups.

For the time it takes to try 20 with uniformed necks it may end up being worth it. FWIW
 
If your chamber was cut at .273 then your loaded ammo should measure .272, you may have to turn your necks down to achieve proper clearance, from there your going to want a .269 neck bushing, those are your baselines and from there you can play with more or less neck tension to see if it makes any noticable differance in group size and flier control, from my experience it never has so I stick with 2 thou under chamber size and 3 thou under loaded neck diameter.
You have to decide on whats working now or how many rounds are you going to experiment with wearing your poor barrel out looking for the holy grail of be all end all loads. For what its worth I have tamed the flier issues by changing powder either up or down one in the powder burn charts, in some rifles just the difference between N133 and N135 was night and day, I just swapped to N133 in a 223 and my accuracy node increased over a wider range of powder weight rather then just hitting it once with one particular weight of N135.
 
It appears you're doing pretty much everything that Tubb does but I see he does a
slight turn and .267 and .265 bushings. Have you tried any 4831 or 4831sc? I would
maybe try that if you had some. I see that Tubb jams his bullets pretty good when
shooting long range.
As far as neck turners go Sinclairs has them from around 60 bucks to 150. I use Sinclairs
deluxe which allows you to make a fine finish cut without changing the initial setting.
You really don't need the pricey one as you only need to cut a few thou off 60-70% of
the neck to make them uniform. The guys at Sinclair will tell you what you need.
 
I use the Forster one because I have their trimmer; but if I was starting from scratch, I think I'd use the Hornady, unit and probably get it from Higginson's.
 
Sorry to hijack the tread but is neck trimming even worth the effort with a factory cut chamber and how would you even determine the diameter?
 
KDX, worth it? maybe. I think if the rifle is capable of better than 1 MOA, then the chief benefit is uniformity, in that it will reduce the unexplained flyers.
Determining the neck diameter? You need to do a chamber cast. Which will actually tell you all sorts of interesting things about the chamber and throat.
 
Would it be safe to assume aftermarket barrels from quality manufactures should be SAAMI spec unless otherwise specified? Reason I'm asking is because I'm thinking of rebarreling my .223 with a Shilen barrel.
 
KDX said:
Would it be safe to assume aftermarket barrels from quality manufactures should be SAAMI spec unless otherwise specified? Reason I'm asking is because I'm thinking of rebarreling my .223 with a Shilen barrel.
Click to expand...

Yup. But they will be closer to proper SAAMI spec. Not like getting a factory barrel that was chambered by a reamer that had previously cut dozens of other chambers and is getting dull or whatever. If you catch my drift.
 
You must log in or register to reply here.
Back
Top Bottom