[spentcase]

I'm new to the RFB, very old to everything else firearms related.
As we transition ourselves from walnut and acraglas to the politically correct "Modern Sporting Rifle" and its parkerized, melonited TiN coated alloys and vunderpolymers, it seems as though some things change, yet some very decidedly stay the same. Case in point: My RFB CAN be accurate. But it is very very decidedly ammo sensitive. My favorite handload for my 18" AR10 consisting of a 155gr Amax over 41.5gr of 3031 and loaded to 2.785 (which is pretty much magazine max with Pmags in the AR10 and the FAL mags..) WILL shoot well at around 1.25". But they all touch at 100 with the AR. If I put some cheap ass perfecta in the AR, they will shoot into 2". The RFB does 4" with them. And I get vertical stringing with heat. Tula steel 147's get 4.5-5". The trigger isn't the issue, because the point of aim changes based on the ammo as well, even with nearly identical bullet weight. The AR will put all 150gr bullets in the same place. Now.. the AR is fully free floated. A wispy gas tube that can slide and move around at will in the upper.. no hindrance to the barrel at all as it heats. The RFB however..
Take it apart. The barrel is thinnest between the two "Towers" The front one of which contains a gas piston that exerts HUGE rearward pressure on the bolt carrier when it fires. This it turn would "stretch" the barrel between the locked bolt and the front tower. The barrel will also grow longer as it heats, and it is thinnest at the place it heats the fastest.. a few inches forward of the chamber. The only resistance is the aluminium rail that is screwed between the two towers an inch or so above the barrel. It's not steel, it has a different coefficient of expansion, and it can only act to cause even more variance in point of impact, depending on temperature, at the moment of firing. With this design, there's no way to fully float the barrel, and no way to fully bed the barrel.. or is there? What if the top rail were EXTREMELY rigid steel or titanium? Could it change barrel harmonics enough to dampen things? Orrrrr.. what if only one end of that rail was actually firmly attached to the barrel/tower, and the other end rode in a dovetail so the two parts could expand and contract at different rates? Thoughts? I want it to shoot 2" with ball ammo all day long.. any ball ammo that meets milspec. I don't want to have to spoon feed handlods to a battle rife knowing if I lose access to my press or run out of 3031 or Varget, that I have to re-zero my battle rifle and reduce my range by 300 yards... I can't handle having to readjust things for every load I feed it... Otherwise, what appears like a brilliant design will be up for grabs and I'll buy another AR...

 

[henshao]

The RFB is a unique rifle and if you expect it to run like an AR, I expect you will be disappointed in some ways and overlook other strengths. You already have to readjust the gas setting for every load you feed it, which some consider to be the ideal time to re-sight the rifle while you're at it. In regards to consistency, the barrel of the RFB is practically a steel girder compared to anything you'd find on an AR. That is not to say it is immune to heat-related shifts, but the biggest hurdle to accuracy in the RFB is the fact it inherited the not only the FAL's magazines, but also its chamber and excessive throat. It is not possible for bullets in standard-length cartridges to engage the rifling and the "jump" from case neck to actual barrel will hinder round-to-round consistency. Some have experienced better consistency from steel-cased rounds, which may be attributed to the stiffness of the case providing a more uniform "jump" to the barrel from the case neck for the bullet.

The same militaristic excessive throat, tilting bolt action, and widely-adjustable gas-systems means once the RFB has been dialed to a specific cartridge you can nearly expect it to run with the reliability of an AK-47, but with the power of a full-sized battle rifle in the size and ergonomics of a fully-ambidextrous sub-machine gun. Hope this helps.

 

[Evil_Edie]

I've managed 2.5 MOA ish groups with Norinco (cheapest ammo i can buy) shooting just off a table and monopoding on a foregrip, no benchrest, no bags. 2ish with PMC. I've tried Tula but that stuff gave me nothing but trouble so i didn't bother remembering the results. Cracked heads, stuck cases and such.

 

[ronmar]

Battle Rifle? the RFB IS NOT a battle rifle, nor is it likley to ever become one as I don't think it is(or ever will be) sufficiently "operator proof" to pass a military trial. You want one of those in 7.62 get an M1A or an AK, battle proven performance... Oh, by the way the M1 and any piston gun(including a piston driven AR) with the piston on the barrel suffers from the "features" you described above The RFB has the advantage of using the minimum ammount of force necessary to compell compliance(cycle the action). Hence the AR like recoil charicteristics in a 7.62.

You want better than minute-of-bad-guy consistency, beg KT to rechamber the RFB in a SAMI spec .308 chamber. I am fairly certain that you could beat 2" with most any ammo with a better chamber.
Your Tula result are interesting, as the steel cased Tula shoots the best in my RFB of all the handloads and commercial ammo I have tried. Kinda convienient that it is the least expensive I have however noticed that it does string a little bit, but IMO vertical stringing is almost always due to powder consistency/thermal stability. I have always wondered how well it would do with a more stable powder like Varget.

Considering different ammo almost always has a differnt POI that requires a sight adjustment. Anyone truely interested in precise marksmanship has no problem adjusting their sighting apparatus accordingly. I don't see why people get so wrapped around a different gas adjustment for different ammo especially if it maintains such a low recoil for a 7.62...

The RFB is what it is. But it has the ability to perform like an M1A never will. I know for a fact my 5'4" wife cannot throw an M1A to her shoulder and drill 20 rounds thru a 100 yard silouette rapid fire. I also can't shoot a M1A like a handgun very well, but it is doable with the RFB

 

[lilwoody]

I was in the same boat as you with the schizophrenic way my gen 2 handled different ammo. I went your route and started loading them down to 2.775/85 to get them to feed and tried everything from 115 JHP to 165 JSPs then I found a deal on 1000 Nosler 125 grain BTs and found the huckleberry. I loaded them in lengths from 2.780 to 2.800 with varying charges of 3031 and low and behold the 2.795/7s were the cats meow. That poly tip slips along the poly mags with great ease and my mag jams went to none. Getting the bullet further down the throat made it shoot right on par with my sons 16" Armalite AR10. And as for punch, I pity the critter that get's within 300 yards of it. The IMR 3031 also seems to be the powder that this gun was made for. I have very high hopes for this rifle to keep my family in venison and hog for many years to come. It should also give me great joy to vaporize a whole bunch of skeet, water bottles, wet phone books (their getting hard to find BTW) and all sorts of other stuff to make fly around the back stop at the range. It is also a very good topic of conversation when the stubby barrel AR guys show up with their breaked 10" rifles and want to know what that cannons my son and I are firing.
I bought mine primarily as a hunting/range gun, if things went south and a rifle was a must the RFB would be bartered away and I'd trust my safety to my tried and true Rock River AR15 HBAR carbine, there's nothing that rifle won't eat and I can carry 3xs the ammo for weight over 308. The Hornady 40 grain BTs I've worked up crono at 3250 with a case full of Varget print MAO and the 55 ss109 are a bit slower but just as accurate, I keep 500 of each on hand at all times. My range stuff is mostly what ever is on sale at Rocky Mountain or sportsman guide.

 

[spentcase]

Thanks Ron, as I was awaiting your reply..

Battle Rifle? the RFB IS NOT a battle rifle, nor is it likley to ever become one as I don't think it is(or ever will be) sufficiently "operator proof" to pass a military trial. You want one of those in 7.62 get an M1A or an AK, battle proven performance... Oh, by the way the M1 and any piston gun(including a piston driven AR) with the piston on the barrel suffers from the "features" you described above The RFB has the advantage of using the minimum ammount of force necessary to compell compliance(cycle the action). Hence the AR like recoil charicteristics in a 7.62.

You want better than minute-of-bad-guy consistency, beg KT to rechamber the RFB in a SAMI spec .308 chamber. I am fairly certain that you could beat 2" with most any ammo with a better chamber.
Your Tula result are interesting, as the steel cased Tula shoots the best in my RFB of all the handloads and commercial ammo I have tried. Kinda convienient that it is the least expensive I have however noticed that it does string a little bit, but IMO vertical stringing is almost always due to powder consistency/thermal stability. I have always wondered how well it would do with a more stable powder like Varget.

Considering different ammo almost always has a differnt POI that requires a sight adjustment. Anyone truely interested in precise marksmanship has no problem adjusting their sighting apparatus accordingly. I don't see why people get so wrapped around a different gas adjustment for different ammo especially if it maintains such a low recoil for a 7.62...

The RFB is what it is. But it has the ability to perform like an M1A never will. I know for a fact my 5'4" wife cannot throw an M1A to her shoulder and drill 20 rounds thru a 100 yard silouette rapid fire. I also can't shoot a M1A like a handgun very well, but it is doable with the RFB

Thanks for the reply, Ron, Because hey... you're the grand pubah around here..
But don't miss my point.. I LIKE the gun. I'm LEFT handed. There's nothing else like it in the the world for me, so I WANT IT TO WORK. I don't have any piston operated AR's and never will. It's an answer to a problem that never existed.. kinda like a double action 1911. I know my gun has a large chamber with an excessive throat. But I was looking for input on how to make this gun BETTER without a custom barrel (which is pretty much unobtainable anyway) An FAL or an M1A in pure milspec form will shoot better than this. I cannot and will not just pass off the advantage of "Short" (and that does not necessarily include "Light") and allow "Inaccurate with standard military ammo" as a concession. I think the gun can deliver more. Now, what do you think about an extremely rigid top rail, and or a "one end floating" top rail as a possible fix for the accuracy issues? Do YOU have any ideas to fix t? Based on my reading in these forums.. issues exist..

 

[henshao]

Well, I always hate to go here, BUT...

The first step is reducing/eliminating user error. So are you testing accuracy off-hand, on sandbags, out of a vice, or how?

 

[Steve912]

I don't have an RFB, just doing some drive-by forum reading.

How about old basics--how's the crown look?

 

[jonnin]

I know you said you didn't want handloads but if you loaded long to hit the rifling and made just generic ammo (lets say you make em 1/2 way between starting and max load for whatever components you are using) it should perform as you are asking. You don't have to depend on a brand of powder or bullets, but you would have to make them yourself. This is going to be your most practical solution. All the other answers mean major surgery to your gun, probably at great expense. Im sure someone would make you a barrel or knock a few thousandths off the one you have and reseat it closer ... what are we really talking here, a hundredth of an inch or two? I don't know if that is doable or not, but it might work if you had someone with skill to take a look.

A rigid barrel customization might help with the thermal issues. It won't do a thing for anything else you are talking about.

It sounds like you have a very nice AR.

 

[spentcase]

Someone with skill..

I know you said you didn't want handloads but if you loaded long to hit the rifling and made just generic ammo (lets say you make em 1/2 way between starting and max load for whatever components you are using) it should perform as you are asking. You don't have to depend on a brand of powder or bullets, but you would have to make them yourself. This is going to be your most practical solution. All the other answers mean major surgery to your gun, probably at great expense. Im sure someone would make you a barrel or knock a few thousandths off the one you have and reseat it closer ... what are we really talking here, a hundredth of an inch or two? I don't know if that is doable or not, but it might work if you had someone with skill to take a look.

A rigid barrel customization might help with the thermal issues. It won't do a thing for anything else you are talking about.

It sounds like you have a very nice AR.

Gee..Thanks. Let me go find someone with skill. Sure as hell isn't me. I can only load rounds that it will shoot well. One at a time. With much attention to detail. Far be it from me to make the GUN shoot plain ol' M80 ball that I didn't load. One at a time. With much attention to detail. It does say.. right on the side of it's receiver "7.62 NATO" Though. Four inches? No wonder it didn't pass any "Battle Rifle" tests. I can spoon feed it.. no problem. But eventually I'll lose interest. "Only accurate rifles interest me"... Ooops.. somebody said that already..

 

[spentcase]

Sorry, I didn't mean to sound condescending. I have built lots of guns and many contained no aluminium or polymer. And yes, My AR10 (a parts gun I built) seems to be exceptional (thanks in no small part to its 3lb Velocity trigger..) But the point is average accuracy with average available ammo that meets milspec of 4 inches off sandbags is less than ho-hum these days. Ask the Scar-SR762-PWS-LWRC-Knights-et-al guys... Like I said.. an average homebuilt or DPMSROCKRIVERBUSHYPSAANYBODY AR10 clone can do better. But it IS longer..

 

[henshao]

I'm not saying you are a poor shot, but I'm just throwing this out there. The RFB and bullpups in general can be more difficult than conventional rifles to shoot well with. The weight is distributed differently. The sight radius is small. They are short in length and hence a small jerk amounts to a large miss.

Furthermore you seem to have a particularly inaccurate RFB. Or others here are being very optimistic about how their rifles shoot. As steve912 asked, how is the crown/what muzzle device are you using? What is your sighting situation? Are your rail screws and mounting screws tight? Etc, Etc.

 

[spentcase]

I'm an average shot. And yes, the gun is quite different to shoot. There's not much room for the short forend on the bags. But I know when a flyer is mine, and sight-picture-squeeze-sight-picture-squeeze-sight pic-BANG! doesn't really change. Sight radius would matter with irons, but the gun is equipped with a Burris M-TAC 1.5-6x 30mm scope in a Burris PEPR mount, and yes the rail screws are tight. This scope has a Ballistic CQ reticle with a 1MOA center dot and a 32MOA circle with other ranging dots (I like it!) and it forms a perfect sight picture on round bullseye type targets.
I just re-measured my groups from the other day, and let me re-state that this mix of ammo I used all shoots to the same point of aim in my AR10, give or take a vertical inch based on velocity. My handload is as stated earlier is using the 155 Amax at around 2480, with the three types of ball (Tula steel, Perfecta brass boxer, and some old Lake City I had laying around) I used running around 100fps faster (all chrono'd out of the AR).
The best handload group measures 1.3" with a flyer taking it to 1.7 (These are all 5 shot groups) I think "Cool! it's a shooter" I zeroed with this expecting the ball to be an inch or so higher like it is in the AR. I put the Tula steel in it and the 5 shots end up in a 4" spread 6.5" low and about 2" right. This is right after the 1.7" centered group. I then try the perfecta brass. I start shooting and they're up higher, but still pretty bad and I know it's not me. With those I let 10 go (with barrel cooling time in between, I was loading 1 rnd at a time in the mag) and ended up with a 10 shot group, exhibiting vertical stringing that measured 4.5", with its center about 2" low and an inch and a half left. I was shooting at the same bullseye with these two, and if you put them together, I have a 15 shot group that measures 10" tall and 6" wide. The Lake city did a little better with a 3.5" group about 2" low. Going back to the handload had it shooting back on point of aim and 1.5-2"
SHTF. You're dragging your ass down an abandoned street desperate for food and ammo. You're out of those pet handloads (but the bad guys are all dead )You run across a Wal mart that no one found yet (Right!) and all they have left are twinkies and Tula..... And I picked the RFB instead of the AR10.. "It's lighter!" she said.. "It's compact and easier to carry!" she said... Then.. the Zombies. Hundreds of them. But I'm sighted for those damn handloads.. Help!

 

[henshao]

You say you've been shooting a long time so I'm just doing my best to not patronize you with things you may already know. Are you running the factory equipped birdcage flash hider, or something else? And, are you adjusting the gas system to these different loads?

The click setting of the gas knob must be made appropriate for every different type of ammo you run through the rifle.

Furthermore the reason we ask about the muzzle is because, well. Maybe someone more articulate than I can explain. As the bullet and the gasses pushing it exit the barrel, they need to do so uniformly in order to have the bullet go where you are aiming. If there is no muzzle device and a damaged crown, the gasses will exit in a haphazard manner and it will push the bullet to places where you don't want it to go. Some poorly engineered muzzle devices will do the same, and sometimes even well engineered ones will if they simply don't interact well with the ammo load/barrel harmonics/man-on-the-trigger.

 

[jonnin]

Gee..Thanks. Let me go find someone with skill. Sure as hell isn't me. I can only load rounds that it will shoot well. One at a time. With much attention to detail. Far be it from me to make the GUN shoot plain ol' M80 ball that I didn't load. One at a time. With much attention to detail. It does say.. right on the side of it's receiver "7.62 NATO" Though. Four inches? No wonder it didn't pass any "Battle Rifle" tests. I can spoon feed it.. no problem. But eventually I'll lose interest. "Only accurate rifles interest me"... Ooops.. somebody said that already..

You seem to have misread something. Im going to ignore you buttholeish attitude and say that the skill part was referring to a qualified gunsmith with tools who can knock a few thousandths off the barrel to move the lands closer to the lead so it will do better with straight up ammo off the shelf. If you can do that at home, go for it. I can't.

Your handloads sounded great and as I said, that is the most cost effective way to handle the issue. The other options are going to cost you more than the gun is worth or more than buying a tricked out ar-10 competition setup would cost (gun and doctoring total will run you more than a basic les baer 308 if you go all in!). You can fix anything with a gunsmith and an infinite budget. I have a single action Makarov that was worked over in our machine shop that shoots better than some competition 9mms and 45s. And it cost a month of man hours in design and twiddling (it was free as we did it on the sly, but that isn't the point).

what I am seeing are the hallmarks of
- heat stringing
- ammo quality
- tolerances

of which the top two are not too hard to fix but the third one will be a nightmare. And without the third one the second one won't matter unless handcrafted to compensate for the issues.



Im also going to argue that the results listed with handloads are proof to ME that the gun's crown / device are not an issue. It would be just as bad with crafted ammo as bought if the crown were fubared.

 

[spentcase]

Doooooods... hang on here. I stated some simple facts. This RFB simply doesn't shoot well. I've compared accuracy with a truly run-of-the-mill AR10 and it simply doesn't measure up. With the same damn loads. You're telling me it has to visit a gunsmith and be rechambered with a shorter throat and I have to adjust the gas for every load while the zombies are chasing me.. This is not a .22 rimfire. I expect to have to go through some ammo and sight my .22's with a particular type because of huge variances in velocity and bullet weight etc. Every gun is finicky. To a point. But a gun that says 7.62 NATO on it's side needs to shoot ALL 7.62 150 grain ammo to a reasonably close zero. Thats why we STANDARDIZE. I'm not being buttholish, just realistic. I shouldn't have to enlist the services of a gunsmith to make my chamber be what it's supposed to be already. Henshao. Jonin, guys... you made a significant investment in your guns. So did I. I like it. I like the way it handles. But I'm just not going to give it a pass. Most guns in this class have an adjustment that correlates to Suppressor/Regular/Dirty/Really Dirty/ Not 40 clicks between me and making my ammo work... with an adjustment I don't have the time or facilities to facilitate every time I switch. Really? Click something every time? What if i've never seen/fired it before.. hell it's M80? It ought to shoot to something close to the same point of aim, right? When I click, it needs to be my scope. For range adjustment. Not my gas system, to make it shoot ammo to the same point of aim. No matter what Ronmar says, this is a battle rifle, and I'm sure George has shopped it around the world as such waiting for someone to bite. It's not a sporter. It's not a competition target gun. It's a freaking BATTLE RIFLE. It should shoot accordingly.

 

[spentcase]

BTW: Jonin: If you look at the way the gun is designed, to fix the throat problem is quite involved. It would almost certainly require a new barrel. Although the receiver is screwed onto the back of the barrel and secured with a lock ring, any rechambering that moves the barrel rearward would require changing the relationship of the two shoulders on the barrel that the "towers" butt up to and are tightened against with their respective lock rings. This also sets the spacing for the stock through-pins. It's not like a bolt action in a wood stock where you just screw the barrel in a few turns and rechamber.. It would be difficult to rework at best and it should be right from the factory in the first place. Why isn't it? I would like to know straight up what kind of accuracy, and consistency you guys are getting with your guns across all ammo types and bullet weights without exagerrating. Forget how much you spent on it..

 

[henshao]

I know it's not what you want to hear, but don't direct your vitriol at us. Direct it at 'George' (so to speak). The RFB really should have a gas regulator of some kind. Until it gets one, you must adjust the gas system to every type of ammo you fire. It is the rifle's design.

Your AR pattern rifle has a huge spring in the stock to absorb excess bolt travel. The RFB has virtually no ability to absorb excess bolt travel (brick wall). Hence you cannot get away with running more gas through the system than is necessary to pick up another round, and obviously you cannot run less gas than is necessary if you are to be semi-automatic. A really really awful jam can occur if you don't have enough gas to cycle the action, as the previously chambered case may be forced back into the chamber and get stuck. And if you run significantly more gas than is necessary, all sorts of funny things can happen including inconsistent accuracy.

The good news is...finding the right gas setting is not difficult. Between similar loads it generally won't be very far, either. For instance, my rifle runs winchester white box at +7. I noticed it was smashing the case mouths of some old military surplus ammo I had (cycling too hard) so I opened to +9, which solved that.

 

[lilwoody]

Jonnin, I really hope you erred in typing when you stated knocking off "a hundredth of a inch or 2". In hand loading stuffing a bullet that deep in a case would be a receipt for very bad things. I've loaded over 500 rounds for this rifle from SAMMI spec OAL 2.805 down to as short as I dare to 2.775. That's 30 thousandths and I reduced the charge significantly to accommodate the extra pressure. In my experience the problem with the mag jams is the cartridges walk forward and dig into the poly mags. The gummy tips of the BT's just slip right along and being able to load them longer gets them closer to the rifling which improves accuracy. The main advantage of this rifle when carried cross shoulder on the chest is the ability to get on target faster than any other rifle I've ever owned.

 

[spentcase]

Henshao.. Did you not read my previous post? NOTHING I have posted so far has had anything to do with brass damage, or cycling. That is not my point. I just built a 7.5" ar pistol with an adjustable gas block. I'm hip to cycling, what's involved, how this gun is designed, how ar's are designed what a buffer is, what it does. Trust me, my gun cycles perfectly, does not exhibit any bad manners with brass, does not punish my shoulder or itself with excessive recoil et al. I'm not running too much gas. It locks the bolt back etc. I know what too much gas is and what it does. My AR10 has an adjustable block also. Geeeeez. You guys are sensitive about your investments aren't you? To me, it's a gun. It's a gun with an intended purpose. That purpose is rugged reliability, and reasonable accuracy across a fairly narrow range of ammo. Henshao, you did not tell me what kind of accuracy and consistancy you are getting..and I asked in my last post. You say I have to adjust my gas system for accuracy with every load I put in the mag. Really? Does that actually seem reasonable to you? How many rounds shall I expend.. in the heat of, well, killing zombies, to get it right each time I break out a new box of.. well.. M80 Ball? In my estimation, the gen1 gas system did not work due to the method of retaining the gas piston in its cylinder. The retaining lugs simply broke. The kludge fix as applied to my gen2 involves eliminating the retaining lugs altogether and using an extended spring-rod arrangement off the right recoil spring to basically retain the gas piston in its bore. It works, but they just didn't get the piston/bore/bleed setup right and there are at least 3 different pistons going out in the guns.. and here you are telling me I just need to keep adjusting it... right.. My problem is: Restated: Ammo consistency with factory M80 ball equivlent and.. overall accuracy. What's yours shooting??