First off, I have tried to do my homework using the internet search engines, but still cannot find definitive answer to my question.

That question is:

Is the Olympic 9MM upper platform harmful to an AR15 receiver (as it appears other  makes may be)?

Background: I have a BFI RR 16 and have a Oly 9mm upper. Not that I think it matters, but it is one of the early OLY units. I have read about "ramping the bolt (really bolt carrier)", modifying hammers, and the dangers of breaking the hammer pin and egging out the receiver holds for the pin. But it appears most of these issues are more aligned with the "Colt" pattern of 9MM conversion, and it is not clear to me if the same issue is with the Oly system.

Please do not start with "the Oly system is crap", because for my purposes and experience it works, is reliable and accurate. The only negative is the magazine (I use STEN with a mag block). It is a "fun gun" and I never intend on "defending my life or the motherland" with it. It is a range toy only.  So please only reply if you have experience or knowledge on specifically the Olympic 9MM FA conversion upper being used on a RR 16. (Yes- I know KNS pins will be recommended, but are the problems with the broken hammer pins more tied to the other "brands" or does the OLY system have the same issue?)

Obviously, if using the OLY system is possibly harmful  to my RR receiver, I do not want to use it.

Many thanks for any future replies  

If you get the buffer weight balanced correctly it's not going to hurt your receiver. Ramping bolts and modding hammers and the like all apply to the colt pattern system.....primarly the RRA version. Oly is pretty much plug and play......play with the buffer length and weight to minimize recoil and you'll be pretty much set .

Many Thanks.

I have had the system many years but only use it occasionally.  My RR 16 has an Enidine hydraulic carbine buffer, and it seems to work with every upper I put on it. That's one thing I love about the Oly system; push two pins, take off current upper, put on Oly upper, insert mag well adaptor, insert magazine and let her rip. Probably can do under 30 seconds.

But the more I read online I believe I understood Oly carrier is fine as is, no real mods had to be done to the hammer, but because all the pistol calibers are blow back, that more than normal force is applied to the hammer and as a result  could possibility  "egg out" the  hammer pin hole. That would be a nightmare!.


I do not currently use the KNS pins,  I just don't like the way they look.  If they are really needed, then it's a no brainer.
.

I have run 1000's of rounds through an OLY 9mm upper and have never had a mechanical issue.  We used to have monthly practical shoots at our club and it ran without issue 12 months a year in mud, rain, snow, low-light, etc..

The OLY lower took Glock magazines.  

The only issue I had was a "training scar" in that I had ran the common sized 9 mm mags so much in both the carbine and sidearm that I would sometimes (out of habit) try to reload a Glock mag into a 5.56 magwell when I ran a regular 5.56 carbine in the events (i.e muscle memory issue).

So I got away from the companion carbine concept a now stick with the just 5.56 carbine.

One good thing about the 22LR conversions is that they have the same manual-of-arms as the 5.56 (same mag size, use of controls. etc.) so the muscle memory is pretty consistent.

Thanks CapeBretoner.

I have found it reliable after I test STEN mags that work well. Of course, I'm not so worried about the upper as I am any potential damage to the lower receiver. I assume you have not experienced any abnormal wear to your lower? Are you using KNS pins?

Thanks

In my case everything was an off-the-shelf  OLY K9-GL (their upper and lower).

Never noticed any wear, pins are original.

I didn't notice any variation between the Glock mags, but they are very consistent to start with...

I had an Oly 9mm upper for a long time on my Tommy15.com lower.  Ran no telling how many rounds through it.  Had heard the horror stories of the egged out hammer pin holes also.  I had never experienced it.  
I wouldn't put much faith in those stories.  
I sold that rifle during the panic for a crazy amount of cash.  Sold all the Sten mags here on the EE.

I need to round one up one of these days.......I have a dedicated sten mag lower I made years ago in the safe.......kindof a shame not to do anything with it.....but probably never will as I have a colt pattern and a glock mag gun in 9,  and a glock mag in 40 , and a Glock mag DI in 10mm and a heap of DI45's.....

My Oly upper broke the extractor twice in 15000 rounds.  The lower had zero damage.  

I have had a 9mm Oly set up for about 12 , 13 years.  countless rounds  I do have the kns set on the trigger and hammer pins, but that was because of a mistake in building my 80% receiver slipping in the jig.

Have not had any appreciable wear in the trigger/hammer pin holes.  

I eventual did a form 1 and cut the barrel down to 10 inches  and use it on either my sbr or my pistol lower

here it is on my pistol lower.


the mag block is of my own design so I can use the standard mag catch by cutting a slot in the mags.

Garyd,  love the mag block!


Thanks to al for the replies!

I will run my Oly upper without worry. Actually, I have been running it but slowed down after reading all the "concerns" on "egged out hammer pin holes". With my usage of the Oly conversion up to now, I have not noticed anything negative on the lower receiver, but- I had concern from what I read on the internet on pistol conversions in general. Your replies have eased my fears I may be harming my RR 16 lower.

I did a registered receiver conversion on a cavalry arms polymer lower back in about 2001, and have dedicated that mostly to full auto rental use with my 9mm Oly system upper.  No bolt ramping, standard M16 FCG, tens of thousands of rounds in full auto on a polymer lower.  No wear I can even detect on the pin holes in the lower, though the upper has gone through two ejector replacements and once an extractor replacement after a double-feed OOB detonation.

I'm not saying hole wear can't happen, or that bolt ramping isn't a good idea - just that I've never observed a problem with my setup and unramped bolt.

The Oly 9mm carrier comes "ramped" at least both of mine are. I no longer run KNS pins as when they do break it is difficult to detect.

Like Snake I also run an Enidine buffer which is hands down the best addition I've made. I believe these buffers greatly reduce the potential for pin damage to the lower. With the Enidine installed the 16 is much smoother, not MP5 smooth but a big improvement over a standard buffer.

I run my Oly upper on a SP1 RR and like others I've broken extractors and ejectors but the set up shoots well even with the PITA to load Sten mags!

I have an Oly 7" pistol & a 16" carbine.

They are my training guns for my
AR platform.

1000's of rounds through each of
them. I have broken one extractor
& one ejector in the carbine &
Oly replaced both of them under
warranty. I broke the ejector
by having the bolt locked back
and seating a mag at a match.
The mag will over stroke &
catch on the ejector, which
can break it. So it was my fault
that it broke.

I modded an UPLULA to load
my Sten mags.

I love them both & I rarely go
to a match, class or range
trip without one or both of them.

They get a bad wrap here, but
they have been some of my
all time favorites.

Good Luck!

John

Oly won't replace a busted extractor or ejector unless you're willing to ship the complete upper back to them for inspection and repair. That's what I ran into about 2 years ago, YMMV.

I will admit they replaced an ejector free many years ago but it took 3 or 4 phone calls to obtain it. Screw that noise just pony up and pay for those parts and keep a few spares on hand. BTW you can make a 9mm extractor out of a regular 5.56 piece if you're hard up for one.

Tom S. sent them to me on my
first phone call. He sent me
2 ejector kits & the extractor.
No charge under warranty.


John

I have one that I run at my clubs once a month pistol caliber carbine plate shoot.
The extractor (spring thing) looks like a weak part , just a spring really . I have intended to get a spare but have not got around to it in 1000s of rounds

I have a block and a stack of stens but because I rarely use them I forget and hit the regular mag release and dump the whole thing on the ground.

I have some of the Olympic style mags that are basically a sten that has a block welded to the front . . Much more handy

When?

About a year ago.

What does it take to mod a 5.56
extractor to use in an Oly?

John

You grind off the lug, really just a nub, on the outside of the extractor and also the tail section behind the pivot pin.
The only tough part is milling a hole for the spring to rest in. This is the spot where mine have all broken.