Jump Test Results

[Petros284]

I thought I would share this with all of you. In doing a jump test with my Dasher I have an example of text book results. I took my optimal load and loaded three rounds of various seating depths with the 105 hybrid. I started with 0 ( touching) and worked out in .005" increments to .025" off. I found that it really likes the .025" off load. As you will see on the target is starts to really tighten up at .020" off. I would like to try .030" but I am happy with what I have. I could have taken it out further, but I believe this tells me what I need to know. It is funny what just some fine tuning will do to tighten everything up and make it "hum".

 

[mr45man]

Thanks for sharing
Have you tried from 0 to increased jam?
John H.

 

[Petros284]

That is the next test, but with what I am seeing at .025" I am going to go with it. I will do it sometime just to see it on paper and share.

 

[snakepit]

That is the next test, but with what I am seeing at .025" I am going to go with it. I will do it sometime just to see it on paper and share.

My results with the Berger 105 Hybrid is very similar to yours but using a 6BR. I have found jumping .025 and .030 to be about the same.

 

[Lapua40X]

I have had almost identical results with my 6BR seating the 107gr Sierra Match Kings at .020 off the lands.

 

[lrgoodger]

When I get results like that, I do the test again, sometimes twice, especially with 3 shot groups, just to make sure it is repeatable. I've had too many tests that looked good the first time around produce entirely different results on the next run.

 

[BoydAllen]

Thanks for sharing. I know that it would take some time, but for strictly academic purposes, I think that it would be interesting to keep going and see if things come together at a longer jump, perhaps .050. Some time back, a friend told me that seating depth has nodes, both going longer than touch, and jumping. The other issue that might make it interesting is to determine the length of the seating depth node, what the limits of a particular node are. Back in the day, I did a little rough testing of seating depth with a custom 6PPC. The thing that I notices was that my jump groups were more regular in shape than my groups loaded into the rifling, but that the ones that were into the rifling, while not as consistent, were slightly smaller. In this test, the largest groups were mid .2s, and the smallest high 1s.

 

[Petros284]

This load has been a lazer, and I will definitely be doing a more complete jump test after the F-natls/Worlds. I was just doing some tweaking since the dasher is my "back-up" rifle to my .284. (The .284 just happens to be giving me fits right now with the load/new barrel. Due to the issues the .284 is having, I may have to go with the Dasher and shoot against the big guns.) I generally do 5 shot groups as well to eliminate that error point. I will share it with you once I get a chance. I will try even a longer jump and jamming, and will take it out to 2-300 yards to see what happens.

 

[Erik Cortina]

This load has been a lazer, and I will definitely be doing a more complete jump test after the F-natls/Worlds. I was just doing some tweaking since the dasher is my "back-up" rifle to my .284. (The .284 just happens to be giving me fits right now with the load/new barrel. Due to the issues the .284 is having, I may have to go with the Dasher and shoot against the big guns.) I generally do 5 shot groups as well to eliminate that error point. I will share it with you once I get a chance. I will try even a longer jump and jamming, and will take it out to 2-300 yards to see what happens.

I hope you don't have to rely on your "backup" gun, as Raton can be brutal even to the Magnums.

See you in Raton!

 

[Petros284]

See you there Erik. It has been a couple of years! last time I saw you was there at the SOA's I believe in 2010. Looking forward to it!

That Dasher has held it's own against the big guns, it has surprised me quite a bit, but you are right...it is Raton! I have other options, but this .284 has been driving me crazy. I should have it settled in by the weekend, then it will be one super long load session!

Have a safe trip and see you on the line.

Pete Petros

 

[expiper]

Pete,,,,accuracy "trumps" everything !!!!,,,and the Dasher (6mm's) have it,,,,when the wind blows lots of shooters rely on BC to save their poor wind reading ability,,,(nuthin wrong with BC) ,,,in the wind its the shooter ,not the rifle , that does the winning,,,,Roger
PS,,,your seating depth findings are typical ,,,it seems to me as the bullets get heavier and the powder get slower ,,a lil jump of .020-.040 works good,((I like to use ~.020" and then as the bbl throat wears you still are in the window)),but in all cases we have to let the gun tell us what it likes,,,and yours is shouting at you,,,and you are smart enuff to listen,,,good luk at Raton...wish I wuz there,,,I can hardly lay down and/or and get up off the ground,,,grrrr,,,

 

[Erik Cortina]

expiper, accuracy only gets you so far. There will be 300+ of the best shooters in the World in Raton, and I doubt any of them will be using a Dasher (or 6mm for that matter) as their main gun.

 

[Down South]

expiper, accuracy only gets you so far. There will be 300+ of the best shooters in the World in Raton, and I doubt any of them will be using a Dasher (or 6mm for that matter) as their main gun.

I agree, its hard to run with the big dogs at 1000 with a 6mm no matter how accurate it is.

Back to the jump topic, last weekend i was shooting the new FTR rig with the barrel setup for the 230s with a loooong throat. I loaded some 185 juggernauts with N-150 just to run some rounds down the barrel, no load developement at all, just threw 43 gr in the case cause it sounded good and shot it......lol...... It was jumping .110 to the lands and it shot a group that measured .489 for 10 shots off the bipod.......lol.......Looks like it doesn't mind the big jump.

 

[expiper]

HI Eric,,,haah,,,I know all about wind and BC and I agree accuracy only takes us so far,,,usually to the winners circle,,!!! wink,,,,,If an experienced wind reader shoots a more accurate gun ,,,he is hard to beat,,,good luk to you also at Raton,,,keep us posted,,,Roger
PS...I know a lot about "wind" and there is a lot of it on the internet,,hahahah

 

[Petros284]

Didn't mean to get this debate going...Better to have a great shooting 6mm than a 7mm that is not tuned. Just nice to have on hand as an extra. If it is a calm day (like that will happen) I may give it a shot in the individuals.
I just hate having the 7mm not tuned this close to the match...
I have never seen anything like this.

Funny how much jump can surprise you. I remember everybody saying you had to jam or touch the VLD's. My last .284 loved them jumped .020".

In my book jump testing is as important as the powder charge test.

 

[jsthntn247]

Petros When you found your ocw load for the 105's what was your seating dept( jam or jump)?

 

[Petros284]

When I found the OCW charge weight I was at .020" Jump. With the Hybrids I start with a jump initially. So I was pretty close with the starting seating depth.

 

[falconpilot]

Pete,

Try them at .050 jump. You'll get surprised!

Jim

 

[savageshooter86]

curious have you shot the OCW load window again since changing the seating depth that much? I am under the impression the OCW window will have moved slightly. And with a shooter/rifle shooting that well it would be nice to hear your results

 

[BoydAllen]

When you get around to testing longer than touching, you might consider an alternative procedure, I think that .005 changes are way too coarse, for a test in this area, but that should not be a problem since the distance between touching and jam (classic old school benchrest definition) is rather limited, I suggest .002. I also do my preliminary testing shooting two shots as fast as I can reliably do so, on the theory that this increases the probability of their being shot in the same condition, and the knowledge that if two shots look ugly, that adding more will not improve that. After I have done the first run, I go to more shots per group at the length(s) that looks the most promising. Of course all of this is facilitated by loading at the range, which is pretty much the method that I use to work up loads for any application, because it is so much more efficient.