Firearm BS thread

We have some pretty cool bipods called Swagger. They move with the user.

 

If you are just using it for accuracy yes, but if you are trying to keep them subsonic, the actual speed is very important. I have always wondered about these chronos that you mount on the end of the barrel. Are you sure it's reading the speed of the bullet, and not the speed of gasses coming out of the barrel?

 

A sonic crack will happen past 1100-1130 fps regardless of what the speed the chrono displays....

 

It’s magnetic so I’m sure the gases don’t effect it.

Yes, and if your Chrono isn’t acccurate you may have a load that is subsonic in some weather and super in some weather, the point of having an accurate chrono is to keep that from happening.

 

Actually the sonic crack can happen at even slower speeds if it's real cold outside. The speed of sound ranges from 1004 fps at -40F all the way up to 1160 fps at 100F. Working up subsonic loads based only on hearing the crack is very difficult. The sonic crack of a bullet going just over the speed of sound can be hard to pick up, it's not very loud. In some settings it is very noticeable, but in others it can be easily missed.

 

Maybe those operate differently, but mine (the old fashion kind) specifically said in the instructions not to have it too close to the end of the barrel for just that reason.

 

Unless you are shooting subs without a can (why bother), a sonic crack is obnoxiously loud.

 

Maybe my hearing sucks, but there are times when I've had a hard time telling if there was a crack or not. And yes, I'm shooting with a can. Many times, yes, it's very obvious, but other times not so much. I don't know if its the wind, or other factors, but there are times when the sonic crack is not near as obvious.

 

Do your conditions change like sometimes you’re in an open field, and then at a range where there are walls and trees and such?

 

Yes. Well never at an actual range, but lots of different situations. Some in very open flat areas, others with hills and trees close. It also seems to make a difference how close the target is. Close targets are harder to hear the crack. I think it's because the bullet travels less distance, therefore making a much shorter sonic boom, and the sound of the bullet impacting the target is louder and covers up the sound of the crack.

 

The magneto speed chrono's are fairly accurate and and easy way to check your speeds. I have one and first couple times I used it I setup my CED m2 in front of it so I could compare. I tested three guns that day and all the readings were within 10-15fps. I also have access to a lab radar and those three guns are measured close to what my magneto speed gave me.

It does change the POI a little bit but that is easy to adjust for. If the load is going to group it will group with or without the magneto speed on the barrel. I usually test for accuracy before I ever test for speed. Once I find a load that groups for the application I plan on using it for then I will chrono it to make sure it is where I think it should be.
Love the magneto speed as I can use it during a match to get a much better ES and SD and in real time conditions. At 500/600 yards the POI is changed at most of 3/4moa.

 

I thought that (bolded) was the typical way of doing it?
GolfIndia’s post made me wonder why he tests groups and velocity at the same time.

 

That is how I was taught but some people like to do both at the same time. In case you can't get out and shoot that much it would make it a tad quicker. I prefer just seeing what the gun/load can do on paper first.

 

Whether it’s the sound of gunfire or a sonic boom, the results are relatively the same as far as sound being throwing down range and obviously in the varying conditions, objects will throw sound back at you. Where the lack of it will dissipate in the air no matter which sound it is. I have shot in conditions where I had a forest 600 yards down range throw all the sound back at me as if I had a wall behind my target and in other open field conditions had the sound swallowed up like I had a sub par round.

 

I have had the unique opportunity In being directly down range opposing the shooter in which I got to experience The sonic boom without having to hear the rifle blast which usually masked the sonic boom when being the shooter. It was quite a unique experience to get the hair that and that alone.

 

I don't really care what the speed is if a particular load doesn't group. So then why do it all twice? I can look in a load data book and ballpark the speed.

 

I completely agree for precision loads. Grouping is everything. I use the chrono after I get the load I like, mostly out of curiosity. With those speed is pretty much irrelevant. Knowing the speed however does give you a head start on working up a good range card.

When I'm working up subs (subsonic loads) I get the speed right first, and then fine tune for accuracy. Continuing to check the speed as I go to make sure it is still within the acceptable range. I'm usually not looking to shoot subs out much past 100 yards, so gnats ass accuracy with those isn't all that important.

I also look at the speed early on with self defense handgun loads. Other things are also important with those, like reliability and low flash. Accuracy is down the priority list a little with those.

 

Handguard project for my VEPR. Just applied some stain.

 

I can’t wait to shoot this thing.