Pushing a rifle to the limit without damaging the bore?

[ny32182]

My experience last weekend has got me wondering...

First, here is what I did. The screw that retains the front handguard on my VEPR K had started to back out a couple times, so I put some blue threadlock on it. Normally I don't get my rifles any hotter than warm to the touch at the range, at most. I wanted to see if the threadlock would hold up to more heat than that. I've seen 150rds referred to as a good number for a "speed test" to see what a rifle/carbine can do in a number of areas more than once. Since the VEPR is built as an automatic rifle anyhow, I figured I would just do it.... after shooting for a group and letting the rifle fully cool back down, I fired 150rds into the berm as fast as I could pull the trigger and change mags.

I discovered a few things that I wasn't testing for at first. 1) blue threadlock doesn't stand a chance against that kind of heat. 2) The VEPR front handguard doesn't either... the area around said screw melted and shifted... I don't think this particular handguard is ever going back on this rifle. It took a rubber mallet to get it off, and the screw hole isn't even close to straight anymore. 3) I had an honest, no-BS-or-excuses mid mag failure to feed in the middle of the 4th of 5 mags. A quick rack of the charging handle ejected the partially fed round, and no more malfs happened for the rest of the day. I don't know WHY reliability drops off when a gun gets hot, but this seems to be the idea.

I figured that since this rifle was designed for high volumes of fire from the start, 150rds wouldn't hurt it. Once I got the front handguard off, everything underneath looks good, and the bore looks the same as ever. I don't think any actual damage occured other than the US made and easily replaceable handguard (though I feel this is the weakpoint of the VEPR as sold by RA). I wasn't happy about the feeding malf, but it was cleared within 2 seconds, and it was back to the races.

I'd like to conduct a similar test on my LMT AR carbine, but: 1) it is much more expensive than a VEPR 2) the barrel isn't nearly as heavy, and would heat up even faster. I want to see if it is reliable under a high rate of fire, but I don't want to do permanent damage to the barrel.

What do you think? How many rounds is too many through an M4 barrel in a brief period of time? Will M4 handguards melt in a similar test?

 

[Cortland]

What do you think? How many rounds is too many through an M4 barrel in a brief period of time? Will M4 handguards melt in a similar test?

Only one way to find out, though I'm not real sure why you'd want to... I've rapid fired 120 subsequent rounds through a Colt M4 in 3-round burst before with what appeared to be no ill effects (i.e. no melted handguard). Then again, it was the game warden's rifle, not mine. I don't think I'd have done that with any rifle of mine.

 

[Magnuumpwr]

Not sure about the M4 but I have one of those Post-ban AR's with the heavier barrel and have dumped (2) 100 rd beta mags with no feed malfunctions and no melting of the handguards. Although, my nieces' boyfriend was dumb enough to touch the A2 birdcage with his fingers within minutes of firing. What do you know it was hot enough to smear his fingerprints! I don't think he will make that mistake again! The only reason I find that funny is because he is old enough to know better (18) and not to mention the steam/smoke rising from the barrel.

 

[Darkmind]

have dumped (2) 100 rd beta mags with no feed malfunctions and no melting of the handguards.

Same hear, dumped two beta mags with my Colt heavy bbl M4. No problems what so ever other than it was hot as all heck but still no FTF or FTE and no melting what so ever. Bore was perfect after a cleaning.

 

[AZTOY]

Last month my pattoon had to run the range. After every one qualified , we got to blow off the rest of the ammo.

I shot 15 full mag in 3 round burst in m-16 and was done in less than 5 minute. The ammo was a mix of ball and tracer ammo.

The hand guard on the m-16 was fine but the barrel was red hot. I made the mistake
of touching it. :banghead:

 

[Scottmkiv]

I melted a penguin handguard on my FAL, and I wasn't shooting especially quickly. Maybe 400 rounds over two hours. The gas block got hot and ruined both pieces of the handguard, and made quite a mess.

 

[ny32182]

I have fired 90 rounds through my LMT M4gery in fairly rapid fashion, but not as fast as I could pull. I wouldn't expect that to be pushing the limit though.

 

[kwelz]

I dumped 15 or 20 Thirty Round Mags through a 16 inch Oly Arms once
Turns out that it didn't have the Heat shield inside the hand guards. The barrel was glowing faintly, the hand-guards started to melt and had my hand print in them. (Yes it hurt like you-know-what) I tried holding it up by the sling and it melted through where it contacted the ring.

I learned two lessons that day.
1: Never have hand-guards on an AR without Heat shields.

2: Heat that builds up over time doesn't feel as hot as it really is but you feel it later!

 

[HankB]

1) blue threadlock doesn't stand a chance against that kind of heat.

Typical adhesives break down at temperatures above 300F or so. (This is handy to know if you ever put something together with red locktite and later want to get it apart.)

The hand guard on the m-16 was fine but the barrel was red hot.

Hmmm . . . if it was red hot, that pretty much anneals it . . . but I'm not sure how important heat treating of barrels is anyway. During the days of the AWB, it was routine to solder on muzzle brakes using, per ATF regs, solder with a melting point of at least 1100F, and nobody seemed to be particularly worried about it.