Initial 9mm AR mods ?

[Biggfoot44]

My usual practice ( barring glaring defects ) is to test , and establish a baseline with totally stock ( or as aquired by me in purported running order ) , before any repairs or modifications.

But are 9mm AR's the exception that proves the Rule ?

It seems from recent threads that consensus that 7.5oz buffers and Tubb .308 Springs or similar strength springs are not only contributing to reliable function, but reduce parts breakage otherwise common to 9mm AR .

What are plus/ minus to preemptively upgrading to my as yet unfired PSA 9mm ?

 

[clandestine]

Tubb .308 Springs and Heavy/Long 9mm Buffers (Spikes/HeavyBuffers.com) work better than any other spring or buffer system currently on the market for a 9mm AR.

If you are determined to prove out what I have found through working on several hundred blowback AR's then by all means do so.

 

[boss281]

I swear I'm starting to shy away from my first build on an AR9 and just do an AR15 pattern to get my feet wet. I've watched with interest this past year the trouble with springs, buffers and in some cases the magazines (Colt vs Glock, etc). My old factory Colt still fires flawlessly bone stock after 32 years on Winchester 124 (NATO or WinClean) and only occasionally hiccups with a FTF with 147 g. My brand new Colt performs identically after I replaced a poorly formed bolt catch when first received. I'm not shy about working the problem but this just seems all to common and sometimes difficult to troubleshoot. Or is that an overstatement?

Bigfoot, I have a Tubbs .308 spring and Kak adjustable buffer laying around unused (new), and you could try finding the right weight to suit your build (or is this a factory PSA complete rifle)? I'm in Carroll County but I could send it out UPS, or we could meet at a range and just go through ammo with various weight combos. Now that it's a bit cooler I go to the Machine Gun Nest for indoor use, and my outdoor range is AGC in Marriottsville. Let me know. We could also run your loads through both my rifles and see what happens...

 

[outrider58]

Upon my prompting, several years ago, I asked clandestine() to produce a full list of parts, particularly required parts, to build a well functioning 9mm AR 15.

After some digging, I found that thread. It starts right here...

https://www.mdshooters.com/showpost.php?p=4275411&postcount=28

I followed his suggestions and barring one experience with some bad brass, my gun has run flawlessly. Thanks Chad!

EDIT: If I would make one suggestion to Chad; If he could make a revised(directed) sticky on 9mm AR recommended build parts, given the increasing interest PCC ARs.

 

[davsco]

Wouldn't hurt to see what jp uses in their gmr13 and now 15. Jp is very well known in the competition world.

 

[boss281]

EDIT: If I would make one suggestion to Chad; If he could make a revised(directed) sticky on 9mm AR recommended build parts, given the increasing interest PCC ARs.

That would be welcome.

 

[teratos]

I swear I'm starting to shy away from my first build on an AR9 and just do an AR15 pattern to get my feet wet. I've watched with interest this past year the trouble with springs, buffers and in some cases the magazines (Colt vs Glock, etc). My old factory Colt still fires flawlessly bone stock after 32 years on Winchester 124 (NATO or WinClean) and only occasionally hiccups with a FTF with 147 g. My brand new Colt performs identically after I replaced a poorly formed bolt catch when first received. I'm not shy about working the problem but this just seems all to common and sometimes difficult to troubleshoot. Or is that an overstatement?

Bigfoot, I have a Tubbs .308 spring and Kak adjustable buffer laying around unused (new), and you could try finding the right weight to suit your build (or is this a factory PSA complete rifle)? I'm in Carroll County but I could send it out UPS, or we could meet at a range and just go through ammo with various weight combos. Now that it's a bit cooler I go to the Machine Gun Nest for indoor use, and my outdoor range is AGC in Marriottsville. Let me know. We could also run your loads through both my rifles and see what happens...

My 9mm AR is my favorite gun to shoot. Don't shy away. Get the Tubbs 308 spring and a 9 ounce + buffer and don't look back. Mine functions flawlessly. Never a FTF or FTE. I have a DDLES lower, same as the QC10 with colt pattern mags. It's a ton of fun.

 

[Biggfoot44]

9oz or 7.5oz for 16in unsuppressed .

If 9oz w/ 308 spring turns out to be too much of a good thing , would switching to std spring be useful to tune ?

( I'm convinced to upgrade , but trying to avoid buying a 7.5 AND a 9.0 .)

 

[outrider58]

9oz or 7.5oz for 16in unsuppressed .

If 9oz w/ 308 spring turns out to be too much of a good thing , would switching to std spring be useful to tune ?

( I'm convinced to upgrade , but trying to avoid buying a 7.5 AND a 9.0 .)

My humble advice, start low and work your way up with buffers. By low, I mean H-3. You can do this very economically by changing the weights in a standard buffer.

Springs. Tubb's 308 FW all the way.

 

[threegun]

I am running a New Frontier 10 oz. blow back buffer and a Tubb AR15 spring. I have only had one test outing with this combination using a suppressor. I was able to run 147 gr ball, flat nose and HP with no problems as long as I used Glock mags. I did have problems with the Magpul versions of Glock mags. The Magpul mag must have a slightly different angle of presenting the round which resulted in the flat nose and HP occasionally hanging up on the lip of the chamber.

 

[alucard0822]

Buffer weight is dependent on load and supressors. The case is locked into the breech when firing only by gas pressure and friction, once the gas pressure drops, and the brass loosens up, then it starts to cycle, the bolt/buffer weight along with spring pressure keep it from cycling too early, or too harshly. If it cycles too fast, it can jam, and recoil can be snappy, if it cycles too slow, it can jam, although the lighter the reciprocating mass, the less movement there is in the sights on target There is also bolt spacing, where a shorter 9mm bolt can have too much clearance between the bolt catch and bottoming in the buffer tube, and get too much power moving forward causing broken catches and harsh chambering, this is why some buffers are extended in the front, or people use spacers in the back of the buffer tube. 7oz extended buffers and heavy tubb springs are a great place to start for a relatively wide range of ammo. Special applications like shorter barrels, supressors, hot defensive ammo, and light match ammo may benefit from an even heavier buffer, or a lighter buffer and spring. A heavy tubb spring is always good to use, but would try it with the included buffer first, and check carrier travel past the bolt catch, should only be about 1/4-1/2" when pushing the carrier back till the buffer bottoms out. Of course most are compatible with standard AR furniture, and PSA ramped bolts work with many aftermarket triggers and selectors, so depending on what you are doing with it, you have plenty of things you can spend money on.

FYI, left to right, standard H buffer, buffer spacer(I machined this out of Delrin, filled with elastomer) 5.5 oz buffer(wide body), 7oz extended heavy buffer

 

[Biggfoot44]

The 7.5oz Kaw valley is solid SS , the 10oz is solid tungsten, so no swapping internal weights .

FWIW , multiple sources have the 7.5 on sale, while the 10 is at msrp .

 

[jimbobborg]

I got the 7 oz Kaw Valley and some super heavy spring in my working 9mm AR that just works. I have a 9mm 6 oz buffer and used both a 9mm CMMG spring and a .308 carbine spring and I get constant FTEs with any rounds out of Colt mags. I'm putting the 7 oz buffer, that's longer than the 6 oz buffer, into the nonperfect rifle and get to testing after I get the bullet out of the barrel. I will achieve Master this year with a PCC, dammit!

 

[Biggfoot44]

Update

Just ordered the Kaw 7.5oz , and JoeBob's Extra Power .308 & Pistol spring.

Because :
1. Couldn't imeadately locate supplier who carried both Kaw Valley and Tubbs for one stop shopping & shipping.
2. At only $5 to add the spring , that seems cheap enough to try .

 

[outrider58]

Just ordered the Kaw 7.5oz , and JoeBob's Extra Power .308 & Pistol spring.

Because :
1. Couldn't imeadately locate supplier who carried both Kaw Valley and Tubbs for one stop shopping & shipping.
2. At only $5 to add the spring , that seems cheap enough to try .

The thing that makes them worth the price, they last 10x longer than standard AR springs and since they are flat, there is virtually no bottoming out no matter how short your buffer tube is. They run in rifle tubes as well as the shortest of pistol tubes. I am interested to hear how the well the J.Bob spring works though.

 

[boss281]

I could be wrong, but I think only Tubb sells Tubb's springs. The thing that makes them worth the price, they last 10x longer than standard AR springs and since they are flat, there is virtually no bottoming out no matter how short your buffer tube is. They run in rifle tubes as well as the shortest of pistol tubes. I am interested to hear how the well the J.Bob spring works though.

I picked my Tubbs up from Midway to use in my upcoming build...

Sent from my XT1254 using Tapatalk

 

[outrider58]

I picked my Tubbs up from Midway to use in my upcoming build...

Sent from my XT1254 using Tapatalk

Thanks boss. I edited my post.

 

[DutchV]

I went with the 9mm-Q buffer (8.5 ounces) from Heavy Buffers, and got a Wolff XP spring from them as well. My pistol has run fine, once I got the feed ramp polished.

 

[notfast]

Both of my 9mm AR's run a 7.5-7.7oz buffer. One has a CMMG standard spring and the other a 308. NO issues with either using 124gr

 

[myn0ck]

I know I'm a little late to this, but I'm going through the process of building a an AR9 now myself.

I've seen a lot of good things said about the Blitzkrieg hydraulic buffer: http://www.blitzkriegcomponents.com/ProductDetails.asp?ProductCode=RB5007

But I'm going to start with the Taccom: https://taccom3g.com/product/taccom-pcc-adjustable-buffer-system/