Question for you Ar15 shooters- changing it to a 9mm ?

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Originally Posted by Dekota56

Just puzzled why would you be changing your AR15 to a 9mm, maybe I am just reading the whole post wrong.
I do enjoy shooting my AR15

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9mm ARs are cheap to shoot and a big pile of fun. Why exactly are you puzzled?

Was just asking...I didn’t think someone would go threw the trouble, but that is me... great if you can do it,
I like shooting 5.56, 2.23. I reload.. Again everyone has a preference.
Great subject,. Hope things are work out.

My Ruger PC carbine is 1/2x28 also, so gotta be careful about muzzle attachments.

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Originally Posted by Dekota56

Just puzzled why would you be changing your AR15 to a 9mm, maybe I am just reading the whole post wrong.
I do enjoy shooting my AR15

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Not really changing it over for keeps, I just want to add another cal. to use on it. Next is to start saving for a 300 upper build. I am a old man on a small SS so it takes awhile.
Another reason is I have plenty of 9mm loaded and no longer have the handgun I used them in. Also if I use a 10 rd mag I can hunt varmints and squirrel with it here in MO.

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Originally Posted by SeabeeMan

They really work well and save the cost of a dedicated lower or adapter and additional magazines. If you already run something (or multiple things) in Glock or Colt mags, it may be worth the investment, but this allows you to just have a dedicated upper and use your existing lowers with no additional changes.

I have 3 of them and as long as you follow the instructions to break them in, which basically amounts to shaving the ejector down to fit inside the bolt carrier, you'll love em.

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Can you give me some details on shaving it down?

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Originally Posted by Dekota56

Was just asking...I didn’t think someone would go threw the trouble, but that is me... great if you can do it,
I like shooting 5.56, 2.23. I reload.. Again everyone has a preference.
Great subject,. Hope things are work out.

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Just because you have a 9mm AR doesn’t mean you can’t have a .223. Get both!

Most have found when switching uppers it does not or should not change sittings of the upper. From shooters I have asked.

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Originally Posted by Dekota56

Attachment 276014That sound great , that you can have both, sounds very dum that I thought you was giving up the 223 to the 9mm.. question that seems like a pain to me.. you would have to re- sight in every time you change over.

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I like 2 complete rifles, but if just swapping uppers and inserting/pulling out a magazine block, zero wouldn’t change. The sights are attached to the upper assembly and would not move relative to the bore.

I enjoyed the topic.

would I need to do any changes to buffer etc if I use a UGT Fixed stock A2 stock. or parts supplied with stock work on the 9mm build?

You will need to change the buffer. A 9mm buffer is much heavier than a standard buffer.

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Originally Posted by Burnt Fingers

You will need to change the buffer. A 9mm buffer is much heavier than a standard buffer.

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I do have a heavier buffer a 7.5 oz one . Would I still need to do the Quarter trick to keep from damaging the bolt stop?

Usually the specific 9mm buffers are longer to account for the BCG difference. You do not have to have a specific 9mm buffer, I run H3's in mine perfectly with spacer in back of extension under spring. You should find that if you stay in window of 18-21 ounces mass weight (BCG, Buffer) combined that the standard 9mm ammo will run just fine. 147's and a can go heavier.

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Originally Posted by Gtek

I have assembled two for myself and two more for buds and they have been flawless with Stern Defense parts for the Glock mag. Living in Anderson houses with zero mods required to any parts, two pins and remove a spacer and one Allen screw mag unit out and drop a 556 on top and go. The mag release is a little different but easy to access ergonomically, a little off instinct but not bad. H3 buffer, standard carbine spring and a spacer I made from Delrin for rear of extension behind spring. Hold in bolt catch with left thumb and bump bolt between that and rear of extension with charging handle, you want to duplicate that distance of standard AR. If no spacer is used Bolt assembly gets a good run on and will beat up the bolt stop and lower in short order. About .700" ball park for spacer to make up for flat face fixed bolt that does not rotate and retract into a BCG when going into battery. All my reading and what we have is blow back mass ending up 18-21 ounces, this has proven 100% with ours with lighter end cheap fodder through the cans. Have not tried 147's and may require mass increase weight to calm down, but the cheap fodder was too much fun and now it is all stupid expensive, if you can find it.

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Bump bolt? Somehow I am not getting the drift. Can you explain once again, Should this distance be measured on the charging handle as to were these bumps take place?

Can’t help you with 9mm as all my pcc stuff is .45 but the rotary bolt cmmg system is da bomb. Much better than a straight blowback system. Bought an 8 inch bcg/ bbl first and now just put together a 16 inch upper this week. So much lighter than my Olympic Arms builds.

With an empty mag or holding bolt stop, grasp charging handle and bump BCG between stop and rear (all the way back) in extension. Depends on which buffer you have, standard AR I would make and use spacer. Some aftermarket specific PCC buffers that has longer body negates the need for spacer. It will not stop weapon from cycling but last round if not correct lets BCG slam the stop and potentially early damage of components. Takes me about two minutes in lathe to make one, PM me and I will send you one.

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Originally Posted by Gtek

With an empty mag or holding bolt stop, grasp charging handle and bump BCG between stop and rear (all the way back) in extension. Depends on which buffer you have, standard AR I would make and use spacer. Some aftermarket specific PCC buffers that has longer body negates the need for spacer. It will not stop weapon from cycling but last round if not correct lets BCG slam the stop and potentially early damage of components. Takes me about two minutes in lathe to make one, PM me and I will send you one.

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PM sent