Overbuffered and Oversprung aka Too Much Of A Good Thing Is A Bad Thing

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[ARCHIVED THREAD] - Overbuffered and Oversprung aka Too Much Of A Good Thing Is A Bad Thing

Posted: 7/31/2014 5:00:37 PM EDT

Just thought I would share the last 24 hr's fun and a minor cautionary note for those who may have never run into a problem of too much spring/buffer for the gun.

Dropped my rifle off at the Gunsmith yesterday for final build out and assembly.
It's a Huldra/AA Gas Piston 14.5" middy pencil barrel sitting on a stripped Spikes lower. This was going to be my first gas piston set-up and with most GP systems there is always the remote possibility of carrier tilt.

To that end I had planned on picking up one of PWS's [breathtakingly expensive] Enhanced Buffer Tubes and a Spikes ST-2 buffer, however, when a Vltor A5 System, Wolff XP Spring, and Slash Heavy Buffer came up for sale as a package in the EE section I changed course on the PWS. I read positive reviews about the combination of Vltor and Slash's and how the pair not only retards timing preventing bolt bounce, but makes your rig's impulse recoil cushy if not buttery smooth even when shooting the hottest loads.

When the packaged arrived and I pulled out the buffer I made a mental note of how heavy it felt. Sort of an amusing, "If I ever get into a street fight, I could use this thing to pack my punch instead of a roll of quarters", but I took solace that when I squeezed the bang switch - it was going to be so smooth on recoil I would barely feel anything at all.

Well, you definitely don't feel anything.

Gunsmith this morning, "Mr. Shadow, your rifle is assembled and ready - but nothing cycles. I tried 3 different types of ammo and it wouldn't cycle anything. I checked the gas plug and made sure it was on full-gas, but nothing. My thoughts are that your buffer may be too much."

Me: "Well how much buffer is in there? I know it's A5 specif..."

Him: "Ten ounces. A little over Ten. I put it on the scale."

Me: "Oh whoa. Yeaaaah, that's a bit much."

Him: "Yes, and I don't carry buffers for this system so I can't test to see if that's the issue, but it probably is. You can pick-it up as is if you want, or I can keep it for a few days and try to sort it out. My diagnostic rate is $45/hr."

Me: "I'll pick it up and try to work it out."

Sigh... I had hoped to have it running for a weekend range day since I've been so pressed for time the past 3 months, but it looks like I'll be going through the standard check list of things to do. I'll have to order a new lighter A5 specific buffer (No quips about this is why you should by Mil-Spec) if I can't knock out the roll pin and dump the inserts - even then I think the empty body comes on Slash's comes in around 4-5oz.
I doubt the XP spring is too strong but I can't eliminate this as a possibility so I may have to standard power spring, and then of course I'm hoping it's not the upper itself.

We shall see though.

Posted: 8/3/2014 7:20:26 PM EDT

[#1]

A5H2 is the standard weight buffer that is supplied with the Vltor A5 buffer kit (along with a standard rifle action spring, and either of the Vltor A5 specific receiver extensions)
I have had great success with the A5H3 and A5H4 buffers running Lake City, IMI and Prvi Partizan M193 and M855. Also Black Hills 77gr .223 red box. Both buffers lock back on empty mags.

.223 loads run better, for me, with the A5H2. Don't know about steel case ammo. I don't use it.

If you have an H buffer, just buy the A5H4 buffer. You could make an A5H3 or A5H2 using the steel weights to swap out the heavier tungsten discs. You can't make a A5H4 from two A5H2, as the tip of the last tungsten weight, on the A5H4, is dimpled for the spring.

Posted: 8/15/2014 2:39:40 PM EDT

[#2]

Just a quick update: Vltor gets a thumbs up on customer service from me. I had a brief online chat w/one of their CSR's this morning regarding what buffer weight they recommend I purchase for a 14.5" middy. Clearly made it known that I was running something that I believed was causing short-stroking problems but working through a punch list of possible culprits.

They have graciously and quite unexpectedly sent me a new A5 buffer at no cost when there was absolutely no need or justification for them to do so.
I know it's probably only a $7-10 (their cost) chunk of turned metal and $3 of packaging and shipping, yet still the sentiment and consumer good will is duly noted and appreciated.

So a tip of the cap to Katie @ Vltor and the rest of the staff that she huddled up to help identify where the hiccup may be.

Full exchange for those interested.

Katie@VLTOR: HI! How can I help you?

Me: Afternoon. Anyone online.

Me: Hi, how are Katie. I have a question about the Vltor A5 system. Speficially what buffer weight I need. Here's the issue.

Me: On the recommendation of others and reviews, I purchased an A5 system for my rifle. Unfortunately I was having some cyclic issues afterward. After reading further in forums it seems the one rifle configuration that the A5 doesn't respond well to is a 14.5" barrel w/mid length gas system.

Me: which is exactly what my rifle is. Some are saying that I need to get a lighter buffer but before I spend more money on the system, I would like to know what buffer weight Vltor recommends for 14.5" Gas Piston systems.

Katie@VLTOR: That's not exactly true. It just might be that you are not utilizing the correct buffer weight for your build. The A5 system is very particular about buffer weight. I am going to have some additional questions.

Me: I figured. Ask away.

Katie@VLTOR: I see that it is a 14.5 length barrel, do you ever run it suppressed? Do you know the gas port hole size that your barrel has? What caliber are you shooting? What grain ammo do you normally run?

Katie@VLTOR: Do you have a standard carrier? Or a low mass carrier?

Me: (a) Never suppressed. (b) I don't know the gas port size, but can find out shortly (I do believe it's the Colt spec size) (c) mixture of 556/223 (d) mostly 55 - 62 - occasionally 77gr. I have never tried to run weak/underpowered Steel case ammo such as Bear/Tula/Wolf etc. Me: (e) Carrier is standard weight carrier, yes.

Katie@VLTOR: What was the specific cycling issue that you are experiencing now?

Me: Short stroking.

Katie@VLTOR: Ok. Let me know on that gas port size when you find it. That will be the last part of the puzzle.

Me: Found the barrel manufacturer. Neither listed the port size only the barrel diameter. Calling both them and the builder... one moment please.

Katie@VLTOR: Another question that I have- is it short stroking and not picking up the next round, or is it not locking back on an empty magazine?

Katie@VLTOR: Does your upper have an adjustable gas system?

Me: They're fetching the information now.

Me: Katie, I was told the port size is .063"

Me: It does have an adjustable gas system. The gas is set to full open - 100% gas return.

Me: The short stroking is the first symptom. It doesn't have enough energy to go all the way back and strip the next round cleanly. It's intermittent.

Katie@VLTOR: Ok. I am just trying to determine how much in weight that I would advise going down to.

Katie@VLTOR: one moment.

Me: Every 3rd or 5th round it happens.

Me: Ok, thank you.

Katie@VLTOR: When you get to the last round, does the bolt hold open function?

Me: If, I get through the magazine, yes. I get bolt hold open.

Katie@VLTOR: Ok so after chatting it out greatly with everyone, we think that the A5H1 is going to work the best. If you would oblige, I would be happy to send you one free of charge for all your helpfulness with your answers.

Katie@VLTOR: Could you please send me your name and address? I will make sure this goes out right now.

Me: Wow, Katie. That's spectacular. I greatly appreciate it.

View Quote

Posted: 8/15/2014 3:12:40 PM EDT

[#3]

.063 is on the smaller side for a 14.5 middy. 10oz is pretty heavy for a buffer. Top it off with an extra power spring and you have a recipe for not running.

I would probably move to the standard weight A5 buffer and standard rifle spring. IIRC, a standard A5 buffer is 5.4oz, same as a regular rifle buffer and about the same as an H3.

Posted: 8/15/2014 3:44:40 PM EDT

[#4]

Quote History

Quoted:
.063 is on the smaller side for a 14.5 middy. 10oz is pretty heavy for a buffer. Top it off with an extra power spring and you have a recipe for not running.

I would probably move to the standard weight A5 buffer and standard rifle spring. IIRC, a standard A5 buffer is 5.4oz, same as a regular rifle buffer and about the same as an H3.

View Quote

TY.
I read on another forum that, as you stated, .063 is on the smaller side for a 14.5"
I'm trying to get some consensus on the ideal port size. Some are writing that boring it out to .080 yields the best results.
Of course I don't think Adams would recommend this.

Finding this all out the hard way.

I have shot my fair share of over gassed and fast running ARs, SBRs, and jolty AR. I was so focused on creating a nice, smooth, buttery rifle that I over did it.

But, we learn through our mistakes and tuning a build is of course part of the fun

... that is until the fun runs out or you can never get the bloody thing to run properly no matter how much time and money you throw at it.

Posted: 8/15/2014 4:03:27 PM EDT

[#5]

Well, I don't have much piston experience. I do have several AR's with a bunch of different gas systems. My 14.5 Mid has a large gas port (around .100 IIRC). Sure it runs fast, but that has only caused problems when using it on full auto with a standard buffer. Once I dropped the H3 in it solved the bolt bounce problem and slowed the rof a bit. The up side is that it eats everything and has no issues with under powered tulammo or wolf.

I think .075 to .08 would be more reasonable, but I didn't drill the gas port. My 16" dissipator has a .110 gas port and doesn't like wolf. Runs great with anything brass cased though. I plan on upping to .125 here pretty soon. Here is a video of it from last weekend:

Posted: 8/20/2014 5:44:19 PM EDT

[#6]

If your gun is over-gassed, a heavier buffer will reduce recoil. However if you have adjustable gas, running a light buffer/bolt and turning down the gas will result in the least recoil.

Mike

[ARCHIVED THREAD] - Overbuffered and Oversprung aka Too Much Of A Good Thing Is A Bad Thing

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