Is there any evidence that thinner profile barrels exhibit port erosion any sooner than thicker barrels? I did search on port erosion and did not find my answer.
I think that’s an insult, do you mean throat erosion and barrel length?
Will a 14.5" pencil barrel port erode any faster than a 14.5" M4 barrel port?
Again are you talking about the throat? I have never heard of a gas port eroding. So my answer yes and no
I just read through all your post expect to see this closed to
what ether is asking is if the gas port on a .625 barrel thickness under the gas block erodes quicker than .750 barrel thickness under the gas block due to less wall thickness of the barrel.
pencil vs govt/m4 profile
sorry. i do not know the awnser i but am curious as well if it’s possible.
Next time instead of insulting a member and showing your ass (by admitting you were too lazy to use the SEARCH feature) try doing exactly that.
I know what he is asking, I am trying to get him asking the right question he is worrying about something that is not going to be an issue at all before the throat is worn out. When a barrel is shot out its not the rifling or the gas port its the throat.
sorry brother, was just trying to help him out.
I think the barrel steel and chrome plating quality play a larger roll than the thickness of the barrel. If you, however, do alot of mag dumps the thinner barrel will most likely wear in all areas faster than a thicker barrel because of the increased heat. Gas port erosion is a non-issue with most guns, unless you are shooting for absolute accuracy.
This isn’t true in every case. To the best of my knowledge.
You know Andrew’s 40K round test that’s been passed around lately?
The “Federal Barrel” only had 10k in it, and the gas port had showed erosion. The rifling and all is still intact. Now he didn’t measure the leade, or throat (I wish he would have, and I’ve thought of contacting him about it.) but I’d be willing to bet that at 10k rounds it would have been mostly intact.
Also. I do think barrel thickness makes a difference. But I don’t know how measurable. And I think it’d have to be a more extreme example to measure it properly. Like SOCOM profile against LW. Not M4 profile.
Assuming both barrels were shot using the same ammo, under similar conditions, and were made the same way, by the same maker, and of the same barrel length.
Not saying your wrong, just never heard of it.
I bet it’s negligible… but I could see how a full profiled barrel would absorb more heat and have the potential for a slight reduction in port errosion.
I’ve always been curious about this too.
What wears faster?
.625" @ gas port or .750" @ gas port?
Assuming same ammo, rate of fire, etc…
Given that the gas port and gas block functional assembly is the same for each barrel profile, they should have similar erosion rates. It should be noted that not all gas ports are the same size and smaller ports should exhibit higher gas velocities and thus slightly faster erosion. Even though the material removal rates may be similar, a gov’t profile barrel has a .0625" wear advantage on a pencil barrel, so it will last longer.
There would probably be less erosion if the port was finished with a slight countersink or radius, but that would add an extra machining operation.
-Hold the phone- are we talking erosion within the bore or at the gas block to barrel interface?
I was talking about gas port erosion.
Will the gas port on the heavier section (.750" OD @ FSB)of an M4 barrel be less prone to wear (given all other factors being equal) than the same gas port on a light (.625 OD @ FSB) barrel.
Does the wall thickness matter?
I appeciate the thoughtful replies and discussion. SMT85 has me right…and I was mainly wondering about any erosion difference on the bore side of the port between .625" barrels and .750" barrels of the same length. It sounds like it should be negligible in the grand scheme, with throat erosion maybe even negating the concern at that high of a round count.
Also, anyone know if port diameters vary between .625" and .750" barrels with the same length and port location?
ETA: I sincerely apologize to the board and to MistWolf for my behavior…we have enough enemies lately without fighting amongst ourselves over the trivial stuff, and I’m sorry I engaged on that level.
Being in the profession I Was in,how much erosion will cause a failure and what will erosion cause? Higher operating [bolt] pressure or will the erosion cause accuracy problems from barrel wear in the area? Guns are a machine and machines wear out and “hopefully not” break.
SteveS - Check out the video link in this thread that Magic referred to:
http://m4carbine.net/showthread.php?t=120917&highlight=40%2C000
Although this was more indicative of a torture-test case than a long-term use case, I was pretty surprised by the visible amount of gas port erosion that these 10K barrels exhibited.
Your question is a really good one though, if I understand it - would gas port erosion start to affect reliability before throat erosion ever would? We know throat erosion can ruin barrel accuracy, but how long will the weapon keep firing reliably until gas port erosion gets the best of it, and reliability is affected?
I know. I wasn’t calling you out or anything. I was just providing my point of view.
Agreed. Negligible. But I think it’s there.
Nope. The port erodes at the bottom… the top of a high round count barrel still has about the same diameter it always had and thus the gas flow isn’t really changing.