Magnetospeed improves groups. What the heck?

[CTK]

I am no expert shooter or reloader. This may be anecdotal but I have now witnessed this phenomenon too many times to be a coincidence. I reload for accuracy in hunting rifles. I use a magnetospeed sporter for bullet speed info. I do not fire a string of Magnetospeed shots for each load. I waste one shot for each powder step to get an approximate speed for the load. I usually dump all of the Magnetospeed shots into one target. I bought a discontinued Sako A7 270 Win. last weekend and ended up giving it to a friend. I bought some standard RCBS dies, Hornady Brass and 130 Barnes TTSX bullets to get started on loading for my friend's new hunting rifle. Loaded some up last night and took the rifle to the range today. I approximated a barrel break in procedure and cleaned the rifle frequently. I shot approximately 10 groups as I stepped up in charge weight. All of my loads were the same seating depth. The best groups fired were at starting load range and near max load. Best groups today were .75"ish. POI for the different powder load groups shifted approximately 1.5". As I said earlier, I shoot one shot per load with the Magnetospeed and dump the shot into one target. My Magnetospeed target tonight had 8 or 9 shots clustered into less than 1". I have seen this happen several with other rifles. The Magnetospeed seems to tame the POI shift of different powder charges and bullet weights. I have previously seen different type and weight bullets group very tightly in my Magnetospeed dump target. All of my rifles have sporter weight barrels as did the rifle today. I am very curious if others have experienced this phenomenon. The last time I saw this happen, I bought one of the 20 dollar rubber doughnut barrel "tuners". It did not fit well on my barrel and I never really gave it an honest try.

 

[elkaholic]

Ive seen my magneto speed tighten groups before as well. I think whats going on is it changes the harmonics on a barrel/load combo enough to correct for a load thats not so good. The answer, I believe, is tune the load to the barrel with out the mag speed and forget about whether the groups are good or not with it on. If you haven't found a load that shoots as well with it off, you probably havent tested enough

 

[dok7mm]

What Rich said.

 

[CTK]

Ive seen my magneto speed tighten groups before as well. I think whats going on is it changes the harmonics on a barrel/load combo enough to correct for a load thats not so good. The answer, I believe, is tune the load to the barrel with out the mag speed and forget about whether the groups are good or not with it on. If you haven't found a load that shoots as well with it off, you probably havent tested enough

Completely agree. Not planning on hunting with the Magnetospeed dangling off the barrel. Just intrigued by the fact that it tightens the poi spread of different bullet and powder loads.

 

[B-LOT Banga]

I'm thinking it helps to dampen the vibration or slow down barrel whip. I wonder if a suppressor does the same?

 

[CTK]

I remember reading an article that debunked the Limbsaver doughnut. It is a PITA to get a light barreled rifle to shoot in the .25" range at 100y. I still may try the doughnut Some time.