Neck Sizing or Full Length Sizing

THIS IS SOMETHING EVERY T/C SHOOTER SHOULD TRY AT LEAST ONCE. IT IS AN EYE OPENER, ONE THAT WILL HELP YOU BETTER UNDERSTAND YOUR CONTENDERS AND ENCORES.

Neck Size or Full Length Resize Cases?An Experiment Every Contender Shooter Should PerformThe purpose of this experiment is to demonstrate what happens to bottleneck cases fired at full normal maximum pressures in the Contender, with applications to the Encore as well.

Preview:

When normal full loads are fired, the Contender frame stretches, allowing the case head to move to the rear. This is normally not observed by the shooter, simply because in normal operation the extractor moves the case out of the barrel as the barrel is opened. Firing the barrel without the extractor installed allows the shooter to observe the position of the case head after the round has been fired, and demonstrates the fact that cases lengthen from head to shoulder. This additional length from shoulder to case head must be removed by pushing the shoulder back in a full length resizing operation, and should not be confused with case trimming. Failure to remove this added length results in a case that is too long from shoulder to head compared to this same dimension from the chamber shoulder to breechface.

A case that is too long:

1) places a “preload” on the frame vertically, and often results in vertical stringing of shots.

2) can prevent full lock up of the barrel in the frame which causes:

• a) misfires due to the retarded falling of the hammer block safety as the hammer travels forward in firing the weapon.
• b) rounding of the “locking table” surface in the frame, which contributes to.
• c) the barrel violently flying open when a shot is fired, especially when the hammer block safety is not functioning correctly.

3) contributes to extraction problems resulting from the overly long case being crammed into the chamber when the barrel is snapped shut. It only stands to reason that there is a correct length for the cartridge. When this length is altered, there will be consequences.

The Experiment:

Establish the relative distance between the closed barrel and frame’s breech face. Start by removing the barrel chambered for a bottlenecked cartridge from the frame and removing the extractor by first punching out the 1/16″ roll pin that holds it in. This pin may be larger than 1/16″ on some custom barrels. You will have to have at least a 1/2″ long 1/16″ pin punch, but the shank of a number 52 drill bit held by pliers works also.

1) Starting with one strip of standard writing paper about a half inch wide placed in front of the breech face of the frame, snap an EMPTY barrel shut on this piece of paper. You may need an extra hand or you may try taping the part of the strip that sticks out above the frame. The object is to have the barrel snapped shut on the paper with the paper in the area where the case head normally is without getting it caught by the locking bolts and still leaving a portion sticking out the top that you can get hold of. Obviously, a barrel with a scope base protruding to the rear past the end of the barrel will get in the way, so remove it, or choose another barrel for the experiment, but it must be one for a bottlenecked cartridge.

2) With the barrel closed on the paper, try to pull it out. If it comes out freely, the gap between the barrel and the breech face is greater than the thickness of the paper, so try the same thing as in 1) above with two thicknesses of paper, or more if needed, until the closed barrel is gripping the paper.

3) Open the barrel and see if the barrel has made a shiny arc-shaped imprint on the paper. On most barrel and frame combinations, the distance between the barrel and breech face is no more than one thickness of paper, and on many the barrel actually contacts the frame as is often witnessed by marring of the bluing on the extreme breech end of the barrel.

Preparing cases:

(Check trim length first. Trim as needed before proceeding.)

1) Partially resize a case by leaving the sizing die backed out one to two turns.

2) With the barrel off the frame, held in one hand, drop the case into the chamber and note how far it protrudes from the end of the barrel.

3) In very small increments, adjust the size die downward in the press until a sized case will drop into the chamber and stick out no more than the thickness or thicknesses of paper you used to determine the barrel to frame gap.

4) Note that the case head must not be below the end of the barrel. It must be perfectly flush with the end of the barrel or protrude only the thickness of the paper. Look carefully, this isn’t much! If your case is too short, meaning it falls below the end of the barrel try additional cases until you get it just right. This may take you awhile. Just be patient and keep trying. This part is very important.

5) When you have the size die adjusted to give a case that chambers just flush with the end of the barrel, resize several more as backups. (Note that some dies may be cut too deep to set shoulder back far enough. Call me for help if you absolutely can’t get the case head flush with barrel.)

Firing the Contender:

1) Load your correctly sized case or cases with a normal maximum load that you know is safe.

2) Make certain the bullet is seated deeply enough to allow the loaded round to drop into the chamber with the case head flush with the end of the barrel, just as it did before it was loaded.

3) Now snap the barrel shut and fire the cartridge into a safe backstop.

4) Open the barrel and note where the case head is now positioned. If the load developed something on the order of around 40,000 psi or more, the case head will now be sticking out of the chamber about .010″ to .015″ instead of approximately flush as it was before it was fired.

Comments:

In the case of .223 Rem. factory barrels some have the chamber cut too deeply and will not fire without the extractor installed. (Ie., they infact headspace on the case rim.) You may have to leave more of the case head sticking out to get it to fire without the extractor. Nonetheless, you will observe a much greater protrusion of the case head after firing. Below about 40,000 psi, the cartridge case contains most of the pressure load and very little stretching of the frame occurs. Thus with moderate loads you can get away with neck sizing, so long as the neck sized cases still chamber with the case head essentially flush with the end of the barrel. However, the Contender will handle pressures above 40,000 psi (with the exception of large diameter .45/70 cases), and most of us want the performance that only higher pressures deliver. But to maintain accuracy and proper functioning, fired cases MUST BE PROPERLY FULL LENGTH RESIZED. Failure to realize this has caused more problems for more people than any other aspect for reloading for the Contender and has also caused more people to abandon the Contender in total frustration.

Now, do you still want to neck size only?Mike Bellm