Beware Of Conventional Wisdom
January 04, 2011
Lane tested the RCBS X-Sizer die to see if it had any effect on the need to trim cases after several loadings and firings. He determined that it worked as advertised.
I recently wrote a column about maximizing case life by simply taking proper care of your brass, i.e., cleaning, resizing, inspecting, trimming, etc.
After Gary Brazo from Fairbanks, Alaska, read the column, he wrote a letter about a piece of reloading equipment that sounded so interesting, I decided to try it. Brazo indicated that he has reloaded thousands of rounds of .30-06 ball ammo to feed a couple of Browning machine guns. He lamented how much he detested having to check each case after resizing to see if it needed trimming.
Then he heard about the RCBS X-Sizer die. It was designed to restrict case growth, so you only had to trim the brass the first time it was reloaded. Brazo stated, "Conventional wisdom hereabouts was, 'How could that thing work?'" Despite some misgivings, he ordered an X-Sizer and loaded a batch of same-brand once-fired cases per the RCBS instructions. He fired them in his M1 Garand and then reloaded them seven more times. None of them needed trimming after the first loading.
Brazo concluded, "'¦beware of conventional wisdom," and suggested that I should conduct a test and evaluation and report the results.
I'd never used an X-Sizer die, probably because I rarely load my brass so often or so hot that trimming becomes a chore. I ordered one for .308 Winchester, selected a box of Federal match ammo, and grabbed a couple boxes of Hornady 168-grain .30-caliber Match bullets I'd been meaning to experiment with in a Ruger Model 77 MKII Target rifle. I fired four, five-shot groups at 100 yards--two measured 1/2 inch or so. I tumbled the cases and began the first of 10 reloading and firing cycles.
Setting up the X-Sizer, I followed the instructions and backed the mandrel and decapper/expander assembly out several turns to avoid inadvertently crushing a case. I was careful not remove it because the expander plug must be in place so the case neck can be sized properly.
Next, I trimmed each case 0.020 inch shorter than the SAMMI maximum length, 1.995 inches. Then, I adjusted the X-Sizer by inserting a sized and trimmed case into the die and screwing the expander rod down as far as possible so the step machined on the mandrel body could restrict case growth.
After wiping off the lube from each case, I primed them with Federal 210M match primers, charged them with 44.0 grains of Hodgdon Varget propellant, and seated the Hornady match bullets to an overall length of 2.830 inches (+/- 0.005 inch). To adequately assess the X-Sizer die's performance, I maintained the arrangement of each round in the cartridge box and the loading block and recorded each case length before and after sizing.
After 10 loadings, they all had grown from 8 to 10 thousandths of an inch. I plotted the data for about half of the batch and noticed a couple of interesting trends. Case growth varied randomly--up to 5 or 6 thousandths of an inch--for the first five cycles. Then the growth rate dropped rapidly to less than 3 thousandths of an inch for the eighth and ninth cycles before converging at 2.0045/2.005 after the last cycle.
I had a small epiphany halfway through the project. What if you want to load another batch of brass? If you repeat the sizing set-up with the same die, you'd have to readjust the mandrel to perform the sizing procedure or risk buckling the brass. Then, when you resize the new batch--after trimming the sized cases to 1.995 inches--and screw the mandrel into the die so it can restrain case growth, it may not be adjusted exactly the same as before. You would at least have to have an extra regular full-length sizer die to perform the initial resizing step.
I called the RCBS technical services to discuss my dilemma. We concluded that trimming the once-fired brass to 1.995 inches before sizing would be okay and would probably achieve similar results. I started another small batch of five cases to see if our premise would hold true. I have five load-and-fire cycles on those so far, and it appears that they simply skipped to the same length attained after the fourth or fifth reloading cycle of the initial 20-round batch.
RCBS doesn't claim you can extend case life using the X-Sizer die. However, the process I described is quite precise, and the rounds consistently chambered snugly throughout the test. There was no evidence of incipient case-neck splits or case-head separations. The velocity and accuracy data remained consistent throughout the testing. I'll get around to loading the rest of these test cases a few more times to see when or if any cases fail and reverify that the X-Sizer has arrested case growth.
However, practically speaking, Brazo is right on about conventional wisdom. In this case, it missed the mark because the X-Sizer performed as advertised for me.
A Better Way To Size
There's the "regular" way to adjust a full-length sizer die, but I've learned a better way. Typically, the instructions say to screw the die into the press until it touches the shellholder with the ram fully extended in the up position. Then back off the ram a bit, screw the die in about a quarter-turn, and tighten the lock ring. This ensures the die will be jammed against the shellholder when you resize each case.
If you're lucky, this method will size the case but not create excessive headspace by setting the shoulder too far back. Proper headspace controls how precisely a loaded cartridge fits the rifle's chamber. Of course, you must have some minimal clearance between the case shoulder and the chamber so the round will reliably feed, fit, and fire.
The bolt will not close or it will be difficult to close if the case is not sized adequately. However, if it's sized too much, and the headspace is excessive, the bolt will close too easily. When you squeeze the trigger to release the striker assembly, the firing pin may just shove the round farther into the chamber, causing a misfire, or there could be a perceptible ignition delay, i.e., a hang-fire. Of course, neither condition is desirable.
The better way to full-length resize is to screw in the die until it touches the shellholder as described above, but instead of turning it in a little more to eliminate any spring in the press, you back it off a half-turn and temporarily secure it with the lock ring. Lightly lube a case, and be sure to brush th
e inside of the case neck. Then size it and wipe it clean with a soft cloth to remove the residual lube.
Next, carefully try to chamber the resized case in the rifle in which you intend to fire the handloads. If the bolt closes really easily, you may have created too much headspace or your rifle needs a gunsmith's attention. If this occurs, have your gunsmith check it out with the proper gauges to make sure the chamber is within allowable specifications.
On the other hand, if the bolt won't close at all or only with extra effort, you're on the right track to achieve the objective. Loosen the lock ring and screw in the die 1/8 turn so that when you prep and size another case, you'll set the shoulder back a bit farther. You repeat these steps until chambering the resized case results in a slightly snug fit.
It may take two or three attempts to achieve the right adjustment. I always use a new once-fired case each time just to be sure I don't achieve a false fit by reworking the same case over and over. When the die is properly adjusted, resize these initial test cases again; be sure to chamber them before loading them. Coincidentally, I eventually adjusted the X-Sizer die so it was screwed in just past touching the shellholder, almost like RCBS suggested.
If you screw in the die until you're back to the "regular" method that I described earlier and the sized brass still doesn't fit, you should have your rifle checked out by a gunsmith. If the gunsmith verifies it's within spec, the die isn't adjusted properly or you're somehow improperly sizing your cases. On rare occasions, there may be something wrong with the brass. Try another brand/batch of cases.