View Full Version : FN 18” heavy barrel accuracy: A little disappointing
I have a couple of heavy Ars.
One is with from PSA with a heavy FN 18” barrel chambered in 5.56 with a 1/7 twist, Faxon nitride BCG, Larue 2s trigger and PSA lower
The other is complete upper (with BCG) from Anderson. It has a fluted 24” heavy barrel chambered in 5.56 with a 1/8 twist, Larue 2s trigger and PSA lower as well.
I loaded a bunch of ammo using:
Once fired processed LC brass
CCI 400 primers
Varget
73 ELDM and 69 SMK bullets
Below pic is the average groups I’m getting with these two uppers at 100Y. The average is for four 5 shot groups.
I’ve borescoped both barrels and the FN looks pristine and better than the Anderson barrel.
I’m thinking the accuracy is a little disappointing with the FN barrel.
What are your thoughts and what kind of groups are you typically out of this type of barrel?
https://i.imgur.com/gpOQLU0.jpg
Let me guess... The FN barrel is chromed and the Anderson barrel is SS. Not to many people make really good chrome lined barrels. If you throw out the largest group of each load they don't look bad for what got to me.
I expect better groups than those for FN barrel. I believe you need to find bullet and load that FN barrel might like better, even changing primer and powder can cut those groups in half. I would continue use 69gr SMK just change powder and primer and vary their charge make sure you employ all marksman fundamentals. Also from my experience single loading produce better group or next best would be keeping magazine mostly full. Like, if you are shooting from 20 rounder magazine refill that magazine every 5 shot never let it go below 15 round to minimize the difference in upward pressure against BCG between round 1 to round 5 of the group printed. The primer and powder change may produce more consistent pressure curve behind the bullet. Consider how different barrel length are between your uppers you need to find load that suit the very different harmonic of 18" barrel from 24" barrel. You may want to check out reloading recipe of others on here or other forums for 5.56 that made tiny groups with similar barrel. I can almost guarantee you the FN can print submoa, you just need to find it's load.
Where does it say FN on the barrel? Check the roll marks and let us know what it says.
I saw that you are chambered in 556, are you reloading for 556 or 223? FN should be more accurate with 77gr vs the 73gr and 69gr rounds. If you are reloading to 223 spec that will screw you over all day in 556 chambered rifles. 77gr SMK reloaded to 556 pressure specs in the FN should be your optimal load and get you where you want to be.
I saw that you are chambered in 556, are you reloading for 556 or 223? FN should be more accurate with 77gr vs the 73gr and 69gr rounds. If you are reloading to 223 spec that will screw you over all day in 556 chambered rifles. 77gr SMK reloaded to 556 pressure specs in the FN should be your optimal load and get you where you want to be.
Some of my loads are pretty stout. I don't have any pressure so I can increase the powder a little more.
Where does it say FN on the barrel? Check the roll marks and let us know what it says.
It's this upper:
https://palmettostatearmory.com/psa-18-chf-heavy-barrel-mid-length-15-precision-lightweight-m-lok-upper-no-bcg-ch-516444448.html
And here's a pic of the roll marks I just took.
Gets some rounds down that barrel and get some copper fouling in it, I bet the groups will tighten up a bunch.
That barrel will shoot 1 MOA or better with the right cartridge. You just need to find it.
I have an FN barrel that I have about 5000 rounds through, I recently bore cleaned the barrel and removed the copper fouling for the first time. Groups opened up just a little. It took about 60 rounds to get some fouling back in it before the gun was shooting 1 MOA or better again.
How many rounds though the barrel?
Honestly I dont think your going to get any better and a couple of the loads your at sub MOA. Just to many variables in the gaser and your screwed by the mag in not being able to seat the bullet where it may ideally want to be. I know I have spent a ton of money trying to get a DMR/SPR to shoot like a bolt gun and they just dont. At the end of the day the system was designed for minute of scum bag. Even if you had some true premium barrels spun up I dont believe you would see anything drastically different. I would be very happy with your third loading and drive on.
Just curious as to what your goal here is, simply accuracy or accurate as can get at longer distances? Did you chrono and if so what did the SD look like?
triggerjerk
05-16-20, 08:14
Are those your only load increments? I think I see .4 and .8. Did you skip or just not show? When starting with new components, I usually do 5 .5gr increments up to listed max. May occasionally follow up with smaller increments to fine tune....
The FN barrel is new and this was my second time shooting the gun. My stainless Anderson did shoot better after a few hundred rounds, so there might be some hope.
My goal is tight groups. It’s for punching papers at 100Y and shooting steel at 400Y. I didn’t chrono last time.
My load increments are typically 0.4 gr. This time I skipped 25.3 gr of Varget with 69 SKM because last time I was shooting that load in both guns, and the FN didn’t like it either.
I’m really hopping the FN will shoot sub MOA. Right now, with the one load it like (24.5 gr Varget and 69 SMK), it shoots sub 1.5 moa. That’s not bad, but it’s no better than a typical M4 profile barrel. I was thinking a heavy profile would give more accuracy, or at least will be more accurate across several loads (like the Anderson upper).
I know I have spent a ton of money trying to get a DMR/SPR to shoot like a bolt gun and they just dont.
This is pretty much it. I mean.. I think, for me, it's jumping off the bolt gun and onto a two stage trigger with the bolt/buffer bouncing around too. It just makes stacking holes hard on a semi. I tend to settle in after a bit. But really, we don't shoot any SPR type guns that really shoot a no doubt sub MOA group.
We still shoot out to 1000 yards with them though.
It's this upper:
https://palmettostatearmory.com/psa-18-chf-heavy-barrel-mid-length-15-precision-lightweight-m-lok-upper-no-bcg-ch-516444448.html
And here's a pic of the roll marks I just took.
Thank you, I most certainly appreciate the follow up. Others have already pointed it out, but it isn't a precision barrel, and that may very well be just how it shoots.
turnburglar
05-16-20, 17:49
I think for a CHF, CL barrel assembled by PSA; 1-3 moa sounds about right for an AR. If you really wanted to chase precision the obvious choice is a stainless steel, button rifled, untreated barrel is what the best shooters use. While there are som posters on the internet with CHF CL barrels "sub moa" it is the exception and not the rule. There is an absolute reason Wilson, Krieger, Bartlan and Rainer all choose a very similar steel and manufacture process.
Also you should consider upper construction. Is your muzzle device and barrel nut properly torqued? Is the receiver laped for the barrel extension? Is the BCG tight? I don't own a submoa AR in any caliber; but those are the things I would chase.
I was cleaning the upper and noticed a problem with the Faxon nitride BCG. The bolt can't support the weight of the BCG which I suppose means the gas rings are toasted. This is only after two range sessions and 200 rounds. I'll probably have to use another BCG and return this one.
I was cleaning the upper and noticed a problem with the Faxon nitride BCG. The bolt can't support the weight of the BCG which I suppose means the gas rings are toasted. This is only after two range sessions and 200 rounds. I'll probably have to use another BCG and return this one.
Another nail in the coffin of me ever buying Faxon anything ever.
I was doing some reading and it appears that if the bolt can hold its own weight, it's good to go. So I should be fine. My bolt won't fall under its own weight (far from it). It just won't hold the entire weight of the carrier.
I was doing some reading and it appears that if the bolt can hold its own weight, it's good to go. So I should be fine. My bolt won't fall under its own weight (far from it). It just won't hold the entire weight of the carrier.
Can you explain what you mean further?
I have noticed that nitrided BCG can be so "slippery" that the bolt doesn't always pass the "place it face down on bolt face and see if the carrier falls down down" test. But it will pass the more official drop free test pictured below.
Either way, as many have tested, even one worn gas ring can still work. I would not blame gas rings for a new BCG (or not) cycling issue. I would also put gas rings way low on a list of issues affecting accuracy.
Dennis.
https://uploads.tapatalk-cdn.com/20200517/62bcfb994454cdbdc1a9005eef80a795.jpg
Thanks, Dennis. I’ve only ever seen if it would support the weight of the carrier.
I loaded the 73 ELDM with 24.6 and 25 of Varget. 25 gr is the maximum recommended load and it's compressed.
I also shot a box of factory 50 grain American Eagle Tipped Varmint that shot pretty will in both guns. The PSA FN rifle shot it's best average group with this ammo (1.25" at 100Y).
It's clear that both rifles favor 69 SMK vs 73 ELDM. I still have 300 that I'll only shoot in the Anderson (it will shoot 1 MOA with ELDM and 3/4 MOA with 69 SMK)
I have also ordered some 77 SMK bullets that I'll test next time.
I hope to find a sub MOA load with the 77gr for the PSA FN. If not I'll just have to accept that it's a 1-1.5 MOA rifle with the load it likes. For me a heavy barrel should shoot sub MOA. If not I don't see the benefit of going with a longer and heavier barrel vs a lighter A2 profile (at least for the type of shooting I do).
Below the file updated with today's shooting.
https://i.imgur.com/hpDllGkh.jpg
PrivateCitizen
05-20-20, 21:32
It is probably worth noting that just because a barrel is made from FN blanks does not mean it it will be as accurate as another makers same offering.
The blank is only one piece of the puzzle. The start, really.
How PSA chooses to make barrels from FN steel vs, say, Centurion, and finished by whom is an immensely critical part of the process.
I have long been curios about this and the FN/PSA items. Is there any actual info the process?
It is probably worth noting that just because a barrel is made from FN blanks does not mean it it will be as accurate as another makers same offering.
The blank is only one piece of the puzzle. The start, really.
How PSA chooses to make barrels from FN steel vs, say, Centurion, and finished by whom is an immensely critical part of the process.
I have long been curios about this and the FN/PSA items. Is there any actual info the process?
The barrel is entirely manufactured by FN. I've posted a pic of the rollmarks (FN logo HF MP 5.56 NATO 1/7) in this thread. PSA just assembles the upper with the FN barrel.
The barrel is entirely manufactured by FN. I've posted a pic of the rollmarks (FN logo HF MP 5.56 NATO 1/7) in this thread. PSA just assembles the upper with the FN barrel.If PSA assembled the upper have you pulled the handguard and checked the barrel nut? They are notorious for loose assembly. I bought a fun 20" A2 upper from them and the barrel nut was barely hand tight. It shot great after I re-assembled it correctly.
As you are going for accuracy I would tear it down and re-assemble to correct spec before anything else.
Dennis.
pointblank4445
05-21-20, 14:25
It is probably worth noting that just because a barrel is made from FN blanks does not mean it it will be as accurate as another makers same offering.
The blank is only one piece of the puzzle. The start, really.
How PSA chooses to make barrels from FN steel vs, say, Centurion, and finished by whom is an immensely critical part of the process.
I have long been curios about this and the FN/PSA items. Is there any actual info the process?
Been back and forth on the whole FN thing. PSA=FN=Noveske=Hodge outside of profile and external specs (gas port)? Used to believe there was special sauce and metalurgy, but not sure. I don't know anymore...I just go by how things shoot and feel when they shoot.
Just for fun, you want to play a game? I'll put up borescope pics of 4x FN CHF barrels (2 pics each)...see if you can tell me who contracted them. For bonus points, rank them in order for how you'd think they'd shoot a 10-round group of Mk262...
BARREL #1
https://i.imgur.com/wsKY3Yz.jpg
https://i.imgur.com/VkdNO1K.jpg
BARREL #2
https://i.imgur.com/D1OVZ0F.jpg
https://i.imgur.com/ix0K8W6.jpg
BARREL #3
https://i.imgur.com/l0Xkw5m.jpg
https://i.imgur.com/vO1EWGU.jpg
BARREL #4
https://i.imgur.com/12aDEFc.jpg
https://i.imgur.com/UEutuCc.jpg
Barrel #3 has some tooling marks and doesn't look as good as the others.
Barrel #1 has some lezard patterns indicating that it has been shot more than the other barrels.
What I can tell you is that the inside of my FN barrel looks really good (better than the Anderson barrel). What I can also tell you is that I have some barrels that are pretty rough when you borescope them, but they shoot amazingly well.
Personally I use the borescope mainly to inspect the barrel and chamber after cleaning and don't rely on it to predict the accuracy of the barrel.
pointblank4445
05-22-20, 08:56
Barrel #3 has some tooling marks and doesn't look as good as the others.
Barrel #1 has some lezard patterns indicating that it has been shot more than the other barrels.
Barrel #3 is the 2nd best shooter of the group...well, I would assume as barrel #1 has never been shot but all of its brothers have exhibited performance within about 0.2" across 5-6 examples
Just because your barrel looks good does not mean it will shoot. Same as a barrel that looks horrible can be one of you most accurate barrels ever. There is a lot more to how it will shoot than the interior finish.
pointblank4445
05-23-20, 07:56
Just because your barrel looks good does not mean it will shoot. Same as a barrel that looks horrible can be one of you most accurate barrels ever. There is a lot more to how it will shoot than the interior finish.
Yep...noted that above.
Only reason I scoped these barrels was to see if the legends were true that Hodge and HK always center the gas port in the groove...they don't
Ned Christiansen
05-23-20, 08:04
What borescope are you using?
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