Full Length or Neck Only; What's Best Resizing for Accuracy?

I don't know how you come to that conclusion, all full length sizing dies come with instructions on how to set them up for neck sizing!
Forster and RCBS dies don't.

Whose do? I'll get instructions from their website to verify.
 
Last edited:

Attachments

  • image.jpg
    image.jpg
    1.6 MB · Views: 46
  • image.jpg
    image.jpg
    1.7 MB · Views: 52
RCBS DOES.
Nothing about neck only resizing is mentioned in those old instructions. Newer instructions state both die types are locked in the press so the shellholder is pressed against the die bottom.

PhotoPictureResizer_200121_211826298_crop_619x596.jpg
 
Last edited:
Sierra Bullets did a lot of testing in the 1950's with different fired bottle neck cases to see what resizing method produced best accuracy. They soon learned that the better centered case necks were on case shoulders, accuracy improved. They knew the case shoulder was hard pressed and centered in the chamber shoulder when fired. Often the case shoulder was set back a thousandth or two from firing pin impact before the round fired. Didn't matter if the case body diameters were reduced a couple thousandths because they didn't touch the chamber except at their pressure ring about a tenth inch in front of the case extractor groove.

Measuring case neck runout on cases neck relative to case shoulder, smallest runout happened when fired cases were resized in dies whose shoulder centered in the die shoulder making the neck well centered on the case shoulder. Didn't matter how much the case body diameters were reduced.

Ferris Pindell (PPC cartridge family co-founder) was a tool and die machinist at Sierra who championed this idea. It was soon part of the trend in benchrest disciplines moving away from neck only to full length resized cases.

Was most interesting that good quality new rimless bottleneck cartridge cases often had necks well centered on their shoulders and were more accurate than neck only resizing routines. All new cases are full length sized.
They have to be FL resized to allow for the different sized chambers (different guns ), now a fireformed case, is already custom fitted to the chamber it was formed into. That being said it no longer takes energy away from propelling the bullet as long as it isn't FL resized. And if the chamber and bore are true, everything should be centered when they are reloaded and chambered. I have loaded them, and shot both Necked only and FL for groups, and I got better groups and higher velocities when I neck sized only the way I was shown in the 70's ! All I can say is try both ways as I did, and use the method you get the results you want from, I only do this for my bench gun, my shoulder gun I FL resize the brass, but it doesn't come close to being as accurate as the heavier barreled bench gun, but great for the woods hunt. All guns are different and some like different things. You all be careful and don't fall off the end of the earth ! :eek: :rolleyes:
 
Sierra had only one test barrel for each cartridge used.

Surely proper full length sizing must be best because of its popularity in competition. The largest groups fired are smaller from full length resized cases.

If the smallest groups fired are the criteria, those happen once in a while with any resizing method.
 
Last edited:
One if the reasons competition guys and hunters should fl size is to avoid potential chambering issues. Not good if your in the middle of a string of fire and your gun won't chamber a round or gets stuck. For a hunter dealing with all the environmental issues in the field same thing. What the target guys have discovered is that proper fls does not hinder accuracy and actually makes your brass more consistent because at some point you have to fls. Also, if you watched the video above you can see where one of the shooters tested velocity, pressure and saw a correlation between sticky bolt closing and pressure increase which means your velocity is changing. Not good for a long range load.
 
One thing to consider is what's the best way to compare die types. Smallest groups fired or largest groups?

One die type produces ammo shooting five 1 to 2 MOA groups.

The other type produces ammo shooting five 1/2 to 3 MOA groups.

Which one's more accurate considering the statistical implications?

Won't any die type produce ammo that shoots groups between zero and some size?
 
Last edited:
One if the reasons competition guys and hunters should fl size is to avoid potential chambering issues. Not good if your in the middle of a string of fire and your gun won't chamber a round or gets stuck. For a hunter dealing with all the environmental issues in the field same thing. What the target guys have discovered is that proper fls does not hinder accuracy and actually makes your brass more consistent because at some point you have to fls. Also, if you watched the video above you can see where one of the shooters tested velocity, pressure and saw a correlation between sticky bolt closing and pressure increase which means your velocity is changing. Not good for a long range load.
That was what many of the 1000 shooters were after, more pressure to gain more speed, some of their loads were so hot they got very few reloads out of their brass, they wanted less wasted pressure, expanding the brass to conform to the chamber, they wanted it pushing the bullet! I never saw an issue at the 1000 yard range from rounds not chambering or getting stuck, that could probably happen if the guns were holding multiple rounds, but the guns then were single shots, just lay the shell in and close the bolt, and seat the bullet at the same time, every round is seated exactly the same ! Many of the guns magazines were filled with lead for added weight. I am talking strictly bench rest rifles. Perhaps they do it different today, but I am satisfied with the results and loads I have achieved, and I have no need or desire to change a thing. This debate comes around all the time, and it's the same as vehicles, some like any vehicle that operates and gets then to where they are going and never has issues, others like to have all the gadgets and latest features, and others like speed ! Guns and scopes and loads and ways of loading also are a persons choice, and solely theirs, and they should try different ways perhaps, but if they find a method they like and it works for them then by all means I'm not going to tell them to change the way they are doing it, and I will leave it at that !
 
I don't think Sierra ever mixed bullet lots. Arsenals did, even with 30 caliber 173 grain FMJBT match bullets.

Lapua did years ago evidenced by 3 or 4 different die prints on their rebated base match bullets and 3 or 4 distinctly different ogive and heel shapes visible in 50X optical comparitors

Sierra had different machines/dies and different operators all running down the line into one box. they had as much as .018 variance in one 100 rd box. I sent several back to sierra techs. Rich M. was a 1k shooter and Sierra tech and was key in getting the one operator/machine into one lot.
 
Last edited:
Let's go at this logically: 1)You buy factory ammo. 2)You fire it through your weapon fire forming the brass to the chamber of your rifle and creating brass that is CUSTOM FIT TO YOUR WEAPON. 3)The only problem is the neck opening won't hold the bullet properly. Why would anyone change brass that was custom made for their weapon and bother to reload in the first place?!
 
Let's go at this logically: 1)You buy factory ammo. 2)You fire it through your weapon fire forming the brass to the chamber of your rifle and creating brass that is CUSTOM FIT TO YOUR WEAPON. 3)The only problem is the neck opening won't hold the bullet properly. Why would anyone change brass that was custom made for their weapon and bother to reload in the first place?!
Because it gets very tight in your chamber after a few firings and can damage the lugs.
 
Let's go at this logically: 1)You buy factory ammo. 2)You fire it through your weapon fire forming the brass to the chamber of your rifle and creating brass that is CUSTOM FIT TO YOUR WEAPON. 3)The only problem is the neck opening won't hold the bullet properly. Why would anyone change brass that was custom made for their weapon and bother to reload in the first place?!
Because neck dies do not support the case wall and can induce runout.
 
Warning! This thread is more than 4 years ago old.
It's likely that no further discussion is required, in which case we recommend starting a new thread. If however you feel your response is required you can still do so.

Recent Posts

Top