View Full Version : Running the bolt carrier on rails...
Has anyone tried this? I mean on an AR15, it's extremely common in other light autoloading rifles.
It would of course require some pretty big design changes. I feel like one of the biggest potential reliability problems with the AR is that it runs the round bolt carrier inside of a round tube and there's limited space for dirt and fouling to go.
this is definitely not one of those "teh AR15 is unreliable!" threads, a properly built AR is very good.
it just seems like running the bolt carrier on rails could potentially improve the reliability of DI guns, and alternately mitigate the whole "off axis force' due to gas pistons.
down side... what do do with the buffer setup....
There's plenty of space for dirt and crap to go. The carrier has bearing rails on 4 sides of it with several thousanths of gap between the carrier and the receiver everywhere else.
Animal_Mother556
11-18-11, 09:56
could potentially improve the reliability of DI guns
Just my opinion...
Sounds like trying to fix something that isn't broken.
There's plenty of space for dirt and crap to go. The carrier has bearing rails on 4 sides of it with several thousanths of gap between the carrier and the receiver everywhere else.
SpringCo would have to come with a totally different color spring for that. :D
Then it wouldn't be an AR.
Stoner went on to develop the 63, which used a stamped steel receiver and gas piston. It saw limited trial use by the USMC, but saw quite a lot of use by the NSW guys in it's beltfed mode
Ok, let's go with this.
Exactly what rail system/style were you proposing? A simple raised area in the upper? Somthing that utilizes the bcg dimensions, and captures an area of it?
Tell me if I'm tracking you correctly.
There is an AR with the bolt on rails, it's called an AR18. Google it for the design.
You wanna make something that already runs on rails.....run of rails instead?
There's a huge "Yo, Dawg...!" Xzibit joke floating around in here, somewhere, just waiting to drop, so you might want to take a moment and re-think how you want to articulate this.
You wanna make something that already runs on rails.....run of rails instead?
There's a huge "Yo, Dawg...!" Xzibit joke floating around in here, somewhere, just waiting to drop, so you might want to take a moment and re-think how you want to articulate this.
I think we can all agree that compared to something like an AK the AR15 has quite a bit less clearance for dirt.
I'm thinking redesigned carrier and upper. It's just a thought... compatibility with as much existing hardware as possible seems to be the route to success in the AR game. This platform is definitely not going away.
Given how many piston guns sell (which tend to be poorly thought out hacks) ... I'm hesitant to completely dismiss this idea.
The AR-18 is the father of most modern designs and it is awesome, they thought it would crush the AR-15 but it was too late, Look at the G36, SCAR, ARX 160.
The AR has a good manufacturing process though, CNC machines are a dime a dozen, no tooling required, simple boring and on axis alignment, but it really makes all the sense in the world when you consider the gas system and how it doesn't provide the tilting moment. So there is no need for a perpendicular surface to cancel the moment.
There is good and bad with all, but the true piston AR was the AR18, I wonder if it could be brought back by a good name and get any real military sales.
There is an AR with the bolt on rails, it's called an AR18. Google it for the design.
The AR-18 is the father of most modern designs and it is awesome, they thought it would crush the AR-15 but it was too late, Look at the G36, SCAR, ARX 160.
The AR has a good manufacturing process though, CNC machines are a dime a dozen, no tooling required, simple boring and on axis alignment, but it really makes all the sense in the world when you consider the gas system and how it doesn't provide the tilting moment. So there is no need for a perpendicular surface to cancel the moment.
There is good and bad with all, but the true piston AR was the AR18, I wonder if it could be brought back by a good name and get any real military sales.
i don't think anything that can't be slapped onto an AR lower is going to see serious sales. The ACR proved that.
I looked into ar18's when i was new to the whole EBR game... they've got some durability problems i guess, and parts support isn't anywhere near where it is with the Ar15.
those daewoo rifles are neat, but hard to come by also.
An Undocumented Worker
11-18-11, 18:41
i don't think anything that can't be slapped onto an AR lower is going to see serious sales. The ACR proved that.
I looked into ar18's when i was new to the whole EBR game... they've got some durability problems i guess, and parts support isn't anywhere near where it is with the Ar15.
those daewoo rifles are neat, but hard to come by also.
Have you looked at a M&P 15-22 it uses seperate rails for the bolt to ride on. Something similar could be done on a full caliber AR but would only be usefull or needed if making a piston gun, at that point why not just buy a SCAR?
Too late
http://i1087.photobucket.com/albums/j468/Danger131/2ueimoj1.jpg
i was kinda hoping for a meme free dialog here but ok....
if you think the AR is perfect you're delusional and this thread isn't' for you.
bottom line is something like an AK is a lot more likely to function when full of sand. Something i haven't really seen addressed in any alternative AR upper is the whole round peg in a round hole situation with the bolt carrier and receiver. It's a design not really found anywhere else.
DeltaSierra
11-18-11, 19:44
bottom line is something like an AK is a lot more likely to function when full of sand.
Sorry to burst your bubble, but NO weapon will function reliably if it is full of sand (or any other abrasive substance.)
The whole "AKs are super reliable" is as much of a myth as saying that "ARs jam all the time."
Both weapons can fail ( I have experienced failures with both types of weapons) and neither one will function without proper care.
I don't think it would serve any logical purpose to redesign a weapon. If you don't like it, get (or design) something else.
Trying to jimmy-rig a weapon is not the way to wind up with a durable reliable end result.
Heavy Metal
11-18-11, 19:48
i was kinda hoping for a meme free dialog here but ok....
if you think the AR is perfect you're delusional and this thread isn't' for you.
bottom line is something like an AK is a lot more likely to function when full of sand. Something i haven't really seen addressed in any alternative AR upper is the whole round peg in a round hole situation with the bolt carrier and receiver. It's a design not really found anywhere else.
Daewoo has it.
Suwannee Tim
11-18-11, 19:56
Instead of making it run on rails, maybe on air bearings. Sure you would have to carry a compressor on your back but think of the improved reliability!
i was kinda hoping for a meme free dialog here but ok....
if you think the AR is perfect you're delusional and this thread isn't' for you.
bottom line is something like an AK is a lot more likely to function when full of sand. Something i haven't really seen addressed in any alternative AR upper is the whole round peg in a round hole situation with the bolt carrier and receiver. It's a design not really found anywhere else.
I think its perfect. Its perfectly killed more people than small pox. That being said you are out of your ****ing league junior. Every half baked design you can dream up has already been tried at least twice. If you want a bolt group on rails, there are a dozen rifles to fit your needs. Unfortunately the AR-15 isn't one of them. Now do us all a favor and go away quietly...
The carrier already has rails
http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0004-2.jpg
If you study it closely, you will see the design is given generous clearances to allow the BCG to float inside the upper. Eliminating tilt with rails means the clearances at those points need to be reduced. If more clearance is needed to assure reliability, this defeats the purpose.
Guide rails do not eliminate bolt/carrier tilt in other designs. Designers just reduce the amount of tilt by keeping the bolt/carrier short and/or controlling where the tilt vectors happen. With the AR BCG, tilt happens at the rear of the carrier where it can rub the receiver extension. This isn't a problem with the original design because little tilt is induced. With the AK, the tilt happens at the front (the AK bolt group is longer in front of it's guide rails than at the rear) and the tilt rubs nothing
steelonsteel
11-18-11, 22:59
what could be easier than the guideles rails already on the BCG?
Now if you're implying you want to add more room around the BCG where the rails AREN'T, to theoretically add more room for dirt and debris to go, a'la AK-47, that would make some sense, though I don't know if that's an answer in and off itself.
I'm not trying to be combative or sound like a know it all but I devoted a lot of personal time and money studying the whole AR15/AK47 jam thing - I discovered some interesting; stuff and broke a lot of gear.
While AK's can be more tolerant of fine foreign objects - i.e. some sand or dirt, a lot of said foreign materials STILL induces jams if it gets into certain spots like the bolt lugs. I woudn't say it happens a lot though - Generally the bolt is forward and that keeps most of the stuff out. Converserly, having all that big room can allow pebbles or small stones inside, and those pieces can work thier way into the fire control group, the auto/safety sear, or into the chamber [if during firing sequence - unlikely] and this will shut the whole thing down pronto.
The AR on the other hand because it has tighter tolerances, doesn't even allow larger bebris to meke it past the port door. Fine abrasives or foreign material can make it in, but if properly lubricated, surface tension generally mves this stuff out of the way of the moving parts. Generally speaking, making sure there is enough lube is usually the problem - I say usually [in some areas where there is baby powder/talcum powder grade fine sand there are other issues but even then the closed port door negates most of this].
So adding more space may not absolutely give you what you desire here.
hope that adds some insight and helps!
SilverTongueDevil
11-19-11, 00:54
If you want rollers just buy a HK
what could be easier than the guideles rails already on the BCG?
Now if you're implying you want to add more room around the BCG where the rails AREN'T, to theoretically add more room for dirt and debris to go, a'la AK-47, that would make some sense, though I don't know if that's an answer in and off itself.
I'm not trying to be combative or sound like a know it all but I devoted a lot of personal time and money studying the whole AR15/AK47 jam thing - I discovered some interesting; stuff and broke a lot of gear.
While AK's can be more tolerant of fine foreign objects - i.e. some sand or dirt, a lot of said foreign materials STILL induces jams if it gets into certain spots like the bolt lugs. I woudn't say it happens a lot though - Generally the bolt is forward and that keeps most of the stuff out. Converserly, having all that big room can allow pebbles or small stones inside, and those pieces can work thier way into the fire control group, the auto/safety sear, or into the chamber [if during firing sequence - unlikely] and this will shut the whole thing down pronto.
The AR on the other hand because it has tighter tolerances, doesn't even allow larger bebris to meke it past the port door. Fine abrasives or foreign material can make it in, but if properly lubricated, surface tension generally mves this stuff out of the way of the moving parts. Generally speaking, making sure there is enough lube is usually the problem - I say usually [in some areas where there is baby powder/talcum powder grade fine sand there are other issues but even then the closed port door negates most of this].
So adding more space may not absolutely give you what you desire here.
hope that adds some insight and helps!
thanks, that's some good insight.
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