VMOS without SCS

[xXSteev0Xx]

Hello,

 New poster as well as new builder here.

Auto Technician by trade, however, still very green as far as rifle work goes.

 

Stringing together a aero M5 build. 

Got a M5E1 upper, Proof barrel...

Anyways most of the components may be irrelevant.

What I'm really wondering is is it possible to run a JP VMOS BCG without a SCS even if I remove the buffer retaining pin? It charges nicely without any obstructions, is headspaced correctly, and chanmbers .308 and 7.62 cartridges without any hiccups but I don't know how it would function under live fire, and don't want to test it if it posses risk of damage

 

I have a SCS on order, but the guys I ordered it from decided to barge ship it, and I currently live in hawaii. May be a while before I get it. Advise is appreciated, thanks

[Lane]

Welcome from NY.

Someone will be by shortly to give you some more advice here... This isn't something I've ever seen before. So I can only say; "glad to see you made it here to the 308ar.com forum"... This looks pretty interesting. While the weights appear to be kind of expensive; I'm actually curious about that JP VMOS BCG in some ways. 

All the best Sir!

[edgecrusher]

So long answer is no. Short answer not always. I guess my first question is do you reload? If no, buying off the shelf, and getting whatever’s available then no, it’s not going to work. JP parts are high quality race gun parts and tuning any rifle to a tailored load will almost guarantee it won’t function properly with others.

 

Think of it like this. You have a guy come in with a 70’ chevelle with a blown Reher Morrison and a TCI power glide tubbed for 33’s on a sick set of RC headlocks. He say it’s a 7.30 car and runs 180’s and you have no reason to doubt it. Next he says it’s built with quality parts, yup, can see that. Then he say he’s running it on methanol but would like to flip back and forth between pump gas. Wait, what? 
 

If you want to feed the beast a specific load using tunable parts, because you have or will develop a recipe, so be it. That’s awesome, show me the end result so I can drool all over my screen. But tunable parts suck if you have one box of 175gr GMM and a box of M80. Too far each other to run if it’s made for one or the other. 
 

And removing the buffer retaining pin and running a traditional set up is not wise. That will cause you to chase your tail under loads that have slightly different pressure zones, never mind what I compared above. 
 

Aloha, welcome to the asylum. We love cool shit. Like cars, bikes, guns, planes, hunting, fishing and all sorts of shenanigans  

[jtallen83]

I think it could be done with some effort, money, and ingenuity, unless you already have a bunch of parts and different springs laying around odds are it's gonna cost more than just getting another BCG and buffer kit. It would not be a straightforward thing and there would be the risk of damaging something expensive but it would be cool to hear about. I'm always skeptical when a manufacturer claims they are proprietary on this platform but without parts in hand all I can do is "think" it might be able to work.

[unforgiven]

Welcome from Indiana brother we have an old guy who's saying is " don't complicate $hit with complicated $hit" myself and many here heed the advice ,for dependability you might consider a regular BCG. Just my 2 mags.

[Cunuckgaucho]

Welcome from BC

All parts are relevant as some parts play better with other parts. This is more critical with large frame AR as the interchangeability between manufactures/parts is not a given.

[xXSteev0Xx]

4 hours ago, edgecrusher said:

So long answer is no. Short answer not always. I guess my first question is do you reload? If no, buying off the shelf, and getting whatever’s available then no, it’s not going to work. JP parts are high quality race gun parts and tuning any rifle to a tailored load will almost guarantee it won’t function properly with others.

 

Think of it like this. You have a guy come in with a 70’ chevelle with a blown Reher Morrison and a TCI power glide tubbed for 33’s on a sick set of RC headlocks. He say it’s a 7.30 car and runs 180’s and you have no reason to doubt it. Next he says it’s built with quality parts, yup, can see that. Then he say he’s running it on methanol but would like to flip back and forth between pump gas. Wait, what? 
 

If you want to feed the beast a specific load using tunable parts, because you have or will develop a recipe, so be it. That’s awesome, show me the end result so I can drool all over my screen. But tunable parts suck if you have one box of 175gr GMM and a box of M80. Too far each other to run if it’s made for one or the other. 
 

And removing the buffer retaining pin and running a traditional set up is not wise. That will cause you to chase your tail under loads that have slightly different pressure zones, never mind what I compared above. 
 

Aloha, welcome to the asylum. We love cool poop. Like cars, bikes, guns, planes, hunting, fishing and all sorts of shenanigans  

Thanks man. 

Was gonna get into the reloading crowd but as it's close to the holidays currently, it's not the best time.

My wife is already flipping out over these parts.

 

But I see what you're saying.

Hadn't even thought about what ammo to tune it for yet, wasn't even sure if it would make it that far.

I just don't wanna damage anything when it cycles in this configuration.

[xXSteev0Xx]

Thanks, I'll probably end up waiting till the SCS comes in someday.

This build was actually for someone close to me so I was kinda hoping it would be functional by Christmas.

 

Anyways I'm probably gonna build a 6.5CM next... 

 

Again thanks for the advice all, I appreciate it

[xXSteev0Xx]

2 hours ago, Cunuckgaucho said:

Welcome from BC

All parts are relevant as some parts play better with other parts. This is more critical with large frame AR as the interchangeability between manufactures/parts is not a given.

I see.

So then I've got a Aero M5E1 upper on it with handguard

Aero Lower with their standard trigger and carbine length reciever extension

Proof Research pr10 20" Bbl

Odin works adjustable gas block

Melonite gas tube

Thread protector where a muzzle device should be (gonna let the person I give this rifle to pick a muzzle device)

A JPE VMOS Bcg and Bolt.

Did I miss anything?

[edgecrusher]

On 12/19/2021 at 12:58 PM, xXSteev0Xx said:

I see.

So then I've got a Aero M5E1 upper on it with handguard

Aero Lower with their standard trigger and carbine length reciever extension

Proof Research pr10 20" Bbl

Odin works adjustable gas block

Melonite gas tube

Thread protector where a muzzle device should be (gonna let the person I give this rifle to pick a muzzle device)

A JPE VMOS Bcg and Bolt.

Did I miss anything?

The Aero receiver extension has been known late to have incorrect dimensions. Please measure the internal depth.

[xXSteev0Xx]

1 hour ago, edgecrusher said:

The Aero receiver extension has been known late to have incorrect dimensions. Please measure the internal depth.

Sorry about that... completely spaced and forgot that the UBR came with its own reciever extension. So I guess that extension is a magpul

6 hours ago, Cunuckgaucho said:

Welcome from BC

All parts are relevant as some parts play better with other parts. This is more critical with large frame AR as the interchangeability between manufactures/parts is not a given.

I see.

So then I've got a Aero M5E1 upper on it with handguard

Aero Lower with their standard trigger and carbine length reciever extension

Proof Research pr10 20" Bbl

Odin works adjustable gas block

Melonite gas tube

Thread protector where a muzzle device should be (gonna let the person I give this rifle to pick a muzzle device)

A JPE VMOS Bcg and Bolt.

Did I miss anything?

[98Z5V]

4 hours ago, xXSteev0Xx said:

Sorry about that... completely spaced and forgot that the UBR came with its own reciever extension. So I guess that extension is a magpul

 

So, for that original UBR, the built-in extension was 7.000" deep.  The UBR 2 setup was made at 7 5/8" deep. 

[Cunuckgaucho]

Hi @xXSteev0Xx,

 The first thing I've learned here is how little I know about large frame ARs. Buying a matching/same manufacture upper/lower set saves a lot of head aches, don't always believe the guy behind the counter selling you stuff. While I own a couple large frame ARs I've yet to build one, fortunately there are people here with the knowledge to answer your questions so like you I'll be learning as you go through this build.

[xXSteev0Xx]

53 minutes ago, 98Z5V said:

So, for that original UBR, the built-in extension was 7.000" deep.  The UBR 2 setup was made at 7 5/8" deep. 

I have yet to measure, but by those specs it should be 7 5/8.

Got it, thanks

[DNP]

1 hour ago, 98Z5V said:

So, for that original UBR, the built-in extension was 7.000" deep.  The UBR 2 setup was made at 7 5/8" deep. 

And I knew nothing about this when I built mine. I got lucky on everything I bought for that gun. 

[xXSteev0Xx]

*Update*

Got an email back from the guys at JPE.  They told me it should be safe 

(Like not damaging to the gun) to run with a legacy buffer, it just might get annoying pushing the buffer back in every takedown.

 

And indeed it does run. Quite well I might add.

So if anyone is ever wondering about running a VMOS without a SCS, as long as you take the retaining pin out, it should run.

(As far as dpms pattern goes, not sure about armalite)

Funny thing is, is that my scs comes in tomorrow

[98Z5V]

You are building a "regular gun" and you're using some serious Race Gun parts.  I wish you luck. 

[edgecrusher]

On 12/21/2021 at 1:57 AM, 98Z5V said:

You are building a "regular gun" and you're using some serious Race Gun parts.  I wish you luck. 

What this means is what I referenced with using ammo and tuning the rifle, then switching ammo and expecting the same results

[DNP]

Glad to hear it works well. What weight buffer are you running with it?  Sorry if I missed that above. Did a quick skim, but couldn’t re-read the thread.