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POF issues in SLC....help

Mustafa

Mustafa

Major League Analyst
Full Member
Minuteman
Nov 26, 2007
404
21
New Braunfels, TX
The equipment: I have a P308 lower with two upper recievers; one 16" one 20". I had a USO SN-3 1.8-10 that was mounted on the upper via badger rings and a [censored] riser.

The situation: I recently acquired the P308 lower and the 20" upper. Before that, I had a (now sold) P308 lower on the 16" upper that worked fine (held 1 MOA, which is about as good as I can hold). So the 16" upper with the USO WAS fine as of a month ago, but on a different lower.

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.

Diagnostics:
1. Switched shooters. Snag got on the rifle and couldn't hold anything better than 4MOA.
2. Switched scopes. Put another SN-3 1.8-10 that was on my M1A (works fine on the M1A). Still all over the place.
3. Switched ammo. Went from the "box o' M118LR" to the SWAmmo 175's that I have been shooting VERY consistent subMOA with on a differnt rifle. Still all over the place.
4. Switched uppers. I went to the 20" upper and tried both scopes again. Still all over the place.

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).

So, is it possible that the lower reciever is causing these problems? I can't see how it is possible, but that does seem to be the only thing that I haven't been able to check.

Any help would be greatly appreciated.

Thanks all...
 
Re: POF issues in SLC....help

Damn that sucks, I feel your pain brother....how does the crown look? I know if it is slightly damaged it will kill your accuracy! I don't think the problem is in the lower.
 
Re: POF issues in SLC....help

I'm far from an expert.
Did you keep the old buffer spring and buffer when you got rid of the old lower? Possibly the bolt unlocking too soon ie. too soft a spring. Have you tried just single loading? I'm trying to think of isolating each part of the rifle to locate the problem. Trigger next? That sucks man- good luck. I hope you find out. Keep us informed. There are ALOT of smarter guys on here other than me and I'm sure they'll chime in soon. Be patient.
 
Re: POF issues in SLC....help

Is the upper new from POF or used?

If its new from POF, call them and explain you are having accuracy issues, they will take care of you.

If its used. Call whoever you bought it from and ask them about it.
 
Re: POF issues in SLC....help

just making things clear here. the 16" had been shooting fine on a the original lower. but on the new lower the 16" is not shooting fine. did the new lower come complete?
 
Re: POF issues in SLC....help

check if the bullet tips are hitting just below the feed ramps
i had this happen with a dpms, it turns out that the face of the
upper receiver just below the feedramps was chipping the tips of
the rounds as well as setting back the rounds in the cases at
varying depths, which was causing a variation in velocity.

just look for copper where the feedramp and upper receiver
transition take place.
 
Re: POF issues in SLC....help

I'll check that out. In the mean time, anyone in SLC have a P308 lower I can borrow to rule that out or confirm it as the culprit?
 
Re: POF issues in SLC....help

ROUGH's input is an upper issue, and Wu's uppers were running fine on a different POF lower.

I gotta say its a little perplexing. How is the upper/lower fit? I know folks say it doesn't matter on AR platforms, since the sights are affixed tot he upper, but if that were true ther would be no reason to bed boltguns now would there?

Also was the lower possibly sent with a 556 buffer and spring? I don't know if that's make enough difference in the pressure on the bolt affecting identical lockup each cycle?
 
Re: POF issues in SLC....help

Bought mine from POF, damn thing thing is a driver. My bolt guns shoot better but not by much. But then again , Im not that great of a shooter...... just sayn
 
Re: POF issues in SLC....help

Just hand cycle a few through it by riding the charging handle forward and watch how they feed. If they are catching you will know.

Strip it down and remove the firing pin before you do this so you don't accidentally fire one off.
 
Re: POF issues in SLC....help

I also suspect a buffer issue since it is the only mechanism in the lower that may effect accuracy.
 
Re: POF issues in SLC....help

With respect to having the wrong buffer in the gun, there should be some evidence on the brass of the bolt unlocking early....you could check there for an indication.
 
Re: POF issues in SLC....help

308and223carbinestockbuffer.jpg
 
Re: POF issues in SLC....help

I have been having similar issues with my new P308 16". Seems very inconsistent. I will shoot one fairly tight group and then the next will be all over the place. Have tried several different scope setups. My handloads are the only loads I can get within sub-moa with but not with any consistency. I have been trying to blame me but I also have a DPMS LR-308 that I can shoot very consistently. .8-.6" groups.

Checked my buffer setup as per POF's site and all is as it should be. Bullet feeding looks good too.

Wu and I are going to try and get together this week and compare notes.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: smokshwn</div><div class="ubbcode-body">With respect to having the wrong buffer in the gun, there should be some evidence on the brass of the bolt unlocking early....you could check there for an indication. </div></div>

What would those signs look like?
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Enmerdeur</div><div class="ubbcode-body">I have been having similar issues with my new P308 16". Seems very inconsistent. I will shoot one fairly tight group and then the next will be all over the place. Have tried several different scope setups. My handloads are the only loads I can get within sub-moa with but not with any consistency. I have been trying to blame me but I also have a DPMS LR-308 that I can shoot very consistently. .8-.6" groups.

Checked my buffer setup as per POF's site and all is as it should be. Bullet feeding looks good too.

Wu and I are going to try and get together this week and compare notes. </div></div>

Not to be a jerk, but are you consistent with other fullsize gasguns? They are a completely different animal to shoot than a boltgun, and mine is a tackdriver. There are major inconsistencies with my results, but it is always traced back to my driving, not the rifle/load.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Enmerdeur</div><div class="ubbcode-body">I have been having similar issues with my new P308 16". Seems very inconsistent. I will shoot one fairly tight group and then the next will be all over the place. Have tried several different scope setups. My handloads are the only loads I can get within sub-moa with but not with any consistency. I have been trying to blame me but I also have a DPMS LR-308 that I can shoot very consistently. .8-.6" groups.

Checked my buffer setup as per POF's site and all is as it should be. Bullet feeding looks good too.

Wu and I are going to try and get together this week and compare notes. </div></div>

Not to be a jerk, but are you consistent with other fullsize gasguns? They are a completely different animal to shoot than a boltgun, and mine is a tackdriver. There are major inconsistencies with my results, but it is always traced back to my driving, not the rifle/load. </div></div>

I think my DPMS LR-308 mentioned above might qualify don't you?
 
Re: POF issues in SLC....help

Sobr,
No offense taken, I DO know that the issue is usually the driver not the rig, but as I said before,

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">I had a (now sold) P308 lower on the 16" upper that worked fine (held 1 MOA, which is about as good as I can hold).
</div></div>

Also, I was holding about 1.5MOA with an M1A on Friday as well. Same ammo and a scope I used on the POF as well. That kinda rules out me and the scope.
 
Re: POF issues in SLC....help

The rail on the upper is bolted to the upper receiver and can come loose. This will cause an apparent poi change. It doesn't seem like it would happen on two uppers, but you never know. Worth checking.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">ROUGH's input is an upper issue, and Wu's uppers were running fine on a different POF lower.

I gotta say its a little perplexing. How is the upper/lower fit? I know folks say it doesn't matter on AR platforms, since the sights are affixed tot he upper, but if that were true ther would be no reason to bed boltguns now would there?

Also was the lower possibly sent with a 556 buffer and spring? I don't know if that's make enough difference in the pressure on the bolt affecting identical lockup each cycle? </div></div>

this is true, but I also found out when I pulled the barrel & looked down the receiver that with the lr-20 mags that the rounds were not sitting high enough to clear the lower half circle of the upper.
this is probably a tolerance stacking issue in my rifle. (the perfect storm)

I just put it up there for another option of something to look at.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">Sobr,
No offense taken, I DO know that the issue is usually the driver not the rig, but as I said before,

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">I had a (now sold) P308 lower on the 16" upper that worked fine (held 1 MOA, which is about as good as I can hold).
</div></div>

Also, I was holding about 1.5MOA with an M1A on Friday as well. Same ammo and a scope I used on the POF as well. That kinda rules out me and the scope. </div></div>


I was there with Wu and SNAG, It wasn't the driver, because regardless of who was wielding the POF, it was all over. Forget about minute of Duck, this thing wasn't even minute of a flock of Geese. Hope you figure it out before the bash Wu!
smile.gif
 
Re: POF issues in SLC....help

Sorry brother, I didn't catch that part. No offense intended, its just a question.

Wu-I caught that it was the lower. Did you check the buffer/spring? I'm at a loss as to what else in the lower would affect accuracy that much, other than a real sloppy fit (but that can be counteracted to a point with some downward pressure with the grip hand between the bipod and rear bag).
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Enmerdeur</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: smokshwn</div><div class="ubbcode-body">With respect to having the wrong buffer in the gun, there should be some evidence on the brass of the bolt unlocking early....you could check there for an indication. </div></div>

What would those signs look like? </div></div>

You might be able to notice some bulges around the casehead if the bolt is unlocking early as it may be early enough that the case is losing chamber support as the bolt unlocks.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: smokshwn</div><div class="ubbcode-body">
You might be able to notice some bulges around the casehead if the bolt is unlocking early as it may be early enough that the case is losing chamber support as the bolt unlocks. </div></div>

Thanks for the input. None of that on my brass. Maybe Wu can comment on his.
 
Re: POF issues in SLC....help

Accuracy can fade with the bolt not locking up the same each time. If the bolt is unlocking early in the pressure curve the rim gets ripped, not bulges on the case web (pressure is still up holding the case in the chamber). Bulges on the web are firing before lockup usually.
 
Re: POF issues in SLC....help

I just took my upper reciever off and looked at it (the 20") and there are two little marks under the feed ramps where it looks like the ends of the rounds have been smashed into the reciever. I was using Magpul plastic mags. Didn't even cross my mind before, but these are new as well. So maybe the Magpul mags aren't holding the rounds high enough and the bullets are getting deformed before I fire them? I'll check this out tomorrow if I can. Snowing too much today to really get out.
I'll let you guys know what I find.
Thanks for all the help so far!
 
Re: POF issues in SLC....help

So the 20" was not shooting well either?
 
Re: POF issues in SLC....help

Correct. After looking long and hard at the magazine issue, I'm pretty well convinced that it is the problem.

Has anyone else ever shot a P308 with Magpul PMAGs? If so, how did they work?

Looks like I might have 10 PMAGs for sale pretty soon here!
 
Re: POF issues in SLC....help

Its not the P-Mags Wu. The dots will show up on the uppers all teh time because that's where the bullet tips in the mag are when the bolt is closed above them and they make the dots during the recoil cycle. Once the bolt comes back the next to feed raises up and is stripped off.
It's not where rounds are misfeeding (I thought the same thing the first time I noticed them).

My 6.5 Creedmoor (everything the same as the P308 except for gas port size and chamber/bore) runs great with P-Mags. P-mags are actually the best running mags in most POF's.

Did you check the buffer assembly yet?
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">
Diagnostics:
1. Switched shooters. Snag got on the rifle and couldn't hold anything better than 4MOA.
2. Switched scopes. Put another SN-3 1.8-10 that was on my M1A (works fine on the M1A). Still all over the place.
3. Switched ammo. Went from the "box o' M118LR" to the SWAmmo 175's that I have been shooting VERY consistent subMOA with on a differnt rifle. Still all over the place.
4. Switched uppers. I went to the 20" upper and tried both scopes again. Still all over the place.


</div></div>

The MAIN thing you didnt check are the bolts that hold the rail to the upper receiver. Check them for tightness at proper torque specification.

The scope is attached to the monolithic rail, if the rail is a little loose you bet the recoil from that piston will make your POA/POI move all over the place.

There are bolts on top of the rail all the way across the top of the receiver, remove the scope and check those allen head bolts.

I'd BET that's the problem. A simple fix it is. Let us know how it turns out.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WuLitian</div><div class="ubbcode-body">I just took my upper reciever off and looked at it (the 20") and there are two little marks under the feed ramps where it looks like the ends of the rounds have been smashed into the reciever. I was using Magpul plastic mags. Didn't even cross my mind before, but these are new as well. So maybe the Magpul mags aren't holding the rounds high enough and the bullets are getting deformed before I fire them? I'll check this out tomorrow if I can. Snowing too much today to really get out.
I'll let you guys know what I find.
Thanks for all the help so far! </div></div>

Hand cycle a few like I said earlier, it's an easy way to tell how they are feeding and you can do it in your own living room.
 
Re: POF issues in SLC....help

please do hand cycle it & measure the overall length of the rounds before & after, this will give an indication of setback if it is occuring.

also look at the nose of the round, as mine were getting deformed upon feeding.

again this was just my experience i did have the correct spring and buffer in my seup, the 308 spring is at a higher poundage than the 556 spring, so this will slam those rounds into the feedramp harder and if it is hitting the upper receiver then the damage is far more noticeable.
 
Re: POF issues in SLC....help

Yup, so when folks say "hand cycle" I would suggest locking the bolt back each time and using the bolt release. "riding" the bolt forward will make it look like there are problems that are not there under real operating parameters (just like 1911s, etc).
Check the nose as noted upon ejection.
Pull the firing pin or use a safe backstop.
 
Re: POF issues in SLC....help

I had the same issue 1 year ago... where the tips were riding below into the feed ramps... I sent my gun back for them to look at it, they polished the ramps and the chamber a little and replace the BCG entirely (i had the gen2 BCG). in the midst of that, i purchased some 20 rnd pmags too and received some c-products mags in... from POF that they said worked. I got it back and have not had a problem since.

I since then took my older cproducts mags i was having an issue with and ever so slightly, bent the mag feed lips up because i believe i may have, or they may have already been, not at the correct angle to allow the round to slide up the ramp. Check around for a discussion of magazine feed lip issues, that could be your issue possibly? I doubt it is the gas plug hitting the inside of the rail issue that some have had.
 
Re: POF issues in SLC....help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sobrbiker883</div><div class="ubbcode-body">Yup, so when folks say <span style="font-weight: bold">"hand cycle"</span> I would suggest locking the bolt back each time and using the bolt release. "riding" the bolt forward will make it look like there are problems that are not there under real operating parameters (just like 1911s, etc).
Check the nose as noted upon ejection.
Pull the firing pin or use a safe backstop. </div></div>

yes, sorry I should have clarified this point listen to sobrbiker883 he knows his business.

I dont think you can pull the firing pin though as it indexes the bolt cam pin and keeps the flats of the cam pin riding correctly in the charging channel, unless it has the pof roller cam, then dont listen to me.

I wonder if this is why the LMT MWS has M4 type feedramps
confused.gif


keep us posted
 
Re: POF issues in SLC....help

155184_458792071746_541086746_5956534_6057632_n.jpg

156115_458792521746_541086746_5956549_2600458_n.jpg

148636_458792666746_541086746_5956556_2741358_n.jpg

154987_458792771746_541086746_5956559_3341512_n.jpg

76673_458793641746_541086746_5956571_3668828_n.jpg


A moment of silence for the two M118LR that gave their lives for these pictures...
 
Re: POF issues in SLC....help

Mine look like your 1st picture
smile.gif
The bullet should never be hitting that low i was told unless your mag catch or magazine was way out of spec. My feeling was that it was the magazine feed lips still... but???
 
Re: POF issues in SLC....help

So we are back to the advice Scottmilk9 gave......

Q-why did you sell one POF lower to get another?
 
Re: POF issues in SLC....help

I didn't sell one to get the other. I bought two rifles and figured I didn't need two complete rifles. Say someone that wanted to buy a lower and sold one. I'd say I sold the wrong one except that I would feel HORRIBLE if I sold someone a broken part. I've had people do that to me a few times and it pisses me off to no end...
 
Re: POF issues in SLC....help

Did you check the buffer and spring? Is it a full length or collapsible stock?
 
Re: POF issues in SLC....help

Wu, Hey man I just stumbled onto the thread... I hope you get it figured out soon. If you want to do some more testing at the range let me know I would be happy to spot for ya.
 
Re: POF issues in SLC....help

yep just like mine was, mine had more bullet contact with the upper on the left side feedramp as well.

It looks as though the feedramps are set back like the M4 type, maybe some light filing with a fine jewelers file would help?
(don't attempt this unless you are prepared to void whatever warranty you may have on the rifle)

I would send those photos to pof and get there take on it.

the scratching on the round is from ejecting a live round, because the bullet is dragging on the back of the barrel extension locking lug, not from feeding.

the other thing i did was to remove the bolt & carrier insert a mag with 2 rounds in it then use a pen and slowly pushed the rounds into the barrel to see exactly where they began to contact the feedramps.

This does not simulate the actual feeding of the rifle, but it may give you an idea on what to look for?
 
Re: POF issues in SLC....help

You will most likely get better results sending an email to/calling Darrell at POF and sending the uppers and maybe whole kit and kaboodle in.

Will probably get you better results than us trying to diagnose online.....
 
Re: POF issues in SLC....help

Yeah, I"m gonna get in contact with POF and see what they say.

Snag, you mind if I come out on Friday and send more rounds down range before I got to Texas on Sat? I probably won't be trying the POF's again, but I WILL bring the shotgun...
 
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