buzz

If you have an M1 or M1A1, I recommend that you put a foregrip band on. Once that band is on and tightened properly, the foregrip becomes extremely rigid. I doubt you could break the grip mount when the band is in place. Unless you pried at it with a screwdriver. Did they use them on 1928A1s also? If so, I would put one on a 28A1 as well. BIG improvement.

you weigh each round? RCBS makes a nice powder checker die also, you can tape a light to your press and peek into each case before you seat the bullet. a visual inspection is as good as weighing the round

I tend to believe that the second bullet hitting the back of the first bullet is what causes the bulge, not an air pocket being compressed. Look at the way the lead squirted out of the barrel in this video. Lead is a weird metal, it has the property of flowing like liquid when under very high stress. I also don't think that a ruptured barrel is a big deal. the PRESSURE of combustion is an accelerant for the combustion rate. so anything that prevents the bullet from uncorking the barrel can drive the pressure way higher than normal. so when a bullet gets stuck or a cartridge is fired out of battery, the effect varies from no harm at all to the gun, to the gun blowing apart. It all depends on how much pressure builds before it's vented and how it's vented.

This is something I have thought about a lot: how much politeness is appropriate in a given situation. We all stand at the altar of stupidity and make a fool out of ourselves once in a while. But when someone acts this ridiculous and malicious, then all obligation to be polite to the guy is gone. Just give him the heave-ho and good riddance.

This is one of the best technical gun forums on the internet. It has been an invaluable source of information for me. If you can't get along with the people on this site, you have "issues".

Scrambles is pathetic and he doesn't belong on a technical forum like this one. I'm not saying that as an insult, it's a simple statement of fact.

maybe a Buffer made of "Flubber" or super ball material? If you really want to make a change in the force on the receiver, you need to make the buffer much thicker. The neoprene buffer that we use now only probably compresses by 1/100th of an inch. You want something that is thicker and squishier. The problem is that squishy elastic materials dampen out a lot of energy, turn it to heat. I would not make a real thick neoprene buffer, you'll just jam the bolt to a stop sooner and use the recoil spring less. The recoil spring is your friend. Why not denser ? what you're trying to do is lower the accelleration force on the bolt if you lower the force on the bolt, you lower the force on the receiver. the softer (or weaker) that the spring is, the more it will compress when the bolt hits it the more it compresses, the longer time it takes for the bolt to stop the longer time it takes for the bolt to stop, the lower the force is if you were bungee jumping, would you want to use a real stretchy bungee cord that took 30 seconds to slow you to a stop, or a real stiff one that jerked you to a stop in one second? same job, different amount of force used the weaker bungee might take 100 feet to stop you, but the stiff one only takes 2 feet. so if you want to stop the bolt with less force, you need a thicker buffer that's made from softer material. The ideal thing would be to use a stiffer recoil spring that stops the bolt 1mm away from the buffer because that way you have the whole length of the bolt retraction to stop the bolt, a nice smooth decelleration

The big mystery is what this means: "And please Buzz, . I see your unproductive posts across many of the boards, "oh that's not gonna happen, too bad etc". It's a reoccurring theme. Pessimism isn't going anywhere. Go radius the sharp cut on your K frame and shoot it forever. You are more of a detriment to this community than ANYthing else." This is the only forum where I use the username "Buzz", so if there is some guy named Buzz being a pain in the ass on some other forum, I can't claim credit. I did a google search on "posts by Buzz" and I found a whole giant bussload of Buzzes. Like this fancy pants guy: http://thebuzzblog.hercules-design.com/blog/author/admin/ I found this guy on a pinball website, seems like a nice sort of person, gives blood: https://pinside.com/pinball/forum/topic/saving-pinball-through-blood-donation So I'm not really seeing all the negative and pessimistic posts by the guys calling themselves "Buzz". Seems actually like an upbeat sort of crowd. Buzzes unite!

That story has a real "my granddad carried this AR15 in WWII in Stalingrad with the 101st airborn" feel to it.

that thing is a headache, in a way its ok it give a certain degree of protection, but if i show you a picture of the trigger frame interior, you will have some real nightmares, you could literally pick it with a spoon. meh, once a gun comes out of storage, I don't see any purpose served by leaving the cosmoline on try heating the gun with the hair dryer, just leave it on the gun for a half hour until the metal stings your skin a little, the cosmo will get nice and runny

maybe a Buffer made of "Flubber" or super ball material? sure, why not? The thing is, if you want to reduce the load on the receiver a lot, you need to increase the distance that the bolt is slowed down. If you brake to a stop in your car in 1000 feet, the braking force required is twice as high as if you come to a stop in 2000 feet. If you really want to make a change in the force on the receiver, you need to make the buffer much thicker. The neoprene buffer that we use now only probably compresses by 1/100th of an inch. You want something that is thicker and squishier. The problem is that squishy elastic materials dampen out a lot of energy, turn it to heat. I would not make a real thick neoprene buffer, you'll just jam the bolt to a stop sooner and use the recoil spring less. The recoil spring is your friend.

Not sure what you mean. There's no way to eliminate the "kick" of the firearm. picture if the gun was floating in outer space and nobody was touching it. when the round goes off, the bullet and the gunpowder go left and the gun itself goes right. the mass of the bullet and the mass of the powder times their velocity will equal the mass of the gun times velocity of the gun M bullet x V bullet + M powder x V powder = M gun x V gun the bullet will go about 850 fps, the powder will go about 4700 fps and the gun will only go about 20 fps because of the heavier weight of the gun. since a moving object has kinetic energy, the kinetic energy of the gun is called "the free recoil energy" and this number is used to compare how hard guns kick. no matter how many springs the gun has inside, the final rearward velocity of the gun and free recoil energy will be the same.

If you set a hair dryer with the hot air blowing on a gun, the metal will become hot enough after a while to liquify cosmoline and you can wipe it right off

I welcome any opinions on any topic, as long as people don't start screeching at me like an angry fishwife. If someone points out a mistake on my part, I figure they did me a big favor. I'm not too proud to take correction when it's offered. This is actually a real good topic, who knows, maybe someone will come up with a miracle buffer. The problem with this topic is there is no data and there are a lot of unknowns. The way the bolt jerks around in there makes it hard to even come up with a comparative or qualitative statement. The only thing i can come up with to say at this point is that the bolt has about 20 ft-lbs of energy and that's not a lot, it's practically nothing. The gunpowder has about 1000 ft lbs of chemical energy, about 400 gets used to propel the bullet, the bolt picks up around 20, the rest is lost to the air as heat. That's not very much energy, it's hardly anything. Your arm can deliver about 17 ft lbs of energy with a 1 lb hammer.

Every time I look at this thread I end up sitting and thinking for 20 minutes. I'm trying to puzzle this out qualitatively because I don't have any data. I found this slow-motion video of an M1A1 firing, you can see that the bolt has some decent amount of velocity when it thumps against the buffer. It looks like it's hitting the buffer fairly hard. But is it hard enough to care about? Think about it, the Garand operates with huge force, the op rod handle comes back so hard that it will split your hand open. If that doesn't bother the Garand receiver at all, would 1/10th or 1/20th of that amount of force bother a Thompson?

What would be a little more practical than nitrogen would be a goldenrod. The goldenrod just elevates the temperature in the safe (or case) by a few degrees this is enough to keep atmospheric moisture from settling on the gun. Apparently the temperature of metal objects like guns always lags behind the room temperature. The air in the room might be 68 degrees, then warms to 73 degrees, but the gun stays 68 degrees for a few more hours. During that time, the 73 degree air in the room dumps tiny amounts of moisture on the gun. So the goldenrod keeps the temp in the safe a few degrees higher than room temperature. That's my understanding of how it works. https://www.amazon.com/Goldenrod-725721-GoldenRod-Original-Dehumidifier/dp/B00DBTCFGY

Looks a little rust freckled it might clean up OK though

"This Shouldn't be Legal" - TD Yeah that's really going to promote your hobby.. Quit being selfish you fools!! I won't forget your words, or shake your hand, EVER. I've never met a higher-regarded and more destructive member of a closed community. There is so much more to think about here.. For what it's worth, my experience with the guys on this forum is the exact opposite of your sad tale of woe. This forum is an amazing storehouse of Thompson knowledge and these guys will go out of their way to inform and assist the new guys. Your arch nemesis TD called me on the phone and gave me a detailed tutorial on how to collect data from official sources. He was extremely helpful to me, a guy he never met. And your other tormentor, Reconbob, who manufactures these guns professionally, was kind enough to give me tour of his shop and answer about 100 questions on metalworking. Maybe if you were to switch to decaf you might fare a little better.

Would you like to address how this doesn't relate directly to you..? Your post is cringe inducing. But I'll answer this, it's a fair question. I get paid to solve problems just like this one. I have a BS and MS in engineering and I studied kinematics at the graduate level. One of the things I learned in grad school is how solve complicated dynamics problems, both by closed form solutions and by numerical integration with a computer. The way these problems are solved is by mathematically representing the system as a series of lumped masses that are attached to each other by springs and dampers. Then the equations of motion are set up using D'Alembert's Principle and the resulting differential equations are solved using a numerical integration method such as the Wilson-theta method. Those are my qualifications for talking on this subject. Six years of training. A Thompson bolt doesn't have to be modelled as a lumped-mass spring system, it literally IS one. I can't think of anything that matches the model better. It wouldn't matter if it wasn't such a close match, the physics involved and the solution method are general and would work on anything from a car exhaust pipe to a skyscraper.

This thread presumes that the bolt delivers some sort of brutal battering to the rear plate of the receiver that needs to be addressed. Before insisting that a spring buffer gizmo was not used due to cost, you first need to establish that such a thing was actually needed. Can you point to all the fancy spring buffers found in other SMGs? Or point to some failure in the Thompson that the spring gizmo would cure?

Anything that deflects elastically under load is technically a "spring". You would use the same energy equations for a rubber band as a steel coil spring. So if you want to come up with a fancy buffer that reduces recoil impulse on the rear plate, then you could use some kind of elastic material like rubber to make a big fat buffer. The most ideal way to lower the thump of the bolt on the rear plate of the receiver would be to use a recoil spring that stopped the bolt 1 millimeter short of the buffer. Let's say that the recoil spring soaks up 95% of the bolt energy and thumping against the buffer uses the last 5%. Since you know that thumping against the buffer is a short, hard deceleration and the recoil spring provides a long, smooth deceleration, having the recoil spring do 100% would be better. Whenever you take a longer time or longer distance to slow something down, that means the force is lower.

Yes, you are correct. The bolt will not stop going backwards until all the backwards kinetic energy gets sucked out of it. So if the recoil spring does less work, then the bolt will be moving faster when it hits the buffer. These guys are talking about some kind of 1/2 inch long spring gizmo to replace the buffer. Like if the last 1/2 inch of bolt travel it hit a supplementary spring instead of thumping against the resin washer. Technically, something like that would reduce the force on the rear plate. The longer distance that you take to slow down, the less acceleration is needed. I was just saying that something like that wasn't really needed or they would have stuck it in the gun in 1921.

The 1921 Thompson is the most over-designed gun I can think of. There is literally no engineering refinement that they left out of the gun. Not to mention the super-deluxe fit and finish by Colt. I highly doubt that they left a 1/2 inch long spring out of a $2,500 gun because of cost. The reason that they did not come up with a spring gizmo for a buffer is the same reason there isn't one in an UZI: because it's not needed. This is an interesting discussion, but I think it's incorrect to assume that some special gizmo is needed to save the receiver from being battered. The bolt is powered by a 45acp round and the impact on the buffer happens at the end of the recoil spring compression. How much velocity do you think is left in the bolt at that point?

My savage commercial was owned by a police department with two thompsons, my savage and a colt. I have a colt buttstock on my gun. I'd love to find the owner of the colt and see if he has a savage buttstock lots of stuff can happen to a gun in 70 years, especially if it's considered a piece of police or military equipment instead of a precious artifact

Good idea with the vice grips. I guess you could dremel a smooth semi-circle on the jaws to grab the rod without galling it I have to assume there is some knack to doing it quickly without vice grips, because it seems doubtful to me that the factory would sell a product that takes their assembly line employees 20 tries to assemble. They would have come up with the hole idea if the employees were struggling with the thing. Also, one time I assembled it without any tools in less than one second, I just jammed the assembly in the gun and it went together easy as pie. I must have done the little hint or trick without realizing it.