Buffer Testing

[Racinready300ex]

I'm still new to the PCC thing, but I'm trying to test out some buffers. Below are two targets shot at 20 yards doing doubles. Splits probably averaged .18's I loaded the mags to 10 rounds shot 5 pairs, reloaded shot 5 more. The switched buffers and repeated. I did this twice, this is the second set of targets. 

 

The target labeled T I felt the recoil was harsher and the dot seemed to move more. I did have one .16 split with this buffer. And it seems this buffer shortened the stroke a little more. Buffer S seems better subjectively. But the hits are what I think should matter and they're vary similar. I'm leaning toward the S buffer at this point.

 

Next I'm thinking I should change the bumper in S to shorten the stroke a little more like the T and repeat the test. Then maybe switch to some Bill drills to see if the any differences seem more obvious. 

 

Does this seem like I'm on the right track? Or am I wasting my time and should just go with either one of them?

[Ner]

[Racinready300ex]

Yeah, that's why I started thinking I should try bill drills instead to see if I can force issues to pop up. Or maybe I need to try to force myself to run faster splits in a attempt to make the group open up doing doubles. 

 

Or I'm just wasting my time, pick one and move on. 

[zzt]

You have to tune more than your buffer to your load.  Spring, weight and short stroke all need to be adjusted to get no, or minimal dot bounce.  I'm there now with two loads, but it took a lot of experimenting to get there.  Set up for my 147 JHP, 145PF load I could put 10 rounds into a 2" circle at 25 yards as fast as I could pull the trigger.  I don't use that load any more because I'm out of 147s.

 

My sub-100PF load with 124s is what I use for steel challenge.  Minimal dot bounce with a different setup.  I'm now in the process of developing a 132PF 124 load for falling steel matches.

[Walli]

There are many variables:

1.       Stance: Shoulder more of less forward. More or less force on the handguard or the pistol grip. (Easy to test, no need to buy new parts.)

2       Ammunition: Bullet weight and power factor.

3     Gun: buffer, weight of buffer and bolt, spring-weight, rifle or carbine spring, carbine or A5 buffer tube, bolt travel, stock, total weight of the gun…

[Racinready300ex]

54 minutes ago, zzt said:

 Set up for my 147 JHP, 145PF load I could put 10 rounds into a 2" circle at 25 yards as fast as I could pull the trigger. 

 

Is that like a 10 shot bill drill you're describing?  That's pretty sick, tells me there is a lot on the table just need to figure out how much is me vs the gun lol. 

 

 

Buffer S is pretty adjustable, so there is more I can do with it looking for gains.

Edited August 31, 2021 by Racinready300ex

[zzt]

10 minutes ago, Racinready300ex said:

Is that like a 10 shot bill drill you're describing? 

 

Not really.  I was simulating shooting at falling steel racks where you have 6" square plates stacked behind one another.  You have to hit the first to get to the second, etc.  There are often two of them plus two Texas Stars back to back on a stage with some other falling steel poppers.  I started using the various factory ammo I had bought and was getting a lot of muzzle rise.  That slowed me down a LOT.  The fast guys were mowing them down with no muzzle movement.  So I worked until I achieved that. Now I can mow down all six in just over a second.  Recoil is a little harsh in a 5 lb. PCC, but it's fast.  I'm hoping I can get a 132~135 PF 124 load to do the same.

 

BTW, some of that was me adjusting.  Taking the buffer retaining pin and spring out so I could cant the stock to match my shoulder pocket made a huge difference.  So did learning to hold the gun properly.  Now, after almost a year I think I have it pretty much down pat.

[Racinready300ex]

12 minutes ago, zzt said:

 

Not really.  I was simulating shooting at falling steel racks where you have 6" square plates stacked behind one another.  You have to hit the first to get to the second, etc.  There are often two of them plus two Texas Stars back to back on a stage with some other falling steel poppers.  I started using the various factory ammo I had bought and was getting a lot of muzzle rise.  That slowed me down a LOT.  The fast guys were mowing them down with no muzzle movement.  So I worked until I achieved that. Now I can mow down all six in just over a second.  Recoil is a little harsh in a 5 lb. PCC, but it's fast.  I'm hoping I can get a 132~135 PF 124 load to do the same.

 

BTW, some of that was me adjusting.  Taking the buffer retaining pin and spring out so I could cant the stock to match my shoulder pocket made a huge difference.  So did learning to hold the gun properly.  Now, after almost a year I think I have it pretty much down pat.

 

I've been tweaking myself too, for this test I tried to do everything exactly the same to make it more apples to apples. 

[Boomstick303]

I would not judge what your PCC is doing in regards to recoil.  Watch the dot only.  I have found similar results as @zzt but I use 124 gr JHP, in that with the higher power factor my dot moved less and the gun ran better.  My PCC is a JP5 with their stock SCS buffer and my PF is around 142.  I do not it has anything do do with gas in regards to the comp either in that the comp only has ports in the horizontal plane and zero ports in the vertical plane.  I am beginning to wonder if it is cycle time of the bolt coming back quicker is minimizing muzzle rise.  Proper grip also contributes a lot as well when you talk  about muzzle rise.  When my shooting with my PCC is on point, the butt stock of my PCC is actually riding on my peck versus the pocket of the shoulder, and I pull the gun into me with the off hand.  You may want to play with placement and grip as well.  I think it is different for everyone depending on their own bio mechanics.  

[Ner]

The next question is..The bolt weight ..in or out ? 

[TonytheTiger]

55 minutes ago, zzt said:

Taking the buffer retaining pin and spring out so I could cant the stock to match my shoulder pocket made a huge difference. 

I thought I was the only one that did that. All my rifles get funny looks because of it.

[zzt]

34 minutes ago, Boomstick303 said:

I am beginning to wonder if it is cycle time of the bolt coming back quicker is minimizing muzzle rise. 

 

Absolutely.  With short stroke it is even faster.

 

4 minutes ago, Ner said:

The next question is..The bolt weight ..in or out ? 

 

In.  With my mouse fart steel challenge load I'm running the Leadstar bolt with the 3 oz. weight in, Blitzkrieg standard hydraulic buffer with their short stroke slug, 308 carbine recoil spring and the MBX small short stroke plug in an A5 tube.  I'll have to chrono this load now that I switched back to the 16.1" barrel.  It may be going faster than I thought.

[Boomstick303]

7 minutes ago, zzt said:

short stroke plug in an A5 tube

 

Do you run the A5 tube on all of your PCCs?

[Racinready300ex]

8 minutes ago, Ner said:

The next question is..The bolt weight ..in or out ? 

 

I'm running a JP bolt, didn't come with a weight. 

 

41 minutes ago, Boomstick303 said:

I would not judge what your PCC is doing in regards to recoil.  Watch the dot only.  

 

Based on what I see, target S had less dot movement. The hits seem a little better but don't really show the difference. My perception was the dot was moving less with that setup. 

[Ner]

1 hour ago, Racinready300ex said:

 

I'm running a JP bolt, didn't come with a weight. 

 

 

Based on what I see, target S had less dot movement. The hits seem a little better but don't really show the difference. My perception was the dot was moving less with that setup. 

is it a Hydra ?

[zzt]

2 hours ago, Boomstick303 said:

 

Do you run the A5 tube on all of your PCCs?

 

I only have one PCC.  I use it for SCSA and USPSA 'style' falling steel matches.  I don't shoot USPSA with it.  The A5 tube softens out the recoil.  If you just switch from a carbine length tube to an A5 and change nothing, recoil is very soft.  With one 3/4" short stroke adapter in place the bolt will lock back.  Adding the second regains short stroke.   I got the idea for the A5 tube from a poster on this forum who raved about how it affected recoil.  So I thought I'd give it a try.  I'd give him a shout out if I could remember who.  It works well.  I can't pull the trigger faster than the gun cycles, the dot doesn't move, so I'm happy.

 

BTW, the 147 145PF load above was using the carbine buffer tube.

[Racinready300ex]

27 minutes ago, zzt said:

 

I only have one PCC.  I use it for SCSA and USPSA 'style' falling steel matches.  I don't shoot USPSA with it.  The A5 tube softens out the recoil.  If you just switch from a carbine length tube to an A5 and change nothing, recoil is very soft.  With one 3/4" short stroke adapter in place the bolt will lock back.  Adding the second regains short stroke.   I got the idea for the A5 tube from a poster on this forum who raved about how it affected recoil.  So I thought I'd give it a try.  I'd give him a shout out if I could remember who.  It works well.  I can't pull the trigger faster than the gun cycles, the dot doesn't move, so I'm happy.

 

BTW, the 147 145PF load above was using the carbine buffer tube.

 

That seems crazy. Not saying it isn't true, just crazy

[zzt]

15 hours ago, Racinready300ex said:

 

That seems crazy. Not saying it isn't true, just crazy

 

What seems crazy about it?

[Racinready300ex]

14 minutes ago, zzt said:

 

What seems crazy about it?

 

Maybe I miss understood. You changed the buffer tube to a longer one, then shorten the stroke. So I'm assuming the stroke is similar once shortened. It seems a little crazy that something like just the length of the buffer tube would make any difference. I assume you can explain the reasoning? 

[zzt]

Just now, Racinready300ex said:

 

Maybe I miss understood. You changed the buffer tube to a longer one, then shorten the stroke. So I'm assuming the stroke is similar once shortened. It seems a little crazy that something like just the length of the buffer tube would make any difference. I assume you can explain the reasoning? 

 

The original poster said that simply dropping your carbine length tube setup into an A5 tube drastically reduced recoil.  It does, because the bolt has a 3/4" longer travel.  It is slowed more and does not bottom out as forcefully.  In fact, with some loads it doesn't bottom at all.  What it feels like is soft and slow.  Adding the Blitzkrieg short stroke slug adds 2.5 oz. to the overall weight, and reduces the length of travel by 3/4".  So now you have the additional weight, but still a full carbine length tube of travel.  It is still soft and  faster than without.

 

I wanted faster cycling, so I added the shorter MBX short stroke adapter.  It was, as near as I can tell, as fast cycling as the original setup, but softer.  You would think because the travel is essentially the same as the original setup, recoil would be the same.  It isn't.  It may be the buffer strikes softer plastic at the end of the stroke instead of metal.  The MBX adapter is a two diameter plastic plug.  There is a .100" long large diameter the recoil spring rests on.  The smaller diameter fits inside the spring to limit stroke.   The extra .100" of length increases preload and delays opening of the bolt a tad longer.  That reduces felt recoil.  So it is probably the combination of increased preload and the buffer bottoming on a softer material that contributes to less felt recoil.  Also, there is no bleeder hole in the back of the A5 tube like there was on the carbine tube.  So maybe air is not evacuated as quickly, increasing resistance to bolt travel.

 

That's my take on it.  It may or may not be completely accurate.  All I can say is the current A5 setup is softer and it will stay on the gun.

[Racinready300ex]

That first part is the part that made it seem crazy. You added a 3/4 longer tube so more travel, I can see that effecting felt recoil. Then you shortened the stroke 3/4" which seems like it would eliminate any benefit. But, you did also add weight to the buffer. So it would be a logical guess that it's not the tube but the weight or like you mentioned the material of the bumper inside. It's obvious there are a ridiculous number of options to play with in search of the best setup. It could be any number of little things or the combination of them to seals the deal. 

 

In buffer S, I'm running a 3d printed bumper to shorten the stroke. I printed a new one last night that should shorten it a little more, so I'll test that next. 

[zzt]

1 hour ago, Racinready300ex said:

But, you did also add weight to the buffer.

 

The setup in the A5 tube is identical to what I ran in the shorter tube, except for the addition of the MBX adapter (which does not reciprocate).  So the only things that changed were the tubes and the MBX adapter.  So it seems to me the tube has to be part of the equation.

[Racinready300ex]

26 minutes ago, zzt said:

 

The setup in the A5 tube is identical to what I ran in the shorter tube, except for the addition of the MBX adapter (which does not reciprocate).  So the only things that changed were the tubes and the MBX adapter.  So it seems to me the tube has to be part of the equation.

 

I see, so you were already running the 2.5 oz short stroke slug. So it's likely the extra 3/4" of stroke you added with the longer tube that made the change. That's reasonable. 

 

See I thought you had a longer tube with more spacers creating the same stroke you had with the shorter tube. I would think if the stoke was the same and the buffer was the same just in a longer tube with the extra space filled with a bumper it would be weird to think it would yield different results. Hence my crazy comment. Not trying to say it couldn't happen just that it would see odd and hard to explain the difference. 

[zzt]

3 hours ago, Racinready300ex said:

See I thought you had a longer tube with more spacers creating the same stroke you had with the shorter tube.

 

That is correct.  I can't say the stroke is exactly the same, but it is so close it doesn't matter.  Some of the reduction is definitely the increased preload.  That delays the bolt opening slightly.  Pressure is reduced because of the delayed opening and the bolt moves rearward at a slightly lower speed.  As I mentioned earlier, the lack of a bleed hole may also help because the compressing air will retard the bolt a little more.  There may be other contributing factors.  All I can say for certain was adding the MBX adapter to exactly what I used in the carbine tube felt softer when dropped into the A5 tube.

 

BTW, why are you selling the delayed opening buffer?  That does the same thing as increased preload.

[Racinready300ex]

4 hours ago, zzt said:

 

That is correct.  I can't say the stroke is exactly the same, but it is so close it doesn't matter.  Some of the reduction is definitely the increased preload.  That delays the bolt opening slightly.  Pressure is reduced because of the delayed opening and the bolt moves rearward at a slightly lower speed.  As I mentioned earlier, the lack of a bleed hole may also help because the compressing air will retard the bolt a little more.  There may be other contributing factors.  All I can say for certain was adding the MBX adapter to exactly what I used in the carbine tube felt softer when dropped into the A5 tube.

 

BTW, why are you selling the delayed opening buffer?  That does the same thing as increased preload.

 

It shot good but I didn't really like how it felt. It was not one of the setups in this test. The one I'm leaning toward is the Scheel delayed buffer. Still allot I can do with it too fine tune.