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November 16th, 2013

New Caldwell Chronograph Displays Shot Data on iPhone or iPad

Android OS ChronographCaldwell will be introducing a new chronograph in early 2014. By outward appearance, this is a fairly conventional unit, with optical (light-tripped) sensors and “V”-profile sky-screens with plastic diffusers supported by rods. However, the big news is the data output. The new Caldwell Ballistic Precision Chronograph can display shot data and string averages on iOS devices such as the iPhone and iPad. A software App allows you to save the data on your iPhone, and you can even export the data via email. That’s handy if you want to archive your test results in a spreadsheet.

Along with the iPhone/iPad display, Caldwell’s new chronograph features a front-facing display screen on the green, barbell-shaped chrono body. As with most other chronographs, the Caldwell unit records velocity of each shot, average velocity (of shot string), Standard Deviation, and Extreme Spread (difference in FPS of fastest shot and slowest shot). One nice feature of Caldwell’s new chronograph is that it can be calibrated. That sounds promising, but remember that to calibrate any chronograph you need test ammo with a very accurately determined baseline velocity. In any case, Caldwell asserts that this new Chronograph is more accurate than some other units on the market, because it runs a faster processor and because it has the calibration option. We haven’t tested the unit yet so we can’t verify claims of improved accuracy.

Android OS Chronograph

The Caldwell Ballistic Precision Chronograph comes as a complete package with carrying case, sky-screens, and data cable. No price has been announced, but we expect it to be under $150.00. Incandescent lamps, which are suspended above the sensors, will be available as an optional accessory. These lights permit the unit to be used indoors.

Android OS ChronographAndroid OS Capability in the Future?
Currently, the new Caldwell Chronograph is only able to send data to iOS (Apple) devices. However, the data cable is not Apple-specific, so there is a chance that we may see Android OS compatibility at some time in the future. At SHOT Show in January 2014 we’ll ask the Caldwell technicians about compatibility with Android smartphones and tablets.

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November 16th, 2013

.308 Winchester — Large vs. Small Flash Hole Test

Conventional .308 Winchester brass has a large primer pocket with a large, 0.080″-diameter flash hole. Last year, Lapua began producing special edition .308 Win “Palma” brass that has a small primer pocket and a small flash hole, sized 1.5mm (.059″) in diameter. Tests by U.S. Palma Team members showed that the small-flash-hole .308 brass possibly delivers lower Extreme Spread (ES) and Standard Deviation (SD) with some bullet/powder/primer combinations. All things being equal, a lower ES should reduce vertical dispersion at long range.

Why Might a Small Flash Hole Work Better?
The performance of the small-flash-hole .308 brass caused some folks to speculate why ES/SD might be improved with a smaller flash hole. One theory (and it’s just a theory) is that the small flash hole creates more of a “jet” effect when the primer fires. Contributing Editor German Salazar sought to find out, experimentally, whether this theory is correct. German explained: “During one of the many internet forum discussions of these cases, Al Matson (AlinWA) opined that the small flash hole might cause the primer flash to be propagated forward more vigorously. In his words, it should be like shooting a volume of water through a smaller nozzle, resulting in a flash that reaches further up the case. Now that kind of comment really sparked my curiosity, so I decided to see what I could see.”

More Primer Testing by Salazar
You can read more about this test and other primer experiments on RiflemansJournal.com.

Salazar Primer Tests: Small Rifle Primer Study | Large Rifle Primer Study

Large and Small Flash Hole .308 Cases — But Both with Small Primer Pockets
To isolate the effect of flash hole diameter alone, German set up a test with the two types of .308 case that have a small primer pocket: Remington BR brass with a 0.080″ flash hole and Lapua Palma brass with a 0.062″ flash hole. NOTE: German reamed the Lapua brass to 0.062″ with a Sinclair uniforming tool, so it was slightly larger than the 0.059″ factory spec. The Remington brass has a .22 BR headstamp as this brass was actually meant to be re-formed into .22 BR or 6 BR before there was factory brass available for those cartridges.

.308 Winchester Flash Holes

German set up his primer testing fixture, and took photos in low light so you can see the propagation of the primer “blast” easily. He first tested the Remington 7 1/2 primer, a primer known for giving a large flame front. German notes: “I thought that if there was a ‘nozzle effect’ from the small flash hole, this primer would show it best. As you can see from the photos, there might be a little bit of a flash reduction effect with this primer and the small flash hole, the opposite of what we expected, but it doesn’t appear to be of a significant order of magnitude.”

Remington BR case, 0.080″ Flash Hole, Remington 7.5 Primer.

Lapua Palma case, 0.062″ Flash Hole, Remington 7.5 Primer.

Next German tested the Wolf .223 primer, an unplated version of the Small Rifle Magnum that so many shooters use. German notes: “This is a reduced flame-front (low flash) primer which has proven itself to be very accurate and will likely see a lot of use in the Lapua cases. With this primer, I couldn’t detect any difference in the flash produced by the small flash hole versus the large flash hole”.

Remington BR case, 0.080″ Flash Hole, Wolf .223 Primer.

Palma case, 0.062″ Flash Hole, Wolf 223 Primer.

German tells us: “I fired five or six of each primer to get these images, and while there is always a bit of variance, these are an accurate representation of each primer type and case type. You can draw your own conclusions from all this, I’m just presenting the data for you. I don’t necessarily draw any conclusions as to how any combination will shoot based on the pictures.”

Results of Testing
Overall, looking at German’s results, one might say that the smaller diameter of the small flash hole does not seem to have significantly changed the length or size of the primer flame front. There is no discernible increased “jet effect”.

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November 16th, 2013

Kirby Allen Rolls Out 300 Raptor — Big Case, Big Performance

300 Raptor Allen PrecisionKirby Allen of Allen Precision Shooting, www.apsrifles.com, has developed a .30-caliber jumbo-sized magnum he calls the 300 Raptor. The 300 Raptor (center in photo) is based on Allen’s 338 Excalibur parent case (far right in photo), necked down to 30 cal with shoulder moved forward to increase case capacity. Allen states: “This is the largest capacity and performance .30 caliber magnum on the market that can be used in a conventional sized receiver.”

Shoot 200s at 3600 fps
Performance of Allen’s new 300 Raptor is impressive. Allen claims that “200gr Accubonds can be driven to nearly 3600 fps, 230gr Berger Hybrids to 3350 fps, and the 240gr SMK to right at 3300 fps. These loads offered case life in excess of 6-7 firings per case and many of my test cases have over 8 firings on each case so they are not an overly hot load showing the potential of this big .30 caliber.”

300 Raptor Allen Precision

To showcase the new cartridge, Allen built up a prototype rifle with a McMillan A5 stock, Raptor LRSS Action with extended tenon, and a Jewell trigger. The first 300 Raptor Rifle is currently on its second barrel, a new 30″, 3-groove 1:9″-twist Lilja in a custom APS “Raptor Contour”. This distinctive dual-fluted contour runs full-diameter almost to the end of the stock, and then steps down and tapers to the muzzle, where a beefy Medium 3-port ‘Painkiller’ Allen Precision brake is fitted.

300 Raptor Allen Precision

Story tip by EdLongrange. We welcome reader submissions.

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Permalink Gunsmithing, Hunting/Varminting 22 Comments »