barrel temps and five shot groups - AR15

[Old Dog]

Ever wonder how hot the barrel gets on your AR15 when you're shooting 5 shot groups?  Now the speed of these was fairly fast, shoot 5, insert new magazine, shoot 5 more, insert new magazine, shoot 5 more, etc. till 70 rounds had gone through the barrel.

Barrel temp near the front sight was 185.5 F.  DO NOT touch that barrel (anywhere in front of the handguard/free float tube) or front sight base. Temperature of the handguard (free float tube) was 112 F just behind the front sight and 110 at the rear of the free float tube (around the chamber).

112 F isn't too hot to hold onto but you'd know it was getting warm. 

Temperature of the bolt face when it locked back after round #70 was 98 F.  On a semi auto the ejected brass take a lot of heat with it.

Need to do the same thing with the M1A or M1 (believe it or not, the M1A gets even hotter than the AR15) and record the numbers.  Maybe next trip.

Oh, rifle is a 20" HBAR clone and the ammo was 55 grain FMJBT with IMR4198 powder.  Temps with GI type ball powder may run even hotter.

[mtmisfit]

I'd be interested in seeing the numbers on an M1A. 

I can say that a .223 suppressor gets hotter faster than a .308 suppressor does.

[Old Dog]

I'd say barrel length with the suppressor probably has a lot to do with it as well.  I was trying to take some pictures yesterday, too.  No once did I see "fire fly" out of the end of that 20" barrel (combination of 20" barrel, flash suppressor and powder???)  The shorter the barrel the more unburned (or still burning) powder goes out the end of the barrel to burn in the air or the suppressor.

[SamD]

Shoot your M1 enough to melt chamber flags and measure that.

Pretty easy to char handguards too

[siglite]

Who hasn't set an AK on fire?      

I was shooting with another IIT on Saturday.  We were shooting ARs at steel at 300 and 500yds, and just loving the sound of that delay followed by the "ponk!" of that steel ringing back to us. 

I was shooting my 16 inch AR at the 500 line, and was pretty deep into my bubble.  I remember being vaguely aware that some stuff was feeling kind of hot.  At the end of my string of fire, as I pulled the rifle out of my shoulder, that vague awareness was not quite so vague.  Ow.

So, now I have a nice pair of blisters on the inside of my thumb and index finger where they were contacting that ring behind the front post.  Funny how you can get so deep into the bubble that you're not even aware your hand is on fire.

It still hurts.  But I don't care.  The plonk of that 20" steel at 500 is like crack to me.  MOAR! GIVE ME MOAR!

[AFTERMATH]

I went through about 60 rounds in my AK one day...
Leaned it against my shoulder to take off my sling, the barrel slid up against my neck.  Right behind my ear.
There was no convincing my mom that it was a burn that stayed there for a week or so.