Alasdair MacDonald

Joe, a slower recoil is accomplished by the lighter bullet not being able to compress the recoil spring back any farther than to cycle the action. (Newton's Third Law of physics) Since the recoil spring is not so compressed, its forward response is slower with the tired spring and therefore lacks the enertia to overide the firing pin spring and cause a slam fire. It can get a little involved sometimes can't it? All the best Joe, cordially, Alasdair. Lets see if we can pick some other brains out there.

Joe, I had extensive experience with rifles doubling. I Have two Johnsons. One is a military and the other a Windfield. I also have an extra barrel in 7X57mm. I first experienced doubling when using the 7X57. It especially did it with 139 grain bullets and even the heavier. It was more consistant with the light bullets. I began replacing every single part with new or new after market parts to see if I could get the doubling to stop. I swapped trigger housings, every single part in the trigger housing, bolts (they all had the firing pin spring attached and in the proper position with zero movement.) I even doubled up on the firing pin springs to increase the resistance and check the inertia of the firing pin and keep it from slam firing. Primers on casings that doubled had only a slight dimple on them and not as severe as the fired rounds, but the dimple was sufficient to set off the primers. As you know, generally military primer cups are usually thicker and therefore take a stronger hit to set them off. I pulled military bullets to use the military powder and primers and replaced them with the lighter 139 grain bullets. Primers and powder did not seem to make any difference, but they did double with the light bullets. The only way I got the rifle to stop doubling was to put back into the recoil tube the 3/4 inch too short recoil spring which caused the bolt to return to battery more slowly and therefore less inertia and therefore the bolts firing pins setting off the rounds was checked. I recreated this problem with both of my rifles. It appears that with the new not yet tired springs being compressed during recoil, causes the bolt to go forward faster and the springs and primer cups can't check the increased celerity. I made some posts on this a few years ago and still have my copies of my research on this problem. Altough you get some evil eyes from the rangemaster, it was kind of neat and fun to shoot them this way. I told the rangemaster what I was doing and he had no problem with it. Not too cool if you are shootin a match though. Hopes this helps, cordially, Alasdair

Capthowie, As Jim said, there is no equal and opposite force to unlock the bolt and cycle the rifle. Keep in mind the four movements that the bolt makes. this was also used to sell the rifle if the rifle fails to cycle as it replicates a bolt action which the shooter can use should the rifle fail to cycle on its own due to whatever. The only thing you need to be aware of is that you may have corrosive primers. Sodium chlorate becomes sodium cloride when fired which is salt. Salt attracts moisture from the air and when in contact with ferrous metal becomes ferrous oxide that we all call rust. Clean it afterwards and the bolt and you should have no problems. Cordially, Alasdair

Class is in session, professor MacYak instructing. Here is the poop on .308 vs 7.62x51 1. The round was invented by the U.S. Army and is basically a 1/2 " shortened .30-06 round and desiginated the T-65 introduced in 1952. 2. It was adopted by U.S. military in 1954 even so they did not have any rifles chambered for it and did not until 1957. 3. It is only @ 100 fps slower at the muzzle than the .30-06. 4. Winchester requested permission to add their name on the round and make it commercially available in the .308 designation. Permission was given to them by the U.S. back in 1952. 5. The basic difference in the interior of the round is that the military case uses a thicker web at the bottom. 6. Commercial producers making head space guages make no difference in using this guage for either the .308 or the 7.62X51 as they both headspace on the shoulder with the same specifications. 7. The only difference is where you want to use a specific bullet and get a chamber reamer that accomodates this bullet. Target shooters have known for years that if the bullet just slightly touches the leade, (the begining of the ramped rifling) one gets the best accuracy as the bullet does not have to jump before contact with the rifling. The downside of this is that it also increases interior ballistic pressures so you should not be using max loads. 8. Headspace can start at a low measurement and increases with wear and pressure until the headspace reaches an unsafe measurement with a no-go guage. The basic measurement differences is found in the leade/freebore. That is why you can get a chamber reamer for a specific bullet depending upon your use. I have a Stoner SR-25 that says to only use 168 grain Spitzer boatail bullets as the leade is cut for this bullet for accuracy. 9. For all practical purposes, they are the same. Cordially, Alasdair

My Johnson barrel has the forward collar marked .30-06 on the 12 o'clock position and 41 at 6 o'clock. The chamber is stamped 7mm. I believe it is one of the Mexican products that were made for this rifle using Johnson collars. Cordially, Alasdair

Uh fellow Johnsonians, I have been around Johnsons a good many years and this "USN" experimental barrel sounds like bovine scat. Possibly a sale idea. Also by reducing the weight of the barrel by shortening, you are reducing the mass at rest which will cause the barrel to reciprocate with more cererity. This in turn will upset the tension in the springs and all those designed to check this rifle as it fires. It is a domino game, and when you change one you affect the entite system. I would love to see that barrel cycle in that rifle. Anyone want to bet it will work? I'll bet it won't. Excuse me, but I have seen recently adds and now listed here that there is a difference between a 5.56mm round vs a .223 round and a 7.62X51 vs a .308. What the hell is the difference" One is metric and the other inches. Ecucate me please. Cordially, Alasdair

Very interesting Jim, I took my book back out and looked through the data on this MacFarland. The author is Harold E. MacFarland and he dedicates the book to his father (Albert A. MacFarland) who was a hardware store owner and who "had no love for guns nor great understanding of them." No other data available on this in the book. Cordially, Alasdair

While reading "Introduction To Modern Gunsmithing" by Harold E. MacFarland, I came upon a small article about the JSAR. P-103, " These rifles were tested by our armed forces BEFORE the adoption of the Garand." Really! "This action can malfunction with even a little DUST in the chamber." Indeed! "Johnson accuracy is very POOR! When the gun is fired, the barrel moves rearward, and it is supported only by two guide collars. If they fit snugly, the action doesn't function; if at all loose, the barrel wobbles and there is no semblance of accuracy." Good lord, you can't win! This is a classic example of bias reporting. It reminds me of the axiom, "opinions are like backsides, everyone has one!" Cordially, Alasdair

That is affirmative Brian. Cordially, Alasdair

19pm45, You must be very proud in having such a patriotic uncle. It is hard these days to fully understand the heroes we had during WW2. Your uncle is at the top of the list. Thank you and your family for their dedication to the United States and all that they gave and stand for. Cordially, Alasdair

JohnSch, I have the 7mm barrel (7X57 Mauser) and it works just fine. You simply depress the pin and lower the barrel lever and out pulls the barrel. Just insert the new barrel and you are back in business. As stated, the barrels are brand new and have been pre fitted to the .30-06 collars. Keep in mind that the bolt face for the 7X57 and the .30-06 are exactly the same so nothing needs to be modified further. Keep in mind that the sight adjustments will be different so mark your sights for the same zero before you change the barrels. The barrel will be stamped 7mm near the chamber if that is the caliber of barrel you have. As to modifying the rifle for the heavier calibers, it probably could be done but would require extensive calcuations for action vs reaction on recoil and different springs to check the increased recoil. As I have mentioned in this site before, I know a gunsmith who made a Johnson in .270 and he had a hell of a time getting it to cycle just because of the bullet size and recoil difference. Unless you have a lot of time, money and patience, I would leave it alone. If it ain't broke, don't fix it! Cordially, Alasdair

LoboMike, The ammo sounds as though there is no problem. Keep in mind that this rifle was tested to handle everyting from 110-220 weights both military and commercial. It sounds as though your cocking problem has subsided. When my rifle doubled, I even put two inertia recoil supressing springs on the firing pin which had no effect in stopping the slam fire and dimpling. I even changed the firing pins with extras I have with no effect. What I concluded was the main recoil spring was the problem. It should rest at 12 inches in length out of the rifle. If less, it has taken a set. When I replaced my set and worn recoil spring, the firing pin springs could not supress the increased celerity, which caused the bolt to go into battery harder causing the slam fires and dimpling. Wow, there is a run on sentence. Have you changed this spring? When I put my old tired spring back in the slam fire stopped. The only problem now is you have to have no one on your right less the brass exiting will kill them. It appears that when you change one part, you change the entire functioning of the rifle through a domino effect. Keep us posted, cordially Alasdair

LoboMike, I had some experiences with this same problem. First do exactly what Joseph Scott recommends. Two, you do not say what type of ammo was used by both of the shooters. This normally makes no difference as this rifle was tested years ago using bullet weights of 110 to 220 grains commercial loads and all military weights without a functioning problem. Keep in mind that this rifle is recoil operated and needs to have a certain resistance against the reciprocating bolt to cycle. It is listed here as "weak shoulder" offering no resistance. In hand gun shooting this same problem is called "limp wristed" holding and has nothing to do with gays. Three, the fact that you are getting dimples on the primers indicates that a slam fire is taking place and causing the doubling. I found that in my rifles they tended to double with lighter weight bullets especially in the 7X57 loads. Four, On the "click issue", it sounds as though the bolt is not going back far enough for the sear to engage the hammer and lock it until depressed. Give us some more poop and we will see if we can correct this problem. Cordially, Alasdair

A couple of thoughts for your match. 1. Is your Johnson and early one or later production? Early sights had a very tall front sight necessitating the rear elevator to be put on 600 meters to hit dead on at 100 yds. I have one of these. 2. I assume that you have zeroed the rifle, and if you have this problem will be evident. I recommend that you sight the rifle in at 200 yards as this is half way between your three distances you will be shooting. If possible shoot all three distances and see where the bullets print at those ranges. Log the "dope." Be sure to use boatail bullets for accuracy, they have an advantage over 200 yards. 3. The terms "barrel time and lock time" is the amount of time the bullet is in your barrel after squeezing the trigger and the shot fires. This will depend on bullet speed and length of barrel. What this extrapolates to is the shooter being able to "hold the rifle" until the bullet leaves the barrel. This is also referred to as the area of "wobble" for both elevation and lateral movement. The reason I brings this up, is you probably can NOT hold the difference it would make on the POI from meters to yards depending on the positions, wind, temperature etc. Let us know how you do. Cordially, Alasdair

A flash suppressor normally has no holes anywhere on the side or top in order to hide the flame following the emergence of the bullet. This only helps slightly as it depends on the powder and length of the flame. If the shooter is pointing directly at you, you will see the flame about the time the bullets enters your body. I have personal experience with this one. A compensator does just that, it compensates. The gas will take the path of least resistance. By re-directing the gasses in a particular direction you counter the movement of the barrel. For every action you have an equal and opposite reaction a la Newton. Example: The Cutts compensator on the Thompson is designed to keep the barrel down and not climb by directing the gasses vertically through the vents. A muzzle brake does the same thing and works the same way as the compensator, but generally directs the gasses in a direction to pull the rifle off of your shoulder and thus reduce recoil and or direction. A good brake will actually pull the rifle from your shoulder during fully automatic fire. Sometimes these devices do two functions and are therefore used synonymously. These devices also change the frequency of the report and make a distinct sound difference sometimes very painful to your hearing. Hope this helps. Cordially (pedantic) Alasdair

Bowed barrels are a normal condition that barrel makers have to live with. When I visited the Springfield Armoury they had several of the look through devices as described by Joseph Scott. They are mounted from the ceiling and are at a 45degree angle so the operator can look through them. The circular wheel has mutiple handles around the edge that resembles a ships steering wheel(helm). They look through it and apply foot pressure to a device that puts pressure where the bow takes place. When this same condition occurs in males, it is called, "Peyronie's Syndrome" and also causes one to shoot in the direction of the bend a la our former President. Cordially, Alasdair

The compensator, as stated by Jim Pullen, was installed on bolt action Mauser action sporters. With this additional weight, I would be curious to see if the bolt reciprocates to unlock and cycle the rifle. The weight of the barrel is critical as was indicated when the Dutch wanted a bayonet and they came out with the long heavy one shown in photos. The problem was the additional weight caused the rifle to not cycle and they eventually came out with the light "tent peg" type. Looks cool, but probably will deter cycling of the action. I know a gunsmith with 50 years of experience who had a customer with a Jhonson in .270 cal. He had a heck of a time to get the rifle to cycle even by this minor change. Everything must be in balance and weight and spring strength. Change one and you have a domino effect that can cause problems. Cordially, Alasdair