User Panel
Posted: 3/26/2006 9:26:40 AM EDT
The other day I was contemplating the various reasons the AR platform has such great accuracy potential when compared to other self loading designs. What I came up with is the inline actuation possible with the direct gas impingement system. There is no bending torque on the bbl due to bolt carrier activation. This is also why the AR system can get by with the upper and lower being non-matched parts and the bolt carrier traveling in both pieces. Only the front of the bolt carrier is semi precisely controlled in it's path. The rear of the bolt carrier is not a precise fit in the buffer tube.
All this is fine with the direct gas impingement because all the forces are directly inline with the bore. Now if we convert the AR to gas piston and feed the tappet forces into the top of the bolt carrier we are introducing a downward thrust on the bolt carrier. The rear of the bolt carrier is going to be thrust downward as it is traversing into the buffer tube. Is the force of the action spring sufficient to overcome this downward torque ? Is the offset between the action spring and the tappet small enough that the torque is not a problem? Are the gas piston upper manufacturers engineering various solutions to this issue ? rj |
|
It is called carrier tilt. The LWRC piston guns use a downward sloping key that re-vector the forces to eliminate carrier tilt. No effects on accuracy.
|
|
It has been acknowledged and addressed by Leitner-Wise, as evidenced by the above post. Ask Paul about it in the LW forum, and he'll likely talk your ear off in "Physics" lingo. He talks right over my head... |
|
|
40 years tells me direct gas works. Pistons in an AR15 need a few more wars or years proving their mustard before I'll bite |
|
|
I'm thinking very seriously about getting an LW. I have a friend who swears by his. I would like to check it out and see the differnce first-hand.
Apparently heat is vented out of the system as well, keeping it runing much cooler than DG. Like I said, though, I'd like to see for myself |
|
|
|
|
heat eats the bolts, extractor, extractor springs and even the mag feed lips.
There is no heat in receiver with gas pistons. Simon |
|
I'm pretty sure that 55,000psi in the chamber is going to direct some heat at the bolt even in a piston system, though maybe less than a direct gas system. The major problem I see with heat in ARs is that the brass stays stuck to the chamber walls longer as the chamber gets hotter and the extractor starts to either slip, rip through rims, or the bolt short strokes. Even that only happens at extremes of heat or in guns that were marginal to begin with.
I think the real test will be LWs new .308... if they can deliver AR accuracy in a reliable rifle there, that should pretty much settle any conceivable issue I can imagine concerning direct gas v. gas piston. |
|
How many offset pistons are winning in F-class, etc competition? |
|
|
How many are being entered? |
||
|
Attend any HK416 demo and after numerous mag dumps, they'll pull the bolt and carrier. It's never warmer than ambient. Same is true for the LW system. The interesting thing we are noting is that we are seeing substantially longer component life including magazines which can only really be atributed to lack of heat and propellant gases in the receiver. |
|
|
My guess would be none because the "No effects on accuracy" claim has a very very very small likelyhood of being true... |
|||
|
Or, and more likely, no one who competes has purchased one yet |
||||
|
They should be beating down your door to get one if it does everything you say it does and has no negatives... Heck, just the claimed velocity increase should have serious competitiors lining up to use your system! If I had a system like yours that overcame long-proven weaknesses of previous incarnations of the same general idea, I'd sponsor a few top competitors to get out there *prove* to the world how great it is... |
|||||
|
In my experience, heat is a big factor. I've seen a lot of guns that won't go down unless you get them warm, and they don't need to be auto to get that hot, esp in the SW. |
|
|
There ARE lots of us "beating down his door" to get one, and THAT is the reason they are backordered! |
||||||
|
At an overseas demo today in 120 degree heat the LW system ran flawlessly for six hours. The same could not be said for the DI guns present. |
||
|
Griz:
We don't have that many systems out there at the moment. Most of those are in serious use (not paper punching). For the time being, I don't see someone who has invested thousands of dollars in a competition gun hanging it up and starting from scratch again with a piston operated system - only time will tell as to whether there will be any move towards such use of this system. In extensive back to back testing against DI weapons the question of accuracy of the short stroke piston system has never been raised and I do not have any experience of negative accuracy reports for OUR system; the only reports we do have confirm the same or better accuracy than DI but these of course are subjective user reports rather than solid scientific studies. These reports are from both commercial users and military. Please bear in mind that the longest barrel we use at the moment is 16.1" and all weapons are configured for military rather than target use. The few DMR's we have built are tack drivers but there is just not enough experience out there to to draw a line in the sand definative. I guess the real point here is we've all shot the competition, very few have shot ours. As for sponsoring a few top competitors to *prove* the system, I don't see any cost benefit to such an activity as it's very unlikely to influence the core customer base that we market to. I'd sooner put the money into hiring more staff to try and get our back order situation under control. |
|
Competition shooters don't go out on a limb with new equipment. They wait for someone to beat them with it. Then, they line up to buy it.
|
|
I understand that your target market is mainly interested in "minute of man" performance... Shooters who pay very close attention to accuracy (ie those who shoot for score) have long ago proven that previous offset piston design are indeed detrimental to accuracy. Given this, surely you can understand that people tend to take all of your claims with a healthy dose of salt when you claim that your system has "no effects on accuracy"... Given the claims of increased velocity and no adverse effects on accuracy, I'd expect competitors looking for an edge to be building spaceguns around your offset piston. |
|
|
Maybe, but I don't see your point? Are you saying that ALL piston designs are handicapped in the accuracy department or all AR type piston designs? You've really lost me. What I suggest is that you come and see us and bring your best target DI weapon. We'll supply ammo, lunch and a selection of our products and we'll shoot them back to back; that way, although it's not scientific, at least you'll have first hand experience and we may capture some interesting data. What ya say? It's getting warmer after all. |
||
|
I'm just saying that unsubstantiated marketing claims are counter-productive...
No, I'm saying that as far as I know, in-line pistons like the AR-15 are proven to have an advatage over more traditional offset pistons. I'm not aware of any accuracy-critical competitions where offset pistons are beating in-line pistons. If you know of a circuit where offset-pistons are dominating, please enlighten me. I don't know if your's follows the pattern or not, I was suggesting that if it really breaks the mold, that the best way to prove it would be to get it in the hands of someone who will start winning matches with it.
That would be fun, but my precision rifle would burst into flames if it got within 100 meters of you (It's a Grendel ). I may have business in the DC area this summer, if I do, I'll give you a shout. Where is the range that you frequent located, and how long is it? |
|||
|
Don't worry about the grendel - we have flame retardent range gear! As for the range, we normally use the St. Charles Sportsman's club in Waldorf MD, max is about 250 yards but you can get a good idea of performance at 200.
I think it would be worthwhile - we're shooting all the time anyway (tough job but someone has to do it), if you can't bring the grendel then we'll just have to pull out a 5.56mm DI for you. As for unsubstantiated claims, I have to disagree; all of the range reports and targets posted here have been from customers. |
|
What a great offer!!! Griz, your even in VA!!! If a manufacturer ever invited me and I was close, I would be there in a minute!!! Go test them out and post your results. |
|||
|
It's a very generous offer (but I wouldn't let him to buy lunch), and I seriously hope to take him up on it. I can't be there in a "minute" though since I'm on the opposite side of the state... It's a 6 hour drive if there is no traffic (last time I had to go to the far side of DC where LW is, construction + NoVa and DC traffic added about 2 hours to that ) |
|
|
Yes, yes, that's all very good...but NOT UNTIL MINE'S FINISHED! |
||||||
|
It's a helluva lot more fun than sizing gasports for DI guns, R&D'ing flashlights, and gel testing |
|
|
Ya know, I've always thought it was funny that long range shooters TYPICALLY have bare muzzles, when it has been shown to me over and over that an effective flash suppressor and/or sound suppressor actually INCREASES the accuracy of a rifle. I understand that they do this by "cleaning up" the gases coming out the front of the barrel and acting on the bullet as it begins its flight.
Explain that one to me? BTW- I think it would be VERY difficult to scientifically prove the effects of the piston, since you'd have to compare the SAME rifle before, and after. However, "after" also involves fitting the parts to a VERY tight tolerance, therefore possibly affecting accuracy. Possibly, you'd have to take a rifle, test fire it, then take it apart, put it back together, test fire it, THEN take it back apart, retrofit it with a piston, THEN test fire it. I'm a "people-shaped-paper" shooter, so I don't give a rip about sub-MOA differences in accuracy, ONE WAY or the other... I'll take functionality over accuracy any day. |
|
My point is that they're always looking for an edge when the wind is blowing. Getting a velocity increase for free is a huge edge. Either you're not getting the word out to them or they don't believe you... I guess it doesn't matter though since you're not interested in that market and can't fill all of your orders anyway. |
|
|
We don't close our eyes to any market - as I said before, time will tell.
|
|
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.