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Posted: 7/16/2006 5:37:32 PM EDT
Following the great instructions found on this site, I was able to install a Sabre Defense Industries 14.5" M4 profile barrel (with permanently attached extended A2 flash hider) on my upper receiver. I went and shot it today. I put 300rds down range without any reliability problems. Instead of being front heavy, my rifle is now very well balanced. The only problem that I had was that the handguards got very hot. After putting a magazine full down range, I could hardly hold the handguards. Even after letting it cool for about five minutes, the handguards were very hot. I had to use a rag to hold the handguard after the first few magazines of ammo were shot. The entire barrel got so hot that it turned an ash color. I guess this was caused by all of the oil burning off. The thing is that I didn't have this issue when I had my heavy 16" barrel. What can I do to make my handguards cool effectively so that I don't have this problem? I'm open to replacing the handguards if there are some that work better. I'd like to keep the look similar though. Here's a picture of my handguards, outside on the left and inside on the right. Here's my new SDI 14.5" barrel. 
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most std. HGs have heat shields (the colt M4s have DOUBLE heat shields), but the recent DPMS glacier guards have plasic internal vents that sub in as shields the wide M4 HGs will fit, they just have a wider circumfrence (some are single heat shielded, others are double) check here for HGs: www.ar15.com/forums/forum.html?b=7&f=119 PS: i also have a couple for sale (both std. Bushmaster CAR HGs w/ single heat shields, and Colt Double Heat shielded wide M4 HGs--IM/EM if you are interested) : www.ar15.com/forums/topic.html?b=7&f=119&t=359467 
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The gray color is from burning off the oil soaked into the porous parkerized finish. It will return to previous color with oiling. You will feel some heat through the vent holes, but the handguards themselves should not get that hot with only 300 rnds... IF you have heatshields. Heat shields provide an insulating layer of air between the shield and handguard. But also the shiny handguard reflect most of the heat back into the air around the barrel. Since "hot air rises" simble convection will let the hot air move up and out through the vent holes to be replaced by cool air entering from the bottom. I have carbines with both M4 double and CAR single heat shields. Can't tell the difference. Even in the summer most of the heat from the handguards is from sunlight on the black plastic. |
| Thanks for the info guys! ALPHAGHOST, I guess that I was too slow to get your handguards. I think that I'd like the M4 style with a single heat shield. This should be able to work with my Sabre Defense Systems M4 type barrel, correct? Do ya'll have suggestions for a vendor who has good prices for quality M4 handguards and won't give me that shaft on shipping? |
You need a bolt-on handguard rail and a vertical foregip with those heat shields. I never feel any heat, even when my barrel is smoking like a tar barrel from the oil burning off under the handguards.  I had never seen a rifle smoke like mine did this past weekend after 120 rounds in less than an hour while sighting in my new scope and plinking for fun afterwards. I was very proud I had my VFG. |
You must have a typo in there somewhere. 120 rds in less than an hour? That's only one round every 30 seconds. Is that even enough to get the barrel warm to the touch? |
It was smoking like crazy (looked like an ashtray full of cigarettes - grayish white smoke), and I only put 4 30-rd mags down it total in a space of an hour while sighting in my new scope. The first two mags were sighting in the scope and shooting 10-shot groups of two different kinds of ammo (Ultramax and Rem UMC 55-gr FMJ) to compare them. Of course, the last two mags went down about as fast as I could pull the trigger because it was so frickin hot in the cow pasture where I was shooting, and I had to get inside to show my wife my targets and bring her out to make her shoot the carbine I built.  I think the last two mags are what smoked up the Rem Oil I keep on my barrel. |
You can have them on the condition that you will, at a later date, give a piece of gear to someone else in need. IM me your name and address. I'll get them out to you tomorrow. E&R |
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