AR15 upper question

[thefish]

So have been thinking about building up a cheap ar15, mostly for 55 grain plunking.

So if I understand it correctly, I'm looking for 1:9 twist.

I came across these 2 uppers, but can't figure out what the difference is. Can anyone lend some insight? One says a4, one m4.

http://palmettostatearmory.com/inde...-a4-melonite-ss12g2-upper-without-bcg-ch.html

http://palmettostatearmory.com/inde...9-carbine-length-w-o-bcg-charging-handle.html

For comparison, this is the one I was thinking about, but it's a 1:7 twist and from what I understand that is not optimal for 55 grain bullets.

http://palmettostatearmory.com/inde...w-bolt-carrier-group-and-charging-handle.html

Thanks in advance.

 

[Fishbed77]

So if I understand it correctly, I'm looking for 1:9 twist.

1:7 will serve just as well for 55 grain bullets, and it with allow you to shoot heavier bullets also.

 

[newfalguy101]

So have been thinking about building up a cheap ar15, mostly for 55 grain plunking.

So if I understand it correctly, I'm looking for 1:9 twist.

I came across these 2 uppers, but can't figure out what the difference is. Can anyone lend some insight? One says a4, one m4.

http://palmettostatearmory.com/inde...-a4-melonite-ss12g2-upper-without-bcg-ch.html

http://palmettostatearmory.com/inde...9-carbine-length-w-o-bcg-charging-handle.html

For comparison, this is the one I was thinking about, but it's a 1:7 twist and from what I understand that is not optimal for 55 grain bullets.

http://palmettostatearmory.com/inde...w-bolt-carrier-group-and-charging-handle.html

Thanks in advance.

The one listed as M4 has M-4 feedramps, the other one doesnt

 

[thefish]

Aha!
Thanks newfalguy. Not sure how I missed that!

I'm reconsidering my first 1:7 choice after looking at some 1:7 vs 1:9 charts. I can't imagine going lighter than 55 grain, but could see the use of going heavier for longer distances. Unfortunately our range here maxes out at 100 yards.

 

[Hacker15E]

Just beware that PTAC is a bit of an unknown quantity at Palmetto right now. PTAC is quite intentionally PSA's low-end brand, and their first few months' of orders have been very hit-and-miss. The big problems have been with barrels that are quite poor quality, or apparently used and sold as new, and a host of other strange issues one would not expect with a new barrel.

Others have received very nice barrels that will be quite sufficient for plinking duty.

Do a little light reading on ar15.com in the PSA section of the Industry forum if you want more details.

If it were me, and if I were putting together my one-and-only AR-15, I don't know that I'd go with a PTAC barrel at this time.

Regular PSA-branded barrels and uppers, however, should be just fine.

 

[atomd]

I don't have a lot of faith in PSA. I got a couple of their lower parts kits (not the ptac, the regular ones) when things were going crazy a while back. I installed one in a lower I had and the quality was so bad I took the parts back out and put them in the trash can. If the ptac line of parts is a step below their regular line I would be very hesitant. You never know though.

 

[Ryanxia]

I browse PSA's uppers on a regular basis and as I'm sure you already know, their chrome molly barrels are not chrome lined unless it says it as well. Seems obvious but I didn't notice the first time comparing.

 

[mtrmn]

Aha!
Thanks newfalguy. Not sure how I missed that!

I'm reconsidering my first 1:7 choice after looking at some 1:7 vs 1:9 charts. I can't imagine going lighter than 55 grain, but could see the use of going heavier for longer distances. Unfortunately our range here maxes out at 100 yards.

IME, 1/7 or 1/9 will have similar results with the full range from 50gr up to 70 gr bullets. Above 70 gr is where the 1/9 seems to drop off. This is with conventional lead bullets. Some 1/9's will go as high as 75 gr bullets with decent performance.

The 1/7 was chosen by the .mil in order to stabilize the very long 62 gr tracer, and at least one of the military rounds has a 75 gr bullet. Bullet length has more to do with proper stabilization than weight-it just so happens that heavier bullets are normally longer. So copper bullets etc will require a faster twist than the same weight conventional bullet due to longer length.

As always-YMMV

 

[thefish]

Thanks guys. After looking at the reviews on ar15.com, I think I'm going to stay away from the patch for now.

 

[46R]

Just beware that PTAC is a bit of an unknown quantity at Palmetto right now. PTAC is quite intentionally PSA's low-end brand, and their first few months' of orders have been very hit-and-miss.

I bought one of those cheap PTAC 1:7 carbine bare-bones uppers on the Black Friday sale.

Visual examination of the barrel shows the bore to look actually pretty good, not scratched or gouged up like some pics that have been posted on other websites, and it looks like its got a good crown as well. However upon taking it out shooting for the first time, I was getting 12+ inch groups (can you even call those "groups") at 50 yds from a bench rest. And those were the rounds that made it onto paper at all. I tried 55, 62, and even some 75gr ammo... Federal and Prvi Partisan. No good at all, at first I was a bit upset that I wasn't even getting at least the 4" groups that some buyers have been reporting with these barrels/uppers, but then it started becoming a really sarcastically funny game with me and my shooting buddy to see if the bullet would even hit the paper at all. I can't believe we actually wasted almost 50 rounds thru this piece of junk barrel, but the laughs were worth it in the end.

This past weekend, I took the PTAC upper apart and re-barreled it with an old Bushmaster 9:1 carbine barrel removed from a fixed carry-handle upper, and now it shoots great! The flattop receiver itself, and the rest of the parts the upper was built from are as good as any generic AR parts, but that PTAC barrel itself is worthless. I'm not even going to bother sending it back. I'll just save all the remaining good parts (flash hider, gas block/front sight, gas tube, handguard) and throw the barrel into my toolbox for use as a prybar or something

 

[au01st]

Ordered a P-Tac BCG because it was cheap. Put it in another AR and had no problems putting 100rds thru it.

Something to note from PSA, they are extremely slow to ship. Had I known this before I placed my order I would not have completed check out.

 

[Mike1234567]

Yeah, they're slow... but their prices are right And, from all I've read, the quality is good.

 

[Quentin]

I've bought many times from PSA over the last two years, including a barreled upper, and found the parts to be high quality. I would skip their PTAC stuff though. And they have a low end 8620 steel bolt that wouldn't go in any of my rifles.

The FN 16" midlength barrel in my upper is high quality, you really can't do much better for a duty style AR.

As usual with anything, get up to speed on the parts you want and pay for reasonable quality. You'll be happier with what you get.

 

[thefish]

Any experience with SAA?

Came across this and am wondering if its a good deal.

http://www.surplusammo.com/saa-comp...-upper-receiver-5-56/#PhotoSwipe1390537255175

I kind of like the clean handguard. With The problems I've read about with the PTAC stuff, I think ill hold off on that brand till they get the bugs worked out with the mill.

I understand its not CHF or chrome lined, but I'm trying to do a cheap build for my first build, and will probably give it to my wife, mostly for punching paper.

I have 3 Anderson lowers on the way with some lower parts kits, and a primary arms 2.5x red dot. I'm thinking ill put the red dot on my m&p 15t and take the flip ups from the 15t and put them on this new build for now. Or possibly another PA red dot.

Thanks again in advance.

 

[Temp430]

A 1:7 barrel shoots 55 gr. ammo just fine. Do yourself a favor and get a chrome lined barrel.