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Posted: 8/5/2005 1:09:30 PM EDT
And no, it's not a thread about if anyone use a FF setup in the movie Heat. I'd like to know from the various users what their experience is with various handguards. Here's mine:

Standard carbine handguards: Get fricken hot after a few mags of quick semi-auto fire
M4 handguards: Not much better than carbine handguards
KAC MRE: Don't get hot at all. Amazing.

Your experiences?
Link Posted: 8/5/2005 1:12:28 PM EDT
I don't think anyone in HEAT used FF handguards. Maybe you should watch it again?
Link Posted: 8/5/2005 1:17:35 PM EDT
During a carbine class in 100 degree heat index, my DD 7.0 rail system on my M4geryish got uncomfortably hot throughout the day, to the point where I had to purchase a FVG on the spot so that I could hold the rifle. Gloves would have helped, but I didn't have any. The FVG (TD) did the trick. Up until that point, I had always been a magwell holder with a couple of fingers wrapped up near the handguard. I'm still adjusting to the damn FVG.
Link Posted: 8/5/2005 1:33:27 PM EDT
Never had a freefloat tube get too hot to hold from firing. I've used both KAC FF-RAS and Daniel Defense - both of them with KAC rail panels. I've had the barrel as hot as 365F and you could still grab it by the foreend and even the exposed rail was tolerable (though just barely).

However, I have had the tubes get insanely hot from just sitting in the Texas sun. Even with the KAC panels on, it was too hot to hold without flight gloves. This is why black is not a friendly color for guns here.
Link Posted: 8/5/2005 1:42:19 PM EDT
The two rails I have used extensively, Grenadier Precision and ARMS SIR, both get too hot to hold if you shoot them enough. Rail covers fix the problem for me.
Link Posted: 8/5/2005 6:36:59 PM EDT
In that same class with Mongo, My custom DD got very hot. I used a TD VFG with thumb forward, weakside hold, and I wasn't at all uncomfortable. I didn't use gloves because I didn't feel the need. I would recommend Magpul or TD panels for anyone serious about training hard and refusing to use a VFG.

Be well!

damian@adcofirearms.com
Link Posted: 8/5/2005 6:56:09 PM EDT
I put a c-more quad rail with 3in rubber panels on a dissipator and that does VERY well.
Link Posted: 8/5/2005 7:21:47 PM EDT
ARMS #50 SIR was cool after mucho rounds.... Heavy yet cool...

J223...
Link Posted: 8/5/2005 7:27:45 PM EDT

Originally Posted By dubb-1:
In that same class with Mongo, My custom DD got very hot. I used a TD VFG with thumb forward, weakside hold, and I wasn't at all uncomfortable. I didn't use gloves because I didn't feel the need. I would recommend Magpul or TD panels for anyone serious about training hard and refusing to use a VFG.

Be well!

damian@adcofirearms.com



Were you & Mongo using rail covers on your DDs ?
I use KAC rail covers on the DD 7.0 & it stay pretty cool,
The Magpul covers that came with the DD do almost nothing to keep your hands away from the hot tube.
Link Posted: 8/5/2005 7:37:25 PM EDT
[Last Edit: 8/5/2005 7:39:53 PM EDT by StealthyBlagga]
I have a "plain vanilla" aluminum FF tube on my IPSC rifle. It gets hot as hell after a couple of rapid mags in the summer AZ sun. My fix, which was 100% successful in eliminating hot-hand syndrome, is paracord:



Cheap, Simple and Good Looking... just like me .
Link Posted: 8/5/2005 7:44:38 PM EDT
The SIR's run the longest before getting hot as there is no alum. under any insulating panel needed due to their design. A panel works great for a very shot while, that is untill the lower alum. handguard that can't radiate heat because of the insulating panel. Alum. attracts heat and poymer not touching alum. much less so. Double insulated M4 handguards, really fry the weapon because the weapon can't radiate the heat away fast enough. Blown barrels from double heat shielding told the military to go free float. The same goes with barrel mounted alum. rails that are in direct contact with the heat traveling into alum. handguards. Direct heat is much more severe and faster than radiant heat transfer.
Free float alum. rails will not get as hot as quickly, but put a cover/panel over them, and they also get hot real fast, campared to no cover. Cover the alum. rails all around at the 3,6, and 9 positions traps heat inside untill it breaks out, real fast once it starts. Naturally, the more the weapon is fired, the faster it gets hot. Other factors govern the speed and heat travel direction, beside rate of fire. The contour of the barrel, ie, a heat sink is created if the barrel is thin in the middle like the now being replaced M4 skinny in the center barrels, Heat like water, seeks the least resistance. Unfortunately, the thinest place on the M4 contour barrels, is right under the place we put our hands.
The military and finley the gov't manufactures, ran thurmal coupling heat transfer tests, and free float came out to be one of the solutions. A heavyer barrel that is not designed to be a heat sink was another. Not covering alum. rails so they can't breath is another one, all contribute to a cooler weapon and longer barrel life, less chance of blown barrels, and or cook offs, and fewer malfunctions do to over heated weapons.
Over heated weapons is like overheated car engines, they don't work as well if there is no heat dispersion.
Jack
Link Posted: 8/6/2005 4:43:28 AM EDT
I concur with 3rdtk about the double insulated M4 handguards cooking the barrel. You might not feel the heat (being blocked and reflected back into the barrel), but its there all the same.
Get used to wearing glooves for lots of reasons that don't have anything to do with heat.
When one of my Platoons completed Jungle Training in the Phillipines, they had about a 90% hand injury rate. So we went down to the Subic Bay/Cubi Point Supply Issue Point and took every pair of Summer Flying Gloves they had in stock. Then we made it Company SOP to wear the glooves at all times in the field.
The 3 subsequent Platoons going through the jungle training had almost nil hand injuries.
Later that year we did a 4 day op in Korea that was about 95% all night time movement to contact accross totally unfamiliar terrain. This meant that lots of guys slipped, fell, or otherwise subjected their hands to injury potential in the dark. However, since we were all wearing the glooves, our injury rate from such was again nil.
Compared to the injury rate suffered by our sister Companies on our flanks who had everything from severe cuts, nasty scrapes, ripped off finger nails, etc., we in Charlie Copmpany were 100% effective.
Its just like wearing a helmet years before Charlie Company. Before I went to Jump School where (1) we were taught how to adjust and wear it properly, and (2) were required to wear it for 3 weeks straight, I was always the first to take mine off because it was so unconfortable, and I falsely felt I was more effective with my head bare or wearing a soft cover.
Link Posted: 8/6/2005 4:55:49 AM EDT

Originally Posted By garr:

Originally Posted By dubb-1:
In that same class with Mongo, My custom DD got very hot. I used a TD VFG with thumb forward, weakside hold, and I wasn't at all uncomfortable. I didn't use gloves because I didn't feel the need. I would recommend Magpul or TD panels for anyone serious about training hard and refusing to use a VFG.

Be well!

damian@adcofirearms.com



Were you & Mongo using rail covers on your DDs ?
I use KAC rail covers on the DD 7.0 & it stay pretty cool,
The Magpul covers that came with the DD do almost nothing to keep your hands away from the hot tube.



Of course. I was using KAC rail covers. It still got uncomfortably hot.
Link Posted: 8/6/2005 5:29:07 AM EDT
[Last Edit: 8/6/2005 5:35:52 AM EDT by Yojimbo]
If you can hold the rail with your bear hands then you aren't shooting...

Before I knew better I thought gloves were for sissys and the vertical grip was a usesless "Tacticool" accessory.

The combination of a black gun sitting in the hot sun and fast rapid fire shooting equals burnt hands.

Heat is also one of the reasons I like the vertical grips. Even with Nomex pilots gloves on it can get too hot to hold the magwell or rail if you're doing a lot of rapid fie shooting.
Link Posted: 8/6/2005 5:34:56 AM EDT

Originally Posted By Yojimbo:
Before I knew better I thought gloves were for sissys and the vertical grip was a usesless "Tacticool" accessory.



Big assed +1.


I was thinking about this a little and I know part of my issue. Being a magwell holder, my hand is also in close proximity to the barrel nut and tube lock nut, both of which are uninsulated. I just cannot hold the rifle by the handguards. My wrist feels all wrong and the front of the rifle feels completely unsupported. YMMV. Anyway, I either hold it by the magwell or FVG and feel like I have more control.

My issue now is after a reload, I automatically go to the magwell, probably muscle memory. I still cannot consistently transition from a reload push/pull to the FVG, even though it is mounted as far back to the magwell as possilbe. I need to work on this some more.
Link Posted: 8/6/2005 9:19:04 AM EDT
Gloves do help the shooter hands, but they don't help to make the most important thing function better, the weapon. If a weapon crashes because of over heating, the soldiers gloves can't protect him/her from an AK that didn't over heat. The most important thing, is to do whatever possible to help the weapon expel heat in the most rapid means available. A pistol grip is very helpful in certain situations. It should not be primarily used just to get away from over heated panels attached to an overheated alum. rail on the bottom of the weapon where the hands go. As mentioned and shown time and again, panels contribute to a weapon over heating, because they trap heat, that wants to radiate. If heat cant radiate, it will travel to the various other places of the weapon, to include the receiver.
A weapon with no hand guards covering a barrel will run cooler, longer and more trouble free, because of rapid heat dispersion.
M16/M4 barrels will and do go up to and in some cases, over 900 degrees in sustained fire. They won't do it long, especially if the barrel is shrouded and can't breathe to radiate heat away to cool the weapon.
There isn't any hand guard that won't get hot, however the degree of temperature felt by the hand is relative to how hot the weapon is being allowed or forced to heat up. The weapon heating, or over heating, is relevant to a lot of contributing factors, some already mentioned.
The SIR systems have run about twice cool than other systems for several reasons. They don't have an alum. lower rail close to the barrel to rapidly attract and store heat. The polymer they use, any polymer, rejects and expels heat about 5 times faster than alum. Since heat rises, and airflow directs it, the shape and larger the volume of air the SIR hand guards provide are pushing heat up and away, like a fireplace and chimney works, the faster the heat will be allowed to escape.
The military and industry have experimented with ceramic lined barrels, just to reduce heat issues. To date, nothing has proven to be practical, do to other problems, rifling for bullet stability the biggest, and adhesion to the steel, and other proprietary barrel making materials tried.
Short of putting on a water jacket, solar elec. storing fans, weapon powered fans, dry ice, and maybe ceramic bores, we are going to have to deal with heat problems as long as we use conventional bullets.
Jack

Link Posted: 8/6/2005 10:33:23 AM EDT
[Last Edit: 8/6/2005 10:34:24 AM EDT by garr]
How about some kind of fin system (Like used on Hot water baseboard heating systems), Enclosed in some type of properly vented free float system designed to draw heat away from the barrel & Expel it upwards (mount the fins only to the upper half of the barrel)?
My thinking is to try & keep the lower handguard cool, While expeling heat away from the barrel.
Link Posted: 8/6/2005 10:51:12 AM EDT
Guys, this is getting a little anal, and perhaps straying into the realm of fantasy.

If you are shooting full auto out of an M16, I can see how you could overheat the barrel to the point where its service life will be dramatically shortened. However, even infantry soldiers in a fierce firefightare unlikely to heat an M16 barrel to the point where it could actually fail right there in a firefight, if nothing else just because of the limited amount of ammo they can carry on their person at any one time. If the barrel wears out prematurely due to excessive heat, well thats what unit armorors are for. Of course, the strory is different with crew-served auto weapons, which have quick-change barrels for a reason.

The risk of real heat-related failure is even more remote in a civy semi-auto weapon... again, how much ammo are you feasibly going to discharge ? IPSC/3-gun is probably the most demanding (or maybe an intensive carbine course), and certainly the handguard can get uncomfortably hot, but damage the barrel to the point of failure ? I don't think so.

Your particular rifle may malfunction as it warms up, but thats a weapon reliability issue rather than heat-related damage per se. Stock ARs are overgassed somewhat to allow for the extra operating force that may be required as the chamber heats up.

My 2 cents worth: for a defensive carbine, find some way to hold your rifle without discomfort when it gets hot (heat shields, pistol grip, paracord or a glove) and don't sweat it beyond that. Match rifles, where accuracy is at a premium, may be different, but I don't think thats what we are talking about here.
Link Posted: 8/6/2005 11:06:23 AM EDT
when i decide i want to dump lots of ammo my handguards get smoking hot!!!!!

had a few times when the barrel rubbed me and seared of my skin!!!!

i have done this with the arms sir, larue, yhm, and stock handguards.

the one that stayed the coolest was the arms sir, probably due to its large amount of metal to offer as a heatsink which dissapated heat faster or stayed cooler longer.

the larue setup had magpuls on one and td's on the other both stay cool enough to hold but its not comfortable. after awhile it gets unbearable. one has a surefire m900 on it so its not bad but i do see the heat coming off of the metal.

the original handguards get super hot!! and feel as though they are going to melt off.


magwell holds work but after awhile the heat gets to it too.



living in hot a$$ tx doesnt help either, all of the high heat issues are usually all day shoots with about 1-2k going down range with occasional 7-8 30rd mag "breath, pull trigger" dumps

nothing scientific
Link Posted: 8/6/2005 11:43:53 AM EDT
PRI carbon fiber
a good thing
Link Posted: 8/6/2005 12:08:27 PM EDT

Originally Posted By doc_Zox:
PRI carbon fiber
a good thing



They get hot, also.
Link Posted: 8/6/2005 12:42:22 PM EDT

Originally Posted By StealthyBlagga:
Guys, this is getting a little anal, and perhaps straying into the realm of fantasy.

If you are shooting full auto out of an M16, I can see how you could overheat the barrel to the point where its service life will be dramatically shortened. However, even infantry soldiers in a fierce firefightare unlikely to heat an M16 barrel to the point where it could actually fail right there in a firefight, if nothing else just because of the limited amount of ammo they can carry on their person at any one time. If the barrel wears out prematurely due to excessive heat, well thats what unit armorors are for. Of course, the strory is different with crew-served auto weapons, which have quick-change barrels for a reason.

The risk of real heat-related failure is even more remote in a civy semi-auto weapon... again, how much ammo are you feasibly going to discharge ? IPSC/3-gun is probably the most demanding (or maybe an intensive carbine course), and certainly the handguard can get uncomfortably hot, but damage the barrel to the point of failure ? I don't think so.

Your particular rifle may malfunction as it warms up, but thats a weapon reliability issue rather than heat-related damage per se. Stock ARs are overgassed somewhat to allow for the extra operating force that may be required as the chamber heats up.

My 2 cents worth: for a defensive carbine, find some way to hold your rifle without discomfort when it gets hot (heat shields, pistol grip, paracord or a glove) and don't sweat it beyond that. Match rifles, where accuracy is at a premium, may be different, but I don't think thats what we are talking about here.



You must have missed the part why the military has gone to free foat, heavier barrels, etc. The weapons have, are, do, and will crash in a fierce fire fight, if they get (too) hot. The barrel extion that goes into the alum. receiver, does become out of alignment by gradually tilting down. When this happens, the bolt head can't lock up to fire. The most common occurance because of this barrel downward tilt, is that a bolt lug breaks. Other things like failure to extract due to a brocken extractor also occure.
It is very easy to see if a weapon with a (barrel mounted rail) is headed to problems, and if the barrel has begun to tilt down. Put a strait edge on top of the receiver, and out over the top of the handguard. If there is air space under the strait edge thats over the alum. rail attached to the barrel, you have a weapon that is headed for malfunctions. Pulling on a pistol grip hasdtens the barrel tilt, when you get to 1/8" to 3/16" of air space under the strait edge to the top on the alum. rail, you will know why problems have begun, the barrel extention is out of alignment with the bolt head.
The barrel is going to get hot, buy not (trapping heat) is the best way of not letting it get (over heated). The weapons that get the hottest, are the p[erfectly round types, and the fewer the vent holes, the more they get hotter, faster.
Fins on barrels do help a lot on barrel cooling for sure, but very expensive. Fluting also helps, the more flutes the better, and not as costly as fins, but still more costly than the new heavy tappered barrel.

Link Posted: 8/6/2005 12:53:16 PM EDT
Clarification. The weapons that get hottest, and the fastest, are the ones sporting perfectly round tubes. The ones with the fewest vent holes get the hottest. No air flow what so ever.
Jack
Link Posted: 8/6/2005 1:00:58 PM EDT
[Last Edit: 8/6/2005 1:02:10 PM EDT by Yojimbo]
If I could just figure out how make a Picatinny mount for the solar fan below I'd be a rich man!

No batteries and it can keep both the user and the barrel cool!



Link Posted: 8/6/2005 1:05:06 PM EDT
SHHHHH!!!! That is a double secret proprietary gov't taxpayer program, If I tell you any more about it, i'll have to kill ya!
Jack
Link Posted: 8/6/2005 1:07:17 PM EDT

Originally Posted By 3rdtk:
SHHHHH!!!! That is a double secret proprietary gov't taxpayer program, If I tell you any more about it, i'll have to kill ya!
Jack



Link Posted: 8/6/2005 1:45:32 PM EDT

Originally Posted By garr:
How about some kind of fin system (Like used on Hot water baseboard heating systems), Enclosed in some type of properly vented free float system designed to draw heat away from the barrel & Expel it upwards (mount the fins only to the upper half of the barrel)?
My thinking is to try & keep the lower handguard cool, While expeling heat away from the barrel.

JP rifles sells a heat sink but it has to be a .650 barrel and you gotta wanna pay $75 for it.only on my space gun project.they got some nice lookin shit but red and blue?
Link Posted: 8/6/2005 4:19:12 PM EDT
Link Posted: 8/6/2005 4:41:09 PM EDT
I like to have a rail that goes the full length of the barrel or nearly so, and thick covers. I also like to wear gloves while shooting. This way, I don't touch my barrel or a hot front sight base. The rail and receiver can get hot, yes, but I've yet to get one of the other too hot to hold by the VFG or with gloves. I have on occasion gotten a CAR handguard equipped rifle too hot to hold with bare hands anywhere but the magazine. Not magazine well, that sucker was hot. The magazine.
Link Posted: 8/6/2005 5:18:56 PM EDT
I usually only run ladders on my carbine. Magpul XT on my SPR, though.

damian@adcofirearms.com
Link Posted: 8/6/2005 5:45:22 PM EDT
Both where not hot after dumping the Beta's. Same with my Knights M5-RAS. So they help a shit load.
Link Posted: 8/6/2005 5:48:25 PM EDT
Link Posted: 8/6/2005 5:51:39 PM EDT

Originally Posted By C4iGrant:
3rdtk, you had me going there for awhile, until I got to the part where you said that plastic is 5x better for heat dissipation than aluminum is. I can't seem to find this miracle plastic on Google that has these incredible heatsinking properties. Additionally, the reason your SIR handguard doesn't get AS hot is because it's nowhere near the heat . FF rails (KAC, DD, TROY, LT, etc) pull barrel-killing heat off of the chamber / throat area and then dissipate it down the tube.



Good Shootin,


C4



Not just my SIR but all the ones tested by the gov't, plus thousands in service with the military in the hot desert and on law enforvement and civilian weapons. The chamber isn't what gets hot first, it's actally the coolest internal place. Why, because there isn't any rifling causing friction, friction causes heat, it must be in google somewhere. LOL
I'd say that it is smarter to keep away from a heat source, rather than put a heat absorbing material like alum. close to it and then even cover it with panels that won't let the alum. cool, just fry everything, before going down a tube. Anyone can try putting a piece of alum. out in the sun, next to a piece of polymer, put a temp guage on them each, and see which gets hotter faster, and cools faster.
Jack
Link Posted: 8/6/2005 6:02:38 PM EDT
Link Posted: 8/6/2005 6:27:55 PM EDT

Originally Posted By C4iGrant:

Originally Posted By M4-TUNA:
img.photobucket.com/albums/v370/M4-TUNA/DSC00314.jpg Both where not hot after dumping the Beta's. Same with my Knights M5-RAS. So they help a shit load.




MMMM BETA!



C4

One more will be added to my stash when they come out with the 308 version. M14 is coming out soon. My buddy is going to love that one. Can you say HOTTTTTTTTTT barrel.
Link Posted: 8/6/2005 6:37:51 PM EDT
Heated (air) is going to escape in any direction it can, just like water pour out of any orifice it can as long as it is not trapped. All railed and tube systems I have seen are open in the front, but only provide a minimum of heat dissipation, thermal coupling test show that clearly, if not vented elsewhere. However, heated air is not the only issue, any material like alum. with extra high heat absorbing mineralogical principles, absorbs and retains the heat, at about a minimum of 5 X's of what any polymer does. The barrel radiates heat, and then the heated alum. rails obsorb and store it to radiate heat back towards the barrel. If all is trapped by rail coves, rapid over heating is accelerated. A polymer lower isn't going to store and radiate heat like an alum. lower, therefore another reason the SIR's run cooler. Gene Stoner and the othe folk at the original Armalite knew enough not to put alum. hanguards over the barrel, but they didn't need alum. attachment tails either. They did design thin (.040) alum. heat shields, but they also made shure there was a stand off from the plastic hand guard, for circulation and no direct complete contact between the plastic and thin alum. Double heat shields without venting made things worse, by masking the real problems with a band aid effect. Like giving somone an aspirin when they are bleeding.
Jack
Link Posted: 8/6/2005 6:38:17 PM EDT
Link Posted: 8/6/2005 6:49:05 PM EDT
Under sustained rapid fire my Knight's Armament RASII is so cool it's almost cold. I'd rest my balls on it.
Link Posted: 8/6/2005 6:51:17 PM EDT
Link Posted: 8/6/2005 6:54:40 PM EDT
Sub calibre weapons don't get as hot , or as fast, because they are at a much lower velocity compared to something like a 5.56. Any all alum. rail system would work just fine.
Jack
Link Posted: 8/6/2005 6:56:44 PM EDT

Originally Posted By Hokie:
Under sustained rapid fire my Knight's Armament RASII is so cool it's almost cold. I'd rest my balls on it.



Hmmmm, the tin man lives. LOL
Link Posted: 8/6/2005 6:57:30 PM EDT
Link Posted: 8/6/2005 7:00:21 PM EDT
[Last Edit: 8/6/2005 7:02:43 PM EDT by Hokie]
< pic removed >
Link Posted: 8/6/2005 7:05:24 PM EDT

Originally Posted By Hokie:
< pic removed >



You can pick up your purple heart in section! LOL
Link Posted: 8/7/2005 8:29:51 AM EDT
Hmmm, I wonder if it is possible to use the heat generated by firing to provide a small electrical charge? It would be neat if you could recharge batteries in some kind of tiny system that is similar to geothermal electricity generation. Not only would you have one more system keeping your barrel cool - you could now have extra power for all the crap hanging off those rails.


However, heated air is not the only issue, any material like alum. with extra high heat absorbing mineralogical principles, absorbs and retains the heat, at about a minimum of 5 X's of what any polymer does.


3rdtk are you claiming that aluminium retains heat 5x longer than plastic because that is not my experience? Aluminium may heat up faster than plastic; but it also radiates that heat away faster too.
Link Posted: 8/7/2005 8:39:47 AM EDT
It never fails to amaze me the sheer amount of information that comes out of the woodwork aorund here. What a great place!

From what you all are saying, I'm getting some sense of why my MRE stays cooler. Lots of holes for venting, lots of surface area for heat disapation (between the radiating surfaces around the edges of the holes and the longer length of the handguard system). I also like the longer length cuz when I sling it or let it rest, the barrel doesn't come to rest against my legs or shoulder. That can leave a mark!

So the physics we seem to be dealing with are materials, surface area and points of barrel contact. Sound right?

Those SIR's are heavy buggers, aren't they?

Anyone taken a PRI FF, drilled lots of holes like a KAC unit and then added offset rail covers? Would that work? I have never worked with CF.

Lots of great information. Thanks.
Link Posted: 8/7/2005 2:19:07 PM EDT

Originally Posted By Bartholomew_Roberts:
Hmmm, I wonder if it is possible to use the heat generated by firing to provide a small electrical charge? It would be neat if you could recharge batteries in some kind of tiny system that is similar to geothermal electricity generation. Not only would you have one more system keeping your barrel cool - you could now have extra power for all the crap hanging off those rails.


However, heated air is not the only issue, any material like alum. with extra high heat absorbing mineralogical principles, absorbs and retains the heat, at about a minimum of 5 X's of what any polymer does.


3rdtk are you claiming that aluminum retains heat 5x longer than plastic because that is not my experience? Aluminum may heat up faster than plastic; but it also radiates that heat away faster too.



Well, I'm not claiming anything just sighting the results reported from tests long ago, currently, and shown again in the field. Polymer manufacturers always point out the thermal cooling abilities, etc. apposed to using metal, and my own experiences and others I have witnesses.
The alum. as you note, does get hotter and faster, but don't forget that these new polymers and even plastic never get as hot as the alum. in the first place. Then consider that alum. can't be hand held nearly as long as the polymer in the same exact scenario of firing. Alum. must be covered by a polymer panel to allow hands to keep holding the weapon, when all tests are conducted evenly. Even then, the (panel) covering up an alum. rail, is going to get much hotter faster than any polymer, especially one that is not required to be in direct contact with alum. rails. Alum. is like a sponge for collecting heat, attaching a polymer to that alum. keeps the alum. from doing it's radiant cooling like it could if not covered by a panel.
I have already mentioned that anyone can check out these things with a temp gauge themselves.
Put a polymer panel out in the sun, and a piece of alum. beside it, then check the temps for the speed of absorption and cooling times.
Jack
Link Posted: 8/7/2005 2:42:43 PM EDT
Originally Posted By IDK:
It never fails to amaze me the sheer amount of information that comes out of the woodwork aorund here. What a great place!

From what you all are saying, I'm getting some sense of why my MRE stays cooler. Lots of holes for venting, lots of surface area for heat disapation (between the radiating surfaces around the edges of the holes and the longer length of the handguard system). I also like the longer length cuz when I sling it or let it rest, the barrel doesn't come to rest against my legs or shoulder. That can leave a mark!

So the physics we seem to be dealing with are materials, surface area and points of barrel contact. Sound right?

Those SIR's are heavy buggers, aren't they?

Well, I don't think my 50C slim line feels any heavier than any other carbine length plus lighter than some, and there is a reason.
When wts. are given, the wt. of the panels needed on all the other type handguards is not included, and my SIR does not need or use protective panels. The polymer lower handguard on the SIR is less wt. than the others that all use alum. lowers. I can select what rail I want and where I need it, with the others I have no choice. The SIR does have exra wt. at the rear that attaches to the receiver, to me it gives more pluses than negatives. It balances the weapon better for me, it gives me an ability to use lower rings for stronger support of optics, provides a lot more strength by attaching to the barrel nut and receiver. Since The SIR doesn't need to have panels under my hand, I have a nice slim handguard to grasp and not as likely to get burned on.
Jack

Link Posted: 8/7/2005 5:29:28 PM EDT
Link Posted: 8/7/2005 8:28:08 PM EDT
I have the YHM ultra light-weight carbine FF tube it does nt get hot at all, well not that I can notice. I got it from jacks black rifle shop for $80 new on gunbroker.
Link Posted: 8/7/2005 8:43:56 PM EDT
Three words. Plastic Verticle Grip.
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