* No flaming or insulting of other members. You will get one warning via a private message. Repeat offenses will result in being banned. (We are quite serious about this folks).
* Vendor bashing will not be tolerated. You will get one warning via a private message. Repeat offenses will result in being banned.
* When posting, try to use descriptive titles for your threads to enhance the searchability of the site. Thread titles such as "Help Me" or "Dang this sucks" should NOT be used. Instead try titles like 'Need Help with Sights', 'How to Perform Stock Refinish', or 'Vibration in Handguard". This will help other people search the site with better accuracy and make it easier for people to help you out.
* Everyone has a personal opinion and they will often differ from others. If you get into an argument over something, debate the issue, not the member. If you feel the need to get into a heated discussion with someone, send them a private message. Personal debates on the forum will not be tolerated.
* Do NOT post copyrighted material on this Forum without consent of the author. This could be from another website, or a book that you personally own. The owner/Admins of this site will not be held liable for any copyright infringement of this type, and as such, will prevent (to the best of our ability) it's posting in public. This is for the protection of ALL members.
* Do NOT post any messages that are obscene, vulgar, sexually-orientated, hateful, threatening, or otherwise violate any laws. These types of messages will not be tolerated. You will get one warning via a private message. Serious offenses may result in immediate permanent suspension. Repeat offenses will result in being permanently suspended.
* Avoid thread hi-jacking. Moderators will be looking for this and will more than likely split the topic if it gets too drastic, as well as take appropriate action where deemed necessary, to include deleting posts and/or enforcement action.
Please do not post the same question or post across multiple forums, or in the same thread. The best way to get the answers you are searching for is to post a clear single question in the appropriate forum and be patient, Replies will come. If you are in a hurry for a particular answer try using the search button or reading through replies to similar questions. It may just contain the information that you need. No need to post the same information again and again as this just clogs up threads/sub-forums.
Do not bump non-Marketplace threads as that can clutter the front page of a discussion forum. Posts bumping discussion threads will be deleted.
* Any members advertising their wares on the site without expressed permission will get banned. Personal items for sale in the classifieds are ok as long as the meet the criteria laid out in the site rules.
* Do not post any info, posts or threads regarding the process of going to the estore and artificially placing a large number of items in your cart simply for the purpose of seeing what inventory remains of an item carried on the estore!
This activity slows down the estore and can cause problems with it crashing, errors with people's orders, and inventory errors, particularly during periods of high demand/traffic.
Anyone making such posts on the forum will be warned once, then have their forum privileges suspended at least temporarily for a second violation. Further violations can result in permanent suspension.
* There will be no posting of links to, or copying information from listings on outside auctions/commercial sites, i.e. -- Gunbroker, Ebay, Armslist, Craigslist, Reddit, gun trader sites, etc, that are still active/live. We will not provide a platform for members to promote said auctions as there is no viable way to determine whether they or someone they know has a stake in the auction. Posts with this information will be removed. Continual violations will result in suspension of forum privileges. You may link to closed/completed auctions in the sake of education and learning.
* Users who post fake information, i.e. - name, location, in their profile, or otherwise provide/post false information/data about themselves will be instantly banned. Users who register multiple usernames will also be removed.
* Your account may be revoked at any time for any reason.
Generally, the following enforcement policy will apply:
1st offense - warning
2nd offense - banned for one week to six month
3rd offense - banned for one year
4th offense - banned permanently
** Depending on the nature of the offense/rule violation, first offense can result in ANY of the above enforcement actions.
ADDITIONAL RULES, TO INCLUDE MARKETPLACE/CLASSIFIED AD RULES:
1. Profile Requirements
To start a sale, buy or trade thread anywhere in the Marketplace, your Profile must contain:
A. Your FIRST and LAST name as well as your STATE of residence. Your profile privacy settings must be set to at least allow registered users the ability to view your profile info, i.e. - Not set to "Friends only."
B. You must "enable receive email and PM’s" in your Control panel if you intend to buy or sell.
Additionally, you must have a valid email address listed in your registration profile (which can only be viewed by moderators/admin in the vBulletin master page).
Users with obvious fake names, or using false names in their profile will be permanently removed from the forum without warning. PLEASE NOTE: When a member has failed to put their full names and location in their profile, their ads will be deleted WITHOUT NOTICE. You are responsible enough to be involved in firearm activity, so you can be responsible enough to read and understand the forum rules. The posted rules ARE your notice as they are posted throughout the forum. Threads/ads will be restored once a member has updated their profile with first and last name, and state.
2. The Marketplace is intended SOLELY for the mutual benefit of forum members as a resource to support each other's collecting and/or shooting goals.
It is NOT intended for, and will NOT be used by members as a repeated, for-profit venture/operation. This includes:
A. Purchasing items from members on the forum, then posting them for sale at a markup/profit on other commercial sites, i.e. – eBay, Gunbroker, etc.
B. Reselling items at a considerable markup that were recently purchased from CMP.
Members found to have clearly abused this policy will lose the ability to post in and use the Marketplace, and potentially have their forum privileges suspended, temporarily or permanently.
3. You may only list personally owned items, and/or request/WTB items for yourself. “Selling (or buying) this for a friend/family member” ads, and 3rd-party sales/purchases are prohibited.
Additionally, NO posting or linking to listings on eBay, Craigslist, Gunbroker, Reddit, or other outside auction/commercial sites. We will not have the items placed here also. List your product here, try to sell it here, then take it to eBay, Craigslist, Gunbroker, auction-arms, etc.
4. There will be no “auction style” selling here…If you post an item for sale and it says anything like "I will take the highest offer" it will be removed.
We ask that you list your item on just one forum, so there is not confusion and/or issues with an item being sold on another forum when someone attempts to purchase it here. If you do list and sell on another forum, it is your responsibility to immediately update your ad on our forum…if you do not, your privilege to post in the Marketplace and even the forum itself may be suspended, at least temporarily.
NOTE REGARDING 1911 PISTOLS PURCHASED FROM CMP: If you are considering selling a 1911/1911A1 you acquired directly from CMP, you MUST obtain approval from CMP1911ADMIN before listing it on the forum as purchasers of these weapons are not allowed to resell them as a condition of the purchase. You may reach him via PM or email: [email protected]
5. Vendors (or people selling large quantities of the same item as part of a commercial venture) must first contact a moderator or admin.
6. Omission of information is also known as fraud. It is wholly the responsibility of the person listing an item to describe it ACCURATELY and TRUTHFULLY.
Example: If you are selling a rifle stock that has a 9 inch crack in it you need to disclose that information to the buyer. Do not describe the item or tell the buyer that the stock has "light scratches" only.
If we determine that you defraud a member by failing to disclose facts about your items, your access to this section will be restricted and you may be permanently banned from the forum.
7. CLASSIFIED AD REQUIREMENTS
A. Briefly describe your item in the title, along with WTS, WTT or WTB.
B. We do not have any rules regarding notification of a purchase or trade in an ad...it can be accomplished via a post on the thread, a PM, an email, a phone call, a pigeon carrier, etc. However, if you set the terms of your sale, you must follow them! We do not require or enforce any conditions of purchase; however, if a member violates their own terms then they are subject to at least suspension from the Marketplace section. For example: If you say, "First 'I'll take it' gets it," and sell to someone via PM or email without updating your ad and someone posts they'll take it, that's on you. We will not be party to a dispute, but you WILL lose your privilege to post in the Marketplace as a minimum since you failed to follow your own conditions.
C. You must list a price, and make it easily visible, not just lost in the description. Ads without a price will be deleted. It is ok to list a price and OBO (or best offer); however, no auction-style listings
D. As noted in item #4, provide ALL and ACCURATE details. i.e color, size, caliber, year, make, model, condition, defects, etc
E. Post pictures, or at least the links to them. If you are unable to post pics, then make them available via e-mail.
F. List shipping, pick-up or delivery options for the buyer, as well as cost.
G. Be sure to mark your ad as "SOLD" once the items are sold.
8. Do not bump ads older than 90 days without moderator approval. Ads older than 90 days will be locked if they get bumped.
9. Do not bump an ad more than once within a 24-hour period. Ads bumped multiple times within 24 hours will be locked or deleted. Members who continually do this will have their ads locked or deleted, and will lose your privilege to post in the Marketplace.
10. Remove previous bump posts so as to keep the size of the threads to a minimum. Nobody wants to have to search through 4+ pages of "Bump" or "ttt" posts simply to find information on the item listed.
If not removed, mods will remove them and/or delete the thread if it gets out of hand.
11. If you commit to buy or sell, please contact the seller or buyer within 24 hours with a PM or email to make arrangements.
12. If an item is sold, please mark the thread as such. This will help eliminate the old threads coming back up, as well as help those looking for specific items.
13. For WTB items anywhere in the Marketplace:
- Only respond to a WTB ad if you possess the requested item or have specific knowledge of that item’s availability. For example, do not post, “Check eBay” or “Check Gunbroker.”
- Once you have found/purchased the item(s) desired, delete the thread so as to not waste other members' time and allow for other threads to have visibility.
14. Keep the classified threads clean of extraneous/fluff comments and questions, regardless of how innocent or praiseworthy. This prevents derailing the thread and generating wasteful, opinionated discussions, as well as surreptitious bumping of threads.
If you have a technical or knowledge question relating to a listed item, start a new thread or search and add to an existing thread.
If you want to thank or praise a seller or item, DON'T do it in the sale thread as it unnecessarily bumps a stale thread, and said comments will be deleted. Instead, do the person the courtesy of posting in the Buyer/Seller Feedback section here: http://forums.thecmp.org/forumdisplay.php?f=81
Basically, if you don't have a question DIRECTLY related to a sale/trade/purchase of a specific thread, don't post! And this particularly applies to stomping a member’s ad concerning their asking price as there is a tendency to post negative replies when someone lists an item for sale that others consider overpriced.
We will not tolerate members stomping another member's ad concerning their asking price.
This also includes posting low-ball offers. If you want to make an offer lower than the asking price, even if it states OBO, do it via PM or email.
If an item is sold and the listing member deleted the price (which is their prerogative) and you want to know what the price was, do NOT post in the thread…send the member a PM.
Those who continually stomp or hijack other member's ads will face temporary, and even permanent suspension of their forum privileges.
15. No duplicate or multiple threads in different sections for the same item. Pick one section, the most applicable, and post there. Additional duplicate threads will be deleted.
16. You may not use the signature block function to solicit purchases, trades and/or sales. That is why we have the Marketplace...post a thread with your specific WTB, WTS, WTT ad.
You may have up to two lines stating you are looking or searching for a particular rifle/weapon and serial number.
As with individual posts, signature blocks/lines are subject to the same forum rules and will be handled accordingly if they violate any forum rules, policies/procedures or take up too much room of a post.
OTHER TIPS/GUIDELINES
- Buyers and Sellers should verify each other’s identity before sending money and/or products. If possible, get each other’s phone number and have a quick conversation to confirm the transaction details.
- As a suggestion: sellers should consider using delivery confirmation to avoid conflicts from buyers; saying they never received the products.
- Buyers, get to know the seller a little before you blindly send cash. If something does not seem right; it probably isn't. If something seems too good to be true; it probably is. Contact a moderator or report a thread/post that appears to be a scam.
- Respect fellow members. This section is a great place to support/help out fellow members and occasionally make new friends. Please be respectful to your fellow members. Maybe try selling here to a member instead of eBay, maybe save them a buck or two. If you have any questions, problems or concerns feel free to contact a moderator or admin.
- We do not require members to keep ads, or keep a listing price in the thread. It is your ad, so you are free to delete it at your discretion, as well as remove the asking price if you so desire. If someone is curious about the price for what an item sold, contact the seller via PM…do NOT post in thread.
- Lastly, don't forget the <b>Buyer/Seller Feedback section</b> http://forums.thecmp.org/forumdisplay.php?f=81
Be sure to express a good or bad experience with your buyer or seller, and let others know what to expect. Also be sure to check there for a member if you are concerned BEFORE you buy.
MODERATION RULES/ENFORCEMENT
1. All spammers get banned instantly and permanently.
2. Inappropriate or out of hand threads shall be closed with or without reason posted for the closure or deleted at the discretion of the Mods/Admins.
3. If you cannot follow the rules set forth, your posts may be deleted, removed, or edited by the Moderators.
4. If you repeatedly do not follow the rules set forth, you will be banned from this section or from the CMP Forum for any length of time from 2 days to permanently, at the discretion of the Moderators.
NOTE: These rules can change at any time. Administrators and Moderators have the right to make any decision that fits the website and its users.
DISCLAIMER
The CMP, any of its staff and forum administrators/moderators assume NO liability or responsibility for Marketplace transactions. Members will use at their own risk, and CMP will not be responsible for any disputes or claims between members involving a transaction.
The Civilian Marksmanship Program forum is intended primarily to be a technically-oriented website for professional, courteous, and intellectual discussion of CMP matches, activities, firearms and related events. We are an online community founded by enthusiasts, for enthusiasts, of all ages and walks of life. Remember that we have youth CMP participants who view this site. Please enjoy your stay and with your help, we can make the CMP Forums safe for all.
The opinions and posts on this site do not necessarily reflect those of The Civilian Marksmanship Program.
If you have any questions, please contact a Moderator
HOW TO measure the velocity of a bullet.
When I began target shooting in the 1970s chronometers available to me started at about $2000. I didn't have one, always planned to make one, but never had the time.
In 1970 chronometers used mechanical switches to start and stop an electronic counter. The switches were two sheets of foil placed close to each other.
When the bullet traveled through them it completed an electrical connection and that that started the counter.
A short distance away was another switch that stopped the counter when the bullet passed thorough that one.
The main difference between chronometers of the 1970s and today is technology changes in the switch.
The inexpensive chronometers available today, for about $100, use much the same technique but with the technology available today.
I have a CHRONY BETA chronometer. It has switches that are operated by light.
A change in light intensity produces a change in an electrical signal which is fed into an electronic amplifier and used to start and stop an electronic counter.
To accomplish this a focusing lens is placed above a light sensitive transducer and with light above it, usually sunlight, anything passing between the light source and the lens will produce a moving shadow.
The shadow is translated to an electrical impulse and that is used to start and stop a counter.
Technology, like bullets, moves way too fast for old retired guys like me to keep up. But I stand back and marvel what these young engineer minds keep coming up with.
If you don't already have a chronometer go out and buy one. You won't regret it even if you don't reload.
They are a heap of fun and can be used to measure the speed of almost anything that passes over the switches (without hitting them of course).
Question: What's Faster Than a Speeding Bullet?
Answer: The PVM-21 chronograph that take it's picture.
Germany’s Werner Mehl is the talented engineer who created the PVM-21 infrared chronograph, in many respects the most sophisticated ballistic speed-measuring system currently available to the general public.
Werner runs a company, Kurzzeitmesstechnik, which specializes in high-tech ballistic measuring systems and ultra-high-speed photography.
Werner has engineered camera and lighting systems that can literally track a bullet in flight, millimeter by millimeter, with eye-popping resolution.
Werner employs digital cameras that record up to 1 million frames per second, with effective shutter speeds as fast as 1.5 nano-seconds.
The videos produced by Werner’s systems are amazing.
This 10-minute video shows the impact of projectiles on various targets, recorded at 1 million frames per second.
(I found that muting the sound allowed me to concentrate more on the video but some may enjoy the music and not be distracted by it.) Enjoy !
Grandfathers Dwight & Percy- Both WWI US Army, Tank Corps & Corps of Engineers
Uncle Colby- WWII US Army Infantry - European Theater / Battle of the Bulge
Dad - US Army 1954-1956 Infantry Radio/Morse Code Instructor, Fort Knox
VFW Patriots Circle Member
NRA Life Member
CMP - GSVMM Master Instructor
Aren't those bullets spinning with a Lefthand twist?
You have a good eye. Yes, some of those bullets are going the other way, but the "other way" depends on what your favorite gun is. Rifling twist can be LEFT -or- RIGHT, and also GAIN TWIST, in either direction. (You would not be able to discern Gain Twist from looking at the bullet while it's traveling). The bullet doesn't care which direction it rotates. Accuracy is ensured if it's rotating at the right speed (revolutions per second). Before this technology arrived, very few people have actually been able to see that bullet spin. High speed photography has come a long way with the introduction of digital photography and VERY FAST electrical switching devices.
A veteran is someone who once signed a blank check payable to The United States of America in an amount up to and including their life.
Thanks for the link and the explanation.. but a minor correction. A chronometer is a very accurate clock while a chronograph is the device you are talking about. I also have the Chrony Beta and love it. While not even in the same league as Werner's PVM-21, for the average shooter it is certainly a valuable tool. Thanks,
A lot of the instruments back in the 50's, 60's and 70's were ballistic chronometers. Basically, you would use a breakwire or foil glued to two sides of a piece of cardboard (so the bullet would make a short circuit connections in passing through) to start the clock. A second identical screen would stop it. The readout would be in microseconds.
You would then have to use your new fangled $150 four-function gee-whiz pocket calculator gadget to divide the resulting time by the number of feet spacing between the screens, then divide that result into one to get bullet speed in feet per second. It was only the later advent of cheap, low power microprocessors that made it possible to have the instrument handle that math on top of making the measurement.
The advent of fast phototransistors and PIN diodes also eventually made economical skyscreens possible to replace the electro-mechanical ones that get shot up, though they're not always more accurate. The electro-mechanical screens don't care what the light conditions are and aren't confused by muzzle blast.
--------------
Nick
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Instructor
NRA Patron Member
ORPA Life Member
Page 251 of Hatcher's Notebook (1947) mentions a Le Boulongé chronograph.
The chronometer is a precision device to measure absolute time with reference to traceable standards. In the era of celestial navigation chronometers with precision movements were built as transfer standards and were periodically calibrated with solar and planetary observation and rated for drift. Consistent drift rate was more important than intrinsic accuracy. Later, electromechanical and piezoelectric standards were used finally culminating in atomic references directly driving chronometric movements. In other words, it's a clock.
The chronograph is a device to record time intervals. A chronograph usually has some form of relative chronometer or timer in it. This is not always the case, such as interval recorders using spark discharge to record motion or periodicity, but generally speaking some form of time interval logging is involved -- usually presented in the form of inverse period (velocity). In other words, a chronograph is a log.
Chronographs have been called chronographs since I can recall interest in them. I've never heard of a device with this specific function called anything else. Doesn't mean it hasn't, just that in almost 50 years I haven't heard it.
Is this important? Probably not. It's just words. With meaning.
The Boulangé chronograph is a 19th century electromechanical apparatus that uses a breakwire screen to open connections to solenoids. The first breakwire would cause a zinc rod to drop, while the second breakwire would release a spring-loaded striker that put a ding in the rod at whatever distance it had dropped to. Like its contemporary, the Bashforth chronograph, which traced a line on graph paper on a fast rotating drum during the interval between two wire breaks, this resulted in a graphical representation of time. Hence "chronograph" or literally "time drawing".
The modern direct reading bullet speed meters (what they really are) revived the use of the term, but not with the original meaning. The readout is a graph in the sense that writing is a graph, as in graphology. But it doesn't display time, so I think it's a poorly chosen term for the modern devices. Bullet speed meter just isn't sexy enough, I suppose, even if it's more accurately descriptive.
The early digital ballistic chronographs were built with vacuum tube logic for counting a crystal time base. The crystals were ultimately traceable to the old Bureau of Standards. I don't know the details of the proximity sensing coil system that was developed between the wars for use in place of breakwires as part of a portable system. I only know that, like the electromechanical devices from the 19th century, its response was slow. Without digital logic, the analog instruments need to make a big enough trace or meter movement to resolve small bits of time. That's why the first screen (wire or coil) was at 6 feet and the second was way out at 150 feet, for an average of 78 feet. That's where the military 78 foot rifle velocity measuring distance came from.
Last edited by Unclenick; 07-13-2011, 11:55 AM.
Reason: typo fix
--------------
Nick
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Instructor
NRA Patron Member
ORPA Life Member
Great info. Thanks. I wondered just how the Boulangé worked since I haven't encountered one. Just read about its use in Hatcher's book
Had some experience in freshman physics with waxed recording paper on disks and drums using spark discharge. Painful, but clever. Later I worked with gated decade counters with high stability piezo oscillators traced to WWVB with a phase metering receiver. Since '94 I've been working with atomic clocks (rubidium mostly) in simulcast trunking systems, but these have recently been replaced with GPS receivers. Time lurches on.
Tried making a crude chronograph - speed meter - back in the early 70s with a gated counter, but making reliable screens was such a hassle I gave up.
All good stuff.
Insofar as the "bullet speed meter" term is concerned it's probably correct. But since the readout of a "chronograph" in this sense is a simple function of inverse frequency (period) and displacement, it's really an interval recorder rather than a time indicator. I think "chronograph" isn't too far off the mark.
No, it's not way off. You know a time base is in there somewhere. But the readout is bullet speed, not time or time intervals. That's why I think of it as a speed meter.
I did build and sell a few breakwire ballistic stop watches at gunshows back in the early 80's. Also messed with, but never sold (too much trouble) a conductive ink pattern silk-screened onto paper to replace the wire. They and the wires were on a PVC pipe frame that set the spacing. Slow work and some bother, but it functioned OK. 4 MHz crystal time base, just as is commonly used today, chosen based on the counter chip's limitations. I've still got one in the basement somewhere. I should probably take a photo to show how technology has advanced.
--------------
Nick
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Instructor
NRA Patron Member
ORPA Life Member
Well, I can disagree with you, but you're not wrong.
There was a chronograph speed-meter in the '70s with a printed grid on paper. I thought it might have been a good system but the cost of a pad of traps was more than I could justify and the thought of replacing the traps after every two or three rounds wasn't encouraging. Also, I had my doubts that the distance would hold constant after fiddling with it every few rounds. Had to wait another 25 years...
Enter the Chrony F1 Master. Soon's I got it one modified it to access the additional firmware features. Been pretty effective, but you get what you pay for. Helps to have a black Sharpie for the bullets. Darkened projectiles make it more sensitive.
Comment