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Posted: 10/20/2014 10:42:34 AM EDT

So to display my ignorance I'm about to ask a possible silly question. I'm thinking about building up a pistol build off a Spike's Gen 2 billet set. I'm thinking of the following-
Spike's Gen 2 lower
Spike's Gen 2 upper for SAR3 rail
SAR3 9" rail
7.5" barrel
Barking Spider 2 break
Spike's low mass BCG

I've not built an AR before so I'm getting hung up on the gas block, gas tube, buffer, buffer tube and spring. What components would work best for this application?

Posted: 10/20/2014 12:01:52 PM EDT

[#1]

pistol length gas systems in 5.56 are kinda known to be shit.sometimes they work, sometimes they're a huge headache. personally i'd go with the piston set up from adams arms, and run a standard carbine set up in the back, since that's what all the adams arms kits are designed for.that should be fairly easy, although a bit more expensive. but the rail may be an issue with an xlp kit since they need a standard barrel nut.

or you can be the guinea pig and try this new piston set up http://www.syracordnance.com/collections/retrofit-piston-kits-available-for-pre-order/products/retrofitpistonkit-2

http://www.ar15.com/forums/t_3_126/658707_Syrac_Ordnance___.html here's the thread on it.

Posted: 10/20/2014 1:22:14 PM EDT

[#2]

If you're sticking with Spikes, you can't really go wrong with the: Spikes Tactical Pistol Buffer Tube Assembly Kit with T2 Buffer. T2 buffer being the important part, although any quality company would suffice. A little extra weight might help the pistol cycle better. Maybe somebody can help elaborate (or correct me), as I'm new to pistol building as well.

Posted: 10/20/2014 1:56:52 PM EDT

[#3]

I'm leaning towards the Thorsden Enhanced AR Pistol Builders Package right now which would include the buffer tube, spring, and buffer. Also, that new piston setup is intriguing especially if the dude from Adams started the company.

Posted: 10/20/2014 1:58:30 PM EDT

[#4]

Although at 1.599", it appears that it won't fit in the SAR3 rail which is advertised at 1.5".

Posted: 10/20/2014 2:05:18 PM EDT

[#5]

Quote History

Quoted:
I'm leaning towards the Thorsden Enhanced AR Pistol Builders Package right now which would include the buffer tube, spring, and buffer. Also, that new piston setup is intriguing especially if the dude from Adams started the company.

View Quote

agreed, i was a bit skeptical of even considering it until i found that out, at which point i was like alright, maybe.

Posted: 10/20/2014 4:19:50 PM EDT

[#6]

Ok, so after a few more hours of reading, I am going with a 7.5" barrel with the pistol length gas setup. What weight buffer should work best with this? Also, is running a lightweight BCG a pro/con/no difference for the pistol length gas setup?

Posted: 10/20/2014 7:59:40 PM EDT

[#7]

Best to run a Auto bolt carrier. It helps offset the over gas situation that can and does happen.

I haven't built a 7.5" 223 (only a 300blk 7.5" and a 223 in 10.5") but others have been successful doing so without much issue. I have a auto carrier in both and heavy buffer.

Make sure you get a steel gas block and align the ports correctly. Mark and measure, not difficult. The type GB that squeezes around the barrel (YHM) is easier to readjust and won't loosen up as compared to the type with the 2 allen screws on the bottom side. I've used both and either will work. Aluminum didn't work out for me because of gas leakage.

good luck on the build. .

Posted: 10/20/2014 8:05:53 PM EDT

[#8]

For a 7.5" barrel, you'll usually need more mass to slow down the action. I would start with a full auto BCG and an H2 buffer, and depending on the barrel's gas port size, you may need some more tuning, but this will get you started...

Posted: 10/21/2014 8:37:53 PM EDT

[#9]

I'm running a 7.5 inch Rainier Arms Select SS barrel with a RA low profile gas block, F/A carrier and, the Thordson's pistol builder's kit. It cycles perfectly fine.

Posted: 10/21/2014 9:11:48 PM EDT

[#10]

Thanks for all the advice. I've started ordering the parts and should start the build in the next few days.

Posted: 10/22/2014 12:33:39 AM EDT

[#11]

What's the final verdict?

Posted: 10/22/2014 10:56:59 AM EDT

[#12]

The final verdict is this as a starting point. I'll see how it runs and change up buffer weights if needed.

Spike's Gen 2 lower
Spike's Gen 2 upper for SAR3 rail
SAR3 9" rail
7.5" Green Mountain barrel with tube
Barking Spider 2 break with Dynacomp end
WMD NiB BCG
Thorsden pistol builders kit
BCM Gunfighter Mod 3
Low pro gas block (haven't decided which yet)
Ergo grip

Posted: 10/22/2014 11:05:36 AM EDT

[#13]

Another dumb question- which gas block would work with this barrel?

http://www.gmriflebarrel.com/gm-m23-5-56mm-7-5-barrel-with-ext/

Clamp on type or slip on? Also, can't find info about which I.D. to get.

Posted: 10/22/2014 12:07:36 PM EDT

[#14]

Quote History

Quoted:
Another dumb question- which gas block would work with this barrel?

http://www.gmriflebarrel.com/gm-m23-5-56mm-7-5-barrel-with-ext/

Clamp on type or slip on? Also, can't find info about which I.D. to get.

View Quote

Any style gas block would work. The main thing you need to figure out is the size of the gas port on that barrel. My guess is it's standard .750" but you want to double check.

This is the gas block that I used in my first 7.5" pistol build. I would stay away from aluminum gas blocks but YMMV.

It looks like you are using a lot of quality parts in this build. I would perhaps look into a different barrel if I were you. Seems kind of dumb IMO to spend all this money on a spikes billet receiver set and a WMD NiB BCG and then put some $99 non chrome-lined, non melonited or CHF barrel on it.

Posted: 10/22/2014 1:38:26 PM EDT

[#15]

Quote History

Quoted:

Any style gas block would work. The main thing you need to figure out is the size of the gas port on that barrel. My guess is it's standard .750" but you want to double check.

This is the gas block that I used in my first 7.5" pistol build. I would stay away from aluminum gas blocks but YMMV.

It looks like you are using a lot of quality parts in this build. I would perhaps look into a different barrel if I were you. Seems kind of dumb IMO to spend all this money on a spikes billet receiver set and a WMD NiB BCG and then put some $99 non chrome-lined, non melonited or CHF barrel on it.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
Another dumb question- which gas block would work with this barrel?

http://www.gmriflebarrel.com/gm-m23-5-56mm-7-5-barrel-with-ext/

Clamp on type or slip on? Also, can't find info about which I.D. to get.

Any style gas block would work. The main thing you need to figure out is the size of the gas port on that barrel. My guess is it's standard .750" but you want to double check.

This is the gas block that I used in my first 7.5" pistol build. I would stay away from aluminum gas blocks but YMMV.

It looks like you are using a lot of quality parts in this build. I would perhaps look into a different barrel if I were you. Seems kind of dumb IMO to spend all this money on a spikes billet receiver set and a WMD NiB BCG and then put some $99 non chrome-lined, non melonited or CHF barrel on it.

I thought about that, but this is going to be a 5.56 in a 7.5" barrel. The ballistics are pretty much sh!t anyways which is why I skimped on the barrel. This thing will pretty much be for 50 yards and in. I can always replace the barrel with something better if I really don't like it later down the line, but as long as it goes boom every time I pull the trigger, it is doing the job I hoped for. If I was building up a full length AR it would be a different story.

Posted: 10/29/2014 11:05:45 PM EDT

[#16]

SBX brace on the way.

Also just ordered a Raptor CH instead of the gunfighter.

KAK SB15 tube setup on the way.

Also just got my Geissele SD3G in the mail today.

BCG and Barking Spider are all that is left. I'm thinking about going with the Cryptic Coatings bronze BCG just for the added "bling".