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Hookster

KZ U.S. made forearm review

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hey PANABAX, if you do make a set of gas pistons that seem to fit/work well in the nelli m4, id be interested in a pair of them whatever the cost. seriously, if you get it all figured out and they work let me know. i know your time is valuable and i dont expect you to spend all that time on parts for me for just peanuts. TS

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Thanks, 'cause the KZ sure looks nice, and I think Botach is the only place that has it.

 

Yeah, I think KZ (KleyZion) is an in house brand for Botach or they are the exclusive outlet for it.

 

www.KleyZion.com

 

Later,

Hookster :)

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hey PANABAX, if you do make a set of gas pistons that seem to fit/work well in the nelli m4, id be interested in a pair of them whatever the cost. seriously, if you get it all figured out and they work let me know. i know your time is valuable and i dont expect you to spend all that time on parts for me for just peanuts. TS

 

I will let you know how the project progresses. I have ordered a small amount of Stainless 15-5 to turn the pistons out of. I will need to figure out what hardness to shoot for. I went with the 15-5 because it has good tensile strength and toughness and is quite abit easier to heat treat that other steel allows. The PH stainless alloys only require heating to a particular temperature for a particular time and then are air cooled. There is no quench and no subsequent tempering involved. The material is used extensivley in areospace applications so I suspect it is up to the job of opening the M4 bolt.

 

I am pretty sure I read that the factory pistons are stainless, but I have no idea how to figure out what alloy it is or what heat treatment was involved.

 

Just curoius, from your name I assume you are in Texas, where? I live in Dallas.

 

Panabax

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The cuts in the pistons are carbon scrapers. There is 4 sets. The outside rings are aligned. The two between them are indexed 120 degrees offset and 240 degrees offset. The purpose is to scrap carbon build up and to moderate gas discharge.

The pistons are a grade of stainless. Unknown exactly which one from the factory.

 

The cuts around the pistons are complex. They will likely require custom bits to cut the steep angles in such small areas. The hole at the end of the piston is likely present as a live guide.

 

Establishing a heat treatment will be the hardest part along with some in the field testing.

 

Awesome job with the KZ rail. It looks very clean. Have you tried shooting high base rounds with it in place? The ARGO rarely vents from the front with low base shells.

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The cuts in the pistons are carbon scrapers. There is 4 sets. The outside rings are aligned. The two between them are indexed 120 degrees offset and 240 degrees offset. The purpose is to scrap carbon build up and to moderate gas discharge.

The pistons are a grade of stainless. Unknown exactly which one from the factory.

 

The cuts around the pistons are complex. They will likely require custom bits to cut the steep angles in such small areas. The hole at the end of the piston is likely present as a live guide.

 

Establishing a heat treatment will be the hardest part along with some in the field testing.

 

Awesome job with the KZ rail. It looks very clean. Have you tried shooting high base rounds with it in place? The ARGO rarely vents from the front with low base shells.

 

Hey SD, What came of your journey to CA to check out piston machining possibilities?

 

Hookster :)

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The cuts in the pistons are carbon scrapers. There is 4 sets. The outside rings are aligned. The two between them are indexed 120 degrees offset and 240 degrees offset. The purpose is to scrap carbon build up and to moderate gas discharge.

The pistons are a grade of stainless. Unknown exactly which one from the factory.

 

The cuts around the pistons are complex. They will likely require custom bits to cut the steep angles in such small areas. The hole at the end of the piston is likely present as a live guide.

 

Establishing a heat treatment will be the hardest part along with some in the field testing.

 

Awesome job with the KZ rail. It looks very clean. Have you tried shooting high base rounds with it in place? The ARGO rarely vents from the front with low base shells.

 

I shot both target loads and 3" 00 buckshot without problems.

 

If you look at the cuts in the gas rings you will see that the cuts are made with an ordinary end mill while the piston is turning. It is the rotation of the piston that creates the apparent complexity in the cuts. If you look down the angle of the cut you will notice that all the cuts are aligned on that angle. I don't believe the angle of the cuts is critical to function, while the offset from ring to ring may be. I will recreate the offset but probably not the angle of the cut. If I was programing it on CNC equipment, the angled cut would be the most efficient way to manufacture as you can make one cut on each ring with a single pass.

 

Panabax

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I'm thinking the cuts are mainly for water drainage. The angled cuts might induce spin during cycling to break up carbon build up, but I don't think it is all that important really. The cuts just give the carbon a place to go rather than bind the piston.

 

Our hobby project is moving along. We spec'd the pistons out last month. The numbers make much more sense in metric than in English. We're working with stainless also, I forget the exact type. It's not really my field. P17 H or something. It is in the annealed state to machine. Then the heat treatment will be outsourced. I'll try to break it before possibly sending the set off to Robar for NP3 coating. The barstock of stainless was pretty cheap. Something like 13 dollars. It was enough to make two pistons.

 

These will be done by hand on a lathe, so mass production isn't really an option.

Edited by StrangerDanger

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We're working with stainless also, I forget the exact type. It's not really my field. P17 H or something. It is in the annealed state to machine. Then the heat treatment will be outsourced.

 

Probably you are using 17-4 PH. The PH stand for precipitation hardening. It refers to the way the metal is heat treated. It is not heated, quenched and heated again to temper. It is simply heated to a particular target temperature and then allowed to air cool. The 17-4 is very similar to the 15-5 I decided to use. I will also do my best to break them. It should be fun.

 

Panabax

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Hookster,

You should try a Magpul Angled Forward Grip on your M80 and see how that feels. It might make the mount useful with a weapon light attached. I have a FDE one coming for my MRP. I dislike FVG's, but this seems quite different.

 

I guess it would work on the KZ rail too. It might be a great way to a lid the pringles can.

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Hookster,

You should try a Magpul Angled Forward Grip on your M80 and see how that feels. It might make the mount useful with a weapon light attached. I have a FDE one coming for my MRP. I dislike FVG's, but this seems quite different.

 

I guess it would work on the KZ rail too. It might be a great way to a lid the pringles can.

 

Yeah, that's definitely something to consider. I've seen the pics of them but I'm not sure if I'd like them or not. I think it's one of those things you'd have to try out to see what it feels like. I may be hitting the Cow Palace gun show up in South San Francisco this weekend. I'll see if there's one there I can check out.

 

Looking forward to a pic of one on your MRP!

 

Later,

 

Hookster :)

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I am in the same boat for the AFG. I like the concept since that is how I hold my MRP anyway. I figure for 30 bucks, I can try it without much regret.

 

I put GearSector's new QD sling mounts on the MRP last week. They're profiled better than the Daniel Defense model. They have the limited rotation blocks too, so you don't end up tangled in a knot. Plus, you can adjust how the rifle hangs by how the swivel is angled in 90 degree increments.

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i was also wondering who makes the best QD sling mounts?

 

btw is Gear Sector in any way connected with American Defense? their website design is pretty similar.

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I'm not sure if they're connected, but I know that LaRue hates GearSector, so that would make sense.

 

The issue is finding a rear QD sling mount. For the front mount, either the GearSector or the Daniel Defense will work when attached to your SideArmor rail.

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I never cared much for QD attachment systems. I'll take a Fastex buckle over QD any day. QD's have a habit of detaching when they're bumped. I freakin' hate dropping hardware. Nothing will illicit a dirty look from your superior faster than the sound of a weapon hitting the ground.

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There are a few different makers of QD sling mounts. Some are easy to release, some are a real PITA. You want the PITA ones. You can generally tell by how small the release button is. They should absolutely be recessed into the swivel too. The swivel studs on the VTAC sling from Vicker's are great as you can see below.

 

4273002037_03e6199500.jpg

http://farm5.static.flickr.com/4038/4273002037_03e6199500_b.jpg

 

Photo taken after several miles of hiking yesterday in some light hail and rain.

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you mean the vickers VCAS slings from blueforcegearDOTcom?

do you also use their Push button QD swivel and QD mount?

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Both are excellent. I have a Daniel Defense mount on my Benelli. I'd buy the GearSector over it though. It's a little more low profile. Both have the same limited rotation feature.

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