chronograph for load developement ?

[jackieschmidt]

OK took me awhile to find the data , I did this test several years ago and I did not mark the notes well . On the bright side I found the case volume test regarding my earlier post which I'll update







Now for the results

Pulled in hard and tight to the shoulder 2559fps avg ES-65.52 / SD- 28.60

Letting the rifle free recoil ( only touched the rifle to pull the trigger ) then catch it as it recoiled 2556fps avg ES-14.5 / SD 5.47

This is using the same rifle , same ammo in the same conditions fired 20min apart to let the barrel cool . FWIW this was from a well fouled barrel . This was a limited test but IMHO clearly shows how you hold the rifle effects velocity . Other then the obvious the other interesting part I thought was the avg velocities where the same but the ES/SD was all over the place on the group that I held the rifle tight .

How did this change my rifle hold , I don't hold it tight in any way . I don't let it free recoil either but I do allow the rifle to recoil rearward a tad when fired . Instead of being tight to the shoulder it's barely touching and this has dropped my ES/SD on the whole but did take some practice to shoot well . Again this is with my heavy target rifles I WOULD NOT shoot my Ruger american rifle the same way or any light rifle with a heavy recoiling cartridge , I recommend you still pull those in tight to your shoulder .

Or perhaps the first five were simply how those five cases/bullet/primer performed, and the second five were simply how those performed. Your real numbers are perhaps the average of the two.

I find it rather far fetched to say that internal ballistics are somehow governed by the way you hold a rifle.

 

[Metal God]

I don’t because my ES/SD were never as bad as they were when I held yhe rifle tight to yhe shoulder which was more then I ever had before .

There’s seversl guys saying this is true . Problem is most shooters don’t run chrono test that have wildly differing holds , why would you ? If you want consistency you need to be consistent.

Yes my test was limited but over time and my ES/SD as a whole being lower and more consistent sinces I’ve changed the way I shoot .

The thing is , this is sn easy test for anyone to test them selves . It only takes 10 or 20 rounds and an honest effort . It’s not rocket science or take any extra tools , time or really effort at you next range trip .

I’ve posted my results many times on forums and asked other to give it a try . Not sure why but nobody to date has tried or if they did chose not to report there results .

This thread may have actually been talking about one of mine
http://forum.accurateshooter.com/threads/tight-hold-vs-velocity.3903806/

 

[rebs]

OK took me awhile to find the data , I did this test several years ago and I did not mark the notes well . On the bright side I found the case volume test regarding my earlier post which I'll update .

In general I was having problems with high-ish Extreme spread / Standard deviations (ES/SD) for quite awhile . I'd keep seeing guys talking about there single digit SD and it never happened for me . I could get into the teens , sometimes low teens but never single digits . I always believed my case prep and loading consistency was above average so I was having a hard time thinking this was my problem .

Also during this time which was over a several year period I'd here guys say how you hold your rifle can effect velocities ??? I never gave it much thought either way but it was in the back of my mind none the less . I'm not a bench rest guy I shoot factory rifles from a front bag or bipod and rear bag . I hold/interact with my firearms when firing so the more I thought about it it started making more sense that how I hold the rifle could effect velocities .

One day at the range I decided to run a test with some loads that I considered some of my most accurate to date . These where all loaded from the same lot components on the same day/session and transported in the same container to the range . Every round was as equal as I could make them .

The test was a simple one all be it limited . I'd run two 5 shot test through the chrono one with a very hard/tight grip on the rifle pulled into the shoulder .The other would be firing the gun with out holding it at all and letting it free recoil . DO NOT TRY THIS TEST IT CAN BE DANGEROUS ! I was able to do this because I was using a 15lb rifle with a muzzle brake . It was somewhat easy to control after firing . A light rifle would likely go flying .

Now for the results

Pulled in hard and tight to the shoulder 2559fps avg ES-65.52 / SD- 28.60

Letting the rifle free recoil ( only touched the rifle to pull the trigger ) then catch it as it recoiled 2556fps avg ES-14.5 / SD 5.47

This is using the same rifle , same ammo in the same conditions fired 20min apart to let the barrel cool . FWIW this was from a well fouled barrel . This was a limited test but IMHO clearly shows how you hold the rifle effects velocity . Other then the obvious the other interesting part I thought was the avg velocities where the same but the ES/SD was all over the place on the group that I held the rifle tight .

How did this change my rifle hold , I don't hold it tight in any way . I don't let it free recoil either but I do allow the rifle to recoil rearward a tad when fired . Instead of being tight to the shoulder it's barely touching and this has dropped my ES/SD on the whole but did take some practice to shoot well . Again this is with my heavy target rifles I WOULD NOT shoot my Ruger american rifle the same way or any light rifle with a heavy recoiling cartridge , I recommend you still pull those in tight to your shoulder .

Thank you for the detailed information. Some guys at our club's 300 F class mach shoot free recoil. Now I understand why. I m going to try it with my 223 rifle