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Ann's Corner

VOLUME 48-----------JUNE 2006



June 1, 2006

Finally did some shootin'!  On Monday, May 15th a friend came up to use my LaserLyte bore sighter and test fire his buddy's varmint rifle.  The Rifle is a Remington XR100 Rangemaster in .223 Remington caliber, a recent Big Green offering built around the legendary XP100 pistol action.

A trip to Montana for a ground squirrel shoot was on the schedule for later that week, and the rifle's owner was traveling on business, so Court was elected for load development and sighting in duties.

I don't recall specific load information as to powder and bullet, but the ammo supply consisted of a "starting load" and two or three other loads with progressively increased powder charges.  The starting load was purported to be very mild in the reloading manual used for reference.

I inquired about setting up a chronograph to monitor velocities before the session began, but the decision was to do without as these were all "mild loads."

After a few of the starting loads were fired, a couple of three shot groups were printed using the two next higher powder charges.  Inspection of those fired cases showed some primer cratering, where the primer extrudes slightly into the gap between the firing pin and the firing pin hole in the bolt head.

Warning sign!  This condition can be caused by soft primer metal and/or excessive clearance between the firing pin hole and firing pin, but is also often a signal that pressures are excessive!  At this point we decided to set up a chronograph.

My new PACT ProXP was placed in service for the first time in its short career.  (We'll talk about that short career later)  After setup, we discovered that the velocities from the "starting load" were registering very near the speed of the hottest loads listed in the manual for this bullet and powder!  This discovery tells us that pressures were very likely too high in the hotter loads and placed pulling some bullets on the agenda.

The lesson here is that rifles are individuals.  One may react very differently from another, even when shooting the same loads under the same conditions.  This holds true for the test barrels used in load development in the laboratories too!

This particular rifle evidently has a short leade, which is the smooth portion of the barrel between the end of the case and the beginning of the rifling.  Initial loaded rounds,  with the bullets seated to a depth that put the overall cartridge length at loading manual specs, reportedly had the bullets contacting the rifling lands upon closing the bolt.  Seating the bullets slightly deeper prevented rifling marks on the bullet, but still may have left very little room to travel before engaging the rifling.  (This travel can easily be measured by using a Stoney Point Overall Length Gauge as described in the August 2002 newsletter)

Any of these conditions could and probably did, cause pressures to be higher than those experienced with the test barrels in the lab, and would likely generate higher than expected velocities.

The new rifle went on the trip with a supply of the light loads ready for duty.  A 'phone conversation last Sunday reported that the ground squirrel shoot was a success, and the XR100 performed well with the lighter loads.

After the session with the .223, and since the new chronograph was already set up, I decided to fire a few test loads that I had loaded last winter for Ann's 7MM-08.  I shot six rounds over the chronograph and one failed to generate a reading.  The other five were close to what could be expected with the data used, but perhaps a bit fast when the 20 inch barrel on the rifle is considered, vs a 24 inch test barrel.  No visible signs of excess pressure, such as cratered primers, were noted on the fired cases.

By this time the setting sun was glaring in my eyes as I sat at the bench, so I called it a day.

Next morning found me with the bright idea of setting up the PACT XP in tandem with my old Shooting Chrony Gamma model, and compare the velocity readings from both machines.  Sounded like such a simple plan.

(At this point you might want to refer to the January 2006 newsletter where I describe the expected features and advertised performance of this PACT ProXP chronograph)

The setup was made, with the bullet path passing over the sky screens of the PACT and then over the Chrony.  The rifle chosen for the test was Ann's .243, shooting Hornady 58 grain VMax bullets behind a charge of Hodgdon's Varget powder.

I shot a couple of rounds and found the Shooting Chrony was giving me velocity readings, and the PACT was telling me there was "no start signal."  Multiple adjustments to the PACT unit to make the bullet pass over the screens in different positions, and three phone calls to the PACT toll free customer service number for advice, resulted in only two readings that made sense.  Two other readings were clearly wrong, and 18 shots provided no velocity readings at all!

About midway through the frustrating effort to get the PACT to measure the .243's velocity, I paused and tried a .22 rim fire from the same shooting cradle, using the same aiming point.  Every shot registered on both chronographs, with readings within 5 to 10 fps of each other!

More frustration followed with the .243 and continued failure of the PACT to register velocities.  Finally, during the last phone call of the day, the PACT representative said they had been having problems with muzzle blast affecting the operation of the unit.  Apparently the problem is with the bench unit and wiring, not the bullet sensors themselves.

Now things are makin' sense but I don't like what it's tellin' me!  The .223 with a 26 inch barrel is pretty soft spoken when it comes to muzzle blast, and the .22 rim fire has no blast at all.  The PACT unit "read" every one of those velocities!  The 7MM-08 with a 20 inch barrel is louder, so 5 of 6 shots were picked up.  The .243 has only a 16.5 inch barrel, and the muzzle blast is kinda' vicious with the loads I was shooting.  Only 2 of 22 shots were correctly read!

Another call to PACT yesterday, and further discussion, resulted in confirmation that muzzle blast was likely the problem.

My next question was, "If the blast of a .243 makes this thing not work, what's it gonna do with a .338 Ultra Mag?"

His response was "The only known solution at this time is to put a sandbag on the sensor wires and cover the bench unit with a towel!  That usually solves the problem."

My reply was, "I'd probably be more tolerant about this if it wasn't for the fact that the cheaper Shooting Chrony unit registered every shot.  The sky screens were within two feet of each another and the bench units were sitting side by side."

I continued, "I'm just not willing to settle for that kind of performance!"

To PACT's credit, they are apparently going to honor their lifetime satisfaction guarantee.

I was told, "Send the unit back with a note to that effect, and we'll refund your money."

At least that was good news!  I have better things to do than try to jury rig solutions to a problem that shouldn't even exist with this piece of equipment.

The one feature of this PACT unit that I've not seen anywhere else and did not try on this one, is the infrared option on the sensors.  This would be nice for indoor range use with fluorescent lighting where regular sensors won't work, but still not worth the extra hassle of making the dang thing work properly.

My advice:  Unless, or until they solve this engineering problem, don't buy a PACT chronograph if you plan on shooting anything larger than an air rifle or mild mannered .22 caliber of some kind!

I believe my next chronograph purchase will be an Oehler.  I'll let you know how that turns out if I can get the extra expenditure approved by Little Heifer!

Turning to another subject, the pocket gophers are attacking again!  I was mowing the other day and discovered some telltale dirt mounds in the middle of the south lawn.  As I passed by on the mower, I saw the occupant of the little village outside the burrow in the grass.  This is very unusual, as these creatures are very reclusive and seldom venture outside when they can be seen.

I quickly shut down the mower and rushed to the house for my latest "gopher getter," the Thompson/Center Encore with a .410 shotshell/.45 Colt barrel.

Thompson Center Encore

As I approached the gopher's village a 3 inch .410 with #6 shot was loaded, ready for action.  I fully expected the gopher to be long gone, but he must have been young and stupid.  He ventured out of his hole again just as I approached, and was dead in a heartbeat.

As I was carrying my trophy to show Ann, I noticed that the gopher's head appeared to be wider than the size of his body would warrant.  Closer inspection revealed that he was in the process of filling those outside cheek pockets that give the pocket gopher it's name, with bits of grass!

Lawn mowing was further delayed while I took some photos of the first actual observance of these pockets being utilized.  As you can see in the following picture, the one pocket was packed full and the other was well on its way.

Pocket Gopher Packin' Grass

As I continued my mowing, I found two other newly established gopher residences just outside the lawn area.  One of those dudes bit the dust last evening, and I'm workin' on the other!  (For more information on my gopher hunting techniques, go to the Newsletter table of contents and look for "gopher hunting" to find additional stories)

I have mentioned the story I wrote for Outlook Magazine about replacing the trigger on Ann's Ruger .243, a number of times in these pages.  That issue was published in late April, and was supposed to be posted on the magazine's website long ago.  I understand that the magazine has changed webmasters for their site, and this has caused them to fall way behind with getting the site updated.  Hopefully this will be corrected in the next few days, and you can then download that issue.  The website is at www.spokaneoutlook.com.  If you don't see this issue soon, and want a copy of the trigger article, email me and I'll email you a copy of the article.

This month's hillbilly wisdom comes from cousin Linda via email.  (Linda was born a Missouri hillbilly girl even though she's lived in Colorado for several years.)

Dig a moat the length of the Mexican border,
Take the dirt and raise the levies in New Orleans
Put the Florida alligators in the moat

Any other problems you would like for me to solve today?

Well, It's time to shut down here, So . . . .

'Til next time, Keep 'em shootin' straight, shoot 'em often, and above all, BE SAFE!!!!!

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