5.7x28mm AR (not AR57)

Post by **Esteves** » 09 Dec 2008, 19:35

22 boomer on Saubier.com has been busy.

http://www.saubier.com/forum/showthread ... ght=5.7x28" onclick="window.open(this.href);return false;

It's a straight pull bolt action single shot test gun at this point, for those of you who started drooling before reading.

Wollychop · Post by **Wollychop** » 09 Dec 2008, 19:36

Very cool conversion.

Post by **f3rr37** » 09 Dec 2008, 19:38

Wow, that is nice.

ArtosDracon · Post by **ArtosDracon** » 09 Dec 2008, 22:53

Nice, good lookin out. I'd assume you'll let us know when he get's the mag done and get's it running in semi-auto, maybe someone in the area can meet up with him who has an M-16 lower to make sure it functions well in FA. This is definitely something to keep an eye on. I'm not a huge fan of the AR57's layout, though bottom dropping brass is really nice.

Post by **jmz5** » 10 Dec 2008, 06:22

Sweet!

Post by **Cyberfly** » 10 Dec 2008, 07:38

And that was in Oct 07! I wonder if he ever did anything else with it?

LK45s · Post by **LK45s** » 10 Dec 2008, 09:54

Fly I thought the same thing you did when I first saw it. His join date was Oct 07. The post date was Nov 24 08.

Cyberfly wrote:And that was in Oct 07! I wonder if he ever did anything else with it?

Post by **Cyberfly** » 10 Dec 2008, 09:57

OH!! oops...my bad.
Okay. Makes more sense now. Otherwise it would have been found sooner, I'm sure!
Well, now. Don't I feel stooopid! :laugh:
You have to admit, that's a pretty ingenious idea. I'm more than curious how far he takes it.

LK45s · Post by **LK45s** » 10 Dec 2008, 10:06

I think it's good to have more choices in arms and ammo, I just wish I had more money to buy them.

Post by **jmz5** » 10 Dec 2008, 16:04

Me too.

Post by **Esteves** » 03 Nov 2009, 23:11

It looks like he got the gas system working and can feed it from magazines now.
Looks like a fun project.

http://www.saubier.com/forum/showthread.php?t=8086" onclick="window.open(this.href);return false;
http://www.saubier.com/forum/showthread.php?t=7691" onclick="window.open(this.href);return false;

Post by **f3rr37** » 03 Nov 2009, 23:33

Wow, looks great!

Post by **Grantness** » 04 Nov 2009, 14:16

Thats pretty F'in sweet. You know, I bet he could use the TC-only brass in that weapon since its got that rotating bolt. Just think, a semi-automatic 5.7x28 that you could load almost to TC velocities! :drool:

He's apparently loading lil' gun and H110 w/ 30gr Bergers. I dont see how he could get much velocity out of those powders w/ such a light bullet. There's not enough case capacity for those powders (in regular FN brass anyways).I think H110 (and I dont know about lil' gun either) could be dangerous in a blowback weapon. He should check out some of our data over here. I bet he could do a lot better w/ a faster powder.

That NVReloader guy is quoting him Win 296 loads w/ pressures. I wonder where he is getting his numbers from. Those pressures seem aweful low for the velocities he's getting. His OAL's seem really short too. Again, I dont know that I'd want to use that powder in a FsN or a PS90. I wonder if he's using the 296 in a TC or some other single shot weapon. He'd pretty much have to if he is trying to directly measure pressure.

22_boomer · Post by **22_boomer** » 11 Nov 2009, 03:35

The project rifle has been converted to gas operation (standard AR DI operation) and works with both commercial 5.7X28 ammo and reloads. Reloading can be done to much higher pressures limited only by the brass itself. Due to the length of the barrel (18.5")I started with slower burning powders but seem to get the best operation with Accurate #9. I built the test rifle so I could use a scope on a rifle that could be used a a varmint rifle. The 5.7X28 can be loaded up to very nice velocities and can come close to 22 hornet specs. The gas operated (DI) version uses the FN 5.7 pistol mags. The picture shows the rifle with an FN magazine and a 10 round extension. The rifle is still being tested.

Post by **jmz5** » 11 Nov 2009, 05:20

That is awesome. :thumb:

Post by **Esteves** » 11 Nov 2009, 07:43

Welcome! Great project.

Post by **Cyberfly** » 11 Nov 2009, 08:57

Welcome boomer! Awesome project. I'm jealous of your ability and tenacity!
Congrats!

22_boomer · Post by **22_boomer** » 11 Nov 2009, 12:00

AS you all know, the 5.7X28 round is really nice. At first, I wanted a simple rifle that I could use for varmint hunting or target work -- something like a bolt action, so I built the straight pull AR-15 bolt rifle. After shooting the rifle for a while I figured it was a waist not to have the AR gas operated. This rifle has been the most fun I've had in a long time shooting because, not only is it accurate, it's easy to reload for. The project had been picked up by a possible manufacturer who is familiar with the AR-15 system.

Post by **f3rr37** » 11 Nov 2009, 12:05

That's awesome, would love to see another 5.7 rifle out there.

Post by **jmz5** » 11 Nov 2009, 12:32

Nice, I would love to see an AR that takes a fsn mag, The ar57 just doesn't do it for me.

Post by **Grantness** » 11 Nov 2009, 12:48

Congratulations. That is an amazing project....and welcome to the forum :cya:

Have you tried anything faster than Acc#9? It's curious that you describe it as a faster powder, when all of the reloaders I know would probably consider #9 the slowest they would choose to use (in a blowback weapon, that is). Have you tried Acc#7, HS7, Blue Dot? Those seem to be among the best out of the FsN/PS90. I think the rotating bolt AR allows more leniency in powder selection than a blow-back like the PS90/FsN. As long as there are no problems with the gas system, you ought to be able to load to significantly higher pressures/velocities than the other weapons. It is a better design and I really hope your project gets picked up by the manufacturers. Good luck! :thumb:

22_boomer · Post by **22_boomer** » 12 Nov 2009, 12:25

To be honest, I have not tried any powders faster than AA #9. I know that the factory ammo has a faster burning powder (something like True Blue) but I wanted to stay with powders I knew. AA #7 will actually work a little better than #9, giving velocities over 2900fps but the pressure is up there for both powders and my main concern was saving brass for as many reloads as possible. I've decided to go with Blue Dot for the time being since good loads (2700+ fps) don't generate as much pressure. I've been using the 30 grain Berger bullets (my favorite) and 35 grain V-max. The brass can be loaded hotter but I guess I've found the best loads for me. That is the good point about the locked breach -- the only weak point is the brass. I have reloaded the same brass over and over as a test and have not had to pitch any yet. When I was first testing the rifle I ran some very hot loads. There is no problem for the action but I started getting over-sized primer pockets that meant the end for that brass.

Post by **Grantness** » 12 Nov 2009, 16:29

yea, one of the good things about the locked-breach design is that there ought to be far less shoulder movement...which equals longer case life. Like you said, the main thing to look out for would be primer pocket expansion. I've found that in the FsN, the first part of the case to fail is usually the shoulder or neck.

22_boomer · Post by **22_boomer** » 12 Nov 2009, 17:43

The part I liked most about the setup was the fact that the cartridge cases required only minimal amount of reforming before reloading. I know this is a pistol and PDW round but it makes a heck of a nice little small game hunting round out to 200 yards.

Pirate · Post by **Pirate** » 22 Nov 2009, 09:39

Coooool!!!!! :drool:

Lonestar50 · Post by **Lonestar50** » 20 Dec 2009, 20:37

Very nice, always nice to have other options out there.

Post by **Esteves** » 12 Mar 2011, 15:56

22_boomer's been busy.

From http://www.saubier.com/forum/showthread.php?t=12556" onclick="window.open(this.href);return false;

PainKillaX · Post by **PainKillaX** » 12 Mar 2011, 15:58

Oooooh nice

Mister Freeze · Post by **Mister Freeze** » 13 Mar 2011, 09:05

OOOOOOOHHHHHH!!!! YESSSSSS!!!!!! That's what I'm talking about!

Post by **blueorison** » 13 Mar 2011, 15:25

brb. Raising money for new pants for Freeze. :lmao:

I have a feeling none of the posts on this thread are going to be too productive other than

"SWEET"

"OH YEAH"

"AWESOME".
:laugh:

Mister Freeze · Post by **Mister Freeze** » 13 Mar 2011, 17:01

That's what she said.

Can my new pants have tacticool purple pinstripes?

Mister Freeze · Post by **Mister Freeze** » 13 Jan 2012, 10:14

Any developments? Magwell adaptor?

22_boomer · Post by **22_boomer** » 13 Jan 2012, 13:58

It's been a long time since I originally started this project and I have to be honest, I've not gotten much further except for changing out the handguard to full floater, changed the scope to one that's a bit more compact. The company that originally wanted to build these uppers kinda dropped out on me a ways back and never returned my parts. I should have known better but that's life. I will be honest -- I really like the FN pistol magazine but I did take a detour for a time and tried one of the magazines from the HK MP7A subgun -- a 40 round magazine. That magazine is all steel -- built like a brick outhouse -- and worked really nice but was just too expensive for me to really mess with. I also built an upper in a modified 4.6X30 round -- it's just necked down to 17 caliber and it runs like a champ and is what I've been playing with lately. My problem is I've gotten into a whole group of small cartridge AR's of different calibers so I have not had time to concentrate on any one. I guess my biggest disapointment is the fact that I never got around to finishing the design on the FN pistol magazine magblock although the originals I have work 100% in both the 5.7X28 AR upper and the modfied 4.6X30 (now 17X30) AR upper. A couple of other fellows have also gone and built their own versions based on the 5.7X28 design and they work great also. By the way -- and I don't have anything to do with their design -- but I believe CMMG has come out with a complete blowback AR upper with a 30 round magazine. It is a more standard design with their own 30 round magazine that fits in the standard AR magwell. Now if you wanted a factory 5.7X28 AR upper that's designed just for the commercial FN ammo and wanted to be able to put a nice scope on top this might be the answer.

Mister Freeze · Post by **Mister Freeze** » 13 Jan 2012, 19:06

What I'm interested in is a carbine that uses FsN mags. Period. Your work was by far the best yet, and I'd certainly be interested in a kit made up of a magwell adaptor, bolt, carrier, and even a chamber bushing. I would VERY much like to see something for the mini14!

What does the magwell adaptor look like and how does it work?

22_boomer · Post by **22_boomer** » 14 Jan 2012, 04:52

Mister Freeze wrote:What I'm interested in is a carbine that uses FsN mags. Period. Your work was by far the best yet, and I'd certainly be interested in a kit made up of a magwell adaptor, bolt, carrier, and even a chamber bushing. I would VERY much like to see something for the mini14!

What does the magwell adaptor look like and how does it work?

There's a picture of the adapter in this thread -- it's kinda primitive looking but it works really nice. The original idea was to have an adapter that held the FN pistol mag at the angle shown in the picture with a catch at the lower front of the magwell adapter to operate with the existing FN magazine catch notches. The idea worked but I don't have the finesse in workmanship to make a really good setup so I just decided to go with an adapter that just incased the magazine and came out with the mag when the mag release was operated. The reason for this was to give me time to find the correct alignment for the magazine to the feed ramps built into the AR barrel extension. The very first one I built like that worked so well I kinda stopped at that point and concentrated on other parts of the operating system. If I had a machine shop or could afford to farm the work out the adapter would be actually simple to make. I'll be honest with you -- due to the type of gas system on the Mini-14 I doubt the longer gas system would work with the commercial FN ammo or even hand loaded stuff. The gas system on my 5.7 AR is the short pistol length system. Too bad there isn't a way to get around the Mini-14 gas system without a major redesign since it would make for a really handy carbine. One of the other fellows that decided to try and make a DI operated 5.7 AR originally tried to go with an AR carbine length gas system and it could not be made to work. He had to thread and plug the gas port and move the gas port back to the pistol length position to get things working right.

Mister Freeze · Post by **Mister Freeze** » 14 Jan 2012, 12:40

I'd guess a larger gas port and/or softer recoil spring would be part of the equation. Reciprocating mass is a bigger issue with the mini too.

Is your barel chambered for 5.7x28?

My penchant for the Mini platform is robustness and ease of maintenance due to the availability of STAINLESS guns.

22_boomer · Post by **22_boomer** » 14 Jan 2012, 13:47

Mister Freeze wrote:I'd guess a larger gas port and/or softer recoil spring would be part of the equation. Reciprocating mass is a bigger issue with the mini too.

Is your barel chambered for 5.7x28?

My penchant for the Mini platform is robustness and ease of maintenance due to the availability of STAINLESS guns.

My barrel is chambered in 5.7X28. I had to modify my AR bolt and carrier to function with the small rim of the 5.7X28 cartridge, modify the extractor to catch the cartridge rim and modify the ejector to function with the small diameter cartridge. The carrier had to be modified to allow it to slide through the narrow FN pistol magazine feed lips and was lightened. Many things are possible and if you could except the possibility that it might not work, Maybe the Mini-14 could be made to handle the 5.7X28 round. Either a new barrel would be needed that was chambered in 5.7X28 or chamber sleeve made for an existing Mini barrel. The sleeve would need to be installed, maybe silver soldered and then chambered. The slide weight could be skeletonized to cut the weight down and the gas port opened some. The bolt face would need to be reformed to accept the smaller rim along with adjusting the extractor and ejector. I can work with the AR-15 since it's just a pile of parts that can be obtained easily and it's easy to swap things around -- I really don't know anything about the Mini-14.

Valorius · Post by **Valorius** » 15 Jan 2012, 21:12

I'd kill to get my hands on an AR that takes FsN mags!

22_boomer · Post by **22_boomer** » 16 Jan 2012, 14:27

Valorius wrote:I'd kill to get my hands on an AR that takes FsN mags!

I just reworked the 5.7X28 AR so it will work better for me. I really do like this setup -- should make a nice varmint rifle and field rifle now. I may get back into working on a magwell adapter some time in the future.

Kilibreaux · Post by **Kilibreaux** » 04 Aug 2012, 02:32

Has anyone considered having a custom barrel made in 5.7x28 for the AR platform? Add in a custom bolt to accommodate the smaller cartridge head and I see no reason why a gas-operated 5-7 cannot be built.

Post by **Esteves** » 04 Aug 2012, 06:40

Merged.

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