Ive just started reloading and for my first handloads i was full length sizing and i was getting some very good results. After reading some threads on here and other sites about neck sizing and how they are usually more accurate, i figured i would give it a try. So i used my lee neck sizing die and made some rounds that i got good results with using my full length sizer. Using the same amount of powder along with some differnt amounts of powder for a few other rounds. And off to the range i went! It was a disaster!! none of them would group worth ####! I was getting half inch groups before and now im.getting almost two inch groups with the neck sizing loads. I went through 6 different loads with 5shots for each one and the results were all pretty close to the same. Any ideas on whats going on? Im thinking im not setting the die up right but i followed to directions and read it over lots.
fl sizing to neck sizing?
- Thread starter notyalc
- Start date
Contrary to what a lot of people think neck-sizing does not increase accuracy unless concentricity of the entire case/neck/bullet assembly can be maintained.
Often when neck-sizing the neck can be "bent" out of line with the case body resulting in excessive run-out after the bullet is seated. The case body is un-supported and is free to move out of alignment with the neck.
Full-length sizing , or better yet partial full-length sizing, maintains the correct alignment of the case body/neck as both the case and neck are supported during the re-sizing operation.
Take your neck sized cartridges and check them for run-out (bullet "wobble") and then compare them to your full-sized rounds and see if this is the problem in your case.
Often when neck-sizing the neck can be "bent" out of line with the case body resulting in excessive run-out after the bullet is seated. The case body is un-supported and is free to move out of alignment with the neck.
Full-length sizing , or better yet partial full-length sizing, maintains the correct alignment of the case body/neck as both the case and neck are supported during the re-sizing operation.
Take your neck sized cartridges and check them for run-out (bullet "wobble") and then compare them to your full-sized rounds and see if this is the problem in your case.
A lot of variables there Clayton. Try loading a few with neck sizing and a few with full length sizing and everything else the same...same bullet..same powder and charge ..same primer. Then take them to the range and do one group with the neck sized and then one group with full length ..try to have the same hold..same wind etc. If you still get significant variation in the groups then you should look at the die.
Just backing out a normal die to partial size may or may not give the results. Check out
Wilson dies and an arbor press. This is what they were designed for. At some stage you
will still have you use your full length dies to bump the shoulder.
Wilson dies and an arbor press. This is what they were designed for. At some stage you
will still have you use your full length dies to bump the shoulder.
Seriously... if you are honestly getting half-inch groups with FL sizing, why would you change anything? What could you reasonably hope to achieve?
What kind of rifle and bullets are you using? If your rifle is anything short of a competitive target rifle (or something similar), you may have already reached the maximum accuracy potential of this rifle, especially if you are using non-match-type bullets.
In any event, most tactical and competitive rifles don't shoot better than half-minute consistently, even with careful handloads and experienced shooters pulling the trigger. So maybe just stick with your loads that shoot half inch groups and leave it at that.
Regarding the Lee Collet neck sizing die: They are absolutely great, but they have one issue that I've needed to address in every single one I worked with. In all cases, I've found that the mandrel is a tiny bit too fat, so your necks don't get sized down tightly enough. (I've even been able to rotate a seated bullet with my fingers when using loads made with these dies, as they came from the factory.) Necks that are too loose can do bad things for accuracy.
The solution is very, very simple and should take between 20-30 minutes of dedicated work. Unscrew the die and take the mandrel out. Then chuck it into an electric drill (from the small end). Now spin it in the drill and use 80 or 100-grit sandpaper to start grinding it down. (Before doing this, measure the diameter of the mandrel.) Make sure to grind all of it evenly because you need it to be basically the same diameter for all the length that the case neck slides over it, on the up stroke and on the down stroke of the press.
When you see that you've reduced the diameter by .001" (at least), then start using 220-grit sandpaper, then gradually move to 400 and 600 grit. You should be left with a perfectly polished mandrel that is smaller in diameter than it was. Now when you use it, the case neck will be sized tighter.
Start conservatively. If necks are still too loose, then grind more down by repeating the above steps.
When using the die after this, I like to size the case once, then bring the ram down and rotate the case in the shell holder 180 degrees, then size it again. This tends to even out any chance that something might have been sized on an angle, and it also tightens the neck even further. FYI, as a rule, I always keep a bullet on the table when sizing with this die, and I put it against the mouth of every sized case, as a final step to make sure that all necks are sized equally tight. If the neck is too loose, I size it again. I find that these dies need to be set up just right, and sometimes the exact amount of force you use when moving the ram up can make a difference.
The solution is very, very simple and should take between 20-30 minutes of dedicated work. Unscrew the die and take the mandrel out. Then chuck it into an electric drill (from the small end). Now spin it in the drill and use 80 or 100-grit sandpaper to start grinding it down. (Before doing this, measure the diameter of the mandrel.) Make sure to grind all of it evenly because you need it to be basically the same diameter for all the length that the case neck slides over it, on the up stroke and on the down stroke of the press.
When you see that you've reduced the diameter by .001" (at least), then start using 220-grit sandpaper, then gradually move to 400 and 600 grit. You should be left with a perfectly polished mandrel that is smaller in diameter than it was. Now when you use it, the case neck will be sized tighter.
Start conservatively. If necks are still too loose, then grind more down by repeating the above steps.
When using the die after this, I like to size the case once, then bring the ram down and rotate the case in the shell holder 180 degrees, then size it again. This tends to even out any chance that something might have been sized on an angle, and it also tightens the neck even further. FYI, as a rule, I always keep a bullet on the table when sizing with this die, and I put it against the mouth of every sized case, as a final step to make sure that all necks are sized equally tight. If the neck is too loose, I size it again. I find that these dies need to be set up just right, and sometimes the exact amount of force you use when moving the ram up can make a difference.
