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Posted: 3/28/2011 2:18:26 PM EDT
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I have an old Pact Model 1 that I've used for years and recently I've experienced some very strange problems with it's ability to "see" the bullet. It will clock 7.62x39 bullets and .22 rimfire all day long and in a variety of light conditions so I am reasonably certain that the sensors/sky screens are in working order. However, it will only clock about a third of the bullets from my 6.5x30-30 Contender if it clocks any of them at all. I'm loading these with a 129 gr. Hornady SST and they should be clocking about the same velocity as the 7.62x39. I experienced a similar problem awhile back with certain 5.56 loads. It was as if the sensors never saw the bullet. I've talked to folks at PACT and ran down the list of do's and dont's and everything seems to be in order. I really can't go any further with load development for this wildcat without the ability to chrono the loads. Has anyone experienced similar problems or maybe have any suggestions?
Thanks |
| Don’t personally have any experience with this interesting problem but I wonder if this could have something to do with the difference in the gas that accompanies the “problem bullets”? i.e. could they potentially obscured the bullet? Are there differences in the distances between the muzzle and the chrono (most likely no, but I have to ask), or compensator/flash suppressor that might be responsible. Finally, I wonder about the powder and the degree of combustion/smoke. |
| Another possibility, I had problems with my many years old Oehler 35P and after a call to Oehler they told me to clean the plugs on the sky screens. It doesn't sound reasonable but there diagnosis was right on. They said that after many years the plugs will oxidize. I thought that they were full of beans since my plugs were clean and shiny. After cleaning the plugs on my skyscreens it never missed a shot under any conditions. To clean plugs on your unit DO NOT USE ANYTHING ABRASIVE like sandpaper. Use a coarse cloth, leather, or anything that will not scratch. Polish the plugs good and possibly use an electronic spray cleaner. Even though I could see no difference after polishing, it worked. Don't know if your unit has plug-ins or not but if so clean the plugs since you said your unit is years old. Also, if it will just not "see" some bullets, take a black magic marker and paint the tip black about 1/2 of the ogive. |
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The muzzle blast was about the only thing I could think of that could be causing the problems. Pushing a 6.5 mm bullet with a nominal 40 grs. of powder out of a 14" barrel definitely belches some gas but I have the screens out at 15' and I really can't go much further without running out of cable. Also, I'm sure their are folks successfully clocking bullets from the high intensity magnums that create as much or more muzzle blast.
Coloring the bullets from the tip to just in front of the ogive with a black marker is an interesting idea. Maybe that will drop the light level enough for the detectors to register. I'll try it and report back. Thanks. |
| Yes, basically there are only two things the rifle outputs other than the bullet, one would be the muzzle blast, the other is the concussion. I have an Alpha Chrony and many times I have the machine error out when someone else was shooting either next to, or even three of four stations down with a large magnum rifle. Here, they are not even shooting through my chrono, just parallel to it. Don’t know if it was the muzzle blast or just the concussion, but it happens enough times that I only go during the week to avoid other shooters when I am chronographic my rounds. Would definitely suggest you push the chrono out as far as possible. |
| We were shooting a 338 Magnum and had problems with a chronograph reading because of the blast form muzzle brake. We put a a piece of cardboard in front of the first screen. We cut a small rectangular hole in the cardboard so we could see the target and for the bullet to pass. There was enough cardboard stapled to wooden legs to protect the front sky screen from the blast. Chronograph started recording the 338 magnum like it had the 22 lr and 5.56. |
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The only time I really had any problems with my Pact Model 1XP, I finally looked closely at the sensors and found a bullet hole in one of the sensors, and when I looked closer found that the bullet had shattered the lens inside the sensor, ordered a new sensor and everything is good. Bad lighting can cause problems also. |
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We were shooting a 338 Magnum and had problems with a chronograph reading because of the blast form muzzle brake. We put a a piece of cardboard in front of the first screen. We cut a small rectangular hole in the cardboard so we could see the target and for the bullet to pass. There was enough cardboard stapled to wooden legs to protect the front sky screen from the blast. Chronograph started recording the 338 magnum like it had the 22 lr and 5.56. Good idea, I have a target stand that may be just the ticket for this sort of thing once I staple a cardboard baffle to it. |
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The muzzle blast was about the only thing I could think of that could be causing the problems. Pushing a 6.5 mm bullet with a nominal 40 grs. of powder out of a 14" barrel definitely belches some gas but I have the screens out at 15' and I really can't go much further without running out of cable. Also, I'm sure their are folks successfully clocking bullets from the high intensity magnums that create as much or more muzzle blast. Coloring the bullets from the tip to just in front of the ogive with a black marker is an interesting idea. Maybe that will drop the light level enough for the detectors to register. I'll try it and report back. Thanks. This is your problem. A heavy cardboard or plywood screen placed between the muzzle blast and the sky screens should fix the problem. Simply cut a 10" 0r 12" circle to shoot through and place it three to five feet in front of the first screen. This will limit the amount of blast that reaches the chrony. If you short barreled "rifle" still has problems, move the scy screens further away. |
| My Pact Model 1 will only reliably work in broad summer day light. I added the infrared indoor kit and rigged it up to a six vilt battery (vs the ac adapter that I had to plug in to a 110 volt outlet). the infrared kit gets me through the winter months when the light is not so bright. Otherwise, it was no go during the spring, winter and fall. |
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My Pact Model 1 will only reliably work in broad summer day light. I added the infrared indoor kit and rigged it up to a six vilt battery (vs the ac adapter that I had to plug in to a 110 volt outlet). the infrared kit gets me through the winter months when the light is not so bright. Otherwise, it was no go during the spring, winter and fall. If you don't mind, how old is your unit and what is the screen spacing? I was told that mine was too old to work with the infrared kit and if I remember correctly it also had something to do with the older 24" screen spacing. |
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I have an old Pact Model 1 that I've used for years and recently I've experienced some very strange problems with it's ability to "see" the bullet. It will clock 7.62x39 bullets and .22 rimfire all day long and in a variety of light conditions so I am reasonably certain that the sensors/sky screens are in working order. However, it will only clock about a third of the bullets from my 6.5x30-30 Contender if it clocks any of them at all. I'm loading these with a 129 gr. Hornady SST and they should be clocking about the same velocity as the 7.62x39. I experienced a similar problem awhile back with certain 5.56 loads. It was as if the sensors never saw the bullet. I've talked to folks at PACT and ran down the list of do's and dont's and everything seems to be in order. I really can't go any further with load development for this wildcat without the ability to chrono the loads. Has anyone experienced similar problems or maybe have any suggestions? Thanks Sorry I didn't click on this post sooner. I have a Pact Model 1 from 1995. It's worked fine for the first 15 years, with the ususal random errors, or not reading here and there do to sun angles. About a year ago, I started getting strange anomalies, like getting perfect readings from the fellow shooting 5' to my left, or right. I mean, I was clocking his bullets with the shades on and whatnot. I was also getting high readings from known loads, that were really out of whack. I called Pact last year and they stated that I could send it in with a check for $14.95 (return shipping) and they'd go through it and bring it up to snuff. I ended up taking the sensors apart (2 screws) and cleaning the two clear plastic prisms with Lexan cleaner and reinstalling them. Be careful of which prisim goes where and which side of each prisim goes up and/or down. Do one at a time, as I lost track and had to call Pact back and confirm, which they graciously did. The Model 1 has worked perfectly for 400 rounds, without a hiccup. Try that first. After years of sitting in the back of my truck, dust and grim had built up on the plastic prisms...not a lot mind you, but enough to alter the readings. It's working like a champ now and I bet that this is your problem. Chris |
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I have an old Pact Model 1 that I've used for years and recently I've experienced some very strange problems with it's ability to "see" the bullet. It will clock 7.62x39 bullets and .22 rimfire all day long and in a variety of light conditions so I am reasonably certain that the sensors/sky screens are in working order. However, it will only clock about a third of the bullets from my 6.5x30-30 Contender if it clocks any of them at all. I'm loading these with a 129 gr. Hornady SST and they should be clocking about the same velocity as the 7.62x39. I experienced a similar problem awhile back with certain 5.56 loads. It was as if the sensors never saw the bullet. I've talked to folks at PACT and ran down the list of do's and dont's and everything seems to be in order. I really can't go any further with load development for this wildcat without the ability to chrono the loads. Has anyone experienced similar problems or maybe have any suggestions? Thanks Sorry I didn't click on this post sooner. I have a Pact Model 1 from 1995. It's worked fine for the first 15 years, with the ususal random errors, or not reading here and there do to sun angles. About a year ago, I started getting strange anomalies, like getting perfect readings from the fellow shooting 5' to my left, or right. I mean, I was clocking his bullets with the shades on and whatnot. I was also getting high readings from known loads, that were really out of whack. I called Pact last year and they stated that I could send it in with a check for $14.95 (return shipping) and they'd go through it and bring it up to snuff. I ended up taking the sensors apart (2 screws) and cleaning the two clear plastic prisms with Lexan cleaner and reinstalling them. Be careful of which prisim goes where and which side of each prisim goes up and/or down. Do one at a time, as I lost track and had to call Pact back and confirm, which they graciously did. The Model 1 has worked perfectly for 400 rounds, without a hiccup. Try that first. After years of sitting in the back of my truck, dust and grim had built up on the plastic prisms...not a lot mind you, but enough to alter the readings. It's working like a champ now and I bet that this is your problem. Chris Thanks for the response. I've ruled out debris on the prisms since I've visually inspected them. When I'm not actually set up and (attempting) to clock loads I have each sensor covered with a small homemade nylon cover that seals out dust, moisture, insects, etc. so they stay very clean. When not in use for an extended period of time I keep the unit boxed up. |
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I have an old Pact Model 1 that I've used for years and recently I've experienced some very strange problems with it's ability to "see" the bullet. It will clock 7.62x39 bullets and .22 rimfire all day long and in a variety of light conditions so I am reasonably certain that the sensors/sky screens are in working order. However, it will only clock about a third of the bullets from my 6.5x30-30 Contender if it clocks any of them at all. I'm loading these with a 129 gr. Hornady SST and they should be clocking about the same velocity as the 7.62x39. I experienced a similar problem awhile back with certain 5.56 loads. It was as if the sensors never saw the bullet. I've talked to folks at PACT and ran down the list of do's and dont's and everything seems to be in order. I really can't go any further with load development for this wildcat without the ability to chrono the loads. Has anyone experienced similar problems or maybe have any suggestions? Thanks Sorry I didn't click on this post sooner. I have a Pact Model 1 from 1995. It's worked fine for the first 15 years, with the ususal random errors, or not reading here and there do to sun angles. About a year ago, I started getting strange anomalies, like getting perfect readings from the fellow shooting 5' to my left, or right. I mean, I was clocking his bullets with the shades on and whatnot. I was also getting high readings from known loads, that were really out of whack. I called Pact last year and they stated that I could send it in with a check for $14.95 (return shipping) and they'd go through it and bring it up to snuff. I ended up taking the sensors apart (2 screws) and cleaning the two clear plastic prisms with Lexan cleaner and reinstalling them. Be careful of which prisim goes where and which side of each prisim goes up and/or down. Do one at a time, as I lost track and had to call Pact back and confirm, which they graciously did. The Model 1 has worked perfectly for 400 rounds, without a hiccup. Try that first. After years of sitting in the back of my truck, dust and grim had built up on the plastic prisms...not a lot mind you, but enough to alter the readings. It's working like a champ now and I bet that this is your problem. Chris Thanks for the response. I've ruled out debris on the prisms since I've visually inspected them. When I'm not actually set up and (attempting) to clock loads I have each sensor covered with a small homemade nylon cover that seals out dust, moisture, insects, etc. so they stay very clean. When not in use for an extended period of time I keep the unit boxed up. It's not debris per se, but it can be a haze, obstructing the light/shadow. Anyhow, it takes about 5 minutes to remove them from the bar, take them apart and clean them. Otherwise, it's screwed up, so send it back to Pact, along with a check and they'll take care of it. Chris |
| Well, I tried both the cardboard blast baffle and coloring the forward part of the bullet and still no dice. It clocked other rounds same as before but it was no-go with 6.5mm SST's. My next option, if I truly want to chrono these loads, is to trade in my old model for the infrared type. Does anyone have any experience with them? Are they actually more reliable or will I just start cussing at the new one as well? |
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My Pact Model 1 will only reliably work in broad summer day light. I added the infrared indoor kit and rigged it up to a six vilt battery (vs the ac adapter that I had to plug in to a 110 volt outlet). the infrared kit gets me through the winter months when the light is not so bright. Otherwise, it was no go during the spring, winter and fall. Counselor, Are you satisfied with your infrared model or were there any hicups, battery problems, etc.? Thanks |
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