- Jun 26, 2017
Neck turning isn't that big of a deal. Generally you are cutting thickness of 0.013. Now I use a tighten chamber in one of my rifles. I have turned necks for over 20 years now. I really haven't had any problem doing that. I want my necks to be the same thickness on all sides.You absolutely can do that. Turning necks is an expensive and time consuming process. I went down that road several years ago but have been trying to simplify my process lately.
Also, most SAAMI chambers are cut with 0.010 clearance between the brass neck and chamber wall. Most SAAMI brass diagrams show an 0.016-0.018 thick neck wall. You start turning necks down and you increase that clearance which also works the brass in the neck more.
Interesting! I'll keep that in mind. Infact I have placed that into my notes. I hadn't put much though into it. Another trick to make your rifle shoot a little tighter.Mike, this is the easiest thing to test. Many things can move the node, like a primer change. However a bushing does not seem to do that. You can simply take your best load and just change the bushing. If I want to find the correct bushing first, I load a mini ladder, 5 shots around the node with each bushing. Usually its pretty obvious. Im not saying you dont already have to best nt for your combo, but I have turned rifles I was about to pull the barrels into excellent shooters by changing nt. It can make a huge difference. You need to shoot this at distance. I have had rifles shoot well at mid range, but were un tunable at 1k until testing this at 1k.
Question?I can give all you guys a perfect example of how bullets are NOT pushed out of necks with neck tension (interference fit) but are released by neck expansion.
How many times have you seen a fired case with the case mouth expanded to fit the chamber (less spring back), but see that the case mouth is turned inward almost to bullet diameter with only the springback amount being left?
This is bullet release by expansion, it shows up perfectly that the rear of the neck expands towards the case mouth but the bullet has moved to a point where the expansion stops.
The ONLY thing that changes start pressure and hesitates bullet movement is a crimp. The ammo factories know this, use this with faster burning powders to get higher velocities without going to bulkier slower powders.
Ponder this, it makes sense even if you don’t have your own pressure testing equipment.
Of course uneven neck thickness will expand very slightly differently, but we are talking ten thousands of an inch, not one thousands of an inch.Question?
Is it expanding equally, or the neck that is thicker on one side takes just a bit more to move. creating an unequal release. Again back to the metal being unequal in thichness. Thinner metal is easier to move, than thicker metal. Or another way is less pressure to release on one side than the other. I realize it's not much, but different. People go to great lengths to have uniformity in there cases for there reloading process. Being case volume, powder, case length, primer pocket, and seating primers, bumping shoulders, annealling, flash hole work over, and neck tension. Blank bullet seators cut from your reamer to achieve a better alinement of your bullet. So why not even neck thickness.
Ever have a tires out of balance or out-of-round? Going down the road. Can't see it, but sure can feel it. That how I see it with necks being uneven.
If you don't want to cut your necks that's find by me. You can leave out other steps of the case workup too. I don't think you will get quite the harmonious outcome.
That part of reloading your own ammo. You can experiment or develop a better load for your rifle.
Interesting! I don't have much choice because I an using a tighten chamber. Thats what I wanted, and got.
Enough on to other things, like where the primers?
Very little.So, if increasing interference fit has no affect on bullet release/start pressure, what difference does reducing inside neck diameter have on accuracy?
Just wondering if you are a QL user. Reason I'm asking is QL gives a start pressure of 3626 psi. When you use a COL that touches the lands QL says to increase the start pressure by 7200 psi for a total of 10826 psi. Some users agree with this # and other users do not. Just wondering if you ever tested this with your pressure testing equiptment. What would be your take on this. TKSHaving pressure testing equipment has learnt me many things