[hotwings]

I have only about 1000 rounds through my 24" RFB.

I have been shooting PMC 147gr ammo only. Note I did not clean the action between any of these range trips:

I got the gas system adjusted reliably and the first 200 rounds (first range trip) i had zero issues once it was dialed in.

The next time i went to the range, i was constantly getting FTFs (about 1 every 5-6 shots). I closed the gas system by 2 clicks and it seemed to operate OK for the rest of the day.

The next range trip, the same thing happened after ~50 rounds. I had to close the gas system 2 clicks, and still maybe had a random FTF (maybe 1/50rnds).

For the other range trips i have not adjusted it any more, and have dealt with the FTF's as is.

The gun looks relatively clean inside... (at least on the action).

Anyone have any experience on this? I dont want to just keep closing down the gas system as i am afraid it could eventually damage something.

 

[hotwings]

FYI - This is exactly what kept happening:

[ame]https://www.youtube.com/watch?v=QD1_YJaAUog&t=2s[/ame]

Bolt would lock back about halfway.

 

[issac575]

Thats also the only problem i have left to fix as well. Except mine will do it once or twice a magazine. Best i can tell that lock up location is right where the bottom of the bolt is pressing tight on the hammer. My next attempt is going to be to run loads of lube to try to reduce the friction there.

 

[ronmar]

Well if you are checking to see that it is only 2 clicks closed from the point where it WON't lock open on an empty, I don't think you are going to damage anything. I would think buildup in the gas system would tend to make it seal better and make it seem overgassed, not under gassed. I don't see it having enough buildup in the gas piston area to rob it of energy, unless the gas port from the barrel into the gashead has become fouled, reducing the ammount of gas reaching the piston and vent(like a clogged gas tube in an AR). I guess if some lube got in there, tht could cause the passage to gum up.

You could try flushing it with solvent. Start by properly setting the gas system. Remove the adjuster(note it's position) and figure out some way to block that port(easy on a first gen, difficult I think on a second gen). Put the rifle muzzle down in something to catch the solvent. Remove the gas piston and pour solvent into the gas piston clinder. If you have sealed the adjuster, the solvent should run thru the gashead and port to the barrel and out the muzzle. When done, blow compressed air into the gas piston cylinder and force out all the solvent/dry the gas passage. If the air gun has a large rubber tip and can seal with the piston bore, that would be great to get some good forced air thru the passage into the barrel. Re-assemble and see if the gas adjuster position moves for a proper setup. If it does(closed) then that was your issue. No change from the pre flush/clean position, look for drag someplace else...

Sticking mid cycle, one place to look would be the pins that hold the bolt to the carrier. In particular the forward rollpin that the front of the bolt hangs from. Make sure it is centered in the carrier. If it is not centered it can interfere with the slide grooves in the receiver...

 

[hotwings]

I will inspect the pins. When i stripped it down the other day, i did not see anything that stood out.

re: Gas system.... Gas Piston design should not fail after 1000 rounds. The gun looks clean.... Either way, im going to wipe everything down again, inspect, lube, and reassemble.

 

[hotwings]

Thats also the only problem i have left to fix as well. Except mine will do it once or twice a magazine. Best i can tell that lock up location is right where the bottom of the bolt is pressing tight on the hammer. My next attempt is going to be to run loads of lube to try to reduce the friction there.

Thats exactly the frequency im getting now. About 2 per mag.

I was thinking the same, going to run extra lube and also take some to the range with me. If it starts to happen i will add more to see if it goes away.

 

[issac575]

Hotwings,
I haven't got out to shoot since my last post, but it should be noted that I have been lubing in accordance with Ronmar's Youtube instructions up until this point. Doing so has served me well so far, and I only think I may need more lube between the bolt bottom and the hammer because the grease I have is sometimes really slick, and sometimes gets tacky like half dry glue. Since I had this particular issue fixed when I was using brass cases, but it has returned with my switch to Wolf Steel case ammo, it may just be that little bit of extra friction I am getting from the steel. (there is a significant amount of extra friction on the steel cases when using my thumb to remove them from a magazine compared to brass cases, also I only own thermold magazines)

 

[hotwings]

Hotwings,
I haven't got out to shoot since my last post, but it should be noted that I have been lubing in accordance with Ronmar's Youtube instructions up until this point. Doing so has served me well so far, and I only think I may need more lube between the bolt bottom and the hammer because the grease I have is sometimes really slick, and sometimes gets tacky like half dry glue. Since I had this particular issue fixed when I was using brass cases, but it has returned with my switch to Wolf Steel case ammo, it may just be that little bit of extra friction I am getting from the steel. (there is a significant amount of extra friction on the steel cases when using my thumb to remove them from a magazine compared to brass cases, also I only own thermold magazines)

Same - Only use the magazines from KT website...

I probably just need more lube. Ive been running it on the drier side... Also - will not shoot steel through RFB. I use to use Tulammo in all my guns, and switched to PMC brass. Never really had a problem with Tulammo in my AR's, but ive seen many people that have. For the little extra $ for PMC it is decent cheap range ammo. Accuracy of both suck

I am going to be shooting some federal match next time out and see what kind of group i get. With PMC @ 100 yards, i shot a 2.5" group of 6rnds...Should be tighter then that... (24" hunter)

 

[issac575]

I had heard reports that the RFB likes steel and produces better groups with it. So far I would say the wolf delivers on that. It should be noted that I have not tried very many types of ammo yet. The brass I had was magtech, and the steel is wolf. of the 500 rounds of brass that I have shot, about 400 survived the ejection shoot in good enough shape for reloading. I got the dies etc... that I need for 308, now all I need is powder, primers, and bullets and I will be ready to go. But I am not in a hurry yet, still have another 500 rounds of steel sitting here so plenty of ammo to keep my busy.

 

[ronmar]

I would not bother trying to reload the RFB brass... The brass forms to the chamber which is on the large size. It is a real bear to squish that back into a .308 spec die. I reloaded for the RFB for a time, looking for a handload that had better accuracy(which i never found). The extra work to get it back into shape really hardens the brass and I had my first case neck sep at 4 reloads. And when I say first case neck separation, I mean EVER, and I have been reloading for 30 years. If you have another 308, which I do, This is easy to demonstrate. Fire a round in the other 308 and fire one in the RFB. Now if you take those two pieces of brass, they will easilly re-chamber in their respective rifles. Now take them and try and chamber them in the other rifle. The other rifles brass will chamber in the RFB, but the RFB brass will NOT chamber in the other rifle... When I discovered that inexpensive Tula from the wallmart beat my best handload by half, I stopped messing with reloading for it.

If you are dead set on reloading for the RFB, look for a neck sizing die and only squeeze it just enough to get it to hold a bullet long enough to crimp. You can kind of approximate this with a regular die by not fully seating it down over the brass, but you Will have to extend the decapping pin far enough to pop the primer. Only go far eough to hold a bulet for crimping. Your arm and reloading press will thank you for it... You of course will be left with the same issue of the case neck being work hardened in a few fire, resize, crimp cycles and failing in short order. To avoid this, you will want to anneal the cases after every 2 or 3 reloads. These reloads will of course only be useable in the RFB.

Good luck...

 

[issac575]

No worries, done initial sizing and decapping on about 120 cases so far. So far i am suprised how easy they are to do on my press, i have the little lee hand press that operates like a clamshell. Using about the same force i need for my 45 LC sizing. I figure i have the brass, might as well see if i can use it to isolate the reliability and accuracy issues. The accuracy i got with wolf was fine, bout 2.5 moa, bout 4 moa with the magtech. I still have over 500 rounds of wolf to use when i care what i hit, just reloading to see if i can isolate the reliabilty cause

 

[Evil_Edie]

i swore off the tula after getting pretty consistent cracked case heads and hard stoppages with each. It was something like 1 in every 10 rounds I've been using norinco without issue since. Have you had any such problems ronmar?

 

[ronmar]

Havn't had any problems with the Tula in the RFB. It has Run great for me... The only thing I have noted with it is in MY AR. With the Tula, it occasionally won't lock open on an empty mag, which goes along with the claimed lower gas output from the Tula. But since the RFB has a fully adjustable gas system, this isn't an issue.

 

[issac575]

So I finally made it out to shoot again today. With copious amounts of lube along the bottom of the bolt (applied every few magazines with the bolt closed and rifle with magwell facing up) gave me no luck on the steel case. Same issue, same frequency. I did fire a couple mags of brass case (I had a bit left over in the bottom of my range bag from a while back) with no issues. Came home to clean, verified the exact point that the friction is too high to strip steel case out of the mag fully, and proceeded to polish the crap out of it. I did the bottom of the bolt since close inspection showed that the finish was rough enough that it may cause some drag. I also worked on the hammer where the bolt rides over it. Particularly slightly rounding the corner between the surface that actually contacts the firing pin and the large surface designed to slide along the bottom of the bolt. This is the location that was where the largest friction was occurring. Manual cycling was a load smoother after doing this. Next time I go shoot I will report back results. I still have a mag or so of brass case ammo, but am only concerned about the steel case performance now.
Too bad the brass case stuff was still overgassed with the gas cap off though. But I am to the point now that I should be able to use reloaded brass reliably once I find the right recipe that keeps the gas cap on the weapon, the rifle cycling reliably and hopefully reasonable accuracy. I have read on other forums that the Hornady 178gr ELD-X actually likes to jump to the lands instead of snuggling up on them. Anyways that is a ways down the road.

 

[ronmar]

You know the symptoms you are talking about could also be a result of an issue with the main springs. Have you examined them throughly, in particular the two tubes welded up inside the carrier that compress the springs when the carrier cycles to the rear? I had one of those welded tubes break free from the carrier(fairly common probem in the first gens) which basically halved the spring pressure. Gun immediatly acted overgassed, but still operated mostly normal with only an occasional failure to feed...

 

[issac575]

Yeah, i keep looking for that problem but everything looks like it should up there. Even the welds

 

[issac575]

Took another range trip today. Bottom line? The polish job on the hammer and bottom of bolt worked very well. Had to re adjust the gas of course, but got down to malfunctions once every few mags or so. Came home and cleaned, checked everything was still attached and functioning correctly, and then put a little more polish on the bottom of the bolt. Got it to the point that there is no noticeable friction when manually cycling with the top cover/but plate removed but everything else together. Doing this is what initially showed me where the friction was located. anyways, next range trip should proof if this works or not. Hoping to get through a 100 rounds or more without malfunctions next time.
Shot nothing but steel case today BTW.

 

[issac575]

Sorry it took so long to get back, Fire restrictions on public land went into effect 24 May and just ended last week. A ban on shooting was in effect.
Anyways I made it out to shoot today and got the attached results with my new reloads.
The loads used 178gr Hornady ELD-X bullets over Varget. the screenshot of my spreadsheet shows the loads I tested, and blanks for those I skipped today. No overpressure signs all the way through. Units of measure used are Grains and Inches. I give the vertical and horizontal spread of each group as well as the biggest measurement over all the shots in a group as well. there is one note where a shot went off target and I will reshoot this group since may have been the smallest one today, or the largest haha!
I shortened my shooting session due to the monsoons coming in and needing to drive through a wash on the way home. Such is life in southern AZ this time of year.
I did shoot the 41's and 42's but the spread was horrible, lots of shots off target, possibly because I didn't want to get caught in a flash flood.
based on today I am interested in loads near 35.5 and maybe near the 40 grain range as well.
I think I was getting around 3 inch groups with my steel case, so I might be happy with groups in the low 2's at 100 yds.

 

[issac575]

one more update for those interested in knowing... I shot the RFB twice since the post above and have narrowed down to 41.4gr varget with the 178 gr ELD-x's loaded to COAL 2.810. Got 1.25 inch group at 100 yds. Loaded up 25 more of those to test at longer ranges. Don't know how far I will push it out, but I already didn't expect 1.25 MOA out of the RFB. Double that would have made me happy haha!

 

[issac575]

Took it out to 200 yards today. Grouped 2.25 inches on center for 5 shot group. Guess Im happy with rifle and ammo, now time to work on my shooting haha.