VZ58 (VZ2008) Barrel/Gas Block Heat

[RSR]

I mentioned that you could drill holes in the upper handguard metal tube when switching over ot a mako polymer forend.  Their upper has "ventilation" holes, but since keeping the stock upper handguard tube, it actually provides no ventilation...

[TJNewton]

I mentioned that you could drill holes in the upper handguard metal tube when switching over ot a mako polymer forend.  Their upper has "ventilation" holes, but since keeping the stock upper handguard tube, it actually provides no ventilation...

What about drilling holes in the factory beaver-barf upper hand guard to ventilate?  I was thinking that some holes in the apex of the curvature on both sides, a roughly 45* "V" pattern if you were to be looking down the muzzle.  That way, vented gases wouldn't blur the sight picture as it may if the holes pointed straight up -- although the thought of a blurred sight picture is just speculation and I have no idea if that would actually happen.

Also, I thought of covering the inside of the lower hand guard with protective thermal tape.  I use it on my spark plugs to prevent them from getting melted by the headers.  Before, I had a dead spark plug every few weeks.  Now, no problems.  The headers are about 1/4" from the spark plug boot and run continuously at about 450* F at idle.  They probably get even hotter with spirited driving.

My concern with the protective thermal tape, however, is that instead of being vented or even warming up the lower hand guard, the heat will be trapped around the barrel instead.  Anyone know if that trapped heat is enough to be detrimental to accuracy or barrel life?

[RSR]

Ventilated handguards work in two ways on the VZ.  One is basic convection, heat flowing from upper to lower.  So for this to work as best as possible, you'd want steady holes across the bottom and slightly bigger volume/area holes across the top -- heat increases volume... 

The second way is just merely by not trapping the heat in there -- less using convection to cool the barrel and more just allowing the exhaust gases a place to go.

I believe bonesteel has holes in the location you mention if not slightly forward.  (Though I believe they're advertised as for set screws for stability/repeat zero.  Don't have BS HGs yet to see if it's stable w/o them.)

NEA has a hole immediately above the piston, with the underside contoured so that hotter gases are encouraged to exit through that hole by the force of convection, as well as through the side gaps between upper and lower.  That's why non-cowitness handguards definitely provide more cooling but worse sight picture, a compromise. 

Now if we really wanted a perfect CZ, we'd have a slightly taller front sight assembly (1/2-1") and run the full sized handguards providing ample ventilation on both the top and bottom.

[TJNewton]

Ventilated handguards work in two ways on the VZ.  One is basic convection, heat flowing from upper to lower.  So for this to work as best as possible, you'd want steady holes across the bottom and slightly bigger volume/area holes across the top -- heat increases volume... 

The second way is just merely by not trapping the heat in there -- less using convection to cool the barrel and more just allowing the exhaust gases a place to go.

I believe bonesteel has holes in the location you mention if not slightly forward.  (Though I believe they're advertised as for set screws for stability/repeat zero.  Don't have BS HGs yet to see if it's stable w/o them.)

NEA has a hole immediately above the piston, with the underside contoured so that hotter gases are encouraged to exit through that hole by the force of convection, as well as through the side gaps between upper and lower.  That's why non-cowitness handguards definitely provide more cooling but worse sight picture, a compromise. 

Now if we really wanted a perfect CZ, we'd have a slightly taller front sight assembly (1/2-1") and run the full sized handguards providing ample ventilation on both the top and bottom.

Thanks, some good info.

What do you think about the thermal tape on the lower hand guard?  It should minimize heat transferred to the hand, but if that heat doesn't go somewhere it will remain, at least for a while.  Will that lingering heat be detrimental? 

Also, if drilling the original beaver barf, wouldn't holes in the top hand guard be sufficient?  Heat rises, although that is probably irrelevant due to the force of the gases.  I'm sure they will follow the path of least resistance no matter which way that is directed.  Anyone tried drilling the factory hand guards?

What about these mods?

http://imgur.com/a/yO5NR?gallery

http://www.theakforum.net/forums/66-czechoslovakian/58103-probs-w-heat-transfer-lhg-fix.html

[marine6680]

I might look into drilling a couple vent holes.

Also maybe try making a heat shield, I have access to various thicknesses of aircraft aluminum.

[RSR]

Thanks, some good info.

What do you think about the thermal tape on the lower hand guard?  It should minimize heat transferred to the hand, but if that heat doesn't go somewhere it will remain, at least for a while.  Will that lingering heat be detrimental? 

Also, if drilling the original beaver barf, wouldn't holes in the top hand guard be sufficient?  Heat rises, although that is probably irrelevant due to the force of the gases.  I'm sure they will follow the path of least resistance no matter which way that is directed.  Anyone tried drilling the factory hand guards?

What about these mods?

http://imgur.com/a/yO5NR?gallery

http://www.theakforum.net/forums/66-czechoslovakian/58103-probs-w-heat-transfer-lhg-fix.html

Good tutorials.  The question is ultimately what you're trying to accomplish -- keep your hand cool or the barrel cool.  If you anticipate ever needing to do a lot of rapid fire, then keeping the barrel cool will extend the life of your rifle.  For relatively slow pace range shooting or hunting, then a deflector is probably sufficient. 

Insofar as air circulation if wanting to mod, I'd personally drill a couple to  holes in the bottom all the way down (1.5-2x the width of the hole in spacing to retain strength if in line), or you could space in jumps from side to side for better strength.  Regardless, there's not a lot of air circulation with the standard setup, that's why the heat radiates through the handguard rather than flowing away through convection. 

Insofar as convection, take a look at how baseboard heaters work.  Basically, air will circulate on its own from bottom to top based upon energy transfer, molecule spacing, weight, etc...

The only difference w/ the VZ is that you have hot air coming directly off the barrel through the piston as well which has an affect to account for... In particular this is what ventilation is helpful for.  If we just had barrel heat and not the gas port blowback, there'd be considerably less heat in the handguard.

No perfect answer here.  Identify your needs and modify to meet them...   

[TJNewton]

I have an extra lower handguard that I'm going to experiment on, but before making swiss cheese out of it (measure twice, cut once), I've been browsing photos of aftermarket lower hand guards and most of them have pretty radical venting with huge holes or slots.  The majority of them also have picatinny rails, which I assume are intended for some kind of additional fore grip that would keep the hand away from the heat.  But then I saw this one:

http://www.vz58rifle.com/images/200000091-1088c11814/quad_rail_troy.jpg

It has no picatinny and is to be held like the original.  Are those giant holes going to fry fingers?  I would not think so as it's a part that's been mass produced, but mass production is not always an indication of efficacy.

I wouldn't drill the beaver barf to that extent due to compromising strength.  I'd start small, test and redrill until the venting seemed adequate.  I'm thinking that 4-6 holes in the lower hand guard, like the ones pictured above but much smaller (1/8"-1/4"), plus eight small holes in the upper hand guard, four on each side at the apex of the curve, would be an improvement.

Does anyone have any aftermarket lower handguards with similar aggressive venting, and holds the rifle with a standard supporting grip, and still has the skin on their fingers intact?

[Sheepdog]

The Troy/NEA quad rail is to/can be used with small sections of rail. If you read the description on that site. It says the handguards come with to rail sections. You can put them a number of places. Google "troy quad rail vz 58". I suppose you could go without a rail for a vertical/angled grip. But I'd bet most people would just buy the upper portion of the handguard. Or use a railed piece.

[muggia59]

I installed the fab defense plastic handguards on my VZ. Today I found some old ar handguards, so I removed the aluminum heat shield. Cut it down, and slid it under the barrel on the VZ with lower handguard still installed. Actually fits pretty good, although it is not secured well. I know it has the holes on the bottom, but I am still going to try it out. If it works, I will do a less hurried job using the 2nd ar heat shield. Just an idea to try out.

[TJNewton]

I installed the fab defense plastic handguards on my VZ. Today I found some old ar handguards, so I removed the aluminum heat shield. Cut it down, and slid it under the barrel on the VZ with lower handguard still installed. Actually fits pretty good, although it is not secured well. I know it has the holes on the bottom, but I am still going to try it out. If it works, I will do a less hurried job using the 2nd ar heat shield. Just an idea to try out.

Looking forward to your results.

[huskerlrrp]

I just couldn't stand paying 1/2 the cost of the rifle for some new aluminum hand guards before trying this.


So far it's kept the heat down and the angled grip is nice for shooting. I used a cheap picatinny rail strip on the bottom and I put another rail on the right side for future use.

Now if I can take care of the fact I'm out of windage adjustment on the front sight this thing is going to be a shooter.

[muggia59]

An update on the ar aluminum heat shield. Worked pretty good. The top guard got warm, and the ends were hot. The lower hand guard was easy to hold. Granted it was only 6 magazines, and I also have a forward grip, but happy with the results, and it stayed in place. By the way Husker. Mine shoots right about 5 inches at 50 yds. And hit 960 gremlin free rounds

[cciman]

I agree with whomever has stated already:  The heat is there and it has to go somewhere, 2 main ways to relieve it- convection, or blocking it

Blocking it (with reflectors) will keep the handpieces cooler, but will keep that section of barrel hotter.

Convection with holes, or more thermally conductive handguards, will absorb the heat elsewhere, away from the barrel.  Increasing surface area (pic rails) or mass of the handguards will help most. 

Wear Gloves.  Framers gloves are great.