Cycling Issues with Reloads and Daniel Defense DD5v5

[MNtadpole]

Hey,

So long story short, I have been trying to work up a load for my 20" Daniel Defense DD5v5(AR-10) chambered in 6.5 Creedmoor. During this process, I have been having many jamming issues with this platform. I believe that I am experiencing a "bolt-over-base" malfunction , which destroys the brass in the process. I know that this firearm cycled factory boxed ammo just fine, so I'm 95% sure the problem is with my reloads. This malfunction is occurring with an approx. 10% chance.

Here's What the jams look like:




Here's the damaged cartridges:



Here are the details of my 6.5 Creedmoor reloads:

Hodgdon H4895 36.4 grains
Hornady 129 grain SP
Hornady brass
Win WLR primers
Velocity: 2668 fps as measured from MagnetoSpeed V3
COAL: 2.775"
Rifle Fire-Forms @ approx. 1.563"
Resized Head Space @ approx. 1.559" (-.004" from fire formed)
Fire Formed Case Volume: approx. 53.3 grains H20

Here is the condition of the case heads (ignore the text in photo):


Here's a screen shot of Gordon's Reloading Tool, based on my load. The software and my case heads disagree with the recorded high pressure levels in the software:



I am very eager to get this issue solved so I can move onto fine tuning my loads for accuracy. Please provide any guidance or suggestions to how and where I could maybe narrow this problem down to. Any and all help would be greatly appreciated!! Thanks.

 

[nagantguy]

Had this same problem with a a 308, my fix was an adjustable gas block- I had the problem with factory ammo as well but more so with home rolled ammo, went to stiffer buffer spring, minimal improvement, then heavier buffer- some what better. Gas block was the fix, horribly over gassed. From half a turn on up until it ran perfect and than one more turn for insurance and problem solved. Your ammo seems fine- and if I missed it is it a factory rifle or a home build?

 

[MPDS13]

I would second the above mentioned idea. An adjustable gas block with possibly a stronger spring and heavier buffer should slow the bolt down and assist in tuning it.

 

[MNtadpole]

Had this same problem with a a 308, my fix was an adjustable gas block- I had the problem with factory ammo as well but more so with home rolled ammo, went to stiffer buffer spring, minimal improvement, then heavier buffer- some what better. Gas block was the fix, horribly over gassed. From half a turn on up until it ran perfect and than one more turn for insurance and problem solved. Your ammo seems fine- and if I missed it is it a factory rifle or a home build?

Thanks for reaching out. Factory ammo seems to run okay, though I need to check it again just to be sure...and get chrono data from it too. My reload ammo is what I've noticed lately that causes problems.

 

[MNtadpole]

All,

Does anyone have any suggestion on the best brands for the following parts:
-adjustable gas block
-heavy buffer spring
-heavier buffer

 

[loveha]

Slash's Heavy Buffers | Home

Custom Heavy Buffers for AR10 AR15 rifle carbine. Home of the Slash CAR-10 Buffer.

heavybuffers.com

Sprinco USA -- Recoil Solutions

I don't have a suggestion on the block.

 

[bigjake83]

All,

Does anyone have any suggestion on the best brands for the following parts:
-adjustable gas block
-heavy buffer spring
-heavier buffer

It depends on your budget..

Slash makes good stuff but I prefer the H2 JP SCS.

For a adjustable gas block I'd say you have more options, best budget AGB Is the Seekins it's like $60, otherwise I'd only look at SLR or Superlative Arms, I prefer the SA AGBs

 

[MNtadpole]

It depends on your budget..

Slash makes good stuff but I prefer the H2 JP SCS.

For a adjustable gas block I'd say you have more options, best budget AGB Is the Seekins it's like $60, otherwise I'd only look at SLR or Superlative Arms, I prefer the SA AGBs

SLR and SA adjustable gas blocks look pretty solid

 

[Rolex24]

I’ve got an SLR on my “dmr” build and like it. Which model SLR is the right fit for the DD5V1?

 

[2grim4U]

All,

Does anyone have any suggestion on the best brands for the following parts:
-adjustable gas block
-heavy buffer spring
-heavier buffer

Springs- go to Wolf https://www.gunsprings.com/
Buffer- just buy the tungsten slugs off Amazon. Way cheaper than buying a heavy buffer.

Amazon.com : T&D Tungsten H, H2 or H3 Weights - 1.5 oz Each, 3-Pack Weights - Total Weight Kit 4.5 oz : Sports & Outdoors

Amazon.com : T&D Tungsten H, H2 or H3 Weights - 1.5 oz Each, 3-Pack Weights - Total Weight Kit 4.5 oz : Sports & Outdoors

www.amazon.com

 

[BrettRay]

I put a slr 7 titanium gas block on mine. Hated that 2 position gas block. Also took the 2 1.5 ounce tungsten weights out of buffer. The DD5V5 already has a weighted bcg. Haven’t fired it since taking the weights out but the next thing I do is find a lighter spring. I think it’s too stiff

 

[MNtadpole]

I put a slr 7 titanium gas block on mine. Hated that 2 position gas block. Also took the 2 1.5 ounce tungsten weights out of buffer. The DD5V5 already has a weighted bcg. Haven’t fired it since taking the weights out but the next thing I do is find a lighter spring. I think it’s too stiff

Okay, that sounds pretty interesting. Did you install the gas block yourself? For me personally, the 2 position gas block doesn't really offer me anything, since I can't run a suppressor in IL. I haven't personally messe with changing the weights out the the DD5v5 yet though. One thing that I have learned about the AR10 platform and reloading for it, is that an adjustable gas block is the most ideal for getting the platform to cycle correctly. I tried 2 different powders (RE17 and H4895) both of which seemed to over-gas the AR10 system at the velocities that I was wanting. The end result for those two powders were bolt-over-base jamming, caused by what I believe was an over-gassed system cycling too fast for the rounds to chamber properly.

Moving forward, I finally broke down and tried reloading with H4350, which is apparently everyone and their Mom's powder of choice for the 6.5CM. This powder's gas profile apparently runs within the DD5v5's optimum spectrum. With that being said, I'm going to be sticking with H4350 until I break down and change out the gas broke for an adjustable one.

My main goal with the DD5v5 right now is to develop an accurate load. After that, I will be in the market for some more ideal glass to put on this platform. Right now I only have A Razor HD 1-6x24, which works for load development, but I obviously can't easily stretch things out with it. I'm contemplating a Nightforce ATACR 5-25x56 F1 or their NX8 2.5-20.

 

[BrettRay]

I don’t reload and I’m not really into tactical FFP scopes so I’m not a help with that. This was more of a hunting rig for me. I put a Leupold vx5-hd 3x15 on mine. The slr 7 titanium gas block is really nice. It has 15 gas positions and seemed like I got to 7 on the clicks where it would lock the bolt back. One thing I did notice is that the case mouths were all dented on the ejected rounds though. The buffer spring, buffer, and bcg are all proprietary so I’m not sure how much I can fiddle with those. I hate proprietary stuff and may end up getting rid of this gun for something I can change stuff on

 

[LukeTheDuke]

I’ve recently gotten a DD5V4 in 6.5 and it seems to do well with H4350 & Hornady 147 ELD-M’s. I’m still developing my load for it, but so far I’ve never had your problem. I am running suppressed, and have the gas block on the suppressed setting.
I’ve got a Razor HD gen2 4.5-27 on it right now, and it’s really nice... but I’d lean toward the ATACR if I had to do it all over again. I got behind an ATACR next to my Razor at the range and got sold on the Nightforce pretty quickly.

 

[MNtadpole]

I don’t reload and I’m not really into tactical FFP scopes so I’m not a help with that. This was more of a hunting rig for me. I put a Leupold vx5-hd 3x15 on mine. The slr 7 titanium gas block is really nice. It has 15 gas positions and seemed like I got to 7 on the clicks where it would lock the bolt back. One thing I did notice is that the case mouths were all dented on the ejected rounds though. The buffer spring, buffer, and bcg are all proprietary so I’m not sure how much I can fiddle with those. I hate proprietary stuff and may end up getting rid of this gun for something I can change stuff on

There is a strong proprietary element to the DD5 platform for sure! I mean you should be able to change out all the BCG and buffer things, if that was a route that you wanted to go. It kinda stinks that the barrel system is proprietary as well. I can say that I'm not a fan of most proprietary stuff either. For right now though, I'm in over my head as far as reloading variables. LOL, I don't need to add more than I need to by tweeking with added firearm variables.

 

[MNtadpole]

I’ve recently gotten a DD5V4 in 6.5 and it seems to do well with H4350 & Hornady 147 ELD-M’s. I’m still developing my load for it, but so far I’ve never had your problem. I am running suppressed, and have the gas block on the suppressed setting.
I’ve got a Razor HD gen2 4.5-27 on it right now, and it’s really nice... but I’d lean toward the ATACR if I had to do it all over again. I got behind an ATACR next to my Razor at the range and got sold on the Nightforce pretty quickly.

Yea its a tough call with scopes at that level. It seems to be a matter of deciding on which scope short-comings you're willing to accept. I've been researching glass for this platform for a hot minute. I was looking at that Razor that you have, the Leupold Mark5s, NF NX8s, and the ATACRs. It seems that the ATACRs have less compromises, likely due to the increase cost associated. I have personally compared the Razor 4.5-27 against the comparable Leupold Mark5...both seemed quite solid as well.

 

[MNtadpole]

I’ve recently gotten a DD5V4 in 6.5 and it seems to do well with H4350 & Hornady 147 ELD-M’s. I’m still developing my load for it, but so far I’ve never had your problem. I am running suppressed, and have the gas block on the suppressed setting.
I’ve got a Razor HD gen2 4.5-27 on it right now, and it’s really nice... but I’d lean toward the ATACR if I had to do it all over again. I got behind an ATACR next to my Razor at the range and got sold on the Nightforce pretty quickly.

Yea so I broke down and went with the Nightforce ATACR 5-25 Mil-XT. I also went with a cantilever Spuhr Mount. I just got the mount today, and Nightforce has told me that I should expect the scope to ship by mid-Nov. FML, this hobby is expensive! I have also chalked up most of my issues, addressed earlier in this post, due to powder selection. I have since tried H4350 and I'm getting almost perfect operation.

 

[BrettRay]

There is a strong proprietary element to the DD5 platform for sure! I mean you should be able to change out all the BCG and buffer things, if that was a route that you wanted to go. It kinda stinks that the barrel system is proprietary as well. I can say that I'm not a fan of most proprietary stuff either. For right now though, I'm in over my head as far as reloading variables. LOL, I don't need to add more than I need to by tweeking with added firearm variables.

I ended up replacing the factory buffer spring with a Tubbs flat wire. Way better shooting gun now. Took all weight out of buffer too. The BCG the best I can tell is a proprietary design. It has a tungsten weight added to the end and is about 3/4” longer than a normal ar10 bcg. With the stock spring, heavy bcg and buffer, and over gassed gas block, it was like a sledgehammer of reciprocal mass. I’ve got it tuned perfect now. No damaged brass on ejection and feeds perfect. The SLR gas blockreally helps a ton. I hate 2 position adjustment gas blocks. I’ll never understand why they put those on there.

 

[MNtadpole]

I ended up replacing the factory buffer spring with a Tubbs flat wire. Way better shooting gun now. Took all weight out of buffer too. The BCG the best I can tell is a proprietary design. It has a tungsten weight added to the end and is about 3/4” longer than a normal ar10 bcg. With the stock spring, heavy bcg and buffer, and over gassed gas block, it was like a sledgehammer of reciprocal mass. I’ve got it tuned perfect now. No damaged brass on ejection and feeds perfect. The SLR gas blockreally helps a ton. I hate 2 position adjustment gas blocks. I’ll never understand why they put those on there.

Sounds all good to me! Yeah, I hear you concerning the 2-way "adjustable" gas block from DD. I think its a manufacturer's solution to keeping a firearm platform customizable, yet idiot proof. I would venture to say that 75% of people who buy factory AR10s aren't interested in tweeting the gas systems.

 

[BrettRay]

Sounds all good to me! Yeah, I hear you concerning the 2-way "adjustable" gas block from DD. I think its a manufacturer's solution to keeping a firearm platform customizable, yet idiot proof. I would venture to say that 75% of people who buy factory AR10s aren't interested in tweeting the gas systems.

Those people have no business owning a gas gun. There are to many variables involved in a gas gunning running reliability. If we were in the military running the same ammo it would be different.

 

[MNtadpole]

Those people have no business owning a gas gun. There are to many variables involved in a gas gunning running reliability. If we were in the military running the same ammo it would be different.

very true about the same ammo. TONS of variables!! Lol, it got me for sure. Shoot, I had to try 3 different powders for my reloads before finding one that made my gun operate well. Granted, I probably could have went the adjustable gas block route, but I was trying to avoid adding more adjustable variables to my platform. At least, until I got comfortable with a few decent reload recipes.

 

[wade2big]

Those people have no business owning a gas gun. There are to many variables involved in a gas gunning running reliability. If we were in the military running the same ammo it would be different.

There are many variables in a direct impingement (AR) gas gun that are necessary to keep it running reliably. Figured I would elaborate on your statement.

 

[2aBaC̶a̶]

Im thinking a 129gr bullet should be going faster than 2668 and you're at the low end of necessary gas needed to cycle reliably. Putting an adjustable gb on only gets you less. If you cant bump up the charge then its on to experimenting with buffer/ spring combos. Or atry a different powder.

Where do cases eject?

 

[MNtadpole]

Im thinking a 129gr bullet should be going faster than 2668 and you're at the low end of necessary gas needed to cycle reliably. Putting an adjustable gb on only gets you less. If you cant bump up the charge then its on to experimenting with buffer/ spring combos. Or atry a different powder.

Where do cases eject?

So right now, I settled on H4350 as a powder, which allowed my AR10 to cycle correctly. I ended up thinking maybe the powders I tried (RL17 and H4895) caused over-gassing allowing the BCG to cycle too quickly causing the cartridge to jam prior to being pushed into battery. So a 129gr could definitely go quicker. I Chrono'd some factory Hornady 129gr Whitetail ammo at approximately the same velocity. IDK, I have more testing to do yet, so we'll see where I go.

 

[BrettRay]

There are many variables in a direct impingement (AR) gas gun that are necessary to keep it running reliably. Figured I would elaborate on your statement.

Yep. That’s exactly what I said. Maybe my wording was off but I was just saying that there are lots of variables involved in a gas gun running correctly and some people think they can just buy a AR and it never miss feed and that’s just not the case. When you have two million different types of ammo and a million other variables involved like weather, things happen. That’s why manufacturers over gas their guns. A fully adjustable gas block is a MUST in my opinion

 

[Billl223]

Yep. That’s exactly what I said. Maybe my wording was off but I was just saying that there are lots of variables involved in a gas gun running correctly and some people think they can just buy a AR and it never miss feed and that’s just not the case. When you have two million different types of ammo and a million other variables involved like weather, things happen. That’s why manufacturers over gas their guns. A fully adjustable gas block is a MUST in my opinion

I'm not using this in a gas gun but I'm loading 41.6 gr. 4350 with 140 ELD bullet and getting 2718 FPS.

 

[2aBaC̶a̶]

.

So right now, I settled on H4350 as a powder, which allowed my AR10 to cycle correctly. I ended up thinking maybe the powders I tried (RL17 and H4895) caused over-gassing allowing the BCG to cycle too quickly causing the cartridge to jam prior to being pushed into battery. So a 129gr could definitely go quicker. I Chrono'd some factory Hornady 129gr Whitetail ammo at approximately the same velocity. IDK, I have more testing to do yet, so we'll see where I go.

Whenever I've had a problem like this its been from not enough gas or too heavy buffer and the BCG not cying far enough back. What happens is the bcg travels just far enough back that the little ledge that the hammer rides on at the bottom of the BCG catches the next round pushing it forward but the actual bolt face is in the center of the cartridge.

 

[BrettRay]

I would buy tubbs flat buffer spring for the DD5. The one that came in it was like a 20 coil that was stiffer than anything I’ve ever seen

 

[bfoosh006]

I will second the 308 Tubbs Flatwire recoil spring.

 

[Unknown]

I changed to an adjustable gas block and small base dies to clear up all my problems. The adjustable gas block didn't seem to do all that much to fix things, but after the small base dies, the rifle ran like a sewing machine. In measuring the base of the cases, the small base dies only squeezed down the cases by about .002 inches, but apparently that was all it took.

Before that I would have bolt over base, and even worse was a fired case stuck in the chamber and the extractor would rip a giant chunk out of the case rim trying to get it out of the chamber....one hell of a good extractor though.

 

[ACK]

Had several malfunctions with an AR 308. Heavy buffer, silent spring, adjustable block, loads... then I noticed that factory ammo had no issues. Went to a small base die and my reloads worked well. Interestingly I do not use SBR for Garand or AR15 (223) reloads.