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HFC M11 / Uzi- T77


ANDY_B

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mine is working fine on green with hfc mags,but behaving badly on the ksc ones!!(for every bb going down range five go out the side)

the stock has some issues but it really is an improvement on the m11 slither and the kwc mini uzi folding stock.(it locks in place open/closed)it needs some work to take up the slack/looseness,extended it is just the right length.

all in all i think this is a better weapon/better value than any m11.

(looks great with the silencer attached too!!)

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I got a PM requesting an update on the poorly advertist M11 I bought.

 

It was returned but I have not yet gotten my refund, due to current paypal issues.

 

Scott acknowledged he got it back though, and wrote saying how he was sorry for being "fooled" by the "high quality" plastic.

 

I should have the refund in a few days though.

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I got a PM requesting an update on the poorly advertist M11 I bought.

 

It was returned but I have not yet gotten my refund, due to current paypal issues.

 

Scott acknowledged he got it back though, and wrote saying how he was sorry for being "fooled" by the "high quality" plastic.

 

I should have the refund in a few days though.

 

I don't buy that Scott was fooled - he was trying to fool you. He sells hundreds of airsoft stuff for a living so there's no excuse. You did the right thing and returned it. Lastly, he should correct his M11A1 product description on the website.

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The use of plastic bolt might be a reason why T77 shoots way over 1J. The bolt is very lightweight. Speaking of KSC M11, it actually doesn't have all-plastic bolt, the rear part (with a hook) of the bolt is made of steal which is pretty heavy. On the other side, magnesium bolt has both parts made from the same material. If you compare their weights, you get almost the same number: about 70 grams.

 

I combined magnesium rear with plastic front and was able to shoot over 1J as well. But I stick with all-magnesium bolt cos it's more durable and the weight is better distributed.

 

Now imagine T77 with all-steal bolt...the power would decrease a lot.

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Utty - youre absolutley right. He's very mixed up.....

 

actually there IS sort of a "free lunch" when it comes to this gun, but it has nothing to do with the bolt.

 

The design is a single-spring for its recoil and hammer spring. So the same spring controls FPS and ROF.

 

Putting a spacer or buffer onto the recoil/hammer spring mech will dramatically increase both ROF (the bolt has less distance to travel, and this doesnt affect feeding because the bolt only has to go halfway back to pick up a bb) and FPS (increase spring tension leads to a harder valve smack).

 

:)

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My assumptions are based on experimental results.

 

Temperature: 22 degrees of Celsius

BBs: KSC 0.20 g

Chronoscope: Combro cb-625 Mk 4

Gas: green (top) gas

 

gallery_7001_612_17234.jpg

 

70 g all magnesium bolt average muzzle velocity = 335.042 fps

50 g plastic + magnesium bolt average muzzle velocity = 346.792 fps

 

Please explain why a light-weight bolt results in higher fps?

Well, think about conservation laws (conservation of momentum) of an assumed isolated system. The gas charge is used 1) to fire the BB and 2) to move the bolt to its original position. This system will have constant total momentum P = mass of BB x velocity of BB + mass of bolt x velocity of bolt. Mass of BB is a constant, e.g. we use the same BBs (0.20 g). If we decrease bolt weight, the velocities increase. It is mostly noticable on the bolt side and you will experience higher velocity of bolt = higher ROF, but from my measurements it is clear that it also has an impact on the velocity of BB (muzzle velocity).

 

In reality you will have to consider many other factors, e.g. pressure & friction losses, recoil spring strength, etc...

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and what's this about better weight distribution, what difference would that do for an internal bolt?

You can assume that the bolt is kind of long piston inside the cylinder (upper & lower receiver). If the weight distribution of the piston is asymmetric (e.g. rear bottom is too down and front top is too up) it increases friction losses.

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I appreciate your graph, den, I think the best conclusion you can gather from this is that for *some reason* the lighter bolt gives you a higher velocity. Balance of the bolt within the gun has little to do with anything, as long as the bolt is machined properly and is lubed.

 

Over the long haul, the magnesium bolt will hold up much better, and a slightly stronger hammer/recoil spring or small spacer added to the stock spring will produce a better increase in FPS (more than the ~10 youre getting for sure) with added durability of a full-metal bolt.

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