Re: C.O.L for 200 gr FTX
Posted: Sun Jan 17, 2016 11:05 pm
pitted bore wrote:...snip...
slugger-
I can see nothing obviously wrong with the bullet seating shown in your image. The length of cannelure exposed seems about right for a taper crimp to move some of the case mouth slightly into the cannelure for bullet retention. Perhaps Hoot has a different opinion. Let us know the results of your range session.
--Bob
Nothing to add. You should be good to go with your setup.
I will say this though it is indirectly related to your question. Cases shrink the first few times you shoot them. Seating dies are set to maintain the same COL from round to round, based upon a limiting how far down into the case the bullet inserts, not whether all the cannelures are seated the same with relation to longer and shorter cases. When I'm doing 5 shot powder charge increment runs, I match up as best as possible, my resized cases by length in groups of 5 so that at least within the respective charge group, the taper crimp engages their cannelures as similar as possible. You want the charge to be tested and not include the impact of the different crimp zones to be included. It's one of the "low hanging fruit" preparation techniques that you can call upon to reduce your velocity SD.
Prepping the inside of the case mouths to a depth that includes how far your bullets seat is another factor. IE When you seat your bullets, if you feel substantial difference in resistance to the bullet's insertion, that will ripple through in the resulting velocity produced. Fortunately, one of the more recent developments in case cleaning is the advent of wet pin tumbling. It can normalize the inside of the cases about as well as it is famous for doing the outside. Blammo ammo is one thing. Ammo for testing load workups is another. If you have a wet tumbling system, remember to deprime the cases before wet tumbling, not just to get the pockets clean, but to encourage the liquid to flow easily down inside the cases along with the pins. If you don't deprime, you can get air pockets trapped down in some cases and/or contaminated liquid carrying the displaced dirt that can not easily be replaced with less dirty liquid as they tumble. Simple technique tricks that stack the accuracy deck in your favor abound. To avoid dragging un-tumbled, dirty cases over the internal surface of your dies when you deprime, just run the stem out further so that the only contact is the depriming pin on the spent primer as it pushes it out. I resize after doing the wet tumble of deprimed brass, so that the crud normally on the outside of the uncleaned cases doesn't abrade the inner die walls over time. Yeah, it adds a step, but reloading isn't just a chore. It has Zen like rewards.
Maybe if I were 30 years younger, I could find more rewarding things to do with the time spent preparing my brass for reloading.
Hoot