From what I could find using 'search,' it seems that it is common for PMC .223 brass to have off center flash holes.  I started prepping some and noticed that quite a few are indeed quite a bit off center.

What I couldn't find is how much this affects accuracy.  A quick google search turned up a few articles mentioning that OCFH's may cause inconsistent ignition which may affect pressure.  What does this translate to as far as 100 yard groups?

My plinking ammo, which consists of Hornady 55 FMJBT tips over TAC, in both LC and Rem brass will yield 1.5"-2.0" groups at 100 yards.  

So what's your estimate as to how big my groups will be w/ the OCFH's in the PMC brass?
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UPDATE:

Here's the test.  I found 15 of the most off center flash holes I could find within the batch of PMC cases that I have.  I also picked 15 of the most centered flash holes I could find from within this batch.  And as a comparison, I grabbed 15 RP and LC cases.  All cases received the exact same preparation and were trimmed to the same length.  I weighed each of them and here's the data and a picture of the 15 cases w/ OCFH's:
             



I weighed and hand charged each load with EXACTLY 24.7 grains TAC.  Each case received a Hornady 55 grain FMJ tip.

Shooting Conditions: 49 degrees, Light wind

I shot three 5 shot groups at about 112 yards off bags on a bench:

 

Although there were many variables not controlled, I think it's safe to conclude that the OCFH's do not cause a significant amount of negative effect. I also thought that the RP brass, being the most consistent on weight, was going to be the top performer.  Not today.

I've reloaded a lot of PMC brass with Hornady 55gr. FMJ's and H335.  They're actually a very accurate load for me, pretty consistently an inch or less at 100 yards if I do my part.

I was thinking the same thing.  I can't guarantee when, but I'll get it done with pics.

Try a Lee Universal Decapper.

Worked for me with some 1K 07 brass with tight flasholes.

The flasholes will be swaged larger as you decap.

Two tricks for success,

Tighten the locking nut on the decapping stem very tight.

Lube the decapping pin every 2 or 3 cases to keep it from pulling out of the decapping stem.

If pin gets stuck in a flashole, you have to remove it and take decapping stem out of die to replace pin. Best to ovoid this. BTDT

I used Imperial sizing wax, but any lube on a Q-tip should work.

What does this "ping" represent?

If the flashole is not centered, the decapping stem is forced out of alignment.

As it clears the flashole, it jumps back into alignment with a "ping" sound.

This alerts me to check to see if the flashole is centered.

If the flashole is WAY off center, the pin will not enter at all and the decapping stem will be pushed up out of contact by design. (Lee die)

Update in OP

This thread makes me feel a lot better about the few unopened cases of PMC ammo that I have tucked away for when I can no longer reload the current pile of .223 brass I am blasting with!

Other than breaking an occasional decapping pin, I have had no issues shooting out of or reloading with the PMC brass.  

I have learned that if I keep an eye on the pin when reloading, I can catch it if it gets too badly 'tweaked' and straighten it back up before it breaks... A new pin will 'ping' quite a few times and still bounce back before it just stays bent and needs attention. It's when you bend the pin real good and keep on cranking out rounds that it breaks on you...  FWIW, I am using the headed type, RCBS decapping pins.

Hope this helps some friend.

Good report d_striker.

Since my first post in this thread, I have loaded and shot some PMC brass with Hornaday 53 gr HP's.

Got the same 3/4 inch groups as I get with LC brass.

For me the OCFH is not an issue in PMC brass.

What I wound up doing for brass with off center flash holes was putting an O-ring around the decapping rod and tightening it down real good; making sure the decapping pin protruded just enough to get the primer out.  The O-ring lets the whole rod move enough to align without bending the pin but not enough to mess up the threads on the rod or the die.

I'm also working on a prototype flash hole enlarger that is made from a RCBS flash hole deburring tool that has had the deburring bit removed and a new hole drill in the end (on a lathe) with a shortened & sharpened drill bit Loctited in place.  The handle unscrews off the rod and can be chucked in a drill press with the pilot set to let the drill bit barely penetrate the flash hole.  Speed has to be pretty high to hand hold the case for drilling.  So far I'm having to uniform the flash hole afterwards because of the burrs left from the drilling operation.  

With 5K Guatemalan pieces to do this is not what I intended way back when.  May just have to use a magnum primer and go from there.

I bought a few cases of loaded PMC when Natchez when running sales on it and I wasn't reloading. I've probably shot 700 reloaded PMC cases and found it to be quite acceptable for accuracy. I haven't noticed any problems with the cases at all.

Sir, FWIW in my experience it is not uncommon for a small percentage of cases to have off center flash holes.  I've observed this trait in LC, Win, and BHA but it seems the percentage is higher with PMC brass.  I stopped using PMC brass for my match ammo all together, primer pocket stretching seemed to occur after only two or three reloads and I had a high percentage of split cases.  When I used once fired USGI M852 brass for my match ammo in .308 a small percentage of pieces would have off center flash holes also.

I never did any specific experimentation to determine if the off center flash holes had any negative effect on accuracy, but I tend to agree with AeroE on this one, the bullet used probably has the greatest effect but then I normally only use SMKs or JLK bullets.  7zero1, out.