I’m looking at getting a PSA kit for a second AR. I currently have a Ruger 556 with a 1:8 twist. Its a great rifle and shoot very accurately, its just a little cumbersome shooting offhand with an optic so thats why I’m looking at a minimalist light weight for another build. I noticed PSA sells majority 1:7 twist barrels in their uppers. Would i expext anything differently than what I’m used to getting out of a 1:8 barrel? I primarily shoot standard 55 or 62 grain. The more I read the more I see that both 55 and 62 are kind of on the light end for both twist rates. Just wanted to see what any of your experiences were, some prefer 1:7 for everything, some say its inaccurate with 55 grain loads. PSA has 1:8 twist barrels but the 1:7 seems to be the better deal.
All three shoot 55-77 gr just fine. If I am looking for accuracy, I will use 62 or better. Usually 77 gr for longer distances (110+ yrds) which yields the best consistent accuracy for me. Of course, the shooter in my case is the weak link in the chain.
i too have 1:7 through 1:9 barrel twists for my 556/223 build…
i prefer 1/8 as it is like the sweet spot in my opinion to be the best all around barrel for all different types of ammo… there is a whole bunch to read about barrel twist versus ammo and all that, so i suggest you do what AZ_Joe said and start reading that thread he linked. it can and will get confusing quickly.
I have a 16 inch palmetto with 1:7 twist. It shoots 55g fmj around 7inch moa. With factory ammo over 60g including 77g tmj it gets around 3 moa. Today i finally got a sub moa group out of it. With handloaded 24g 8208 xbr and 62g fmj boat tail by hornady. By sub moa I mean just over half inch. I was starting to think psa was just not capable of less than 3 inches but i gave it a shot and it paid off big. Ida been happy with 1.5 inches.
I revived wisdom from an uncle who was a serious hunter/shooter and all around “Gun Guy” when he was teaching me to shoot and develop my love of shooting, “Every weapon barrel has a different taste for ammo”
What barrel length is sitting on your rifle?
All of my 16" BBL 1:7 PSAs shoot better with 62 grain and higher weights.
62 grains give me a decent 3" to 4" at 100 yards with 4x and 6x optics (I’m old open sights are long gone for me these days) and bipod, with 55 grains I get a huge spread (I’m talking Minute Of Buick), but with 75 grains in 3 of my 5 16" it gets spread again, but in two of them (from a supported bench) I get an honest 2".
Now for the good part, with my 18" upper in .223 Wylde, I get five shot groups (once more supported) with an Arkin scope of usually 1 MOA with 75 grain .223 Match ammo, and just a smidge bigger with AAC 75 grain in 5.56
I have been playing around with with the twist factors for the last 25 years, and finally just decided to buy what I want or think would suit my needs, and just find that magic round that that one barrel likes
The twist rate calculators are helpful to put some outer bounds on what you can use, but every barrel most definitely has a different taste for ammo. All my 5.56 barrels seem to be about the same as yours, so I use that to buy a smaller selection of ammo. I stopped buying 55gr because one gun hates it. Everything tolerates 62gr, and everything loves 75+gr. Why buy ammo I know I can’t always use.
If I didn’t have a stack of 62gr in a variety of high quality rounds, I’d probably go 75 and 77gr exclusively. Probably AAC for general use and IWI Razorcore for some higher cost variety. Both shoot great.
I ordered some 77 grain OTM ammo made by AAC from PSA. I only ordered 200 rounds until I can test some of it out. If my rifle likes it I’ll be replacing a lot of my crappy 55 grain in my stockpile. Will update with groupings.
my plan is to do the same, and replace all my ammo eventually with a single grain that works best in all my rifles. its gonna take me some time but i’l get there eventually.
Just an update. Shot a few boxes and the AAC 77 grain OTM yesterday evening and it was a great success. I would guess if not sub MOA, then extremely close. Also tightest groups ive ever shot out to 200 yards. Probably like 2/3 inch groups. Wish i would have kept my targets. I’ll probably take it out again and update with pics. I ended up staying pretty late so I was rushing to clean up and go. Definitely going to look into grabbing more very soon.
Hey Sam, I’ve got a 1:7 twist PSA barrel and it shoots 55/62 grain just fine. Might be a bit better with heavier bullets, but probably not a huge difference from your 1:8. If the 1:7 is the better deal, go for it!
In my limited experience, the difference is between hitting a baseball at 100 yards and hitting a quarter at 100 yards. They’re really isn’t anything wrong with either but I would definitely recommend the 77 grain OTM loads from AAC if you wanna stretch out the accuracy. The run of the mill 55 grain loads just don’t seem to get me very great accuracy, although still serviceable all things considered.
I look at it a little differently, in terms of how many complete twists the bullet will do in the barrel. Barrel length is a factor. A 1:7 twist on a 7-1/2” pistol barrel will get most of a turn, not a complete turn because you have to subtract chamber length from barrel length. A 10-1/2 inch barrel 1:7 or 1:8 would get a full turn, whereas a 1:9 10-1/2 barrel would not for the same chamber length reason. If you were making long range guns with long barrels, a 24” 1:7 twist rate would net 3 twists. To get the same 3 twists in 1:8 you would need a 26” barrel length. I usually opt for the fastest twist rate available in the length of barrel I want, and then match ammo to the project.
If you’re of the other category of shooters who looks at ammo availability and builds guns centered around that, here’s your quick rule of thumb.
1:9 twist, 55 or 62 grain only, the original compromise
1:8 twist, 55, 62, & 77 grain, the new flavor of compromise
1:7 twist, 62 & 77 grain, every service rifle since M16A2, it will also shoot 55 grain well, but can drift from over-stabilization when nearing max effective range between 300-500 yards
