OK, 'bout time for a chronograph

[Bart B.]

Never used a chronograph to develop any loads. The only way they show precise and useful data for velocity data is when the barreled action in clamped in a fixed mount. Free recoiling rifles are almost as good and shouldered rifles are even less precise as their recoil subtracts their velocity from that of the bullet.

Loaded ammo for two 22 caliber, one 24 caliber, two 26 caliber, one 27, two 28, four 30, one 31, two 32 and one 35 caliber rifle. Very good accuracy with all. Only worked up loads for one 26 caliber and one 30 caliber for a new bullet no data existed for. All without a chronograph. Sight dope showed their velocities were within 100 fps of predicted speeds. Good enough for me.

 

[Gtscotty]

Never used a chronograph to develop any loads. The only way they show precise and useful data for velocity data is when the barreled action in clamped in a fixed mount. Free recoiling rifles are almost as good and shouldered rifles are even less precise as their recoil subtracts their velocity from that of the bullet.

How is knowing that the load your working on shoots 2700 fps instead of 2500 fps not useful? How is knowing that your ES with one load is 20, while another is 100 not useful? Not everyone only shoots Sierra bullets out of match .308 Win chambers. If you want to experiment with different chamberings, or new powders, or new bullets it's not critical to have a Chrono, but it is useful.

 

[JimKirk]

It's my opinion there us no need to use such a precise chronograph as the Ohler P35. There us always a chance if shooting if which will be expensive.

Several years ago I bought a PACT Model 1 XP and I like it. The chronograph works sit safely on the bench next to you while only the sensors are out in harms way. When you shoot the sensor it's only a $29 repair in parts.

If you want to spend more than $109 you can buy the PACT Pro XP and the printer for a paper readout at the range.

This is the same type as I have ... the brains all set on the bench and just the sensors are near the line of fire ... if I shoot one it is a few bucks ...unlike some of the other ones that everything sets in the line of fire .... it is not a matter of if they will get shot ... it is a when ....

 

[murf]

chronys are useful. chronys are not necessary for working up accurate loads. chronys help diagnose over pressure problems. low extreme spreads and standard deviations don't guarantee an accurate load (holes in paper guarantee an accurate load).

i've had my shooting chrony for over 15 years and use it all the time when working up loads.

murf

 

[The_Next_Generation]

Never seen any need for a chronograph in 40 years of reloading.

Sure, you could develop a drop chart based on data you gather on your own in various atmospheric conditions, but its pretty tough to beat a good ballistic calculator with reliable BC and velocity data. In my experience, a chronograph is an absolute necessity for anyone wishing to shoot long-range on non-square ranges. I have one of those cheaper "Chrony" units...so far it has worked ok.

The magnetospeed sporter seems like a good unit, without the price tag of the LabRadar. The downside is that you wouldn't really be able to shoot for groups with it attached to the end of your barrel as it would interfere with its harmonics. You'd have to shoot for velocity first, then pull it off and shoot the groups. I guess it wouldn't be so bad if you shot groups first, then picked the most accurate load and chrono'd that.

 

[Bart B.]

Anything attached to the muzzle will change the barrel fundamental and harmonics thereof.

If it's the right weight and in the right place, the barrel vibrations at the muzzle may change favorably and bullets will exit at the right place on its up swing shooting slower ones at a slightly greater angle and compensate for their greater drop at target range

 

[The_Next_Generation]

Anything attached to the muzzle will change the barrel fundamental and harmonics thereof.

If it's the right weight and in the right place, the barrel vibrations at the muzzle may change favorably and bullets will exit at the right place on its up swing shooting slower ones at a slightly greater angle and compensate for their greater drop at target range

I'm glad we agree on the harmonic issue posed by the magnetospeed product.

With regard to compensating for drop through harmonic tuning, is that really something that is done? I respect your credentials, but on the surface this sounds impractical. I agree that it could be done, but why would anyone want to spend the time and ammo on such an endeavor when there are better solutions available - like canted scope bases, or sights with larger adjustment ranges.

Edit: Because I never get anything right on the first try...

 

[The_Next_Generation]

I'm glad we agree on the harmonic issue posed by the magnetospeed product.

With regard to compensating for drop through harmonic tuning, is that really something that is done? I respect your credentials, but on the surface this sounds impractical. I agree that it could be done, but why would anyone want to spend the time and ammo on such an endeavor when there are better solutions available - like canted scope bases, or sights with larger adjustment ranges.

Edit: Because I never get anything right on the first try...

Besides, isn't the point of developing a load for a rifle to get a node to be located at the end of the barrel? Not to have an antinode there?

ETA: Whoops, hit reply instead of edit...was trying to add the above paragraph to my previous post.

 

[Bart B.]

If a vibration node (place that doesn't wiggle) could be at the muzzle, the bore axis there would still point at different angles because all bullets fired don't spend the same amount of time in the barrel. Besides, there will never be a node at the muzzle.

First article published in 1901 on barrel vibrations compensating for bullet drop:

https://archive.org/details/philtrans05900167

Modern info on how barrels whip and the use of barrel tuners:

http://www.varmintal.com/atune.htm

http://www.varmintal.com/aeste.htm

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/modelling_barrel_vibrations.htm

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm

Anything that adds weight to or puts pressure on the barrel changes its vibrating frequencies. One was scopes with external adjustments (Unertl, Lyman, Fecker and others) and if not repositioned the same way after each shot, bullets went somewhere besides point of aim. Internally adjustments on good scopes attached to the receiver only fixed that problem.

Another was Remington's infamous tuning screws on their 40X rifles contacting the barrel near the stock fore end tip at 45 degree angles at each side; smart competitors backed them out clear of the barrel for best accuracy.

Neither of these systems were firmly attached to the barrel.

 

[Reloadron]

The subject of barrel vibration and barrel harmonics has been beat to death before:

Forced vibration as it relates to firearme accuracy. The High Road

Point of Impact Changes With Different Loads. The High Road

Those are but a few of the many threads on the subject. That said the thread title is "OK, 'bout time for a chronograph" which has been somehow lost. Yes, if we go hanging things, any things, off the end of the barrel the point of impact is likely to change. That is really all that needs said in keeping with the subject of the original thread which seems to be drifting off topic.

Ron

 

[The_Next_Generation]

If a vibration node (place that doesn't wiggle) could be at the muzzle, the bore axis there would still point at different angles because all bullets fired don't spend the same amount of time in the barrel. Besides, there will never be a node at the muzzle.

Ah, now I see what you're talking about. Thank you for the links!

Reloadron, sorry for the drifting...

In summary for the OP: The magnetospeed units are popular and accurate, but they will change how your barrel vibrates and therefore may effect your groups. Personally, I'd still choose it over the LabRadar unit. Yes, the LabRadar uses some cool tech, but I have to hike my gear in to my shooting spot. The magnetospeed definitely has the size/weight advantage.

 

[RussellC]

Well, I consider the magnetospeed a viable candidate, but some saying it doesnt work with some railess guns, or compact Glocks with short rails sort of leads me back to Labradar,
Lots of info out there and thanks for all given here.

Russellc

 

[cfullgraf]

I have a Magnetospeed V2 and it does not have the rail capabilities of the newer unit. My version Magnetospeed only works with certain long barrel handguns. Even so, I elected to get a LabRadar because the Magnetospeed upgrade still did not work with many of my handguns.

With my rifles, the target information gained while shooting with the Magnetospeed bayonet in place was still useful but not final. I did find the point of impact moved some with and without the bayonet.