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Posted: 11/6/2008 6:37:37 PM EDT
| I ran across a 7.5 pistol upper that has carbine length hand guard with car length gas system. I am having trouble deciding between that and a 10.25 or 11.5. The gun will be used as a trunk gun/pdw if ever needed and for range time. Any input would be great. I need to decide in the next day to get one-can't afford both. |
| I don't want to give you the idea that I know too much as far as pistol builds. I'm working on my 1st. I'm going by what I have found in here. I will use a carbine buffer set up. It all revolves around getting enough gas through the gas port for cycling. Someone will come along with 1st hand knowledge of 7.5" 5.56. I'm not sure what size port is used for a 7.5" |
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Quoted:
When you get below 10" it's more of a fun gun that a weapon. It will still work at short distances but you loose a lot of velocity. Also the shorter it is the more prone it is to cycling problems. But they look damn nice and can be made to run reliably. +1...if it's really going to be used as a "duty weapon" then the min length you really want is 10.5" Personally I'm partial to the 11.5". I'll explain my reasoning, I noticed you said you found a 7.5" that uses a CAR gas system. I'm not calling you a liar, it could potentially have one but generally speaking, lengths that short use "shorter than CAR" gas systems. The only reason this is bad is the increase in preasure over the CAR system which already operates at twice what the "full length" systems do. I own a 7" A4 from RRA and love it but in a pinch I'd rather have something I know I can count on for realiablity (not that my RRA has had any issues but it's just a peace of mind issue.) Starting with 10.5" barrels the manufacturers start using standard CAR gas systems. I like the 11.5 since it gives a little more barrel past the gas port to promote more equal preasure in front and behind the gas port and promote better cycling, though I would think this really only becomes an issue at higher cyclic rates. |
| I think I am going to go with the 11.5 knowing that know. I thought it was odd about the 7.5 having a car system but the maker said it was custom. Thank you for explaining about the reliability/cycling issues of shorter systems-I had no idea. Like I said the gun is going to be used as a trunk gun/pdw if needed and for ranges so I do want the relibility. |
| first off who was the one selling it. second off u can buy what is called a pigtail gas tube from brownells fro around $80 i think and its made for a 7 to 7.5 inch barrel and pretty much "tricks" your short barrel into thinking its a car length by giving it more dwell time. the tube wraps around the barrel which in turn makes it much longer than the standard 7 in. tube. |
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