6.5 Creedmoor short stroking

[Dario Velarde]

The year is 2019 November and I am having the same issue with the same gas block and I was told that the buffer spring was to step I haven't tried to change to a lighter spring but if anybody has found the remedy to this can you please text me or reply thank you

[98Z5V]

10 hours ago, Dario Velarde said:

The year is 2019 November and I am having the same issue with the same gas block and I was told that the buffer spring was to step I haven't tried to change to a lighter spring but if anybody has found the remedy to this can you please text me or reply thank you

Working on it, so just watch this thread for results. 

[Arcanum]

I just found this thread, I'm having the same issues here.  I have a similar build to  Rougaroux22  same barrel, gas block, bolt, charging handle, trigger but on a Seekins precision receiver set..  I am using a Tubbs flat wire spring and a CTS Engineering Aktive recoil buffer.  The few times it has locked back, it was caught on the bottom of the carrier, not the bolt face.  It doesn't seem like it's getting enough gas back through the system.  I'm hoping there will be a successful update from  Rougaroux22  or someone soon.

[Rougaroux22]

I ended up sending the entire rifle to Proof Research. After some testing they opened up the gas port a hair and sent it back. Gave it a good cleaning and lube and readjusted the gas block until it would hold open on an empty mag. Haven't had a problem since. 

It seems that Proof Research has the gas port opened up to get just enough gas through to cycle, however a small percentage of builds need the gas port to be larger. I spent a lot of time and $ getting it to run and don't mind answering any questions to save other people the trouble.

[98Z5V]

On 1/15/2019 at 7:21 PM, 98Z5V said:

IMHO, I think that gas port is too small - and that fits what is happening with the gun.  I think my setup should be at that size, minimum, and I'll be drilling mine to 0.081" to start, soon, and going up from there if I have to.  The gun is coming apart for Cerakote anyway.  I honestly think - with that gas system of yours that's 2" less than what I'm running - needs to be in the 0.090"~0.100" range, with 0.090" being the minimum for your setup. 

 

 

On 2/25/2019 at 9:50 AM, Rougaroux22 said:

**UPDATE***

After a lot of back and forth, I sent the rifle to Proof Research. To make a long story short, they widened the gas port to .088 and they say it runs like a champ now. After reading around it would appear that I am not the first person to have a 20" barrel not cycle the rifle with the gas port length/size they ship their barrels with. Seems to work okay with their 22" and 24", but I guess the 20" barrel gas port needs to be wider or be at rifle length?

Pretty much just what I said it would be. 

[Rougaroux22]

Yeah you nailed it. Thanks again

[Pilgar]

So I have been fighting a guys PSA Build for weeks,  I can get it to run just fine but I can't get rid of the primer issues.  I have attached photos.  When I get the primers look better then the gun won't cycle properly.    The one on the left is from my gun.  

308 adjustbale buffer, armalite ar10 buffer spring, 

Any Ideas on this one.    

[Matt.Cross]

Undersized firing pin or oversized firing pin hole. 

[98Z5V]

7 hours ago, Pilgar said:

So I have been fighting a guys PSA Build for weeks,  I can get it to run just fine but I can't get rid of the primer issues.  I have attached photos.  When I get the primers look better then the gun won't cycle properly.    The one on the left is from my gun.  

308 adjustbale buffer, armalite ar10 buffer spring, 

Any Ideas on this one.    

 

 

5 hours ago, Matt.Cross said:

Undersized firing pin or oversized firing pin hole. 

Yep, what he said.  Plus, all the specifics on this build are needed. 

What I highlighted above in red just isn't enough information. 

[Pilgar]

It has been awhile but I am getting back to this rifle.  The buffer is from Odinworks and is an actual 308 size buffer, the spring is for a 308 make by armalite

I will check the firing pin but I do not think that is it because I have used the same bolt in another rifle that cycles fine and the ignition impressions look normal. 

What other details do you need, In previous posts I have pretty well described the rifle.

 

[98Z5V]

7 hours ago, Pilgar said:

It has been awhile but I am getting back to this rifle.  The buffer is from Odinworks and is an actual 308 size buffer, the spring is for a 308 make by armalite

I will check the firing pin but I do not think that is it because I have used the same bolt in another rifle that cycles fine and the ignition impressions look normal. 

What other details do you need, In previous posts I have pretty well described the rifle.

 

Just to streamline this conversation - that was started on someone else's thread on the subject, I've compiled every post you've made in the thread, directly below.  They're all chronological, in order that you posted them, appearing below. 

On 10/27/2019 at 7:56 AM, Pilgar said:

Great discussion on getting the 6.5 creed to function properly as a AR10.  My name is James and I manage a gunshop and build all our custom AR variant rifles/pistols.  

I am amazed at how many times I have had to open a gas port to get a rifle to function properly.   I came across a problem I have not seen before last week and I am still trying to wrap my head around it.   Guy brought in a AR10 in 6.5creed it was not able to pick up the next round or lock back on an empty mag.  The shell ejected at between  3 and 4 oclock.  The primers on the ejected shells had a rebound dome inside  what looks like a normal depth firing pin dimple.  The rebound dome extended beyond the end of the case head enough to feel it raised with your finger, there is also a ring around this dome that is sharp.   So far no adjusting the gas block or changing buffers and springs has made much difference.  Our two gunsmiths think it is overgassed and the bolt is opening to soon causing space where the pressure can pop out that primer dome.  I am not so sure.   It is a 20 inch barrel, standard rifle length gas port.  

This is the first one I have not just been able to fix directly.  I have not seen primers like that before.  

If anyone here has any ideas I would love to hear them, this is the best discussion I have read yet on this subject and that is why I am asking here.

 

 

On 10/28/2019 at 11:13 AM, Pilgar said:

I got a chance to take this apart this morning.  It is a PSA upper 20" barrel the gas port diameter is .073"   The Lower is PSA the buffer is a 3.25" H the spring I don't know it is 11.25 inches long.  The buffer tube is 7.75" long.   This is the first I have had a chance to look at it.  I think the gas port enlarging is going to fix it.

 

 

 

On 10/28/2019 at 3:33 PM, Pilgar said:

I opened up the gas port to .096   It had an adjustable gas block.  The gun functions correctly now but the primers still are looking weird.  There is a reverse dome inside the firing pin depression.  I will try and take a photo and post it.  

 

On 10/29/2019 at 9:09 AM, Pilgar said:

When the gun doesn't cycle the primers look like on the right.  

when it does it looks like on the left  (Domed in the depression.

 

 

 

On 12/13/2019 at 1:06 PM, Pilgar said:

So I have been fighting a guys PSA Build for weeks,  I can get it to run just fine but I can't get rid of the primer issues.  I have attached photos.  When I get the primers look better then the gun won't cycle properly.    The one on the left is from my gun.  

308 adjustbale buffer, armalite ar10 buffer spring, 

Any Ideas on this one.    

 

[98Z5V]

Our detailed responses, as you posted those entries - are not posted in that recap.  In order for others to see that, and see what was told to you, they'll need to go back to Page 2 (on a computer - might be different on a phone), and look at your first post in this thread.

Maybe this collection of posts will help with a diagnosis.  My first recommendation is to shoot different ammo - S&B ammo can SUCK, lot by lot.  Shoot something different, something quality, and see what the rifle does.  If all you've been shooting is S&B, you're flying blind here, on your side of diagnosis.  See is some Federal Gold Medal Match ammo does the same thing.  Shelf-Ammo for 6.5 Creedmoor is everywhere.  All your pics are with S&B ammo here.

Edited January 11, 2020 by 98Z5V

[Pilgar]

98Z5V,   Thanks for the help,  I have shot different ammo, Hornady 140gr ELDM  then I switched to the S&B because it was less expensive.  The same thing was happening to the primers.  I also built another 6.5creed during this and used the same ammo with no issues, that build produced a fantastic rifle.  During the construction I swapped out parts with the PSA rifle I am having the issues with and the only part that causes problems is the PSA upper.    With the Odinworks adjustable buffer I can change the weights such that the gun cycles fine, locks back on an empty but exhibits the primer issues.  Or the primers look fine but it won't lock back.  I think that the bolt is opening too soon and I am not sure now how to correct that and still have the gun lock back .    If there is any more information needed to help diagnaose this PSA rifle let me know,  I am about to return it to the owner.  

 

  

[98Z5V]

9 hours ago, Pilgar said:

98Z5V,   Thanks for the help,  I have shot different ammo, Hornady 140gr ELDM  then I switched to the S&B because it was less expensive.  The same thing was happening to the primers.  I also built another 6.5creed during this and used the same ammo with no issues, that build produced a fantastic rifle.  During the construction I swapped out parts with the PSA rifle I am having the issues with and the only part that causes problems is the PSA upper.    With the Odinworks adjustable buffer I can change the weights such that the gun cycles fine, locks back on an empty but exhibits the primer issues.  Or the primers look fine but it won't lock back.  I think that the bolt is opening too soon and I am not sure now how to correct that and still have the gun lock back .    If there is any more information needed to help diagnaose this PSA rifle let me know,  I am about to return it to the owner.  

 

  

Hold on before you return that gun!  What I highlighted in red above is usually a gas port issue.  You have one example that does this to primers - and one that doesn't. PERFECT!  That gives you a great example, for specs, to find the differences in the one that's giving that owner issues...

I'd pull the bolts of both those and measure the firing pin holes in the bolt faces, first. Then, I'd pull the gasblocks, and measure gas port diameters in both.  I'd start with those two things, right off the bat. Don't forget to check the length of the gas tubes in both - those gas tubes should end right in the center of the cam pin cutout in the upper receivers.

Edited January 12, 2020 by 98Z5V

[98Z5V]

9 hours ago, Pilgar said:

 With the Odinworks adjustable buffer I can change the weights such that the gun cycles fine, locks back on an empty but exhibits the primer issues.  Or the primers look fine but it won't lock back.  I think that the bolt is opening too soon and I am not sure now how to correct that and still have the gun lock back .    

Let's separate proper cycling of the gun, and non-damaged primers, from locking back. Those are two separate issues here.

Gas pressure, OR recoil system weight, is causing that gun to unlock early and bulge the hell out of those primers.  When the buffer weight is correct to lock the gun back, it bulges primers - is that correct?  Once you ADD WEIGHT to the buffer, you slow down the carrier and cyclic speed, the primer issues go away - but it won't lock back anymore...

Do I have that right?

First, verify the recoil system, make sure it's right.  Length of buffer, good (appropriate) buffer spring, internal depth of receiver extension, measure at the top of the receiver extension. 

This gas port is too small (surprise, for a PSA large-frame gun, total shocker...).

Receiver extension depths,and buffer lengths, SHOULD be one of these combos below.  No other way around it, and "close" won't cut it.  If your receiver extension is "close" but a little longer than what I'm listing below, you WILL crash the BCG into the ears on the lower receiver - that will completely fuk your entire recoil impulse up, and it WILL affect the cycling of the gun...

1.  Rifle receiver extension - 9 11/16" internal depth, with a buffer that's 5.200" long.  Weight should be 5.4 oz.

2.  AR-10 Carbine receiver extension - 7 5/8" internal depth, with a buffer that's 3.250" long.  Buffer weight can be anything from 3.8oz to 5.4oz, but you WANT 5.4oz for proper operation on a large-frame AR.

3.  AR15 Carbine receiver extension - 7.000" internal depth.  True Armalite depth is 6 15/16" internal.  That has to run a Shorty 308 buffer in it, and it's 2.500" long.  Weight can only be (max) 3.8oz, if it's an aluminum-bodied buffer.  You have to go to the aftermarket to get a 2.500" buffer up to 5.4 or 5.3oz, proper weight, and they're going to have stainless bodies to achieve that weight. Aluminum bodies will never get you there.

^^^  That gun has one of those combinations.  Chances are very, very high, that the receiver extension is NOT the correct internal depth.  You must start there, and have a proper recoil system, before you can get into the gas port info for the barrel... 

 

Edited January 12, 2020 by 98Z5V

[Pilgar]

On 1/11/2020 at 6:20 PM, 98Z5V said:

Hold on before you return that gun!  What I highlighted in red above is usually a gas port issue.  You have one example that does this to primers - and one that doesn't. PERFECT!  That gives you a great example, for specs, to find the differences in the one that's giving that owner issues...

I'd pull the bolts of both those and measure the firing pin holes in the bolt faces, first. Then, I'd pull the gasblocks, and measure gas port diameters in both.  I'd start with those two things, right off the bat. Don't forget to check the length of the gas tubes in both - those gas tubes should end right in the center of the cam pin cutout in the upper receivers.

The PSA upper that I am having issues with does not allow the gas tube to end in the center of the cam pin cutout.  Unless I manufacture the correct length there is no available gas tube that is the correct length.  So I have assumed I can get around that issue to make the rifle function properly but maybe not.  

[98Z5V]

12 hours ago, Pilgar said:

The PSA upper that I am having issues with does not allow the gas tube to end in the center of the cam pin cutout.  Unless I manufacture the correct length there is no available gas tube that is the correct length.  So I have assumed I can get around that issue to make the rifle function properly but maybe not.  

Okay, we can deal with that.  What about gas port diameters and recoil system details?

[Pilgar]

Sorry it has been awhile since I got back to this, very busy and I had to put this rifle on the back burner.  Anyway I installed a JP Enterprises high pressure bolt and the rifle now functions perfectly and responds the way I would expect when opening up the gas block and or changing the buffer weight.  This ended up being the easiest and cost efficient fix. 

The Primers all look great and the rifle cycles perfectly and locks back on an empty mag, the casings eject at the proper angle.  I figured I was going to have to make a custom gas tube for this rifle next, then I found out about the JP bolts at the Hicks show in Minneapolis.

Thanks 98Z5V!!!   This has been a great learning experience!!!  

[98Z5V]

The have smaller firing pin protrusions (firing pin is smaller in diameter, where it strikes the primer) and smaller firing pin hole in the bolt face - is that correct?

Edited February 5, 2020 by 98Z5V

[sagebrush]

4 minutes ago, 98Z5V said:

The have smaller firing pin protrusions (firing pin is smaller in diameter, where it strikes the primer) and smaller firing pin hole in the bolt face - is that correct?

those bolts do have a smaller pin hole. the pin itself measures .062 and fits the hole very closely. you're correct

[98Z5V]

So, those original issues that he had probably didn't have anything to do with ammo quality - but his original bolt and firing pin.  Well, maybe the ammo, and maybe that specific bolt (more than the firing pin, but the bolt hole, at the diameter of the firing pin hole).

I've never had this issue with .260 Rem, running a .308-spec BCG and bolt - ToolCraft complete BCG is what I have, not that "special" Creedmoor bolt that they have, with dual ejectors.  In light of that, is this 6.5 Creedmoor stuff putting out THAT much more power than .260 Rem?  The numbers on both those cartridges don't state something like that - .260 is a little more powerful than 6.5CM, based on case volume, possible max powder charge weights, etc.  So, why is 6.5CM doing that to his brass, and primers? Bad bolt face, and firing pin hole in the bolt?

I wanna dig into this one...