January 27, 2011
Savage Model 220 Extraction Problems?
Savage Model 220 Extraction Problems?
Q. Some 20-gauge Savage Model 220 bolt-action slug guns, which Dick Metcalf recently detailed in Shooting Times, have shown difficulty in extraction of shells due to clearance issues with scope mounts. Possible solutions have been suggested both by Savage Arms and also general discussion on Internet forums. Could Mr. Metcalf comment on this topic — specifically if he had any issues with his setup and if he did, to what extent and if he found a viable solution?
--Jared Compton, West Portsmouth, OH
A. There are two considerations relevant to extraction/ejection with the 20-gauge Savage Model 220F bolt-action slug gun.
1. You need to make sure that the scope mount system does not in any way block or reduce the ejection port. The one-piece Warne Tactical long-action mount I used in my review provides ample clearance.
2. Cycle the bolt completely and aggressively. The 220F is built on Savage's long-action rifle receiver, which is a bit longer than it needs to be for a 20-gauge shell (but a short-action receiver would not be long enough). Clean extraction and ejection requires the bolt be continuously and firmly pulled all the way to the rear so the ejector will kick the case free of the action. If you short-stroke it or pull the bolt slowly, the case can slip off the extractor before encountering the ejector and will be left in the receiver. Likewise, feeding a fresh shell requires a full-length smooth and firm forward stroke. If you baby it, the blunt-front shell may get slightly out of line and not slide cleanly into the chamber. This is a factor with any type of bolt-action slug gun.
--Dick Metcalf, Executive Technical Editor
Why Did My Cases Split?
Q. Recently, I fired some Winchester .41 Magnum 210-grain factory loads from a new box that I had recovered from my ammo inventory. The box had not been opened previously; it had been sitting on my shelves for at least 10 years. When I fired the loads, I noted that there was a little more recoil than I associate with the .41 Mag. Ruger Blackhawk; however, it wasn't so severe as to concern me. I ejected the cases from the cylinder and placed them back in the box with the unfired rounds.
Then I shot some handloads, which seemed to be much more forgiving in the recoil department. I returned to the box of factory ammo and examined the spent brass, and I found that each one of them had split at the neck. I examined the spent brass from the handloads, which showed no defects at all.
I repeated the sequence, with the same results.
I examined the gun, and it appeared to be fine. The revolver was not new, having had probably 200 rounds fired through it without incident. The cylinder walls were smooth; the forcing cone was clean, as was the barrel. Everything appeared normal. However, every case that I fired from that one box of ammo split. None of the handloads nor several boxes of other factory ammo exhibited any problems. The ammo storage area is a cabinet that has a constant dehumidifier running to keep the humidity at 40 percent. Does Allan Jones have any idea why those case necks split?
--Frank Bowersox, Mechanicsburg, PA
A. I suspect there is nothing wrong with your fine Ruger nor your storage conditions. Split necks almost always indicate a minor metallurgy problem with the case dating to the time of manufacture. It can arise from improper heat-treating, age, or the two factors working together.
After coming off the final forming operations, most cartridge cases are stressed and harder than needed. The aspect ratio of the case (length divided by body diameter) affects the stress buildup. The .41 Magnum has one of the higher ratios, meaning it went through one more forming (draw) operation that the maker would apply to a case the length of, say, a .44 Special. Formed cases usually go through either an anneal or a stress-relief stage (less aggressive than annealing) to relax the metal to a point where the metal is more flexible.
Nonferrous metals like copper and brass have a tendency to slowly migrate to a harder state with age. The anneal or stress relief forces a change to the fabric of the alloy that is a little softer than the "natural" state. Nature tends to slowly overcome our efforts to change metals, and that is usually manifested as a case that is harder today than it was when it was tested at the time of manufacture.
It is common to find very old cases (like more than 50 years) that split at the neck simply due to the long-term stress of holding the bullet. You can find this on ammo that's not even been fired. Even if the case is properly annealed, there is a modest stress applied to the neck when the bullet is seated, work-hardening the neck; it is more prevalent with nonyielding jacketed bullets than with soft lead bullets.
I'll admit that this is not very common with handgun cartridges. However, if the ammo has been on your shelf for at least 10 years, it could have been on a dealer's shelf for a long time before you bought it. Twenty-year-old ammo doesn't usually sound a "hard case" alarm in my mind, so what you see is unusual but not without precedent or explanation.
Both annealing and stress relieving require incredibly tight temperature tolerances, in the order of a few degrees out of hundreds. Temperature is measured with thermocouples, and a quarter-century ago those electronic devices were not as capable as those today. Combine that with the huge leap in digital control technology in the last decade and today we now have ways to control oven temperatures to the narrow ranges required for superb heat-treating. In the 20+ years I was associated with CCI-Speer, I saw a huge leap in this technology, from tray ovens with one or two old thermocouples to new belt-fed linear ovens with arrays of many sensors, all feeding data to a computer that controls the material feed rate and the temperature to "bullseye" the desired heat-treating effect required.
I suspect that your old ammo was made at a time when sensors were not as good as today's, so the temperature was detected as being in the proper range. However, with the "plus/minus" nature of the old sensors, the actual temperature may have been just a few degrees under the sweet spot for a level of anneal or stress relief that would let the cases survive unchanged for decades. Your batch of cases probably passed every test that Winchester applied at the time they were made. It is the normal action of time combined with the challenges of older temperature-sensing technology that every manufacturer once faced that caused the cases to harden with age.
As for the greater recoil, that's probably not related to the splits either. When there were few options in .41 Mag. ammo, I recall thinking the factory 210-grain jacketed loads produced a
s much felt recoil in S&W revolvers as full-power .44 Magnum 240-grain loads. Felt recoil can be affected by something as subtle as the propellant burning rate. If the batch of factory ammo was loaded with a faster-burning propellant than your handloads, the kick would be applied to your hand over a shorter time interval and feel more severe.
The bottom line is that you and your revolver are safe. I've never seen a handgun damaged by a split case neck. Although you lose the case for future reloading, it is otherwise almost a "nonevent."
--Allan Jones, Ballistics Editor
Why Won't My Mauser Barrel Turn In All The Way?
Q. I am trying to put together an 8mm Mauser. I recently picked up a barrel and a receiver from two different vendors. I am having a problem with the barrel fitting into the receiver. It starts to thread but stops only after a couple of turns. I just noticed the markings on the barrel, and I saw "7.3" or "7.9." It is hard to make out. Can Reid Coffield help me resolve this issue?
--Anthony Kline, Via e-mail
A. I would be willing to bet that your problem is related to normal variations in the barrel threads. Keep in mind that the barrel was probably made in one place and the receiver was made in another, perhaps even in a different country and many years apart. Over the years I've frequently had combinations of barrels and receivers that would not initially thread together. However, I was always able to get the barrel to fit by simply running a threading die on to the barrel shank. Brownells Inc. offers Mauser 98 barrel thread dies and receiver taps. I have to warn you, these specialty taps and dies are not cheap, but they'll literally last a lifetime if you take care of them.
The other option would be to use a lathe to clean up the threads on the barrel, but "chasing" threads on a lathe is a task that requires a heck of a lot of skill and experience. Even a lot of folks who can run a lathe would shy away from a job like that. I know I sure do! It's all too easy to ruin the existing barrel threads.
Finally, you could simply try another barrel. As you can see, none of the options are cheap, but the problem can definitely be resolved.
--Reid Coffield, Gunsmithing Editor