AR Cycling Issues with Vmax Loads...Typical?? (Final UPDATE - 22 APR 2008)

BBsteel

BBsteel

New member
Okay here goes...hope this isn't a stupid question. I thought I read up on this somewhere before.

I have a Bushmaster 16" Heavy Bbl. A3 Carbine rifle. It shoots all Remington .223 ammo flawlessly with no hang ups. I wanted to run some hornady v-max loads through it but they will not cycle. The gun fires and cycles but fails to extract the next cartridge from the magazine and load it in the chamber. Basically I end up with a "bolt action" AR when shooting these. Which is too bad because the groups I get are awesome.

Is it due to the overall length of the vmax loads (slightly longer) or sharp tips on them? I've tried both the regular vmax loads with the polly tips and also the molly tips with the same results. I've also tried numerous magazine brands knowing they all work fine with any Remmington brand ammo namely, UMC and the next cheap load up from that.

See my last post for the update.
 
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"Short stroking" is usually a sign of low gas port pressure, or a really dirty gas system (not likely).

What weight bullets are in the loads?

Are they handloads or factory?

.
 

It is not the V-Max bullets. I have both 50 gr. and 60 gr.
V-Max loads that run through two different AR-15s, with
no problems. I am going to guess that the Hornady ammo
is the problem. Some powders/charges don't produce a
stiff enough pressure spike to cycle AR-15s. I use Varget,
Benchmark, and VV N133, in my AR-15 loads, and none of
these powders have given me cycling problems. I do keep
the charge weights in the upper half of the published data
ranges.

Squeeze
 
I haven't shot any VMaxs through our 16" yet, but I have ran a couple of hundred through my 20" DTech that were reloads....no problems so far. /ubbthreads/images/graemlins/confused1.gif
 
Do you by chance have a Tubbs or some other heavy duty buffer spring installed. If so, this may be the problem..Guess#1 for me since factory loads!!
If the problem were with the moly bullets only, they could be the problem.
I'm currently chasing a simular problem with a 16" 17 Remington upper.. Some powders wont cycle it for squat and they give the better groups as well.. Bummer
Mine are all hand loads...
Later
DF2
 
Must be my gun. I have noticed some hang-ups as of late with it...especially when others are shooting it. If the shooter is not holding the gun tight to the shoulder the gun will short stroke or the bolt will remain stuck near the locking position but not all the way locked.

Great, now I have to mess with this. It does it with both my Bushy lower and DPMS lower.
 
Check your bolt carrier key to make sure the screws did not work themselves loose. I had the same problem. To fix it I had to take the bolt carrier key screws out and clean the threads I then put a small amount of blue locktight on them tightened them and restaked the screws.
 
I've shot one box of the Hornady Varmint Express 55 gr. V-Max. loads. They are showing excellent accuracy, but if you look at the primers, they show some flattening. I'd say they are the upper pressure I would like to see in my rifle.
None of the other ammo I've been shooting (UMC and Winchester white-box 55 gr. FMJ) is showing any pressure signs.
It's not short-stroking from too little gas pressure with the Hornady's, I'm willing to bet. Does it always chamber a round when you use the bolt release on a magazine change?
 
Quote:
"... It's not short-stroking from too little gas pressure with the Hornady's, I'm willing to bet. Does it always chamber a round when you use the bolt release on a magazine change?



It can be a max load, but too little pressure at the gas port.

Short barreled ARs have the gas port further back.

My SP-1 shoots the Hornady 55 load just fine, but is there is some other minor issue, it might be enough to make a difference.

I had a similar problem with my 308 SA M-21. Hand loads with H-4895 were showing very high pressure, but cases were not ejecting because of short stroking. The H-4895 was peaking too soon...

... I switched to Varget at the same velocity (2650) and all was fine, no signs of pressure, and full ejection.


.
 
Not typical!!

1- Check your gas rings on your bolt to insure they are in non-alignment as far as the spaces in each. They should all be offset from each other. Just like the rings of a piston.

2- As stated above, check the tightness of your gas port on your bolt carrier for looseness.

3- Check around your gas block at the front of the barrel to see if there is powder residue, indicating you have a gas leak there.

4- While your bolt carrier is torn down, look closely at the extractor and even take it apart and clean it and the bolt face thoroughly (watch the small spring under the extractor bar when you remove the retaining pin).

5- Use a quality lubricant and make sure all bolt parts, including the underside of the bolt carrier are lightly lubed.

6- If it is still doing the fail to feed, screw in your chamber brush to a short section of cleaning rod, chuck it in a cordless drill and with a few drops of lubricant on the brush, run it in the chamber for about 30 seconds. Swab out the chamber until the patches come clean.

7- If none of the above solve the problem, look at replacing the action (recoil) spring, but I doubt if you will have to go that far.

Keep us informed of what solves the problem, as we are all prone to the same situation. Good Luck
 
Guys, thank you very much for the valuable info. I leave for vacation for a week tomorrow so I'll tackle this issue when I return.

I will provide an update when I get going on it. It's good to know that the Vmax loads should work since they shoot so well for me. I can get .75" 5 shot groups at 100 yards off sand bags. I just hate the manual action!LOL
 
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It can be a max load, but too little pressure at the gas port.



Yes, or maybe the gas system has a leak and it isn't providing enough force to extract a tight case.
I've only shot one box, but as I said, the amount of primer flattening is what I would consider a warning sign of a "near max" load if they were my reloads.
They were grouping at 1/2" shooting prone off the bipod out of my truck bed (no sandbags) at 100 yds.
UMC was about 1".
I have a 20" barrel, not a carbine, so you may be correct on the pressure problem. My Hornady brass landed right alongside the UMC, seemed perfectly normal in that regard.
/ubbthreads/images/graemlins/confused1.gif
I was just saying, the Hornady is loaded on the hot side, not underpowered. I shot them with both an Oly pneumatic buffer and the Superior Shooting Systems flat spring, no malfunctions.
 
Quote:
Not typical!!

1- Check your gas rings on your bolt to insure they are in non-alignment as far as the spaces in each. They should all be offset from each other. Just like the rings of a piston.

2- As stated above, check the tightness of your gas port on your bolt carrier for looseness.

3- Check around your gas block at the front of the barrel to see if there is powder residue, indicating you have a gas leak there.

4- While your bolt carrier is torn down, look closely at the extractor and even take it apart and clean it and the bolt face thoroughly (watch the small spring under the extractor bar when you remove the retaining pin).

5- Use a quality lubricant and make sure all bolt parts, including the underside of the bolt carrier are lightly lubed.

6- If it is still doing the fail to feed, screw in your chamber brush to a short section of cleaning rod, chuck it in a cordless drill and with a few drops of lubricant on the brush, run it in the chamber for about 30 seconds. Swab out the chamber until the patches come clean.

7- If none of the above solve the problem, look at replacing the action (recoil) spring, but I doubt if you will have to go that far.

Keep us informed of what solves the problem, as we are all prone to the same situation. Good Luck



I agree on all these ideas and those of the other guys who have posted, but am puzzled by the idea that it would shoot Remington ammo and not malfunction and then mess up with the Hornady stuff. I've shot the Hornady through my 16 and never had problems but maybe the OP has some ammo from a bad lot....Anyway the great thing about this site is the knowledge base you can tap into instantly, he'll figure it out and we'll all learn something in the process.

Also I've started running my AR a little wetter than I did in the past, I had some problems with it early in the winter but that seemed to solve them.
 
So far I have started on OldTurtle's list above. I have not yet taken apart the bolt from the carrier. The gas port was good and solid.

When looking at step #3, I see a fair to good amount of powder residue on the entrance of the gas port near the beginning of the barrel. You can tell it's right where the end of the gas port on the carrier meets the gas port coming from the barrel. Is it typical to have some residue here or should it be bone dry? I'm still under my 1 year warranty with BM should I need a new part.

I also notice that the bolt neck has a lot of black gunk built up on it. Probably from too much rem-oil application. Should I be using a better lubricant in this area? I'll continue to disect the gun unless the residue near the gas port is abnormal and should be looked at by BM.
 
This is an interesting thread, My new Remington R-15 will shoot about everything except the UMC ammo. Same problem as described above. Rifle will fire the first round but will not pick up the second round from the mag. Have to load them manually. The gun shoots everything else flawlessly, it really likes the Black Hills 52gr molly hollow points. Got one 5 shot group the other evening that measured 9/16ths center to center. The UMC ammo wont shoot a 2" group. It doen't make sense to me that your BM likes the UMC ammo and my Remington wont feed it at all.
 
I would try another box of loads from a different store try the easiest variable first. I would be surprised if Hornady is loading them hot enough to cause a pressure problem.
 
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