This is the first in a series about a “new to me” Barra 1100z Gen. 1 PCP air rifle. This Barra is in .22 caliber and it’s unregulated. In fact, it’s the same gun that has been used by Hard Air Magazine for a series of articles.
The previous articles included the following:
– comprehensive review (it was a HAM Gold Award winner!)
– power tuning
– trigger tuning
– tinkering
– stock change
This series will include things that I will do to customize this gun to fit the gun to my potential uses. My goal is a gun that fits the requirements for Hunter Field Target (U.S. rules). This means .177 caliber, less than 20 Ft/Lbs (27 Joules), and the best accuracy that I can get at 55 Yards.
For this series, I’ll start out with the gun as I received from HAM, in .22 and with the Buck Rail Tactical Chassis and Leapers UTG stock.
I’ll run it through a set of shooting tests that will include shot count and velocities, and pressures. That will give us a baseline for performance in .22 caliber that we can compare to .177 caliber in future. Note that the pressures will be read from the gun’s own pressure gauge.
As always, this is small and somewhat challenging to read precisely. However it calibrates well to the large diameter gauges I have on my compressor and HPA tanks. So the readings should be pretty accurate.
Having collected and analyzed this data today, my first real mod will be conversion to .177. That will be covered in Part Two of this series.
This involves partial disassembly of the gun, replacing the barrel and bolt. Both are available at a very reasonable cost directly from Barra, as is the .177 caliber magazine I need.
At the same time, I’ll revert the gun back to its original stock. After the caliber change, I’ll see what I can do to tune the gun to meet my power requirements in .177 caliber. That will be Part Three of this series.
Hopefully we’ll get a reasonably good velocity curve and shot count!
After that, I’ll install a regulator and tune the gun for Part Four. Again, it will be in .177 caliber and I’ll be recording the shot counts and velocities.
A possibility for a further article would be a Stopped Spring Guide, if I can figure out a good design for one.
Oh, and let’s not forget accuracy testing…
Baseline 1100z Gen. 1 PCP Performance Data
Here are three sets of test data for our 1100z Gen. 1 PCP air rifle. All start with a 3000 PSI fill, and are shot with HAM Gold Award-winning H&N Baracuda 15 (15.89 Grain) pellets.
For all of the shooting tests that I’ll be doing with this gun, I’ll be shooting down to about 1500 PSI, as that will be close to the regulated pressure further off in this series of articles.
1100z Gen. 1 PCP Power Tune Performance
The first series was shot as the gun was received, and would best be described as a power tune. The hammer spring adjustment screw is about eight turns in from flush with the back.
This tune would be very suitable for hunting. Maximum power for a small number of shots – actually about 10.
Now let’s take the same graph and add pressure gauge readings to it (the purple bars). As we can see, both pressure and FPS drop together.
1100z Gen. 1 PCP Best Shot Count
The second series was shot with the screw three turns in from flush (Flush was just too wimpy to do.).
This time, we see that the pressure falls away as the Muzzle Velocity increases, up to a maximum of 810 FPS. At this point, the gun is working with 1,900 PSI of pressure. After that, both pressure and FPS drop together. This would be a “handpump tune”, giving around 20 acceptably-consistent shots for a fill to around 2,100 PSI.
This is typical performance for an unregulated PCP air rifle.
1100z Gen. 1 PCP Best Shot Overall Performance
The third series was shot with the screw about five turns in from flush. This is apparently about the factory setting.
This time we can see that the gun gives a Muzzle Velocity of around 850 FPS at pressures of between about 2,200 and 2,400 PSI. Then both fall together. Here we have a “general tune” where a fill to 2,500 PSI would give up to 20 reasonably-consistent shots, but more powerful.
What’s that “blip” at the end? I’m not sure. Suggestions, please via the HAM Community!
1100z Gen. 1 PCP Performance Comparison
If we take the Muzzle Velocity curves for the three hammer spring settings and plot them together, we have a graphic comparison of what’s happening.
1100z Gen. 1 PCP Total Power Comparison
Finally, I calculated the Muzzle Energy for every individual shot in these tests. Adding them together for each of the tunes we can compare the total power produced for each fill of the gun from 3,000 PSI down to 1,500 PSI. Interesting!
| Hammer Spring Setting | Shots Per Fill | Total Muzzle Energy | Difference To 5 Turn Setting |
|---|---|---|---|
| 3 Turns In | 53 | 1,070 Ft/Lbs | Minus 7.7% |
| 5 Turns In | 50 | 1,135 Ft/Lbs | - |
| 8 Turns In | 28 | 728 Ft/Lbs | Minus 32% |
Yes, the “power tune” actually produces – by far – the lowest TOTAL amount of power generated by the airgun. Most likely this is due to hammer bounce of historic proportions. But you do achieve a small number of very strong shots. It’s “horses for courses”.
Next-up will be the caliber change conversion…
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Barra 1100z Air Rifle
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