Seating Depth Testing: Round Robin or All At Once?

[Tim Singleton]

Yeah, but would probably be cooler "Round Robin Tactical"..

Precision Round Robin
PRR!

 

[Dusty Stevens]

Practical round robin marksmanship series.

 

[Tim Singleton]

Practical round robin marksmanship series.

Awesome!

 

[Dusty Stevens]

Awesome!

Sounds like a playground game you play right after red rover

 

[Fotheringill]

The Berger method works well.

 

[dcali]

Round robin isn't a good idea when shooting groups. Adds too many unhelpful variables with only dubious theoretical benefits.

 

[Fotheringill]

The whole Berger method with its very large spread of .040 for each group of six shots is based upon the fact that one of the groups, no matter what the charge used for all, is going to be significantly better than the other groups. Still, without changing the charge, refine your depth spreads. You will get there after three or so range sessions. I found that using the median charge for all of the testing and keeping to that weight, gave me the most reliable results. THEN, I started to refine the charge weight to get my best charge with keeping the best seating depth. So far, it has worked for me.

I would recommend shooting either in a calm or light, consistent wind for these tests.

 

[dsculley]

Round robin will spread changing conditions across all groups so one group will not be more adversely affected than another. Shooting the Berger test at 100 yds I have done it both ways with good results, but I always wait for good shooting weather. The Berger test calls for 5 shots per depth, I usually just do 3. A small group will not get any smaller with 2 more rounds and a large group will only get larger.

I prefer to find my seating depth with this test, then test for powder charge. Once i find my powder charge I will test around this area to find my best seating depth.

 

[X-Caveman]

When I know I'm close I like to run the test twice. Once RR, once as groups, but always at the same POA with ogives colored to tell what's what. It gives me more data to be unable to decipher.

Seriously, tho... as I dig deeper into this rabbit hole, I'm starting to become a believer that the smallest groups in good conditions don't necessarily translate into the best condition beating loads or match scores. We don't shoot groups and rarely have good conditions, so i'll gladly give up little raw accuracy (in fantasy land) for better consistency across conditions (reality).

 

[T-shooter]

I think round robin is a better way. As "dsculley" said, it spreads changes across all the groups like temperature changes, barrel temp, carbon or copper buildup, and the shooter getting tired, plus makes you re-setup each shot. I think 5 shots are better than 3 and if you find a group that is good, confirm it with at least 10 with time to cool the barrel in between. Also it would be a good idea to have an extra round in each category in case you know you pulled a shot and can re-shoot it.

Weird things happen when firing only 2-3 rounds. I fired the 6 shots below at 215 yards. I don't remember what order but they made 3 touching pairs. Why???

 

[bsekf]

With a hunting rifle. After I "think" I have all my ducks in a row and have settled on a charge and seating depth. Then I shoot a cold dirty barrel group over several days. And, sometimes it's "back to the drawing board"! What do you find?

 

[dmoran]

Round robin isn't a good idea when shooting groups. Adds too many unhelpful variables with only dubious theoretical benefits.

Many 1000-BR competitors that I know will disagree with you on that. Round robin testing does a fairer job of equalizing effecting variables across all the increments. Besides ambient variables, aspects such as barrel heat and barrel fouling are other variables that get spread across the increments more equally when utilizing round robin strings into testing/development.

Having done it both ways (several years of each method), for me the round robin method has proven itself to be superior to most scenario's.

 

[Winny94]

I only had time for some foulers, a quick pressure check, and 1 round of depth testing. Was surprised the result was so obvious. Hoping the next round confirms

 

[dolek]

Regarding a seating depth test ,to me the tighest group wins . That shows what that particular depth is capable of in the best scenario . Anything after that you know something is off if you can not reproduce that same size group.

 

[Dusty Stevens]

I only had time for some foulers, a quick pressure check, and 1 round of depth testing. Was surprised the result was so obvious. Hoping the next round confirms

Looks like the wind finally got in your favor on the third group at .090. You need a bit more powder then see if it repeats (dont think it will). .010 with a touch more powder and wind flags is a good starting point. Looks like .090 is your next step

 

[chop house]

at 200 over the hood of a pu . Close enough

well, if'n your jus' road huntin' mebbe. howzit do offa hay bale?

(you know i;m just poking you, right?)

 

[dgeesaman]

I don't understand this "Round Robin" approach...what can be learned from introducing all the extra variables ?

I've seen it used on the OCW load development process, which 'reads' the charge ladder target based on the position of the group centers not the size of the groups.

During that first charge ladder the center of the groups is more comparable if you spread the conditions out equally across all groups.

After that, normal group shooting works to finish refining the load.

 

[Alex Wheeler]

Typical long range 3 shot ladders are usually 12-15 shots. They are run as a group. Probably takes about 30 seconds. Whether you shoot them as groups or as round robin, it still only takes about 30 seconds or less. I would not shoot multiple groups over a time period round robin.

 

[mjl650]

I just got into long range shooting as well as reloading my own. Lot's of great info in this thread, my head is spinning but I'll get it figured out and enjoy doing it.

 

[dsculley]

If the op's test was shot at 100 yds as I suspect then I doubt the wind is the culprit in the horizontal spread at 0.010". The vertical is about the same at 0.010" & 0.090". I would expect that a good load could be developed at either one of these seating depths. There is no information about the rifle or the use of the round, but if feeding from a magazine is an issue then 0.090" may be the better choice. If there are no magazine restrictions then it is up to the shooter. In this scenario I would probably test both seating depths to see how they develop, but I would be surprised if both were not more than adequate.