That's interesting Brocock Bantam .25 accuracy, with Altros reg installed

[Smitty911]

So I started to dial in my Brocock Bantam in 0.25 cal. I noticed when doing a shot string prior to installing the Regulator that the grouping seemed to tighten up while shooting from 200 down to 110 Bar. So I filled it back up to 150 Bar, and shot at targets in 5 shot groups and using the LabRadar recorded the speed and wrote down the pressure on the gauge.

150 Bar - JSB Exact Kings 25.39 Grain, 50 yard target (laser Ranged) Scope was not adjusted during test. Caldwell Sled used to hold rifle. Clearly Group 5 is the tightest at 110 Bar

150 Bar - 753, 751, 749, 745, 743 - 140 Bar
140 Bar - 741, 736, 730, 732, 729 - 130 Bar
130 Bar - 727, 724, 722, 721, 714 -120 Bar
120 Bar - 714, 712, 708, 705, 702 - 110 Bar
110 Bar - 699, 697, 694, 688, 688 -100 Bar

Installed Altors regulator set at 110 Bar, Gun gauge said 110 Bar and Bottle Gauge read 2500 PSI. which is what was in my tank.
676, 685, 688, 685, 685
Scope adjusted 8 clicks up - 6854, 684, 685, 686, 692, 687, 692, 694, 694, 695
Scope adjusted 4 clicks down - 699, 681, 691, 691, 690
Scope adjusted 1 click down - 687, 686, 697, 687, 693

The groups really never were as tight as Group 5 in the photos, but the speeds were the same. Not sure I should move the regulator up and down some and see where it settles in.

Smitty

 

[elh0102]

Where is your HST relative to maximum velocity at this reg setting? Generally, 95-97% is where you want it, so that should suggest whether or not a reg adjustment is appropriate. Of course, what the target tells you is always most important, but usually good accuracy and balance are close together.

 

[Emu]

In order to get REALLY good accuracy with my bantam sniper .25 Cal I had to:

Change the barrel for a poligonal LW.

Change the cheek piece.

Change the spring of the hammer.

Adjust the trigger.

Now that rifle is a favorite for going hunting. But it was a mess of accuracy.

 

[OldSpook]

That looks about right .to me as far as the regulator is concerned. There's probably a little bit of error in the actual marking of the regulator and the other gauges in the system. That would account for the velocity being a little bit lower than you would expect that 110 giving your first five shots at 110. I think you need to shoot it in and tweak the other parts of the system at this point I group number five looks like a good group depending on what distance you were shooting at.

 

[Aimright]

Another suggestion is to try shooting from bags or if you must use the sled be sure you maintain the exact same hold on the gun/sled each time and to maintain good follow-through after trigger pull. I think the sled can introduce a little “spring” and cause the barrel to move slightly vertically during shooting. I find I shoot more accurately with bags at both ends or a front rest and a rear bag.

 

[Smitty911]

Where is your HST relative to maximum velocity at this reg setting? Generally, 95-97% is where you want it, so that should suggest whether or not a reg adjustment is appropriate. Of course, what the target tells you is always most important, but usually good accuracy and balance are close together.

HST????

 

[Smitty911]

In order to get REALLY good accuracy with my bantam sniper .25 Cal I had to:

Change the barrel for a poligonal LW.

Change the cheek piece.

Change the spring of the hammer.

Adjust the trigger.

Now that rifle is a favorite for going hunting. But it was a mess of accuracy.

Not sure I'm up for a barrel change if I can keep Group 5 from above.
The check piece could use some more adjustment, about .25" to low to have good check weld.
Not sure what spring to use, nor how to take it apart, but I can look into it.
Trigger is factory stock, I know I could polish parts and then adjust it to a lighter pull.

Good information, Thanks,

Smitty

 

[Smitty911]

That looks about right .to me as far as the regulator is concerned. There's probably a little bit of error in the actual marking of the regulator and the other gauges in the system. That would account for the velocity being a little bit lower than you would expect that 110 giving your first five shots at 110. I think you need to shoot it in and tweak the other parts of the system at this point I group number five looks like a good group depending on what distance you were shooting at.

OldSpook, It only has maybe a tin through it, I've polished the barrel, and put in the regulator. I may drain the tank and put a scrunch of a twist on the reg.
It seemed after shooting another 100 pellets the reg. started to settle in and the shots became closer in speed.
The target was 50 yards, laser ranged to verify.
Shooting without my glasses and making sure everything was in focus was the bigger issue.

Smitty

 

[Smitty911]

Another suggestion is to try shooting from bags or if you must use the sled be sure you maintain the exact same hold on the gun/sled each time and to maintain good follow-through after trigger pull. I think the sled can introduce a little “spring” and cause the barrel to move slightly vertically during shooting. I find I shoot more accurately with bags at both ends or a front rest and a rear bag.

I don't like the sled my arms and cheek are all over the place, I'm sure that didn't help. I have a Bi-Pod, I'll get a rear bag.

Smitty

 

[Emu]

Not sure I'm up for a barrel change if I can keep Group 5 from above.
The check piece could use some more adjustment, about .25" to low to have good check weld.
Not sure what spring to use, nor how to take it apart, but I can look into it.
Trigger is factory stock, I know I could polish parts and then adjust it to a lighter pull.

Good information, Thanks,

Smitty

Mine got broken, so I had no alternative.

I disassambled it and took it to a spring a manufacturer to make another.

They made me two springs for peanuts. Now the cocking works perfect.

 

[elh0102]

HST????

Hammer spring tension. The spring tension and reg setting need to be tuned to a combination of reasonable balance.