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Feed Issues, Rock-ola James River Armory

8K views 81 replies 22 participants last post by  ripsaw 
#1 ·
I recently purchased a slightly used James river armory with a Rock-ola receiver. After the first 200 hundred rounds I have a consistent failure to feed 1 in every 5 magazine fails to feed, although the hammer is cocked and fires. The same results with 4 different 10 round magazines, 3 Checkmate and 1 Springfield, all new. Two different brands of NATO ammo. Rifle is super accurate, but failure to feed is extremely disappointing. Occasionally a round is jammed at a 30 degree angle in the breech. Any advice would be extremely welcome. Gas system is clean, although I haven't done a complete disassembly, just piston removal and cleaning.
Phil
 
#45 ·
Finally able to test cleaning and new parts, still short cycling

Fired 60 rounds, three different types of ammo and four magazines. New extractor, ejector and spring, thourough cleaning of entire gas system. Can't cycle 4 rounds in a row.
I called Jame River Armory, very friendly. We went over a lot of items. Diagnosed as either gas piston or gas cylinder. They suggested Sadlak NM with coating. On order. Will update after installing and test firing. It is very accurate, I must say. USA2
 
#48 ·
Fired 60 rounds, three different types of ammo and four magazines. New extractor, ejector and spring, thourough cleaning of entire gas system. Can't cycle 4 rounds in a row.
I called Jame River Armory, very friendly. We went over a lot of items. Diagnosed as either gas piston or gas cylinder. They suggested Sadlak NM with coating. On order. Will update after installing and test firing. It is very accurate, I must say. USA2
Hi Mass Patriot,
Don't waste your time or money getting another piston, that is not it, providing you did get the right small drill bit and clean the tail of all carbon fouling too. It is not your gas cylinder either, unless the rear ring that holds the spindle valve port tight to the barrel is leaking massive amounts of gas and is shaky loose. Which reminds me, make sure your spindle valve screwdriver slot is straight up and down, vertical, when holding the rifle horizontal, not partially sideways or horizontal. In other words, perpendicular to the barrel. 90 degrees, not 75 or 80

That would be easy to spot, either condition above. One because there would be black marks from the gas leaking around the ring, and etching, and the other because it would be rattling loose.

In all the years of inspecting hundreds and hundreds of gas cylinders with ball micrometers and snap gauges, I've only seen one that was worn out from firing....and have never seen a g.i. piston worn out....and I've seen some rough ones.

If you didn't mount a scope and put too long of a machine bolt in and it is not dragging on the left bolt locking lug and robbing gas, and the left helix side wall cuts aren't interfering with bolt travel, there are only two things that can cause this issue.

One, I already covered before is the chamber reaming job being too rough and hanging brass until enough gas is robbed to not allow a complete cycle.
Two, is the receiver bridge cut for firing pin retraction.

You can visibly check the first by looking at the chamber with a good bent neck light with the trigger group and bolt out of the way.

You can check the second by removing the trigger group and taking the action out of the stock and standing it on the flash suppressor, barrel down and heel straight up like a tomato stake. Leave everything else in the action.

With bolt closed in battery, reach under the receiver heel and push the firing pin forward, as if your finger were the hammer hitting it, then hold the heel with that hand and with your other hand, take one finger and pull gently on the op rod handle and watch the firing pin and see if it rotates and will allow the bolt to open. If it takes a lot of force or more than one finger, the cut is wrong or insufficient to allow retraction under normal and violent retraction.

The tail of your firing pin and the bridge will tell the tale and show gouges or bad wear characteristics on it. Read, shiny spots, cuts, scrapes, etc.etc....You can polish them up and it may help. If the cut is wrong, very common by the way, it can be fixed easily.

If it's a rough chamber or too tight a headspace, or combination of both, it will need to be fixed by a professional. Post pics of the receiver bridge from the rear and underneath it, looking forward with the bolt and trigger group out of the way. If it is the problem, I can identify it. So can username Ironworker here. He has an excellent thread in the Gunsmithing sub-forum here that you can compare yours to.

Let me know what you find........rip
 
#47 ·
I just took the pistons out of my LRB and JRA rifles and found that despite never having cleaned them or had issues that may be caused by dirty pistons; they weren't that dirty, very little carbon buildup in either one and I cant imagine the amount of crud it would take to cause feed issues. I do always clean out the cylinder and clean the pistons, which are standard types in my 4 M14 rifles.
 
#49 ·
Wow, I'll check both of those items tomorrow. When I was working on the bolt, I did notice a rough edge on the firing pin and think it might be hitting something. I was trying to find a picture of how the receiver should look in that area and what the FP might be contacting.
Thanks everyone, and the offer to test a new piston.

Phil
 
#52 · (Edited)
I believe the FP and safety bridge is the issue

Ripsaw, I believe nailed it. I have captured a video showing that if I keep slight pressure on the firing pin will pulling the op rod back, there is a catch, then enough pressure gets the bolt to jump and retract. Is there a way to upload a short video?
 
#55 ·
More pictures after tear down

I removed scope and mount (screw was not protruding). Removed clip loading block. cleaned grease. Took pics.
One thing I noticed: The firing pin does not retract without force from the bot. It resists at the last 32nd of an inch. Should it move freely back and forth, maybe by shaking the bolt? Also the firing pin is showing signs of battering. The safety bridge looks close to other's pictures, no visible wear marks.
 
#61 ·
Try a different firing pin or stone this one...yours may be out of spec. It looks like the cam surface on the tail isn't cut deep enough preventing it from properly engaging the cam surface on the safety bridge. This is causing the peening you see on the tail.

I had one that would bind on the safety bridge as yours appears to be doing and a little stoning of the firing pin cam surface remedied it.

The firing pin should move freely in the bolt.
 
#63 · (Edited)
I too have seen this on Bula / Rock-ola receivers. Are you using a Bula bolt or a USGI bolt? In my experience, using a usgi bolt and pin, there was insufficient space between the tail of FP and bridge. Basically, as the pin retracted it was at full throw before it cleared the bridge. In the few examples I have encountered this, switching to a Bula FP helped, and switching to both a Bula bolt and FP helped more and provided a few thousandths clearance. However, if you swap bolts, you MUST check headspace. Measuring the few Bula bolts I have, they are approx .004" longer than GI.

**Edit- to add some measurements, I grabbed a stripped Bula receiver. Using USGI bolt and FP I am getting less than .002" clearance between FP tail and bridge. Swapping to a Bula/Bula combo increased that gap to .008".

This is not a post attempting to bash Bula. Jeff makes a fine product and at a reasonable cost. These are simply my experiences. YMMV.

Rip,

How much clearance should their be between the tail and bridge? I haven't played with enough real M14's to get a good idea, but with an M1 there is usually quite a bit.
 
#66 ·
50 more round, no feed 3 times and failed to stay open on last round. One jam where bolt closed on round halfway in the chamber. Waiting for new firing pin and piston. Could the spring be too strong?
Oh man, I know that sucks. If you cleaned the bridge and pin tail up good, only one thing left, other than a mis-located bridge or cut ....the chamber. Did you ever look at it under a bright light?....Another guy just got a bad chamber too, so maybe there were others went out in a batch that were reamed improperly. His was chrome lined too.

A spring isn't going to be able to be strong enough to cause this issue. I suggest replacing nothing with any more new parts....... and sending it back to the manufacturer. They should pay for shipping both ways if it's something that is their fault.

If they won't fix it for free, send it to me and I will see what I can do for you. If it's the chromed chamber, which is highly suspect at this time, there isn't much you can do except replace it. It could be reamed but eventually it will cause peeling of the chrome later, on up and into the rifling and then rust under that. It would be good for a blaster though, until that happens. It won't affect accuracy either to ream a chrome chamber. I have a carbide reamer for doing it.

So those are your choices as I see it right now. Good luck, we've done all we can do. Let us know.
 
#70 · (Edited)
Firing Pin comparison & pictures of chamber

I received the new FP from Fulton. I posted pictures of both. I've made notes regarding what mods I made to the original. The new pin sticks slightly in the bolt at the last 32nd at max protrusion. I/m an optimist, and I'm going to test this out at the range. I also attached the best photos I can get of the chamber with a bore camera.

Notice the difference in the shape of the two FP. The new one has less radius and more of a sharp transition. Its also beefier in the inner lo elbow area. Why so different? Is one not GI specs?
I do not know if my "original" FP is actually from JRA.
 
#73 ·
Test results

Finally got to the range. New Sadlak piston and new firing pin. fter 11 rounds, failed to pick up next round. Changed op rod spring to new GI and also Sadlak NM op spring guide. 35+ rounds, no short cycle or fail to remain open after last round. I always load 5 rounds in a mag. All rounds through a single hole size of a silver dollar at 25 yards.
Could it have been an extra power spring?
Seems to be resolved. I usually dont change more than one item, but this is getting expensive as far as ammo.
Thanks everyone.
 
#74 ·
So called high power op rod springs and cause all sorts of troubles.
Glad the USGI fixed your rifle.
I think you will be amazed how smooth it gets after break in.
Sounds like you have a winner.
Congratulations.

Semper Fi
Art
 
#75 ·
For am amateur like me it sounds like the problem is still an unknown; whether it was the firing pin, firing pin bolt combo, or op rod spring. It doesn't seem to answer the question of whether a GI bolt assembly can be used in a Bula receiver, or whether the GI bolt can if the FP is modified. On the flip side, it seems like Bula bolts can be used in non-Bula receivers without issue (?)
 
#77 ·
My mostly Winchester build uses a Bula/James River receiver and a Winny bolt with USGI internals and Winchester barrel. They work together perfectly with a headspace of 1.633 and lug contact was fine on both sides with no lapping, other that just checking for initial fit. Stop by and check it out Rick.

[URL=http://s1180.photobucket.com/user/nf1e/media/IMG_0333_zpsf7ezsh7s.jpg.html][/URL]

Semper Fi
Art
 
#78 ·
Is the headspace a variable that could affect whether a USGI bolt works in a Bula, ie, whether the headspace is 1.6315 (such as mine) vs 1.633. So one would only have to be particular in the headspace used on a Bula receiver?
 
#80 · (Edited)
Not at all. The headspace of 1.633 without needing adjustments indicates that Bula products are comperable to USGI spec. When using a chrome lined barrel it is general practice not to ream for headspace. Some lap the bolt to their receivers to set headspace. Others that use barrels that are not chrome lined, more common, are usually short chambered meaning that they are a few thousandths under where the desired headspace needs to be use a reamer to set headspace by cutting the barrel internally. Some like 1.630, very tight others a little more. I prefer keeping my headspace closer to NATO spec.
One should always be aware of headspace no matter what brand receiver is used. I have just found that Bula Defense Systems are one of the easiest to work with.

[URL=http://s1180.photobucket.com/user/nf1e/media/IMG_0987_zpskzdnewsi.jpg.html][/URL]


Semper Fi
Art
.
 
#82 ·
Hi Mass,
I was finally able to view your video. It is definitely the retraction cam and it's location. It is too far rearward and the angled cut needs to be advanced toward the front of the receiver. It is the surface contacting the right side of the firing pin tail from the shooters position.

It will void your warranty if you do it yourself, but if you fix it, who cares? You need a specially shaped saucer stone to do it though, and a really good tool like a Foredom, not dremel or other high rpm tool. Must be a variable speed controlled unit.

The combination of an over powered op rod spring and the mis-located retraction cam caused your problems. You have to get all that grease off the bottom of the bolt too. It transfers to the cartridge case and can actually cause rounds hanging up in the chamber too.

I highly recommend you send the rifle back to wherever you got it from. Sorry, but that is the only way to make sure you don't get a warranty slap in the face.

If the receiver bridge is mis-located in the receiver altogether, (common among some commercial makers) and we don't know that yet, it would also cause the retraction cam to be mis-located. A badly located bridge is a bad thing because it is what stops out of battery detonations, and if it is merely the cam that is off, not so bad. Fixing either yourself is risky as pertains to warranty and exclusions.

I don't know if you have calipers but the back edge of the receiver bridge at the bottom, should be 3.935" with a variance of no more than minus .010" from the front of the receiver. So anywhere within 3.925" to 3.935" should be fine and safe. If it is anything else outside these dimensions, send it back immediately.

As for headspace, tell them you want to know the chamber headspace before it is sent back. See if you can get a video with a bright light of the chamber reaming job. We need to know if there are rough lines in the bottleneck area. This also greatly contributes to gas robbing. A good pic will work too, one from bottom of receiver to see top side of bottleneck, and another from top side of receiver to see the bottom of the bottleneck. Will require a bent neck or flexible light and removing the bolt.
 
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