I understand the differences in between the 223 and 9mm   AR15s.     I have a few of each.     The carbine/pistol buffer for the 9mm is heavier.      What would be the effect/result of running a 223 buffer in a 9mm?

IIRC broken bolt stops and out of battery kabooms. The extra weight is needed to create the proper amout of time the bolt is locked.

Having a few of each 9mm and .223 you should understand that the 9mm in blowback and the extra weaight is needed to keep the bolt in battery just like weptek911said.  Just spend the extra money and get a 9mm buffer.........preferably a heavy 9mm buffer.

As I said,  I understand the differences.     I know how they work, and the parts, generally, are different.    

I have a few Colts, plus some that are others, such as  RRA.    They are are all factory complete guns.    

Some people are hung up on money.     Every other thread seems to make some offensive comment about 'just spend the money and get . . .'    When I am concerned about money,   I'll mention it.    So far,   it just has not been a concern to me.       For example,   people mention cost on guns and tax stamps.  Those are never my concerns.    The restrictions are my concern.

Now,  in this case, my question is again straight forward,   what is the effect of swapping a 223 buffer into a 9mm AR?

Yeah, there will be a LOT of force on the backswing and on the foreswing - you can damage your lower's buffer tube/extension and the bolt catch if it is ever hit.  I'm not sure about the kabooms, as it only seems to hit the primer (at least with my RRA bolts) if the bolt is fully seated against the chamber.  If it doesn't close completely, I get a click and no boom.

ETA: I'm not trying to be a bunghole or anything, but if you say you know how they work, why do you want to know how they work?  Are you testing us?  Is this a trap?  

I did NOT ask how the buffer works.      I  did NOT ask about the diferences in the parts.      

I have an idea of the effects, as do others that have posted thus far.    

What I asked would be answered by observed 'testing'  or computer aided modeling an/or testing.      I am looking for more than guesses.  

People add heavier bolts, springs, buffers to slow things down.     No manufacture or smith has tested speeding things up by litening components?     Hmmmm . . .

Ok.  Sorry I responded.  You didn't say you were only interested in computer simulation or actual testing of a .223 buffer in a 9mm blowback system.  Maybe you should edit the original post so people like me who are trying to help don't disappoint you again?

By the way, you could ask Ron ("ronaldmwilliams" here on AR15.com) for anecdotal replies on what he has seen in this regard.  He makes gas blowback systems for odd calibers and such.  He would probably know.  I read where he was making lower mass buffers to get a system he was working on to work right.

I'm going to have to respectfully disagree with those comments.

Broken bolt stops are caused by bolt/buffer overtravel and there is a "fix" to reduce/eliminate that phenomenon and it will work with either a std. .223 or std. 9mm buffer.

In semi, I do not believe it is likely that a .223 buffer will cause out of battery kabooms, unless there is some other factor/s at play - very dirty gun preventing a round from chambering, super hot +P+ ammo is used, bolt is ramped, reduced power hammer springs, or whatever else is done that will make the bolt easier to blow back, thereby reducing the amount of time it will stay "locked".

Without knowing the other specs of the OP's 9mm AR, it is not possible to say what will happen when running a .223 buffer.

In my experience, with my 9mm AR's (semi, non-ramped bolts, 9mm or DPMS hammers, 9mm buffer, std. AR15/M16 action springs, reduced power hammer springs), running WWB or RemUMC factory ammo, I have not had any issues when running a .223 buffer.  It does give the gun a little different feel because you have about 3 oz. less mass bouncing around inside every shot.

Noone needs to be sorry.     As specific and detailed as I am,   these things happen.  

It is not a big deal.     Heck,   you have served, as have I, to clear it up for others that may respond.

It is all in the silly game of human interaction.

Thanks.

Keep in mind, that some of these things are added for reasons beyond the scope of your question.

Lots of folks are pretty juiced about "ramped" bolts.  Ramping changes how the bolt interacts with the hammer and actually speeds up the bolt.  It is necessary to then add weight either to the bolt, the buffer, or both to help counteract that change.  Hence you have people that offer mods to increase the weight of the bolt and others that offer specialty buffers that can be nearly twice as heavy as the std. 9mm buffer.

As far as speeding things up, that is a pretty common thing to do with handguns, by lightening slides, changing recoil spring weights and such.  Those are typically locked breech designs, which are not the same as a 9mm AR which is pure blowback.  Lightening components too far in a pure blowback design will require compromises.  If you lighten components too much, you may have to use special loads (reduced power/pressure), that are matched to the action or if you used +P+ loads, you would most certainly risk problems.

That is not surprising to hear.

My two 9mm ARs are both factory complete, standard guns, with factory/standard and stock internals.     No internal mods on either have been made.      One is a 16 inch Colt carbine, and the other is a 7 inch RRA  pistol with the new integrated mag well.

Both are semi auto, non class III, non NFA .


With the carbine,   I can run 25 rounds  in   about 1.5 to 2 seconds.   I am not that used to the RRA pistol yet.

   

I just finished a 9mm build, and I've kept the .223 buffer in the stock without any issues.  I've fired Win White Box, Barnaul steel-cased 9mm, and some Prvi brass-cased 9, all of it with good results, and not a single issue with bolt carrier bounce or breaking the bolt catch.  I am planning a range trip where I swap the buffer with the Colt 9mm buffer I have on hand to see if it works better, but I don't think a properly tuned, properly built carbine will break the bolt catch just because of a lighter buffer.

.
You think you can pull the trigger at 750 rpm  I bet you cant shoot one 25 round mag in 3 seconds
without bump firing.
It would be fun watching you try to shoot a semi at MGun speeds and hit a target at 25 yards with 90% of the rounds..

The extra weight in an Oly is added to the bolt.  They run with a standard .223 buffer.  

About 750 - 1000 RPM and reasonably accurate.

I shall neither confirm nor deny how such is accomplished.

I believe this thread has officially "jumped the shark"...

No gimmicks.     Box stock internals.     I've only added a rail system and forward verticle grip for better control when 'firing rapidly'.

No trigger adapters, like Hell Storm, Tac Trigger,  nor cranks.    

Nothing fancy.   I just throw it to my shoulder and do it.

Be careful telling people that of the fed boys just might want you to register your trigger finger as a machinegun

Bee Ess

Hey Bud!

I understand.   Maybe we can get togehter and chat a bit, or shoot a bit?

Roger that.

Any way, it sounds like messing with the buffer might be interesting.

Having played with various weight buffers I highly recommend NOT putting a lighter buffer in your 9mm.  You will feel the recoil much harder as the buffer strikes the end of the buffer tube.  Another side effect of putting too light of a buffer in is that you get trigger slap, this is when the end of the hammer strikes against the back of the trigger and disconnector and will result in  broken trigger and hammer pins, (ask me how I know).  You can swap out the stock weight in the bolt for a heavier tungsten weight to help with slowing down the bolts recoil and then go with a stock H or H2 buffer but why spend the extra money?

In your case, a lighter weight buffer might allow you to fire even faster than 1,000 rpm, due to the lower weight of the cycling mass.  I wouldn't be surprised if you could do maybe 2,000 rpm with a carbine buffer in there.

I used to do 1,500 rpm with my old Hi-Pointe Carbine, using a modified (top secret) 300 round drum.  Now THAT used to get a lot of questions, especially from the local FBI and SOCOM guys!