PSA AR-9 Buffer & Spring Questions

[Captains1911]

I just purchased this PSA Glock lower (http://palmettostatearmory.com/psa-9...lower-blk.html)
and this upper (http://palmettostatearmory.com/psa-1...516447421.html)

This is my first AR-9 and I have a few questions regarding the buffer and spring. The lower came with a 5.5 oz. buffer of the same length as a carbine, H, etc buffer. I’ve read that without a longer buffer or a spacer/cushion at the rear of the receiver extension, there is a risk of breaking the bolt catch from the bolt slamming into it. However, since this particular lower does not have a last round bolt hold open feature, am I correct in assuming that there is little risk in breaking the bolt catch? Is there any other benefit to a spacer or cushion, like reducing excessive wear on the lower?

My other question relates to the spring. I read somewhere that the PSA AR-9 lowers come with an AR-10 spring. How can I tell an AR-10 spring apart from a standard AR-15 car spring? I have a spare Wolff extra power car spring laying around, how does it compare in terms of strength to an AR-10 spring, and is there any benefit to using it instead?

Thanks for the help.

[uffdaphil]

With the stock PSA buffer/spring combo I was getting burst fire and violent cycling. A heavy Q buffer/Wolff XP spring solved both problems.

http://heavybuffers.com/9q.html

[Captains1911]

With the stock PSA buffer/spring combo I was getting burst fire and violent cycling. A heavy Q buffer/Wolff XP spring solved both problems.

http://heavybuffers.com/9q.html

What is the likelihood of a heavier 8.0oz. buffer causing reliability issues? I'm just wondering if I should go ahead and order one without first trying the 5.5 oz. buffer.

[uffdaphil]

Mine is just one example, but from what I’ve read it sounds like it would be more, not less, reliable.

FWIW I have the PSA BCG and lower on an 8” pistol.

[Captains1911]

Mine is just one example, but from what I’ve read it sounds like it would be more, not less, reliable.

FWIW I have the PSA BCG and lower on an 8” pistol.

Mine is a 16" barrel, so wouldn't that make the blow back pressure even greater?

[uffdaphil]

Mine was also gtg with supressor which increased pressure. I think you would be fine.

[Captains1911]

I went ahead and purchased the Spikes Tactical ST-9X 8oz. buffer. I will try that first with the Wolff XP spring to see how it runs. Thanks for the help.

[RWA007]

I did way too much research before building my 16" AR9 early last year and came to the conclusion that the carbine buffer and spring would not work well either so I purchased the stripped lower from PSA instead of the built lower and then bought the Kaw Valley 7.5 ounce 9mm buffer and the XP SS AR10 buffer spring which is recommended for the 9mm ARs.
I think the 8 oz buffer you got will work well. I bought a complete 16" Upper from Joe Bobs. It was the Kaw Valley with the Hybrid BCG. I think the ones that PSA sells are made by Kaw Valley and use the same bolt but I may also be wrong. I'm not usually a fan of Anti Rotation pins but they are recommended due to the blowback being a little more violent than the DI bolt so I put some KNS pins on it also. I tried to use a RRA single stage (notched) trigger, but found out it would not work and ended up putting an ALG trigger in it, which works great.

I keep a shot-log of all my guns (cause I'm ocd) and I've got 661 rounds thru my 9mm AR so far and I have not had one single misfeed, stovepipe or failure of any kind. The action is smooth and with the Linear Compensator on the end of the barrel it is also almost ear-safe quiet. Everyone likes to shoot it as it's as easy as shooting a 22 but you still get the feeling of a little more power and it hits steel targets with authority! Based on what I've read the key to these working well is that heavier buffer and spring, so I think you will be happy with your setup.

Anxious for a report! I've got the bug now to build a 9mm pistol.

[Captains1911]

I guess I forgot to report back. The 8 oz. buffer with the standard carbine spring seems to work well. I ran about 150 rounds of a mix of 115gr, 124gr, and 147gr through it, all of which functioned flawlessly. Recoil felt ok, and ejection was around 4:00. It worked so well I didn’t even try the xp spring, but I still might.

[Captains1911]

Mine is just one example, but from what I’ve read it sounds like it would be more, not less, reliable.

FWIW I have the PSA BCG and lower on an 8” pistol.

Unrelated question...I just noticed that there is a fairly sharp edge on the bottom of my PSA bolt where it contacts the hammer (unlike standard AR bolt carriers that are rounded at this location), and it’s wearing two small nicks in the face of the hammer. Is yours this way, and is it anything to be concerned about?