Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
BCM
User Panel

Posted: 7/26/2015 1:09:53 PM EDT
I have a 10.5" SBR which won't cycle common 55gr .223 (Remington, Federal XM, Fiocchi, etc).  Rainier installed the gas block and pinned it after I had an experienced gun smith install it and noticed leakage (not pinned).  I still get some gas block leakage.  It will either not feed a round all the way or will not feed a round at all (last pic).  It is beyond frustrating at this point since I have no issues with a 300 Blackout upper in 10.5 on the same lower.  Let me know if you all have any questions/need additional info.  When it shoots, it is very accurate...but that does me no good since it is not reliable.  Should I sent it back to Rainier to have checked out?

Specs below and all are new parts:

Aero Precision Upper
Rainer Arms Select Grade stainless barrel 10.5 w/carbine gas system
Rainier Arms Low Profile Match Grade - Stainless Steel - pinned
DSG Arms Enhanced BCG (I've tried a standard BCG in auto as well as semi)

Buffer/Springs I've tried:

JP polished carbine spring
LaRue Tactical carbine spring
Flat spring
Stock carbine spring

Standard carbine buffer
Spikes T1 buffer
Spikes T2 buffer








Link Posted: 7/26/2015 1:17:21 PM EDT
[#1]
What mags?
Link Posted: 7/26/2015 1:39:19 PM EDT
[#2]
All sorts of mags from milspec to hexmag and magpul...20 round and 30 round..  Same mags for the 300 and with a normal AR, no issues.
Link Posted: 7/26/2015 1:57:54 PM EDT
[#3]
If you haven't taken the bolt carrier out yet do that and check if the gas key is loose at all. I had my gas key come loose at the range and it was doing the same thing shown in your pictures.

EDIT: I missed the part about you trying multiple BCGs, so disregard
Link Posted: 7/26/2015 2:13:33 PM EDT
[#4]
Can you describe the mechanical issue its having in more detail?
Link Posted: 7/26/2015 2:19:24 PM EDT
[#5]
When I pull the trigger, it fires, next round does not feed all the way.  The above pics are after one round is fired and what happens to the next round.  Extracts the spent round fine.  I'm not as experienced with this as most on here so hit me with specific questions and I'll try to answer them.
Link Posted: 7/26/2015 2:27:54 PM EDT
[#6]
A typical problem with 10.5" guns. I'm not sure what the fix is, as I've always maintained that 11.5" is the minimum for a AR.

I suspect it's a gas problem.
Link Posted: 7/26/2015 2:36:05 PM EDT
[#7]
Does the bolt lock back after firing the last round out of a mag?
Link Posted: 7/26/2015 2:37:18 PM EDT
[#8]
Yes, it will lock back on the last round fired.
Link Posted: 7/26/2015 2:41:07 PM EDT
[#9]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
A typical problem with 10.5" guns. I'm not sure what the fix is, as I've always maintained that 11.5" is the minimum for a AR.

I suspect it's a gas problem.
View Quote


I hear you.  I have a 12.5 LaRue barrel...I may have that installed and sell the Rainier 10.5 if I can't resolve the issue.

Is it possibly under gassed?  Would an adjustable gas block, like the Syrac help?
Link Posted: 7/26/2015 4:17:46 PM EDT
[#10]
The bolt looks dry.  How are you lubricating the gun?
Link Posted: 7/26/2015 4:46:58 PM EDT
[#11]
It's not dry, I use FireClean over the black nitride coating.  I also switched out the BCG with a new Nib coated version wiped down with FireClean.
Link Posted: 7/26/2015 5:59:47 PM EDT
[#12]
Do you have acess to a H3 buffer?  It is possibkly overgassed.  Undergassed would not lock back on an empty mag.  

MAHA
Link Posted: 7/26/2015 7:19:31 PM EDT
[#13]
Spikes T3 (5.4 oz) or H3 (5.6 oz)?  I'll need to order it.
Link Posted: 7/26/2015 7:29:22 PM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Spikes T3 (5.4 oz) or H3 (5.6 oz)?  I'll need to order it.
View Quote


Both.  

It's always a good idea to have different buffers on hand to trouble shoot issues like yours.
Link Posted: 7/26/2015 7:34:22 PM EDT
[#15]
Buy an adjustable gas block for ~$50-80 and be done with it. Won't need to play with buffers. If it's over gassed, you should fix the problem rather than use a bandaid.
Link Posted: 7/26/2015 7:37:04 PM EDT
[#16]
Might be the gas port opening. On my 607 SBR I had it opened to .093 and run an H2 buffer, the bolt has a Crane gas ring, Wolf extra strength extractor spring and D ring seal.
 
Link Posted: 7/26/2015 7:45:38 PM EDT
[#17]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
It's not dry, I use FireClean over the black nitride coating.  I also switched out the BCG with a new Nib coated version wiped down with FireClean.
View Quote


Looks dry to me. I also use fire clean. I had a similar issue with my 11.5 when it was brand new. It would fail to feed randomly.  I just lubricanted it more in the break in period and now I have 1000s of rounds through it with no issues.
Link Posted: 7/26/2015 7:50:20 PM EDT
[#18]
Gotcha but I also used a Nib coated bolt, wet and a standard one, wet.
Link Posted: 7/26/2015 8:20:59 PM EDT
[#19]
You mentioned gas leakage. How do you know that it is happening what is indicating that?





My guess is that you are short stroking.(undergassed)
Link Posted: 7/26/2015 8:22:16 PM EDT
[#20]
Do you have any idea what the diameter of the gas port is? My 10.5 with an .078" gas port runs great. If yours is larger an adjustable gas block is in your future.
Link Posted: 7/26/2015 8:29:52 PM EDT
[#21]
I'll call Rainier tmmw to find out the gas port size.  There is some residue at the front of the gas block, which is pinned.
Link Posted: 7/26/2015 9:42:30 PM EDT
[#22]
Start with a heavier buffer if that doesn't work replace the gas block, preferably with an adjustable one.

If that doesn't work come back here and ask for more help.
Link Posted: 7/26/2015 9:57:44 PM EDT
[#23]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Gotcha but I also used a Nib coated bolt, wet and a standard one, wet.
View Quote


I use fireclean with my spikes nib coated BCGs in all my rifles. They work great. Sorry just an observation and personal experience on lubrication. I would do as other say and ditch the gas block for an adjustable one. I think I read this was a 5.56 build correct? Adjustable gas is almost a must for 5.56. Look at Micromoa.com they sell a gas block that is easy to adjust. I am sure the AR15.com rep for the company will chime in also.
Link Posted: 7/26/2015 10:19:01 PM EDT
[#24]
I also say try the heavier buffer first.
Link Posted: 7/27/2015 8:02:55 AM EDT
[#25]
I appreciated the insight, I went ahead and lubed the BCGs down just in case.  I also ordered the PWS H3 buffer and the Syrac adjustable gas block.  If the buffer doesn't work, I'll have a gunsmith install the new gas block.  I'll see if I can film it next time I go to the range, which won't be for about two weeks unfortunately.

Thanks for all of the suggestions, hopefully I can get this to cycle reliably.
Link Posted: 7/27/2015 11:46:08 AM EDT
[#26]
Looks to me like the only issue you're having is a failure to feed.  I'm no expert, but I really see only limited ways how the gas pressure will effect that.

If it was undergassed, the bolt wouldn't lock back consistently on the last round.  You sure it does?  

Undergassed guns that extract fine usually fail in one of two ways.  They either 1) failure to feed because the BCG doesn't travel far enough rearward to generate the necessary momentum to feed a round when coming forward or 2) don't travel rearward enough to even pick up a new round out of the mag.

Assuming you're not having the second problem and it is consistently locking back on an empty round for the most part, you're probably right on the edge of being undergassed.  In that case, you have to get the bcg to travel farther rearward to generate that forward momentum to feed the next round.  That means going to a lighter buffer or spring to reduce the resistance.

This assumes also that you never have issues actually chambering a round with either the charging handle or the bolt release.  If you did in either of those conditions, I'd say you had a mag, feed ramp, or chamber problem.  In such a condition, the round would keep getting hung-up, regardless of whether manually chambered or automatically by the firing action of the gun.

If it were overgassed, you could get any number of problems, but I don't see how a FTF would be one of them.  Normally in an overgassed condition, you have excessive ejection, the possibility of the buffer colliding with the rear of the receiver extension and over time destroying it or the lower, or bolt-bounce when seating that results in a light primer strike or no strike at all.  Bolt bounce is only really noticeable on full auto or really high-speed guns though.  I don't see how you'd have a failure to feed out of a good mag on an overgassed gun though.  The bcg has plenty of momentum at that point to seat the round.

My guess is either you're very slightly undergassed, which is resulting in it teetering on locking back and not generating enough forward momentum to seat the next round (in which case the solution is to go to a lighter spring/buffer or swap the gas block) or you have a defect in the feed ramp or chamber that is resulting in the rounds getting hung-up while the rifle automatically cycles.

Good luck
Link Posted: 7/27/2015 12:03:55 PM EDT
[#27]
Thanks, I was leaning towards under gassed as well.  It definitely is inconsistent and I'll document/vid my next session to the range.
Link Posted: 7/28/2015 3:29:16 PM EDT
[#28]
Topic Moved
Link Posted: 8/4/2015 8:26:19 PM EDT
[#29]
I'm going to hit the range this weekend and report back.  I'll note if it locks back on an empty mag as well as try the H3 buffer.  The enhanced BCG has been lubricated as well.  

I also have the Syrac adjustable gas block just in case it is needed.  Thanks again for the help.
Link Posted: 8/4/2015 9:06:30 PM EDT
[#30]
I have the same barrel and gas block. Im running a BCM standard bolt, standard recoil spring and a Spikes T2. I had some feed issues to start also. I put in a D-Fender Ring on the extractor and all was well. Guessing it had to do with getting the spent round out of the way faster. Just enough less drag or something. Either way it was a cheap fix.
Link Posted: 8/5/2015 11:38:35 PM EDT
[#31]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Yes, it will lock back on the last round fired.
View Quote


If the bcg locks back and it ejects ok,  than I would say it is not a gas problem and more of a mag problem.

I had a similar problem on my 18" SPR.  The bolt kept riding up over the first or second round.  Turned out that the mag springs (new USGI mags) just needed to be broken in a bit because after hand charging it a bunch of times with each mag....it began to work just fine...picking up each following round.
Link Posted: 8/5/2015 11:40:21 PM EDT
[#32]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Looks to me like the only issue you're having is a failure to feed.  I'm no expert, but I really see only limited ways how the gas pressure will effect that.

If it was undergassed, the bolt wouldn't lock back consistently on the last round.  You sure it does?  This...

Undergassed guns that extract fine usually fail in one of two ways.  They either 1) failure to feed because the BCG doesn't travel far enough rearward to generate the necessary momentum to feed a round when coming forward or 2) don't travel rearward enough to even pick up a new round out of the mag.

Assuming you're not having the second problem and it is consistently locking back on an empty round for the most part, you're probably right on the edge of being undergassed.  In that case, you have to get the bcg to travel farther rearward to generate that forward momentum to feed the next round.  That means going to a lighter buffer or spring to reduce the resistance.

This assumes also that you never have issues actually chambering a round with either the charging handle or the bolt release.  If you did in either of those conditions, I'd say you had a mag, feed ramp, or chamber problem.  In such a condition, the round would keep getting hung-up, regardless of whether manually chambered or automatically by the firing action of the gun.

If it were overgassed, you could get any number of problems, but I don't see how a FTF would be one of them.  Normally in an overgassed condition, you have excessive ejection, the possibility of the buffer colliding with the rear of the receiver extension and over time destroying it or the lower, or bolt-bounce when seating that results in a light primer strike or no strike at all.  Bolt bounce is only really noticeable on full auto or really high-speed guns though.  I don't see how you'd have a failure to feed out of a good mag on an overgassed gun though.  The bcg has plenty of momentum at that point to seat the round.

My guess is either you're very slightly undergassed, which is resulting in it teetering on locking back and not generating enough forward momentum to seat the next round (in which case the solution is to go to a lighter spring/buffer or swap the gas block) or you have a defect in the feed ramp or chamber that is resulting in the rounds getting hung-up while the rifle automatically cycles.

Good luck
View Quote

Link Posted: 9/30/2015 6:28:17 PM EDT
[#33]
I finally had time to have a trusted gun smith check it out.  The gas port in the barrel is undersized so they are going to fix that and install my Syrac adjustable gas block then function check it. They also properly head spaced the new BCG.
Link Posted: 9/30/2015 9:27:58 PM EDT
[#34]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I finally had time to have a trusted gun smith check it out.  The gas port in the barrel is undersized so they are going to fix that and install my Syrac adjustable gas block then function check it. They also properly head spaced the new BCG.
View Quote


Cool, let us know how it goes.
Link Posted: 9/30/2015 9:29:45 PM EDT
[#35]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I finally had time to have a trusted gun smith check it out.  The gas port in the barrel is undersized so they are going to fix that and install my Syrac adjustable gas block then function check it. They also properly head spaced the new BCG.
View Quote


Was it not in spec?

Did they tell you what the gas port size is vs what they're going to change it to?
Link Posted: 10/1/2015 1:53:22 AM EDT
[#36]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Was it not in spec?

Did they tell you what the gas port size is vs what they're going to change it to?
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
I finally had time to have a trusted gun smith check it out.  The gas port in the barrel is undersized so they are going to fix that and install my Syrac adjustable gas block then function check it. They also properly head spaced the new BCG.


Was it not in spec?

Did they tell you what the gas port size is vs what they're going to change it to?


Either way this is interesting with a rainier barrel. I have a match barrel on my SPR which was from Rainier. They kept telling me my gun wasn't overgassed. I was getting shearing on the brass as well as heavy dents. The recoil was excessive too. Ejection was all over the place but mostly forward. Installed an adjustable gas block and what do you know...it was overgassed. Shoots beautifully now.
Link Posted: 10/1/2015 10:26:13 PM EDT
[#37]
ditch the spikes buffers and get a real H2 or H3 buffer.





Link Posted: 10/2/2015 9:19:53 AM EDT
[#38]
Here is some good AR15 Mechanical Trouble Shooting info
http://www.majorpandemic.com/2013/06/troubleshooting-your-ar-build.html
http://www.majorpandemic.com/2012/06/all-about-adjustable-ar-gas-blocks.html
http://www.ar15barrels.com/prod/operation.shtml
Link Posted: 10/2/2015 12:10:07 PM EDT
[#39]
Link Posted: 10/2/2015 12:11:20 PM EDT
[#40]
Link Posted: 10/6/2015 5:54:05 AM EDT
[#41]
Are all the mags new?  I had a very similar problem with a 14.5" middy where the bolt would initially catch the shell rim and begin to send it up feed ramps and then the bolt would slip off and jam up.  

In my case I narrowed down the problem to the mags which were brand new.  The more I worked the mags...loading and unloading...the problem resolved itself.  In my case I speculate that the new springs in the mags were overly tight and not allowing the first round to be picked up because of the spring tension.  The more I worked the mag spring, the problem worked its way out.  I did noting with the gas block of BCG.  It was just really working the mag springs.  the springs were really jamming that first round of a full mag pretty hard up against the bcg.  As the tension against the feed lip was just slightly reduced from the constant loading and unloading, the top rounds began to feed properly and have never had the problem again.

I know I will get a lot of skepticism but ....the logic was sound and it worked.

OP...does yours just do it on the first round in the mag or all rounds?
Link Posted: 10/6/2015 5:55:38 AM EDT
[#42]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Looks to me like the only issue you're having is a failure to feed.  I'm no expert, but I really see only limited ways how the gas pressure will effect that.

If it was undergassed, the bolt wouldn't lock back consistently on the last round.  You sure it does?  

Undergassed guns that extract fine usually fail in one of two ways.  They either 1) failure to feed because the BCG doesn't travel far enough rearward to generate the necessary momentum to feed a round when coming forward or 2) don't travel rearward enough to even pick up a new round out of the mag.

Assuming you're not having the second problem and it is consistently locking back on an empty round for the most part, you're probably right on the edge of being undergassed.  In that case, you have to get the bcg to travel farther rearward to generate that forward momentum to feed the next round.  That means going to a lighter buffer or spring to reduce the resistance.

This assumes also that you never have issues actually chambering a round with either the charging handle or the bolt release.  If you did in either of those conditions, I'd say you had a mag, feed ramp, or chamber problem.  In such a condition, the round would keep getting hung-up, regardless of whether manually chambered or automatically by the firing action of the gun.

If it were overgassed, you could get any number of problems, but I don't see how a FTF would be one of them.  Normally in an overgassed condition, you have excessive ejection, the possibility of the buffer colliding with the rear of the receiver extension and over time destroying it or the lower, or bolt-bounce when seating that results in a light primer strike or no strike at all.  Bolt bounce is only really noticeable on full auto or really high-speed guns though.  I don't see how you'd have a failure to feed out of a good mag on an overgassed gun though.  The bcg has plenty of momentum at that point to seat the round.

My guess is either you're very slightly undergassed, which is resulting in it teetering on locking back and not generating enough forward momentum to seat the next round (in which case the solution is to go to a lighter spring/buffer or swap the gas block) or you have a defect in the feed ramp or chamber that is resulting in the rounds getting hung-up while the rifle automatically cycles.

Good luck
View Quote


This...^^.
Link Posted: 10/6/2015 6:34:41 AM EDT
[#43]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Buy an adjustable gas block for ~$50-80 and be done with it. Won't need to play with buffers. If it's over gassed, you should fix the problem rather than use a bandaid.
View Quote


That won't do any good if the hole is too small.
Link Posted: 11/12/2015 9:00:35 PM EDT
[#44]
Sorry, I don't recall what size the hole was just that it was too small.  

I cycled about 150+ rounds through it yesterday with no issues - all sorts of mags (new, old...about 6 different types) and ammo...it was great to shoot.  I won't go with Rainier again though for a barrel...way too much of a pain in the arse.  My 10.5 DSG/Seekins upper ran from day one without issue as did the inexpensive 10.5 PSA 300 blackout barrel.  I'm still using a Spikes T2 buffer and JP polished spring with a DSG NiB enhanced BCG.
Link Posted: 11/13/2015 12:04:19 AM EDT
[#45]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Majorpandemic also reviewed our Govnah after doing those articles: http://www.majorpandemic.com/2014/04/micromoa-govnah-adjustable-gas-block-reviiew.html
 
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Here is some good AR15 Mechanical Trouble Shooting info
http://www.majorpandemic.com/2013/06/troubleshooting-your-ar-build.html
http://www.majorpandemic.com/2012/06/all-about-adjustable-ar-gas-blocks.html
http://www.ar15barrels.com/prod/operation.shtml
Majorpandemic also reviewed our Govnah after doing those articles: http://www.majorpandemic.com/2014/04/micromoa-govnah-adjustable-gas-block-reviiew.html
 


I'll back up the Govnah as I have one installed on my 10.5" Noveske and may be the best upgrade I've performed on my SBR.  I figured that I would have some initial issues with FTF or FTE, but from the first shot an on I've never had an issue.  Plus the fact it only has 2-3 settings (depending on the GB you get) it makes it so much easier to dial in.
Link Posted: 11/13/2015 9:29:09 PM EDT
[#46]
I'm just curious why you didn't send it back to rainier?

Link Posted: 11/13/2015 11:06:13 PM EDT
[#47]
Funny, my Rainier is the best barrel I have.
Link Posted: 11/14/2015 9:47:25 AM EDT
[#48]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I'm just curious why you didn't send it back to rainier?

View Quote


I did and had them rebuild/inspect the upper, which a gunsmith just put together, for about $150 and was told it was GTG...but it wasn't.  It is accurate for sure just expensive to get to where it needed to be.  I'm sure it was just a fluke...I just have no patience for such things.
Link Posted: 11/14/2015 2:41:39 PM EDT
[#49]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


I did and had them rebuild/inspect the upper, which a gunsmith just put together, for about $150 and was told it was GTG...but it wasn't.  It is accurate for sure just expensive to get to where it needed to be.  I'm sure it was just a fluke...I just have no patience for such things.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
I'm just curious why you didn't send it back to rainier?



I did and had them rebuild/inspect the upper, which a gunsmith just put together, for about $150 and was told it was GTG...but it wasn't.  It is accurate for sure just expensive to get to where it needed to be.  I'm sure it was just a fluke...I just have no patience for such things.


You probably  need to learn to do more to your AR, replacing gb is simple, checking gas port size simple. You should have been up in running and had more money in your pocket all in a day or atleast knew the culprit sooner.

Glad your up in running and every once in awhile things slip by the initial qc. But when you sent it back to Rainier this should all have been caught. Not good on them...happy shooting!
Link Posted: 11/14/2015 3:14:02 PM EDT
[#50]
No probably about it :)  I did learn a lot thanks to this forum as well as the place I sent it to.  Patience is not my strong suit but I'm working on that...just not quick enough :)  I have another SBR build that will go smoother thanks to the input here - you guys are a huge help.
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.
Top Top