Barrel warp

[robm]

Has any one experienced a shift in POI due to long term storage with a load on the barrel? I know it's an apples to oranges comparison, but you can warp an engines crank shaft (4340 steel capable of high rpm) by laying it on it's side. I know allot of people will store a rifle with it's muzzle leaning against the wall, it's very small but this is a load on the barrel. With a precision set up any warpage can ad up to an issue.

What are your thoughts?

[danco]

Thank goodness the AR/M4 platform is not a precision instrument, but a battle implement... ;)

[robm]

Oh I'm with you on that, but this is an issue I'm curious about

[Iraqgunz]

Never heard of it happening. My guess is that you will discover a golden unicorn first.

[justin_247]

This is total crap. Just letting a crankshaft sit around is not going to cause it to warp.

The idea that a crankshaft, which is subjected to endless ft lbs of torque for hours at a time, sometimes day after a day, will warp when it's just sitting under its own weight, but won't warp after all those forces are applied during operation, is simply ridiculous.

Again, total crap.

[robm]

Justin this is isn't crap, I spent 5 years building racing engines (vintage Porsche stuff that made 450+ hp at 8k rpm naturally aspirated out of 3 liters) and we had a special fixture to store cranks standing on end.

Do your research, before you call crap.

Im not talking about the old 305 in your clapped out farm truck

thank you Iraqgunz

[justin_247]

Justin this is isn't crap, I spent 5 years building racing engines (vintage Porsche stuff that made 450+ hp at 8k rpm naturally aspirated out of 3 liters) and we had a special fixture to store cranks standing on end.

Do your research, before you call crap.

Im not talking about the old 305 in your clapped out farm truck

thank you Iraqgunz

I'm calling crap again, because you know nothing about this subject. The idea that a piece of equipment can survive thousands of pounds of force exerted upon it every second in a myriad of directions, but deteriorates under its own weight, is ridiculous.

Why do you have a fixture? Well, duh... everything has a place. My iPod came in a box that was cut out to hold it. Does this mean that the iPod would come apart if it were not in the box? Really, your argument is THAT dumb.

The fact that you worked on racing engines is meaningless to me. I help manage an aircraft maintenance unit and we have technicians who work on engines that are dozens of times more powerful than yours. And they laughed, just like I did, when I brought this up to them. You guys are shadetree mechanics in comparison to the professionals who I work with.

Apparently, this is an old meme that's been floating around with auto mechanics for a long time. It's superstition, plain and simple.

I bet you also believe in unicorns and fairies, too.

[robm]

Justin,

Just just do a basic google search and you'll get pages and pages of info. I wont argue with you.

I am a professional who does this for a living, its not an old wives tail. I went to school for engineering and then I went to SAM (school of automotive machinists). I know a thing or two about metallurgy and I know allot about engines.

cranks DO sag if you lay them on their side, then you WILL spin bearings if you are dumb enough to run the engine. we didnt buy this fancy fixture so we had a place to put a crank like an ipod case

shade tree mechanics don't build 30+ thousand dollar racing engines that win PCA, IMSA, NASA, SCCA, Porsche mobile 1 super cup races. these are the engines we put together for hobbyists..... never mind the pro level cars that need a complete tear down after 12 hours of operation

[maddawg5777]

Very doubtful it would happen, also take into consideration that the upper and lower have a little play in them, this would relieve a small amount of stress but since theres so little stress in the first place it doesnt really matter. Also we have a bunch of m4s and a2s that are locked up all the time and their barrels are sometimes resting against the rack and none of them ever experience problems and hell i know some of them are older than me.

[justin_247]

Justin,

Just just do a basic google search and you'll get pages and pages of info. I wont argue with you.

I am a professional who does this for a living, its not an old wives tail. I went to school for engineering and then I went to SAM (school of automotive machinists). I know a thing or two about metallurgy and I know allot about engines.

cranks DO sag if you lay them on their side, then you WILL spin bearings if you are dumb enough to run the engine. we didnt buy this fancy fixture so we had a place to put a crank like an ipod case

shade tree mechanics don't build 30+ thousand dollar racing engines that win PCA, IMSA, NASA, SCCA, Porsche mobile 1 super cup races. these are the engines we put together for hobbyists..... never mind the pro level cars that need a complete tear down after 12 hours of operation

It's mentioned on a bajillion different forums, with usually a ton of people laughing at the end in the replies, but I have yet to hear from a legit source that this will happen.

It's a myth, I don't care what your supposed qualifications are. I can throw out more of mine, or my of fellow maintainers, or some of my family's, if it somehow helps. But the entire premise is ridiculous.

Here's how the myth probably began - a mechanic screwed it up by doing something he wasn't supposed to, set it in the corner, and then invented this elaborate story. It spread from there.

[TomD]

Justin,

I was going to add a reply but I seem it would be useless to try to influence your thought with fact.

[Iraqgunz]

OP,

It seems as if you believe it's possible and then use the "crankshaft" theory to prove it. Which begs the question of why ask in the first place?

[kartoffel]

Here's how the myth probably began - a mechanic screwed it up by doing something he wasn't supposed to, set it in the corner, and then invented this elaborate story. It spread from there.

Yep. Or maybe the Porsche mechanics needed to justify their sweet crank storage rack. It *is* important to protect the bearing lands, though. Hence, a gucchi crank-holder for the guys who rebuild engines every 12 hours.

Justin_247 is right. robm's smoking some good stuff.

[CarbonCycles]

I think the only way you could cause a barrel to go out of true is to apply a constant AND SUBSTANTIAL load on it while being stored. These barrels are spec'd to withstand some fairly substantial forces, and I don't see material deformation/creep being something to worry about.

[robm]

Justin,

I was going to add a reply but I seem it would be useless to try to influence your thought with fact.

Tom hit the nail on the head.



Iraqgunz, I was asking if any one had ever seen this happen... thats all, thank you for the responce

[Moltke]

If I store my rifle vertically for long enough is the rifling in the barrel going to slide down into my upper receiver? :jester: