I changed my buffer from a carbine to h1 (midway ar stoner) because my gun was chewing up brass and way over gassed suppressed and I dont have an adjustable gas block, 16 barrel mlgs.
Cool thing is my groups shrunk in half, but my POI shifted to 2 higher.
Just wondering why that was, did my muzzle velocity increase?
Your MV is not going to change by changing the buffer because the bullet has to leave the barrel and pressure drop before its unlocks and the new buffer has any influence on things. A heavier buffer will affect felt-recoil and cycling, but that's after the bullet has left the barrel.
Also, 2" (at 100?) is a lot of POI shift; it will be related to something else like how it is jumping in the recoil, or whether you cleaned the barrel, or different ammo, or a different shooting position, or something to do with your sight system.
If I've got this right, the heavier buffer kept the brass in the chamber a bit longer, a bit more lock up, if that's the right word. You were getting some early unlock that's why brass was getting beat up. I'm shifting mostly to H1 although some 100's might need the regular weight (still testing). I don't shoot suppressed.
Klem is right in that the bullet has passed the gas port, but I think the heavier weight also lets the backpressure die down more than it was...
Agree that all of that wouldn't cause a 2" shift by itself.
"Down the floor, out the door, Go Brandon Go!!!!!"
Ive already put them in the tumbler. They were totally black with carbon before now they look like they would w/o the can on since I changed that buffer. If I didnt change my mv then thats all I really cared about I dont want to chrono again.
05-18-2023, 10:42 PM (This post was last modified: 05-19-2023, 12:06 AM by Klem.)
65Grendelier Wrote:Ive already put them in the tumbler. They were totally black with carbon before now they look like they would w/o the can on since I changed that buffer. If I didnt change my mv then thats all I really cared about I dont want to chrono again.
65,
The difference between a MILSPEC and H1 is only 0.8 oz and still a lot less than a rifle buffer. So your buffer change is unlikely to explain the noticeable difference between 'totally black' and 'super clean' cases. Suppressor soot under pressure comes back around the case when the neck unseals and then this backwash is made even easier when the case extracts from the chamber. But even if you slow the extraction it still leaves your cases and action noticeably dirty. The type of powder used makes a difference as some burn dirtier than others, but to go from dirty to clean with once increment of buffer weight is unusual. Truth be known, a suppressed rifle never really gets to the case clean ejection of a non-suppressed rifle, even with the heaviest 5.4oz rifle buffer.
As you know, when you take on and off a suppressor the POI always shifts, and about 2" at 100 sounds about right. The shift is so predictable that we record and expect it to be the same every time. Here's a bolt gun with the shift recorded on the gun, and this is for a specific suppressor - a different suppressor will have its own unique shift. Your 2" shift and cleaner cases match what you would expect if the gun was shot suppressed, and then unsuppressed, regardless of the slight buffer change.
[ATTACH=CONFIG]19755[/ATTACH]
05-19-2023, 12:17 AM (This post was last modified: 05-19-2023, 01:53 AM by Klem.)
65,
No offence, but I find that hard to believe.
Suppressor manufacturers often tout how there is no POI shift with their suppressors, but that refers to when it is taken off and put back on again. Each time the POI is supposed to be the same as before and with careful machining this is achievable. The claim however does not extend to shooting with it on, and and then shooting without it, as this is a physical impossibility. With a suppressor attached there is free-bore-boost to consider, plus the added weight on the end of the barrel affecting jump and harmonics. Plus the way gasses are trapped and channeled behind the exiting bullet, shifting its ballistic arc. Adding to the science, I have never seen a gun not change its POI between shooting with a suppressor on, and then without it - this is what I was referring to.
05-19-2023, 02:47 AM (This post was last modified: 05-19-2023, 03:11 AM by 65Grendelier.)
I misunderstood you meant poi shift suppressed vs un-suppressed. Im speaking only suppressed. I can unscrew that can off my 65 and put it on my 7 WSM and hit steel at 1000 with a cold bore. Im just wondering about the physics or whatever why my group went from .85 to .256 and two inches higher. I checked to make sure my computer was plugged in, I restarted it, cleared my cookies
Maybe my scope got bumped then idk. Just find it interesting and I know this question has been asked on other forums but theres not a clear answer on those either that I can find.
Changing buffers changed something with accuracy, poi, gas blowback in my face, etc all for the better and I have a thirst for knowledge to understand why.
I have no reason to dream all of this up for entertainment
How many shots were in each group? How many groups did you shoot to arrive at your .85" "group size" and your .256" "group size"?
It sounds to me like your dealing with randomness rather than the buffer causing anything, at least concerning group size. As for the buffer change, causing a POI shift of 2," I've never seen anyone else report anything like that nor do I know of anything that could cause it.
Not sure if Klem mentioned this, but one more thing will also cause some poi shift (altho not 2"), the barrel is mounted to the action as a cantilever beam, secured at one point and free on the other, therefore there is some minute amount of droop due to gravity acting on the steel-barrel-beam's mass. Adding a suppressor to the free end causes more mass at that tip and thus more of that droop, however minute. But in 100 yd distances let alone farther ones, every 0.0005 means some shift. A relatively stiff barrel might minimize or have less droop but it won't be zero; and the added suppressor will not cause a zero addition - there will be a change in poi induced. This is physics.
"Down the floor, out the door, Go Brandon Go!!!!!"
So, by adding a H1 buffer your group sizes have shrunk from 0.85" to 0.26" in a semi-auto?
How many groups and rounds are we talking about? How many rounds per group? At what range? How do you measure groups size? What ammo? Any details on the rig and photos of the targets? Is this a Grendel?
Have you tried swapping the original buffer back in, re shooting for group and poi, then repeating with the heavier buffer to try duplicating/confirming results?
There has to be an explanation... I dont think it requires a detailed explanation about every detail. I measure groups the right way and I shoot the right amount of rounds. If you cant explain it, thats not my fault, I cant either. It has been asked on other forums do your own google searches if youre that intrigued, lol.
I'm still stuck on how you don't clean your barrel, ever, yet brass is coming out of a suppressed chamber "super duper clean"?! Just the fact that the chamber is sooty from never being cleaned should make your brass sooty.
123 eld-m MV 2425 SD 9
31.2 cfe 223
Bto 1.658
Cci 450
Starline brass base to shoulder 1.212 fired cases 1.2165-1.217 (.005 bump)
Trim length 1.510
Charge master link powder measure
Lots of precision shooters dont clean their barrels until they stop grouping.
Im not an amateur, well at least not a noob just trying to understand what I altered, was it barrel harmonics?
65, changing the buffer weight will not effect POI, it will effect carrier velocity and could have an impact on the ammunition being fed into the chamber.. If the lighter buffer allows the rifle to cycle too fast, damage to the bullet tip, seating the bullet deeper into the case, etc could possibly occur effecting accuracy.. If in doubt, shoot some groups with the light buffer and then with the heavier buffer and compare groups. Easy-peasy..Process of elimination..
