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Posted: 2/12/2006 8:00:32 PM EDT
[Last Edit: 2/17/2006 2:09:41 PM EDT by ru4freedom]
I put a RRA 6-Pos M4 Stock on my Colt MT H-Bar II and now it is short stroking!

Should I take some weight out of the Buffer? It is the standard Buffer that came with the RRA, not an "H" Buffer.

It has always cycled great with both the A2 Stock & ACE Stock useing the original extention tube, buffer & spring.

All using the same load: 63 gr. SP @ 2900 fps

Any clues?????
Link Posted: 2/12/2006 8:14:38 PM EDT
[Last Edit: 2/12/2006 8:21:21 PM EDT by theshootersden]
No, don't compensate for the problem by altering a perfectly good buffer... You want to find out what is causing the trouble, and then correct it...

Compare the springs length to your others... Check the buffer tube for dings or dents and to make sure it is round and not egged... Check the spring and buffer for burrs or sharp edges that might be dragging inside the tube... Also examine the inside of the tube for burrs or obstructions...

Also look at the buffer retainer to see if its dragging on the BC...
Link Posted: 2/12/2006 8:58:33 PM EDT
make sure you are using the carbine buffer and spring


check out these tacked threads in the trouble shooting forum which might help you.

www.ar15.com/forums/topic.html?b=3&f=66&t=240052

www.ar15.com/forums/topic.html?b=3&f=66&t=266108
Link Posted: 2/12/2006 9:05:22 PM EDT
[Last Edit: 2/12/2006 9:55:21 PM EDT by ru4freedom]
Everything seems to be OK. All the springs I have (4) measure out the same 11" +/- 1/8"

Tube & buffer are both smooth & un-marked. No sign of any damage.

Hand cycling is slick & just as smooth as my other AR Carbines & Rifles.

I'm dumb founded......., or maybe just dumb, but I don't have a clue what's going on!!

I've swaped out a lot of AR stocks before of differant configurations but have never run into this problem!

I guess I'd better check the gas system



Link Posted: 2/12/2006 9:17:14 PM EDT
When mine started short stroking it was becuase the gas tube wasnt FULLY lined up on the hole in the gas block. It worked for 40 or 50 rounds, then started short stroking. Why it worked then quit, i have not a clue.
My next short stroke issue the first thing I'll check is the gas tube alignment.......
Link Posted: 2/12/2006 10:03:04 PM EDT
What ammo are you using? Did you change brands/loads?

Also, is it a Colt's bolt carrier? If it is, I'm sure the key is staked properly, but you can never be sure, check to see if the carrier is loose.

I second checking the tube alignment, though it's easier to check the carrier first.
Link Posted: 2/13/2006 8:38:33 AM EDT
[Last Edit: 2/13/2006 8:39:35 AM EDT by greco]
Every time I've had this problem, it's always been corrected with new gas rings on the bolt. That's not to say you shouldn't check the items mentioned above.
Link Posted: 2/13/2006 8:44:59 AM EDT

Originally Posted By ru4freedom:
I put a RRA 6-Pos M4 Stock on my Colt MT H-Bar II and now it is short stroking!

Should I take some weight out of the Buffer? It is the standard Buffer that came with the RRA, not an "H" Buffer.

It has always cycled great with both the A2 Stock & ACE Stock useing the original extention tube, buffer & spring.

All using the same load: 63 gr. SP @ 2900 fps

Any clues?????



Read what he wrote:

Same load (same ammo?)
Cycled FINE w/ A2 stock and ACE stock but with rifle spring and buffer.

Short strokes when he switched to a RRA M4 buffer/spring/stock.

Why would this happen? The carbine buffers are all lighter than the rifle buffer, w/ the exception of the 9mm buffers.

I'm sort of in the same bolt - I switched to carbine stocks but never tested the firearms. I'm hoping this doesn't happen.
Link Posted: 2/13/2006 8:50:27 AM EDT
Link Posted: 2/13/2006 8:58:53 AM EDT
The rifle should not short stroke even with the gas rings aligned.

I've made it almost standard practice to buy a set of 3 gas rings whenever I buy something from the large vendors. It's about $1.50 each time.
Link Posted: 2/13/2006 9:16:51 AM EDT
I think the original poster should explain exactly what it is doing. I have a feeling the rifle is not shortstroking .

Is it double feeding? FTE? FTF? Is the hammer dropping on an empty chamber? Light promer strikes?

Link Posted: 2/13/2006 9:23:29 AM EDT

Originally Posted By ian187:
I think the original poster should explain exactly what it is doing. I have a feeling the rifle is not shortstroking .

Is it double feeding? FTE? FTF? Is the hammer dropping on an empty chamber? Light promer strikes?




Good point.

Short stroking on my rifle was basically where my AR-15 became a single shot rifle. After each shot, it would extract the spent case but slam home on an empty chamber.

When single loading the mags, the bolt carrier would get hung up on the bolt catch mid-way, rather than stopping with the bolt face hanging on the bolt catch.

Sometimes, the bolt would try to feed the next case and make a BIG dent in the case.
Link Posted: 2/13/2006 10:05:56 AM EDT

Originally Posted By ian187:
I think the original poster should explain exactly what it is doing. I have a feeling the rifle is not shortstroking .

Is it double feeding? FTE? FTF? Is the hammer dropping on an empty chamber? Light promer strikes?





+1
Link Posted: 2/13/2006 10:07:39 AM EDT
I used to think shortstroking was common, but an instructor named Dean schooled me on it at the Colt class. If you went from the full stock to the short one... you obviously replaced the spring and buffer with the collapsible equipment that came with the stock.

The gun should function with only one gas ring, if everything else is in place correctly.

You may be soaking recoil. Make sure you've got a tight stock weld in your shoulder.

Make sure that there are no burrs or bends in the receiver extension tube. I've never seen it, but I'm sure it could happen.

If the stock was the only thing altered... that's about all I can think of that could contribute to your problem.
Link Posted: 2/13/2006 1:36:47 PM EDT

Originally Posted By theshootersden:
Also look at the buffer retainer to see if its dragging on the BC...



+1

Make sure that the buffer retainer is installed correctly.
Link Posted: 2/13/2006 5:08:24 PM EDT
[Last Edit: 2/13/2006 5:38:56 PM EDT by ru4freedom]
--------------------------------------------------------------------------------------------------------------------
Originally Posted By ian187:


I think the original poster should explain exactly what it is doing. I have a feeling the rifle is not shortstroking .

Is it double feeding? FTE? FTF? Is the hammer dropping on an empty chamber? Light promer strikes?
--------------------------------------------------------------------------------------------------------------------



These are the symtoms:

a. Always ejects

b. Only picks up another round from the mag about half the time.

c. Hardly ever locks open after the last shot.

d. Always locks open when hand cycled.


It does the above will all the mags I've tried..., even my HK mags!!

Gas tube is properly aligned & clear or obstruction.

Stock RRA CAR spring & Buffer......., not "H" or 9mm Buffer

All parts, bolt, carrier, ect... are the original Colt that has always worked flawlessly in this Carbine.

Gas rings are in good condition and properly staggered.

Buffer tube is new, straight, burr free, and hand cycles smoothly.

I'm baffled!!!
Link Posted: 2/13/2006 5:37:29 PM EDT
Sounds like gas loss from some where,,check the carrier key.
Link Posted: 2/13/2006 5:38:46 PM EDT
This is what I would do... Im not saying it is what you should do...

If I couldn't find any defects in the new parts...

I would try a different buffer to see if that is the problem... If still the same I would test a different bolt/carrier group... If that didn't fix it I would then say f**k'it and knock the taper pins out of the FSB, remove the FSB and punch out the gas port hole and be done with it...

I don't recommend for any home viewers to attempt the above procedure... This type of insanity should only be performed by a certifiable person, like me...
Link Posted: 2/13/2006 7:34:24 PM EDT

The only change I've made to the Carbine is the stock....., I don't think I'll be "punching out" The gas port hole!!
Link Posted: 2/14/2006 1:01:11 AM EDT
[Last Edit: 2/14/2006 1:01:21 AM EDT by metroplex]
The standard carbine buffer is also lighter than the rifle buffer.
Link Posted: 2/14/2006 4:45:49 AM EDT

Originally Posted By ru4freedom:
The only change I've made to the Carbine is the stock....., I don't think I'll be "punching out" The gas port hole!!



Good idea you have there...

Like I said, I don't recommend for you to do it, it is something I would do to get my AR running again...

BTW... You'd be surprised at some of the problems that are created by using different size buffer tubes and buffers...

Anyway, good luck to you...
Link Posted: 2/14/2006 4:57:29 AM EDT
Did you lube the buffer spring and buffer tube? Run a patch with CLP through the buffer tube interior and then wipe some CLP onto the buffer spring itself.

Are you sure its just the standard carbine buffer spring and not an "Extra Power" spring? To test:
Verify gun is unloaded, no mag inserted, etc...
Lay buttstock of rifle onto floor, with muzzle straight up and pointedin a safe direction.
Pull back charging handle, and ride it until the latch is contacting the upper receiver. Let go.

Does the charging handle automatically slap back home (with the latch "locked" into its resting position)?
Or does it stay there?
If it stays there, its got the standard spring. The XP spring will be high rate enough to slap it home by itself in a vertical position against gravity.
Link Posted: 2/14/2006 5:43:01 AM EDT
Not sure if this helps, but I just built my first AR a few months ago. It's a 16" mid-length with a David Tubb's CS (ISMI flat-wound) recoil spring made to work in either the rifle stock or CAR collapsible. It also has an "H" buffer and D-Fender extractor D-ring. The CH latch closes itself as described above. I haven't had any problems in 250 rounds of WWB Q3131 and WWB 45 gr. Varmint...bolt lockes open after every shot. I'm using D&H black T mags with MagPul Gen2 followers. I recently added a McFarland gas ring but I'm sure this won't be an issue either. My brass ejects at about 2 o'clock after hitting the very front edge of the BD. So, if my middy with the above configuration doesn't short-stroke, I'd say something else is wrong...???
Link Posted: 2/14/2006 6:04:47 AM EDT
Have you put back the A2 Rifle stock with rifle buffer, tube, and spring and tried it?
Link Posted: 2/14/2006 5:22:20 PM EDT
[Last Edit: 2/14/2006 5:40:38 PM EDT by ru4freedom]

Originally Posted By metroplex:
Did you lube the buffer spring and buffer tube? Run a patch with CLP through the buffer tube interior and then wipe some CLP onto the buffer spring itself.

Are you sure its just the standard carbine buffer spring and not an "Extra Power" spring? To test:
Verify gun is unloaded, no mag inserted, etc...
Lay buttstock of rifle onto floor, with muzzle straight up and pointedin a safe direction.
Pull back charging handle, and ride it until the latch is contacting the upper receiver. Let go.

Does the charging handle automatically slap back home (with the latch "locked" into its resting position)?
Or does it stay there?
If it stays there, its got the standard spring. The XP spring will be high rate enough to slap it home by itself in a vertical position against gravity.




Bingo!!! After preforming your test...., apparently it does have the "Extra Power" spring!

I then tested the A2 Stock, Tube & Buffer which is now on my Varmint AR...., and if the spring test works the same on the A2....., the A2 spring has much less power & does not "slap back home" like the RRA M4 stock in question does!! Also you can easily tell when pullinh back the charging handle that the RRA is a much stronger spring!!

Can I take a bit of length off the spring...., or will that create a diffreant problem?


I have another MForgery that I built with the same RRA Stock & Spring. Your spring test indicates XP spring in this one too! The only differance is the I have aa "H" Buffer in this one....., and it shoots like a SOB!! Is the XP Spring intended for use with a "H" Buffer?
Link Posted: 2/15/2006 12:48:27 AM EDT
I know someone is going to say, "but that doesn't mean it is absolutely an XP spring.." I have two carbine stocks that came with springs. None of them are strong enough to let the charging handle return home by itself against gravity. The only time I saw this happen was when I used a Wolff XP action spring in my rifle config AR-15.

Make sure you don't slap or jar the rifle, just gently ride the CH until the latch contacts the edge of the upper. Let go and see if there's enough spring force to force it home by itself. Do you have any other buffers to try? Maybe "break it in" by cycling it a few times.
Link Posted: 2/15/2006 12:51:36 AM EDT
I know someone is going to say, "but that doesn't mean it is absolutely an XP spring.." I have two carbine stocks that came with springs. None of them are strong enough to let the charging handle return home by itself against gravity. The only time I saw this happen was when I used a Wolff XP action spring in my rifle config AR-15.

Make sure you don't slap or jar the rifle, just gently ride the CH until the latch contacts the edge of the upper. Let go and see if there's enough spring force to force it home by itself. Do you have any other buffers to try? Maybe "break it in" by cycling it a few times.

How many coils does your spring have? You said you have 4 carbine buffer springs? Fine the one that doesn't slap the CH/BC home and try that at the range.
Link Posted: 2/15/2006 6:42:15 PM EDT
[Last Edit: 2/15/2006 6:55:23 PM EDT by ru4freedom]
All four springs are 11" long and have 33 coils includung the end coils. All four came with my RRA M4 Stocks two with each stock.

Each spring tests the same. I gently ease the charging handle down to the latch (no slapping or jaring) and as soon as I take my fingers off the CH it closes completely!!

When testing my A2 Stock set-up, it does not even make an effort to close completely.

I don't know if these M4 springd are XP springs or not..., but they are definately stronger springs than that of my A2 stock!!

I have two spares M4 Springs . Can I cut a coil or two off of one until it tests properly & see how it works???
Link Posted: 2/15/2006 6:52:08 PM EDT
Dont cut coils.Change out the spring or get a heavier buffer..more weight should have a bit more force to the rear.I cured my short stroke problems in my rifle by going to a heavier buffer and it hasnt happened since.
Link Posted: 2/15/2006 7:04:26 PM EDT
I'll try my "H" Buffer

Not sure if it matters ...., but when I put the "H" Buffer in the CH still closes under test!
Link Posted: 2/15/2006 7:06:11 PM EDT

Originally Posted By pun:
Dont cut coils.Change out the spring or get a heavier buffer..more weight should have a bit more force to the rear.I cured my short stroke problems in my rifle by going to a heavier buffer and it hasnt happened since.



This is backwards, no...???
Link Posted: 2/15/2006 7:10:29 PM EDT

Originally Posted By JackalAR:

Originally Posted By pun:
Dont cut coils.Change out the spring or get a heavier buffer..more weight should have a bit more force to the rear.I cured my short stroke problems in my rifle by going to a heavier buffer and it hasnt happened since.



This is backwards, no...???



no...
Link Posted: 2/15/2006 7:36:43 PM EDT
[Last Edit: 2/15/2006 7:38:22 PM EDT by pun]
For some reason I was getting bolt bounce with my carbine buffer causing the same problem..I went H and it went away except when I used that polymer cased ammo.So I went 9mm buffer just a gram heavier than a standard full size buffer and the rifle has never worked better even with the lighter polymer cased stuff.
Link Posted: 2/15/2006 8:25:47 PM EDT
Seems backwards to me to......., but it wouldn't be the first time backwards worked!!

I'll give it a try & post the results.
Link Posted: 2/15/2006 9:21:56 PM EDT
[Last Edit: 2/15/2006 9:24:05 PM EDT by Creeper]

Originally Posted By ru4freedom:
I put a RRA 6-Pos M4 Stock on my Colt MT H-Bar II and now it is short stroking!

Should I take some weight out of the Buffer? It is the standard Buffer that came with the RRA, not an "H" Buffer.

It has always cycled great with both the A2 Stock & ACE Stock useing the original extention tube, buffer & spring.

All using the same load: 63 gr. SP @ 2900 fps

Any clues?????




Probably a bad design flaw- course these guys will find the right exact measurement for spring length, buffer weight, tube design, etc. I wish someone would redesign the thing to eliminate the need for a buffer tube return spring anyway. The carrier return spring should be captured inside the reciever, same as a FN Para 50:63, with SS Gas Piston, and charging handle mounted on carrier.

Link Posted: 2/16/2006 3:40:09 AM EDT
I know nothing of Colt's lines, but is the Match target Hbar-2 the 16" M4-style rifle with the A2 buttstock? And you're just going to a 6-position stock?

With the car stock and buffer, do you "feel" the recoil and the buffer hitting the end of the buffer tube? I noticed that when my 24" AR-15 short stroked on Wolf, the recoil was very light and I'd see long dents on the side of the cases. Recall that a rifle buffer is about 5.2 oz while the carbine buffer is 2.88 oz.

I just changed over to a 6position stock on my 24" AR-15 and never tried it yet. Before the stock change, it was cycling Wolf like a champ.
Link Posted: 2/16/2006 5:52:51 AM EDT

Originally Posted By metroplex:
I know nothing of Colt's lines, but is the Match target Hbar-2 the 16" M4-style rifle with the A2 buttstock? And you're just going to a 6-position stock?





Yes...., M4 style w/Heavy Barrel & A2 Stock.

Only change was to M4 Stock
Link Posted: 2/16/2006 6:01:32 AM EDT

Originally Posted By ru4freedom:
All four springs are 11" long and have 33 coils includung the end coils. All four came with my RRA M4 Stocks two with each stock.

Each spring tests the same. I gently ease the charging handle down to the latch (no slapping or jaring) and as soon as I take my fingers off the CH it closes completely!!

When testing my A2 Stock set-up, it does not even make an effort to close completely.

I don't know if these M4 springd are XP springs or not..., but they are definately stronger springs than that of my A2 stock!!

I have two spares M4 Springs . Can I cut a coil or two off of one until it tests properly & see how it works???




They should be stronger at length but the springs should have the same power under load at max compression. The last thing I would do is try the gas keyway. Though it may be staked in and running fine, there may still be a gas leak. That's from a factory tech, not me. I've never seen it, but it could happen.
Link Posted: 2/16/2006 6:33:10 AM EDT
I wouldn't cut the coils. That will effectively increase the rate of the springs.
FWIW, my DPMS 6-position stock and some Leapers-like 4-position stock I just bought both have springs that will not allow the CH/bolt carrier to slap home by itself going against gravity unless I jar the rifle a little.

I would try switching back to the A2 stock and see if it runs fine. This will eliminate the possibility of other parts in the rifle causing this problem.

The only things I can think of would be that your springs are somehow too stiff, the spring and buffer needs some lubrication, your buffer detent is dragging on the bolt carrier, or your gas is somehow leaking (either gas rings worn or leaky gas key).

Hold your bolt into the carrier (push it in), spray some light oil in front of the gas key around where it seals into the carrier. Use a rubber hose or straw or compressed air and blow air into the gas key. If there are bubbles coming out the front, it means there is a leak. If not, then you're fine.

Check your gas ring OD, it should be around 0.5"-0.510"
Link Posted: 2/16/2006 8:04:14 AM EDT
Does the bolt drop free with the cam pin removed when you turn it upside down?
Link Posted: 2/16/2006 8:46:17 AM EDT

Originally Posted By JackalAR:
Does the bolt drop free with the cam pin removed when you turn it upside down?



+1 That's a good test to see if the gas rings are worn.
Link Posted: 2/16/2006 7:44:08 PM EDT

Originally Posted By metroplex:

Originally Posted By JackalAR:
Does the bolt drop free with the cam pin removed when you turn it upside down?



+1 That's a good test to see if the gas rings are worn.




Nope....., bolt is tight from gas ring tention!


I took out the gas tube & found some excessive wear on the top side of the "bulb" (carrier key end) Just installed a new gas tube & tuned it for a smooth even fit with the carrier key.

Will post results upon test firing.

BTW...., thanks to all for your help!!
Link Posted: 2/17/2006 1:07:13 AM EDT
That top wear suggests the gas tube and gas key alignment isn't correct.
I hope you adjusted it enough to make it align properly?
Link Posted: 2/17/2006 1:55:36 PM EDT
[Last Edit: 2/17/2006 2:14:31 PM EDT by ru4freedom]
Sure enough......, it was a leak @ the Gas Tube/ Carrier Key!! Apparently it was not aligned properly & excessive wear @ the top of the tube eventually produced enough of a leak that when I put the M4 Stock on, the stiffer spring was just enough to make it short stroke with the gas leak!

One new gas tube later & proper Tube/Key alignment and she's off & run'in like a champ once again!! I ran 4 30's through it as fast as I could without an issue!!

I had no idea the AR gas system was so touchy!!
Link Posted: 2/17/2006 1:58:10 PM EDT

Originally Posted By ru4freedom:
Sure enough......, it was a leak @ the Gas Tube/ Carrier Key!! Apparently it was not aligned properly & excessive @ the top of the tube eventually produced enough of a leak that is began to short stroke when I put the M4 Stock with the stiffer spring on!!

One new gas tube later & proper Tube/Key alignment and she's off & run'in like a champ once again!!

I had no idea the AR gas system was so touchy!!



Thats most peoples only complaint. The direct gas system can be a PITA, but now that you got it squared away I bet it'll run perfect for many moons
Link Posted: 2/17/2006 2:44:31 PM EDT
[Last Edit: 2/17/2006 2:45:05 PM EDT by metroplex]
That's great news! There's no feeling like being able to blast away hundreds of Wolf cartridges through your AR when everyone says not to use it or it won't work
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