.223 Chambered Oly Arms

[Iraqgunz]

Our BM's have been in country since late 2004 and they have unknown rounds put through them. Thus far almost evry one that has been reamed has resulted in material being removed. We als ohave semi auto guns that are as of yet unfired and when I reamed two them a significant amount came out.

It's my belief that the tight chambers are a contributing cause of the popped primers, blown anvils and failures to extract that we have had with the Prvi Partizan and Bulgarian 5.56 SS109 ammo. In fact, in most of the guns that I reamed the problem was reduced though not 100% eliminated.

After viewing this thread, it got me off my ass and out to the workbench to make a cerrosafe cast of my BM's chamber.

I just took the measurements after waiting the required one-hour cool down time, and my throat/freebore diameter is right at .2265. Neck diameter is .2553 ( about 1:15 after making cast). It's very difficult to make a measurement of the freebore length because it's difficult eyeballing exactly where the rifling begins, but it looks very consistent with the example that Ned posted on his .223 vs 5.56 article in the Sep issue of SWAT (pg 68, chamber cast pics). This barrel was purchased in spring of 03. Round count is approx 3,000 but that's just a WAG.

Now I wonder if Grant reamed it whether or not any metal would come out, but hypothetically speaking, if it did remove some metal, what would be the conclusion?

[Heavy Metal]

After viewing this thread, it got me off my ass and out to the workbench to make a cerrosafe cast of my BM's chamber.

I just took the measurements after waiting the required one-hour cool down time, and my throat/freebore diameter is right at .2265. Neck diameter is .2553 ( about 1:15 after making cast). It's very difficult to make a measurement of the freebore length because it's difficult eyeballing exactly where the rifling begins, but it looks very consistent with the example that Ned posted on his .223 vs 5.56 article in the Sep issue of SWAT (pg 68, chamber cast pics). This barrel was purchased in spring of 03. Round count is approx 3,000 but that's just a WAG.

Now I wonder if Grant reamed it whether or not any metal would come out, but hypothetically speaking, if it did remove some metal, what would be the conclusion?

You used the 3000 step reaming process

[decodeddiesel]

Our BM's have been in country since late 2004 and they have unknown rounds put through them. Thus far almost evry one that has been reamed has resulted in material being removed. We als ohave semi auto guns that are as of yet unfired and when I reamed two them a significant amount came out.

It's my belief that the tight chambers are a contributing cause of the popped primers, blown anvils and failures to extract that we have had with the Prvi Partizan and Bulgarian 5.56 SS109 ammo. In fact, in most of the guns that I reamed the problem was reduced though not 100% eliminated.

That is impressive that this was able to fix those problems you were having. I remember reading about them and thinking, it's one thing if some guy is having problems like that in a class in CONUS it's something entirely different when it happens in theater...

[uscbigdawg]

Wow! I've had good luck with Oly barrels. One of the few places to get a stainless 1:8 barrel. THE top 3-Gun shooter in the world swears by them, but is quick to say don't fall in love with them.

Rich

[C4IGrant]

After viewing this thread, it got me off my ass and out to the workbench to make a cerrosafe cast of my BM's chamber.

I just took the measurements after waiting the required one-hour cool down time, and my throat/freebore diameter is right at .2265. Neck diameter is .2553 ( about 1:15 after making cast). It's very difficult to make a measurement of the freebore length because it's difficult eyeballing exactly where the rifling begins, but it looks very consistent with the example that Ned posted on his .223 vs 5.56 article in the Sep issue of SWAT (pg 68, chamber cast pics). This barrel was purchased in spring of 03. Round count is approx 3,000 but that's just a WAG.

Now I wonder if Grant reamed it whether or not any metal would come out, but hypothetically speaking, if it did remove some metal, what would be the conclusion?

If it removed a little bit of metal, I wouldn't think anything of it. If it removed the amount of material like the above pic, you would have a .223 chamber.


C4

[C4IGrant]

Wow! I've had good luck with Oly barrels. One of the few places to get a stainless 1:8 barrel. THE top 3-Gun shooter in the world swears by them, but is quick to say don't fall in love with them.

Rich

He is also most likely shooting .223 ammo.

Nothing Oly does is high quality and am not sure why anyone would buy their stuff. Even if it was given to me, I still would not use it.

One last thing, your sig line should also read "Gun games also create a lot of bad habits that can get you killed in a real gun fight."

"Speed is great, Accuracy is final!"


C4

[Don Robison]

He is also most likely shooting .223 ammo.

Nothing Oly does is high quality and am not sure why anyone would buy their stuff. Even if it was given to me, I still would not use it.

One last thing, your sig line should also read "Gun games also create a lot of bad habits that can get you killed in a real gun fight."

"Speed is great, Accuracy is final!"


C4

Come on Grant, you know Oly is "just as good."





Sorry couldn't resist

[Robb Jensen]

Olympic typically works very good and accurate with .223 Rem ammo, but put some 5.56mm NATO ammo (M855, Canadian IVI, MK262 or XM193 ammo, IMI ammo) and then all the sudden popped primers, failures to extract etc.

I've reamed at least 50 Oly barrels with my Ned Christiansen 5.56mm NATO reamer and it's ALWAYS fixed these problems........

[ST911]

I've reamed at least 50 Oly barrels with my Ned Christiansen 5.56mm NATO reamer and it's ALWAYS fixed these problems........

That's my experience as well. Oly 5.56 chambers...aren't.

I've removed material from Bushmaster chambers, but it was substantially less to minimal. Bushmaster chambers, for the most part, are okay.

[jmart]

Our BM's have been in country since late 2004 and they have unknown rounds put through them. Thus far almost every one that has been reamed has resulted in material being removed. We also have semi auto guns that are as of yet unfired and when I reamed two of them a significant amount came out.

It's my belief that the tight chambers are a contributing cause of the popped primers, blown anvils and failures to extract that we have had with the Prvi Partizan and Bulgarian 5.56 SS109 ammo. In fact, in most of the guns that I reamed the problem was reduced though not 100% eliminated.

If using Ned's throating reamer, you are probably aware that it is machined to dimensions more generous than standard 5.56 NATO dimensions. So it wouldn't surprise me if you used one on a NATO chamber that was in spec, you'd still remove some material. But if using a full-chamber NATO reamer, I really don't have any insight how much, if any, additional material might be removed from an "in-spec" NATO chamber.

I ain't no expert, but I believe a chamber cast is the way to go to understand what you're dealng with. In a perfect world we'd have a chamber cast made of the "as manufactured chamber", then ream it and note the amount of material removed, then a second chamber cast to see where you end up in the end.

I'll concede that the pic that Grant posted certainly suggests a significant amount of material was removed, but you still don't know from where: the shoulder, the neck, and the throat, just the neck and throat? That's the beauty of the cast, it lets you know where critical shoulder diameter, neck diameter, freebore diameter dimensions run, and gives you a visual of the throat length so you have an informed understanding of if you have a .223 style throat or a 5.56 style throat. And if you made enough casts, pretty soon you'd have a good ability to be able to correlate the amount of material removed to predicting how tight things were before reaming.

If you have the opportunity you might try taking some chamber casts of your BM's in your posession and see where you stand. It would be interesting to get some good data to see if indeed BM's are manufactured closer to .223 SAAMI specs or closer to 5.56 NATO specs.