AR15 buffer for rifle length and mid length

[P89DCSS]

I have an Stag Varmint 556 AR15 with a 24" barrel, rifle length gas tube and A2 buffer and spring. I ordered a PSA 16.1" upper with BCG and CH. I was hoping I could just swap out uppers but some simple research has alerted me that I also may need to swap out the buffer and spring.

What say ye experts?

- Do I need to swap out buffer and spring to make the 16" barrel and mid-length gas tube work on my existing lower configured for a 24" barrel and rifle length gas tube?

- Is there a buffer and spring that will work with either barrel/gas tube so i can swap uppers without changing anything on the lower?

I'm new to the AR platform, thanks for your help.

 

[chicharrones]

Hmmm.

I can tell you that my ArmaLite M15 midlength came with a plain "mil-spec" carbine stock/carbine extension/carbine spring/carbine buffer and when I changed it out to a plain "mil-spec" rifle stock/rifle extension/rifle spring/rifle buffer . . . the gun functioned as successfully and as reliably as before the change.

Old pics below. The "after" is on top.

View attachment 956406

 

[bfoosh006]

The new upper might need a break in period, allowing the parts to smooth up... but for the most part, it should be ok.

Also use full power 5.56 ammo to break it in.

I have run some crazy heavy buffer weights / CWS's on broke in AR's... with no ill effects. ( Heck, even the blowback 9MM Colt pattern would run with a 10oz buffer )

Bear in mind, if you want a worse case scenario to test the Middie on.... put the upper and lower in the freezer over night ( while still lubed ) then test fire it.

If it doesn't choke then, you are GTG.

 

[Charlie98]

No, you should be OK, either or. The middy gas system is quite reliable, and I've not had any problems when I swapped mine to my A2 lower just to see.

 

[BigBlue 94]

I run an A2 buffer in my lower and never change it for a carb length 5.56, mid length 50 beo, and 6.5 grendel rifle length. Never had an issue

 

[P89DCSS]

Thank you for all the helpful responses. I'll start with the rifle buffer and see what happens. Love the modularity of this platform after owning a mini14 for the last 28 years.

 

[VoodooMountain]

Most people use a carbine buffer or 3.8 oz buffer with midlength.

 

[BigBlue 94]

Thank you for all the helpful responses. I'll start with the rifle buffer and see what happens. Love the modularity of this platform after owning a mini14 for the last 28 years.

They dont call em the Legos of the gun world for nothing!

I hope you still have the mini

 

[P89DCSS]

Yup, never letting the mini14 go. Or the P89DC in stainless. They're ultra reliable tanks paid for decades ago.

 

[gotboostvr]

Like has been mentioned, try it first. Probably won't be an issue. At the very least you won't break anything if it dosen't jive.

 

[BigBlue 94]

Yup, never letting the mini14 go. Or the P89DC in stainless. They're ultra reliable tanks paid for decades ago.

Grandpa had a stainless P89. They are indeed tanks.

 

[js8588]

Push pin the new upper on and go have fun. No need to change a thing.