POF issues in SLC....help

[Mustafa]

Re: POF issues in SLC....help

First pic is a 5 round group from the 16" upper firing semi-auto from a PMAG

Second pic is a 5 round group from the 20" upper firing semi-auto from a PMAG

Third pic is a 5 round group from the 16" upper firing single, hand fed rounds.

Fourth pic is a 5 round group from the 20" upper firing single, hand fed rounds.

Windage looks pretty damn good, but it is stringing BAD vertically. These were shot off a bench with a bi-pod and rear bag.

 

[Badshot308]

Re: POF issues in SLC....help

Just to eliminate damage done to the bullet during feeding or bullet set back during feeding, have you shot any groups by hand feeding the rounds directly into the chamber with your fingers, then closing the action?

 

[Mustafa]

Re: POF issues in SLC....help

Yeah, the second two pics were done like that Badshot. It helped drop the groups down a little, but they are still pretty loose.

 

[Badshot308]

Re: POF issues in SLC....help

Wow, the mystery continues...

 

[Mustafa]

Re: POF issues in SLC....help

Yup.

 

[cyrekzz]

Re: POF issues in SLC....help

as for what sobrbiker883... you should check your buffer spring and buffer if you haven't. When i had my VTLOR emod stock - i had the carbine 308 buffer and buffer spring. When i switched to the Magpul PRS - i was directed to get the DPMS standard A2 buffer tube, buffer spring and buffer. I can't remember the weight of the buffer - but it's the standard weight that goes with all of that.

 

[cyrekzz]

Re: POF issues in SLC....help

I retract my earlier statement about the mag feed lips since you have pmags - i have 2 and they work. So it wouldn't be the feed lip angle of the rounds coming out. Maybe you do need to send your upper back in... but i suspect they would want your entire original setup, like they needed from me, to diagnose and fix your problem. It shouldn't matter what upper/lower combo you use IMO. I used a POF upper on a dpms lower at one point, and it worked just fine.

 

[sobrbiker883]

Re: POF issues in SLC....help

Those groups don't look like what I was expecting from your post.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">.....................
The problem: The issue is that the rounds are walking all OVER the place! Yesterday I was out with Snagglytooth and couldn't hit the broadside of the barn. It took FOREVER to get the thing on paper, then when it was there, it was shooting five round "groups", if you can call them that, that were around 4 MOA. Tried again today and got the same results shooting from a bench with sandbags. I've seen the rounds spread 4MOA vertically AND horizontally.
..........................
The only way I could keep MOA groups was to shoot at 25yards. This is KILLING me! I've already forked over about $100 in ammo trying to figure out what's wrong with the damn thing (plus trying to get on paper with a broke ass gun).

</div></div>

The dots on your upper below the ramp aren't from rounds being chambered as I already told you. The impacts just below the ramps in my opinion could use some attention, bul look more like case necks hitting the edge than bullet tips.
You haven't checked the buffer/spring (or told us what gen receiver, with what kind of buttstock)........

Four days of complaining, without calling POF, or checking what was suggested, then posting groups that exhibit no worse stringing that poor cheek position or improperly adjusted parallax can cause? Really?

Are the 1.8-10 USO's ERGO or fixed parallax? If fixed, what distance are they set for from USO?

 

[txhippo]

Re: POF issues in SLC....help

This is just a thought you probably have already checked the trigger the pull on mine was about 8 lbs and rough as hell.
My 16 was stringing side to side also because i was having to yank the trigger i installed a set of lighter springs and buffed the trigger and it is about 4 lbs and smooth helped me alot.

I also had the problem with the feed ramps.

 

[Mustafa]

Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Those groups don't look like what I was expecting from your post.....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">.....................
The problem: The issue is that the rounds are walking all OVER the place! Yesterday I was out with Snagglytooth and couldn't hit the broadside of the barn. It took FOREVER to get the thing on paper, then when it was there, it was shooting five round "groups", if you can call them that, that were around 4 MOA. Tried again today and got the same results shooting from a bench with sandbags. I've seen the rounds spread 4MOA vertically AND horizontally.
..........................
The only way I could keep MOA groups was to shoot at 25yards. This is KILLING me! I've already forked over about $100 in ammo trying to figure out what's wrong with the damn thing (plus trying to get on paper with a broke ass gun).

</div></div>

The dots on your upper below the ramp aren't from rounds being chambered as I already told you. The impacts just below the ramps in my opinion could use some attention, bul look more like case necks hitting than bullet tips.
You haven't checked the buffer/spring (or told us what gen receiver, with what kind of buttstock)

Four days of complaining, without calling POF, or checking what was suggested, then posting groups that exhibit no worse stringing that poor cheek position or improperly adjusted parallax can cause? Really?

Are the 1.8-10 USO's ERGO or fixed parallax? If fixed, what distance are they set for from USO?</div></div>

Yeah, really...

First, I"m not complaining, I'm trying to figure out what's wrong.

Second, I figured out that one of my USO's is broken. The spreads I was getting with THAT scope were side to side and vertical. When I used the other two scopes today it only strung up and down. Today I used a 3.2-17 with adjustable paralax, so that was not an issue as it was set for 100 yards.

And I tried calling POF and got no answer. I sent them an email and got this reply this morning:

Accuracy issues wouldn't be caused by how the ammo feeds.
Do you have any pictures of the groups you have shot?
How are you setting up for checking accuracy?
Are you using optics on your weapon?
Also, and don't be offended, but how would you describe your experience as a shooter?

The problem is also not with the buffer spring as I checked for that already. I'm not sure what Gen it is but it is stamped 09-#### and the upper that came with it uses the roller cam on the BCG.

I appreciate your help so far. Thanks

 

[sobrbiker883]

Re: POF issues in SLC....help

I'd answer their questions and ask for an RMA. You may have difficulty with them since it is two uppers and a lower rather than a rifle.

I'd stick with one known good scope/mount for troubleshooting.

Cycle rounds (or dummies) and see if they are whacking the projectile when feeding and setting them back or banging them out of concentric. Note what and where with each upper.

The perplexing part is that you say everything was cool with the previous lower. Was it a POF lower? Was anything different (rifle vs carbine buttstock)? If the mag release and placement were out of spec you'd be having FTF's not bad accuracy.

And you checked that you have a 308 buffer in it?

 

[snaglytooth]

Re: POF issues in SLC....help

Wu, If we are still shooting friday I will throw in a DPMS lower just to see if there is any accuracy change at all.
That is if they are even interchangable, never owned a POF.

 

[sobrbiker883]

Re: POF issues in SLC....help

POF has AR15 diameter takedown pins so DPMS lowers need a sleeve.

 

[snaglytooth]

Re: POF issues in SLC....help

Thanks Steve, didn't know that little bit of info.

 

[Mustafa]

Re: POF issues in SLC....help

Sounds good. Thanks. I tried another guy from SLC's POF lower on my rifle today and didn't see any change though.

And Sobr, yeah I checked it does have a 308 buffer. The old lower was also POF. Wish I still had it right now to at least check things out.

What I'm thinking right now is that the new lower is somehow improperly holding the mags so that the rounds are impacting the lip causing damage to the bullet and the scarring on the two uppers. I'll probably end up sending it back to POF because I'm frankly tired of shooting $5 groups to try and figure this out.

Only reason I changed scopes around was to discount them as a cause of issues, and a good thing too since I discovered a bad scope by doing it!

 

[Mustafa]

Re: POF issues in SLC....help

And I sent POF an email answering their questions and showing the groups I've posted here.

 

[sobrbiker883]

Re: POF issues in SLC....help

I'll bet. Hopefully they get you squared away.
I'd send them the worse looking/shooting of the uppers too, couldn't hurt.
Good luck with it.

 

[pupdawg]

Re: POF issues in SLC....help

That vertical stringing looks like improperly adjusted parallax and or inconsistent pressure on the stock or rear bag. If you hand fed (single feed) rounds and it still gave vertical strings then its not the mags, lower, or feed ramps.

Just for the hell of it did you check that the rail bolts are in fact tight?

Also just because the USO is marked for 100yd parallax doesn't necessarily mean it will be parallax free when set on that number.

Explain how you go about adjusting and checking for parallax just so we all know if there is a step you might be missing.

 

[Moadster]

Re: POF issues in SLC....help

I think I might have an possible answer to your problem. I have a 20" .308 POF as well, and the second time I went to the range with it, I was running into the exact same problem...bad vertical stringing. About 3-4" worth.

I was finally to pin it down to a couple problems. I found that there are 2 set screws oriented horizontally on the hand guard that secure it to the barrel nut. I had put some XTM rail covers over them, and after removing the covers I found that both screws had backed almost all the way out. Little bit of blue locktite and they are holding strong again.

The second problem I was able to more directly pinpoint as being a culprit for significantly larger groups. It came from the way I was holding my Red Tac rear bag. Because the weapon has a much higher stance than most bolt guns, I was holding the bag oriented vertically. When the gun recoils and the action cycles, it was causing me to pull shots pretty badly. I put the bag back horizontally and placed it on top of an empty magazine and have been shooting good ever since...easy Sub MOA out to 500 or so. I have also found that whatever direction I am pointing after the shot was taken is usually the direction the bullet pulled. Try to get that gun to recoil and come to rest looking at the target and it should help a lot with accuracy.

Hope this helps!

 

[sobrbiker883]

Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Moadster</div><div class="ubbcode-body">I was finally to pin it down to a couple problems. I found that there are 2 set screws oriented horizontally on the hand guard that secure it to the barrel nut. I had put some XTM rail covers over them, and after removing the covers I found that both screws had backed almost all the way out. Little bit of blue locktite and they are holding strong again. </div></div>
<span style="color: #3366FF">
Actually the two set screws you can see are on top of 2 set screws below them, that index the wedge block between the rail and barrel nut. Take the top two out, then torque the inner ones to 15 in/lbs, then torque the top ones the same on top of them.
***this <span style="text-decoration: underline">will</span> change your zero most likely***</span>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Moadster</div><div class="ubbcode-body">
The second problem I was able to more directly pinpoint as being a culprit for significantly larger groups. It came from the way I was holding my Red Tac rear bag. Because the weapon has a much higher stance than most bolt guns, I was holding the bag oriented vertically. When the gun recoils and the action cycles, it was causing me to pull shots pretty badly. I put the bag back horizontally and placed it on top of an empty magazine and have been shooting good ever since...easy Sub MOA out to 500 or so. I have also found that whatever direction I am pointing after the shot was taken is usually the direction the bullet pulled. Try to get that gun to recoil and come to rest looking at the target and it should help a lot with accuracy.
</div></div>

Shooter/technique is usually part of the problem, esp if the groups are as consistent ans those pictured.

 

[Moadster]

Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">
Actually the two set screws you can see are on top of 2 set screws below them, that index the wedge block between the rail and barrel nut. Take the top two out, then torque the inner ones to 15 in/lbs, then torque the top ones the same on top of them.
***this <span style="text-decoration: underline">will</span> change your zero most likely***

</div></div>

I believe the screws you are talking about are on the top rail, the ones I am talking about are 2 single screws set in the small pieces of side rail.

 

[Mustafa]

Re: POF issues in SLC....help

Well both uppers are going off to POF so they can take a look at them.

Maybe I do just suck at shooting gas guns... But until I know the equip isn't the issue, then there really isn't a way for me to know.

I'll let you guys know how it turns out. Even if it was just me sucking all along...

 

[sobrbiker883]

Re: POF issues in SLC....help

Yes, I'm talking about the set screws on top. Usually the side ones are countesunk socket head screws. I think they've done away with the side ones.

Anyway, let us know how it turns out Wu!

 

[Mustafa]

Re: POF issues in SLC....help

Thanks for all the consideration and help fella's...Turns out, I just suck... Apparently I developed a flinch in my shoulder with the POF that then spread to my DTA the day before the Bash Train-Up. Needless to say, the Bash did not go so well for me...

The good news is that the POF's are the sh!t, son!