I guess it could be, but I've always attributed it to reamer marks.

Better barrels are lapped or honed post reaming, both to improve the finish and true the dimensions of the bore.

It's a common scope location for people who rifle shoot prone with a sling.  In that position, nose to handle and scope needs to be mounted pretty far forward.  I find I prefer mounting my scopes forward like this; and feel like most folks mount scopes a bit further back than they really need to.

For example, here's how US Army Marksmanship Unit does it, as well as pretty much all High Power Service Rifle shooters run it:

6/16/2019 update  - Cleaned the rifle.
Using a Hornady Headspace gauge with a 147 gr Hornady ELD-M as the test bullet.  Where the tool pushes the bullet to where it engages the rifling, and stops there.

@ 0 rounds: no data
@ 100 rounds: 2.786" OAL ( early life readings tend to be misleadingly short - I suspect, due to tight throats)
@ 200 rounds: 2.897" OAL
@ 500 rounds: 2.912" OAL

That's a pretty impressively fast creep-rate on OAL.   A decent 223 barrel after initial break-in, typically only creeps about 0.010"/1000 rounds or so.   This one looks to be doing it 3 times faster.  Throat visually looks OK.  But it does seem to be moving out, based on these readings.  Still, this gage is tricky to use, so the numbers probably shouldn't be taken too literally.  The data tends to be noisy, so the trick is to try and get a lot of data to see through the noise; which I'll try to do.

Total round count: 509

Thanks for the answer. Very interesting, did not know that. I have heard the phrase "nose to the handle" before and didn't realize the prone+sling fit into that method. I may have to try it out sometime.

You raise an interesting point though.  While I'm quite happy with my skill-set as a prone sling shooter; I'm not very satisfied with my performance with a bipod on a bench; I'm not sure what my limiter there is...

Having the scope that far forward likely won’t work very well for running a stock at max length, an A2 or PRS stock with a high power optic and larger objective.

The most important thing is to have a good sight picture in the position you’ll be shooting from. Setting up a 1-6 to be shot from a sling is far different than setting up a 6-24x50 that will be shot from a bipod using a stock with a longer length of pull. If you set the scope too far forward, you’ll fatigue out from stretching your neck to try and get a solid edge/edge sight picture.

6/17/2019 update  - scope manipulations.

Contacted Primary Arms to RMA my 3-18 scope.  My list of concerns was:
They wrote back and suggested I loosen my first ring on the scope mount.  This was absurd, as I only had maybe 20 in-lb on that ring (I use a torque wrench on such), but to humor them, I did so.  And I'll be damned, now the parallax dial spins consistent and properly.   So the good news, is that appears to have fixed the main issue I have with the scope.  The bad news is.. just how do I mount this scope??  I've asked them for guidance on how to properly mount my scope, if I can't put any torque on the front ring.

All that said, if the answer comes back where they say I need to scoot the scope back an inch (for example - they haven't said that yet), that actually plays into some of the above conversation....

Total round count: 509

Also, tested the trigger pull of PSA's 2-stage trigger.  It's a good trigger, and breaks at 4# 1oz on my rifle right now.

The only real defect on the PSA rifle is the ejection port door.  They didn't line up whatever right, and it takes inordinate force to get it to latch into the closed position.  I have to whack it with a wrench or something (under a cloth), to get it to close.

Total round count: 509

Vortex recommends 15-18lbs iirc (which I use with all my rings), but moving the rings away from the turret housing isn’t a bad idea. I’ve read of ppl having similar issues as you are describing when mounting their rings right next to the turrets.

I became aware of that with a first gen Razor. My boss mounted his like he mounted everything, to German torque specs, and froze his adjustments.

Apparently that applies to this one too.  I talked to PSA today.  Sure enough, when that ring is too tight (or not too light, more to speak), then the parallax knob doesn't work right, and the tracking can be affected as well (which I think I saw).  Their recommendation with that scope and mount is 10-15 in-lb.  To me, that's damned light, and it sucks when a scope slides under recoil; which I'm now nervous about.  But OK.

I mentioned sliding it back a half inch as well, to see if that would help - to which he said can't hurt, but wasn't able to comment on.  I also asked about the back ring, to which he's not aware of that ever causing issues, but recommended running it at the same torque.  I guess so, but I'm rather tempted to run my front ring at his 15 (or less) in-lb; and then running that back ring at something a little closer to 15-20 inch-lb (which is hardly oh-so crazy); haven't decided.

Lapping and bedding does wonders for scope security.

7/7/2019 update  - Fired 31 rounds - no failures of any kind.
After getting the PA 3-18 scope working correctly, but adjusting the torque on the front screws - returned to the range to confirm zeros.  I also scooted the scope back a little bit.  Fired 3 types of ammunition.  Results were fine, but not really stellar.  Then again, this wasn't really match ammo either, so can't really judge too harshly.

-Federal Non-typical 140 gr:  around 2 MOA, about typical.  It's basic cheap hunting ammo.
-Mild reloads with 140 gr fusion and IMR 4064 powder (Lot 65-55).  As described before, this is mostly a budget plinking round, as these particular bullets and powder were very cheap through some deal'n; though it's only clocking 2553 FPS.  Once again, the standard deviation of this powder is very good, at just 7 fps.  It shot about 1.3 MOA, which is ok.
-Hornady 129 gr interbond hunting ammo.  This ran 2808 fps, and grouped OK at 1.4 MOA.

Again, while none of that accuracy is all that impressive, neither was any of the ammo being fired either.  Anything better than 1.5 MOA is "good enough", but on my next outing, I'll return with some better quality ammo and work anew on getting that down closer to 1 MOA, which should be doable.  At the end, zero'd the rifle at 100 yards using the Fed Non-Typical 140 gr ammo, so that the bullet-drop compensator Christmas tree on this Primary Arms scope can be used.

Intend to clean the rifle tonight, and adjust the scope dials to read zero for wind at current setting, and 1.0 mil, for the 100 yard zero.

Total round count: 540

This is merely a suggestion and please take it fwiw.  I have the exact same upper as you and tried many factory and handloads and could not get sub moa with anything except 140 gr nosler bt over RL15 at about 2550-2600.

I'm guessing that everyone reading this knows that ymmv, just trying to save you some effort and $

7/12/2019 update  - Fired 100 rounds - no failures of any kind.

Took it out to a 200-700 gong range yesterday.  It was almost boring.  Put the scope distance marker on the gong, pull the trigger, and DING!  Pretty much every shot, any distance.  It was interesting how fast the 6.5 bullets get onto target even at 700 yards; it just felt faster than what I'm used to seeing.  Gun cycled very well.  Folks I was with, were sufficiently impressed with the 3-18 scope in conjunction with the rifle, that I know at least 1 of those 6.5CM reticle scopes got ordered last night, for his identical PSA 6.5 CM.  Oh, side issue, on his rifle, just like mine, to replace the jamming that starts after 50 rounds, he replaced the extractor with the DPMS Gen 2 version (with the rubber disk, rather than a spring), and his rifle ran 100% with that modification now.  Mine still has PSA's extractor, but with two O-rings around the spring, not just one, and that is working 100% for me.

All in all, a good day at the range.

On a side note, I took the time to pick up brass at the range; as at this facility most people just leave it.  6.5CM brass is all over the place, and was equal to if not exceeded the amount of .308 brass.  Here's what I picked up; it filled two cotton grocery sacks.  Found some 6.5 Grendel too, but not nearly so much.  .223 was of course everywhere, and I only picked up a small portion of what was laying on the ground.  I left all the .308.
The box of yesterday's field pick-up 6.5 CM brass is on the left; probably 300+ casings picked up that day.  Probably a lot more then that actually, it's a deeper box than it looks.  

Point being, I think 6.5CM kinda won  

I intend to clean and measure the latest on throat erosion in a few days.

Total round count: 640

That scope is based on the ELD match round, which has a high ballistic coefficient (G1=.646). Looks like you used the Non-typical as well which has a significantly lower BC (.439). Was there much difference in impact between the two or did you just aim slightly higher for the Nontypical at long range? I was thinking for the S&B 140gr 6.5 (similar BC to non typical I suspect) that it might be better to zero it somewhat closer, like 65yds, instead of 100 yards, but maybe holding slightly higher is sufficient. ELD is a little pricey to plink around with (like twice the price).

Glad you got it working. Hard rifle/scope combo to beat for long range shooting for under $1300.

Good question.  With Federal Non-Typical 140's, it was sufficiently enough on to work at 200-600 basically straight up.  At 700 yards, I was using the 800 yard markings on the optics; erroneiously thinking the 700 yard was actually 800 yards.  Later, when we switched ammo to a much better BC Hornady bullet, the 700 yard tick mark was indeed correct for 700 yards - go figure!

For the 100yd zero and nontypical these are the yardages for the marks in that reticle, generated from Strelok Pro:

dupe

If you host the pic on a website like https://imgur.com/ and then click the image icon and paste the direct link to it the image will show.

@erichard

Thanks, yeah I hosted it on dropbox and got the image address off the preview of the file. Seems to be working now. Earlier it would show up in the ar15.com preview of the post but not the actual post, but now it seems to show there too (?).

Not showing up for me yet. I haven't used dropbox but don't you have to save it there and not run off the preview? Just the naming conventions illustrate that to me.img]/images/smilies/smiley_abused.gif[/img] Its free and easy to setup an account at imgur if your interested.

@erichard

Not sure why it shows up for me and not you. I do have it saved in a dropbox folder on the web. The preview of the file gives you a picture of the jpg file, and it has a web address to see the jpg. Yours is probably more reliable. Thanks.

Since I'm the only one that's reported not seeing the image that must be what it is. I don't have dropbox, just Imgur.

@erichard

Thanks for your patience. I'm a little slow. I checked it on another computer, and it doesn't show, nor does the link work. So I made an imgur account and uploaded it. Here's the link. Maybe it will load, maybe not:

No worries, pics are looking fine now.

@erichard

7/16/2019 update  - Cleaned the rifle

Measured the throat erosion, OAL with a 147 Hornady to be 2.914", which is 0.002" growth in 100 rounds.

Total round count: 640

Thañks for taking the time to do this. I purchased the same upper with the 6.5 lower. I know it's the same as the 308 but thought it would be a great to spend another $20 needlessly. Topped mine off with a Burris PEPR mount and an athalon 6x24x50 scope, Magpul bipod and that same muzzle break. Had the rings lapped. I've only tired it to break the barrel in (without optics). Only one box through it but it functioned flawlessly. Can't wait for a day off to play.

8/31/2019 update - fire 10 rounds - no failures of any kind

[NOTE, TINYPIC IS CLOSING - so after ~15 years of using them as my image host, in about 2 weeks all of the above images are going to go away]

Spent most of the day on a Grendel project, but had a few moments for two 5-round strings through this Creedmoor rifle.  Holy crap, what a dream.  Both groups were under 1 MOA, and one of them was at 1/2 MOA, at 200 yards.

I'd post images of the groups, but need to find a new image hosting site to do that.

Total round count: 650

9/9/2019 update - fire 60 rounds -

Took the Creedmoor out to 1100 yards, and it shot great.

Total round count: 710

OP, thanks for the info on the extractor Oring.

I have the same upper. Mine has had the same malfunction from the first magazine. The extractor is extremely easy to move and upon disassembly I have a single Oring.

I feel what what is happening is the ejectors are overpowering the extractor's grip on the spent case and it slips out of its grip and doesn't eject.

I contacted Josiah about perhaps just getting parts, I don't want to send it in.

I may just add a second Oring myself and test it again.

I have the vampire marks on the neck too but they're not as bad after a little file work.

The rifle is shooting under an inch with Hornady American Gunner 140 and when it doesn't jam up the ejection is strong and at 4:00 with the gas set at 1.5 turns out.

I have a Tubbs flatwire AR10 spring, H3 buffer and CMC 2.5lb flat trigger. The muzzle wears a KVP linear brake and the scope is a 4.5-27x50 Ares BTR mil/mil. Coyote Norrell's is by me.

I found Viton #006 (or 60 depending on brand) o-rings at Napa, bought 5 for like $2. I can get 50 from McMaster Carr for about $10 but I don't need that many LOL.

I cleaned the bolt very well, lubed it all and put the ejectors and extractor back in. Then assembled the bolt to the carrier and the super clean firing pin and cam.

I was told that the extractor should be so stiff that you can't move it with your finger, mine is exactly like this. I can flex it over with a screwdriver. If it works to fix the "2 hotdogs in one bun" issue, LaRue makes a double AR10 spring assembly where one rests inside the other that I will buy to permanently fix it. I just don't know long term how double O-rings will hold up.

https://www.larue.com/products/larue-7-62-extractor-spring-set/

Note* it wasn't like an AR15 where the o-ring was putting tension on the extractor at rest, the AR10 has a larger space so the o-ring was only touching the extractor when flexed almost to full travel. I could easily move the extractor with my fingers.

So... I will try to go out to the farm tomorrow and verify function.

I look forward to the update.

Went this morning to the farm. Put two 20 rd magazines though it with zero issues. Strong extraction/ejection at 4:00 and was able to make 1 ragged hole with 2nd 20 rd magazine of American Gunner 140s.

Gotta get some ELD and get to the range!

What distance? Maybe I missed it, factory barrel? What trigger?

9/14/2019 update (postdated) - 97 rounds fired.  


Took it out to 1000+ yards again on this lovely day.   It shot very reliably and accurately.   Upon taking it home, I did discover a little erosion on the firing pin tip, that was 100% due to some remaining rounds of that lot of reloads the weak-cup S&B primers.  Absolutely not PSA's fault, that ammo they would pierce in a RPR as well.  So I wrote PSA and asked to purchase a replacement firing pin.  Their reply, was no problem, we'll take care of it, and send you a replacement for free (because that's how PSA rolls).

Here's what I got in the mail


An entire replacement BCG - which is one way to get a firing pin!  So, have to say, I'm a little more than impressed with PSA right now.  In any event, the gun continues to be a pleasure to shoot, and is quite accurate.

In other news, the Primary Arms 3-18 scope has a noteworthy limit I've discovered.  The Bullet Drop Compensator only goes out to 1000 yards.  If you want to shoot at 1200 yards, this gun can do it, but where do you hold?  So I tried just dialing up the correct number of clicks total, via a calculator; but that didn't work, because the dial bottomed out way before I got there.  So I tried dialing up the correct clicks to essentially move the 1000 yard drop indicator, to push out to 1200 yards.   But to do that, I need the actual .mils (or MOA) of the BDC markings.  Which is to say, if the 1000 yard marking that is etched in the glass is for 12.5 mils [made up number, I don't know what it is], and my ballistic calculator for todays load of the day, says I need 18 mils [made up example number] for 1200 yards, then I could preload 5.5 mils via my dial on the scope, so that the 1000 yard markings could be used for that 1200 yard shot.  But nobody actually knows what the mils are for the markings on the Primary Arms 3-18 scope!  They aren't in the manual, and when I asked them directly here, they didn't know.  So... for now at least, this gun is limited to being a 1000 yard gun with that scope, until I can get that figured out.

Oh, and in other news, this is how much 6.5 Creedmoor brass I picked up off the ground at that range in 2 outings (in the 40 mm can), and the rest of that is the .223 brass I picked up there as well.  I'm finding more 6.5 CM brass on the ground now, than .308 brass.


Total round count: 807

This is why I prefer the all-mil based R-grid reticle and a drop table based on mils, rather than a range scaled reticle. You can dial your hundred yard zero up in mils above the central cross hairs effectively extending the reticle tree “deeper” into hold over.  This might require a canted scope base to get enough vertical dial range.  This also keeps longer range targets closer to the optical center of the scope.  Dialing does induce error from lash-back in the scope erector screw system though.  Some Chinese scopes don’t  manage this task very repeatably.

Don't buy crappy scopes.

The reticle is based on Hornady 140gr eld match so if you enter that data into your calculator, you can see how many mils Primary Arms needed to move vertically to mark 1000yds in that reticle. I tried it, and for me, it looks like it's 8.4 mils (ie. 1000 mark on the scope equals 8.4 mils approximately). And by dialing 3.1 mils vertically, you can change the last line to represent 1200yds. But that's for ELD. I guess figure mil drop for 1200yds for your ammo and then subtract 8.4 mils to get your dial in number for that 1000yd hash mark.

(not sure what atmospherics they used for ELD, but I used 59F, 28.5 in Hg, 68% humidity, and 2000 ft elevation to get that last line to equal 1000...but other combinations would work also)

And maybe contact Dimitri at Primary Arms for the real answer. He will know for sure and is very eager to help. Can probably get him via Facebook or youtube or maybe someone has an email address for him. He invented ACSS and calibrated the scopes.

Once we know the real 1000yd hash mil number, should be a piece of cake dialing in longer distances.

I agree with you on paper, but I do have to say, it's very easy and a crowdpleaser just running the BDC scope.  You can hand your rifle to someone and they're ringing steel out to 700 yards with no effort, just line up and shoot.  (once past that, then your actual velocity and Bullet BC and weather conditions are never the same as they used, so it starts to add up when you're getting out to the 900+ yard range)

Factory barrel, lapped by me with JBs when I had it all apart.

CMC 2.5lb flat shoe trigger.

100 yards from bench. Corn hasn't been cut so that's as far as I can shoot at the farm. About a 1.5" group and pretty much just a hole after 20 rounds, nothing left to aim at LOL. Couldn't get low enough with bipod height so I modified the Magpul to go to 45* this week. Ordered an American made brake similar to the Fortis Red, the KVP is not loud but does little for recoil. I also ordered a Sprinco AR10 double extractor spring set to replace my doubled O-rings.

Going to Colorado next Friday, when I get back I will put the new brake on and the Sprinco double extractor spring set, shoot it with some match ammo and see how it does.

Well... I asked, and they declined.  Quoting fears that someone else will then steal their retical design.  I can't tell if they're actually serious, or just wanted me to go away. Anyhoo, drop their image into RangeBuddy app, run the top distance going to 10 mil as the ruler of 10 units, and then just tick off the markings manually.  I get (see next post):

[background music for todays post]:

Scope currently in use (PA 3-18)


PUBLICLY AVAILABLE IMAGE and personal data analysis.

yards   Mils ( +/- 0.1 ;  on Apollo 3-18 6.5CM)
300 = 1.0 Mil
350 = 1.4
400 = 1.8
450 = 2.2
500 = 2.7
550 = 3.1
600 = 3.6
650 = 4.1
700 = 4.7
750 = 5.2
800 = 5.8
850 = 6.4
900 = 7.0
950 = 7.7
1000 = 8.4

Top of post = 9.4

The range on the dial itself isn't very far, and I can only load an additional 5.5 mil on the scope, before it tops out (which is more than a little disappointing).  Meaning the max I can load on the gun with this scope (using the PA mount - which I don't really recommend) is 13.9 mil for the 1000 yard tick, or 14.8 mil if I use the top of the post.

OK, so if I take a box of S&B 140 gr FMJ ammo out tomorrow, and I want to shoot 1000+ yards:

Inputs:
-This PSA 6.5 CM rifle.  Measured MV = 2666 FPS.  
-Manufacture's listed BC (G7) = 0.275 (which might be about right)
-Conditions: 1000' elevation
-87 °F; -50% humidity; -7 MPH, at 30 degree's from the right.
Run a handy ballistic calculator (I kind of like Hornady's right now):

IF USING THE DIAL and shooting center (elevation clicks UP are clicks added to whatever the 100 yard zero setting is):
Yards,   Up   Wind (mils)  Velocity (fps)
600:    3.9   R 0.3   1826
700:    5.1   R 0.3
800:    6.4   R 0.4
900:    7.8   R 0.4
1000: 9.4    R 0.5    1351
1100: 11.2  R 0.5    1244
1200: 13.3  R 0.6    1143 (should still be supersonic - but bairly)
1300: 15.6  R 0.6    1043 (subsonic transition)

And we're done, even if I preload my max of 5.5 mil on the scope, I don't add up to 15.6 mil, so looks like I'm stuck with aimed fire at 1200 yards max.  I go transonic past that anyway.   Hornady bullets have a better BC and I run a bit hotter, so will go farther.  But for this ammo with this scope in this gun, 1200 yards is about it.

Ok, so - moving on, how do I run this scope with this ammo from 300 to 1200 yards?

For 300-500,  the scope is going to be about spot on.
Yard  /  With S&B 140, hold it at:
600    640 (ish)
700    750
800    850
900    950
1000  Top of Post
1100  ADD 2.8 clicks and aim at 1000 yard marker (to read 3.6 on the dial, since +0.8 clicks is the zero of this ammo at 100 yards and was already preloaded)
1200  ADD 2.1 MORE clicks and aim at 1000 yard marker (to read 5.7 on the elevation dial)

That scope sounds like a dumpster fire to me.

Wow. I was mad when the Argos FFP 6-24 on my Kidd would only give me 9 mils elevation. The old PA 4-14 FFP gave me 18 (it wears a 20MOA rail) I was able to hold on the reticle with that scope to shoot subsonic 22s out to 400 at between 22 and 24 mils.

A 20 MOA Mount would give you more. I have a Leupold MK4 20MOA on my 6.5 and it is working great with my Ares BTR mil/mil. I have 17.5 mils elevation left with that combo from a 100 yd zero.

In theory with 147 ELD running 2600, using all the reticle, that would get me to over 1800.

Thanks again OP for the extractor info, you saved me a lot of grief.

Indeed, but no one appears to make a cost-effective +20 MOA mount.  All the examples I have been able to find, are priced at 20% the value of the gun!   That, well heck - the current range capability of the scope is about as far as the gun pragmatically can go anyway.   I can now make it goe as far as the round goes before going transonic.  So dropping >$100 for a 20 MOA 1-piece scope mount is an iffy priority right now.