Consistent Accurate Bullet Seating Depth

[Webster]

I think that some of the discussions in the several forums get kind of confusing because of one basic reason. In the Reloading Forum you have hunters, casaual benchrest shooters and serious competitors making comments. It's like someone that drives a Corvette on the street sharing driving techniques and engine building with a Formula one driver.

 

[normmatzen]

I think Boyd had the answer.

I used a Forster precision seater for my old 243 WIN BR gun. Had a problem with the spring and the spring pressure was modulating the seat depth. Changed spring and problem went away.

Now I have a Redding seater for my 6BRX and didn't like the directions to leave clearance between shell holder and barrel of seater as this gap tolerance controls seating depth.

I use a LEE press which does not cam-over. I adjust the die to allow the shell holder to depress the barrel to just touch. Seating depth variations are now a thing of the past!

 

[BoydAllen]

Norm,
On the Redding, your shell holder is just touching the die body, the part that threads into the press? Just want to be clear, since it is working well for you.
Boyd

 

[Steve Blair]

Boyd, [br]
Both of your points about reloading equipment simplicity and accuracy factor weighting are well taken. What is required is a very accurate rifle, consistent technique and careful attention to external factors to evaluate reloading effects. That said; Years ago, I was not consistently hitting 5" circles at 1000 yards. The cumulative benefit of excellent barrels, actions, stocks, rests, technique, wind doping and all that we have learned about assembling ammunition has made this possible. The process that we undertake when seeking ultimate accuracy is exactly analogous to manufacturing Quality Assurance. The goal is to engage in a process of continuous improvement, reducing variability and designing experiments that will prove effectiveness of a specific procedure. If we do not manage to isolate each factor when evaluating, it becomes very difficult to determine effect. It would be great if we all had access to tunnels with machine rests, but we must make do with what we have. That includes dealing with the environment. Here in the Southwest, calm days are not common and wind flags are mandatory if valid, repeatable results are expected. [br]
My testing has shown me that seating depth can be very important to both grouping and velocity spread. I use Bob Green's tools in calibers 6mm, 7mm and .308. For my type of shooting, I am satisfied that his tools have produced a provable improvement. That may not be true for another discipline.

 

[BoydAllen]

I find nothing to disagree with in what you have written. The method that I described in an earlier post allows a shooter who is curious, and on a budget, to find out something about his bullets that might have otherwise gone unnoticed. It accomplishes the same thing that Bob's gauge does, in a more labor intensive manner, to establish that there is something that is measurable to be concerned with. The advantage to his gauge and that method is that one can avoid assembling ammo with bullets that will have different seating depths, relative to the rifling. In any case, we can still sort with an attachment to calipers that allows us to measure from where the rifling would touch to the case head, and if there are differences, group like with like, to be shot within the same group. Personally, I have not done enough of this sort of quality control, not because it takes too much time, but simply because I become so preoccupied with other things that I forget. I will have to put a note in my range data book as a reminder, and pack the necessary tool in my range loading kit.

 

[DennisH]

Gentlemen you cannot nor never will have consistent bullet seating depth unless you have consistent neck tension, you won't have consistent neck tension unless you anneal, sort brass, brush necks, properly fitted to your chamber f/l sizing die, etc,etc,etc.
The above is a fact. I started paying attention to neck tension and brass prep. I am definetly getting consistant Seating Depth measurements now. If I seat one that's a little harded to seat, I check it and its always a few thou longer! I put it to the side and keep going.

I know the orginal subject is "Accurate Bullet Seating Depth"

As I stated earlier and after loading 30 rounds today, my neck tension was very consistant, and most of all, I did not put any bullets to the side. All were within >.001 COAL after seating!

I'm sold on proper brass prep as stated above!

Dennis

PS: Now I am going to see if they shoot!

 

[jcinsa]

Consistent Accurate Bullet Seating Depth

Thanks very much for the discussion, I've got plenty to consider now.

I'm shooting F Class, shooting a 308 with 155gn HBC projectiles.

I completely agree with Russ :

'So Step one.
Get a load that shoots 1/2MOA elevation at the distance your shooting at.
Step two.
Learn how to shoot and read the wind.
Step three
More shooting less tinkering.'

With different barrels I have achieved different levels of accuracy - to be expected.

I'm very particular about my whole reloading process ( I don't anneal ), and just wanted to improve seating depth consistency as much as possible.

Because it was something I could easily measure, and I hope that it will improve elevation.

Everbody's comments are very much appreciated.

Thanks, John

 

[ThunderDownUnder]

Does .002" seating depth variation matters?
Yes.

Do I achieve .000" variation in seating depth?
Yes.

Does it matter where your measuring tools contact the ogive?
Yes.

Does .000" variation help with accuracy?
No, it helps with consistency. If your gun is not properly tuned consistent seating depth will not make gun more accurate, but if your gun is tuned, it will shoot tighter with no flyers.

How can some shooters do so well without obtaining .000" seating depth consistency?
They might have perfect ammo, but their measuring tool is measuring at the wrong place. Also, this is where "good" bullet lots and "bad" bullet lots come into play.

Hi Erik, With respect what statistical data based on testing do you have to support your statement that 0.002" seating depth variance matters????

Its easy to make unsubstantiated statements and word them like they are facts. Its another matter providing the data you have based this "fact" on.

If your jumping a bullet 20+ thou then the measured 2 thou variance means nothing, based on my personal experience!

Ian

 

[bozo699]

Does .002" seating depth variation matters?
Yes.

Do I achieve .000" variation in seating depth?
Yes.

Does it matter where your measuring tools contact the ogive?
Yes.

Does .000" variation help with accuracy?
No, it helps with consistency. If your gun is not properly tuned consistent seating depth will not make gun more accurate, but if your gun is tuned, it will shoot tighter with no flyers.

How can some shooters do so well without obtaining .000" seating depth consistency?
They might have perfect ammo, but their measuring tool is measuring at the wrong place. Also, this is where "good" bullet lots and "bad" bullet lots come into play.

Hi Erik, With respect what statistical data based on testing do you have to support your statement that 0.002" seating depth variance matters????

Its easy to make unsubstantiated statements and word them like they are facts. Its another matter providing the data you have based this "fact" on.

If your jumping a bullet 20+ thou then the measured 2 thou variance means nothing, based on my personal experience!

Ian

Ian,
What makes you think Erik hasn't tested his statements, I would imagine he has myself.
Wayne.

 

[Steve Blair]

Hi Erik, With respect what statistical data based on testing do you have to support your statement that 0.002" seating depth variance matters? ???

[br]
My experience with Green's tools and sorting is that it reduced the average group size of five 5-shot groups ~11% as compared to unsorted bullets. The sorted cartridge base to ogive as measured with a Sinclair tool was ≤.001" and the unsorted was ~.003". This was shot in a proven .284 Shehane match load with 180 Berger Hybrids where the target distance was .013" off the lands. Additionally, the extreme spread was reduced an average of 2 fps. I also sorted 6mm 105 Hybrids and saw some reduction that I have not quantified. The barrel is new on my 6BR Viper and I've not yet found the right seating depth. [br]
Full disclosure requires that this was not a double blind test. The tester (me) knew which rounds were which but I was trying hard to shoot as well as possible in all groups. An added uncertainty element is that I am a better long range shooter than I am benchrest and all test groups were fired at 100 yards from a bench.

 

[Rtheurer]

Hi Steve

So if your 284 is producing 5 shot groups in the .375 (3/8") area at 100 yards with unsorted bullets and a variation of .003 total ES, after sorting your getting ~11% decrease in group size, that would be an improvment from .375 to .33375? My math skills are something close to a 5th grader's so I may have computed that incorrectly. Ha! With a 2fps less ES.

Like Erik mentioned its probably more important to Consistant ammo than actual group size... That makes sense to me. An increase ( or decrease in group) that small for me at least would not be worth the effort. Dont get me wrong I like to tinker and test with the best of them and have done plenty but as time goes by I seem to be doing less and become less worried about small improvments and more about shooting ability. (wind reading and shot execution) When a US National team coach tells you to shoot you better be ready and shoot and it better be X ring elevation.

Thanks to all who have posted, this has been a intresting thread. Steve, Allen, Wayne, and Erik Thanks for the input.

RussT

 

[Steve Blair]

I understand, Russ. My problem is that I cannot leave a proven, positive contributing factor off the table. My Shehane was averaging just under .300" 5-shot groups at 100 and is now averaging ~.260". The ES dropped from ~12.5 to 10.5. My target is under 1 MOA at 1000 and I am looking for every advantage I can get. Even if all it did was eliminate unexplained flyers, I would still do it. It actually goes pretty fast and I have seen no difference for bullets sorted into .001" groups and seating depth adjusted accordingly. I still shoot them separately but they go to the same place. So, other than the odd light or heavy bullet, I shoot them all. The attached image shows three groups from that series.

 

[Erik Cortina]

Does .002" seating depth variation matters?
Yes.

Do I achieve .000" variation in seating depth?
Yes.

Does it matter where your measuring tools contact the ogive?
Yes.

Does .000" variation help with accuracy?
No, it helps with consistency. If your gun is not properly tuned consistent seating depth will not make gun more accurate, but if your gun is tuned, it will shoot tighter with no flyers.

How can some shooters do so well without obtaining .000" seating depth consistency?
They might have perfect ammo, but their measuring tool is measuring at the wrong place. Also, this is where "good" bullet lots and "bad" bullet lots come into play.

Hi Erik, With respect what statistical data based on testing do you have to support your statement that 0.002" seating depth variance matters????

Its easy to make unsubstantiated statements and word them like they are facts. Its another matter providing the data you have based this "fact" on.

If your jumping a bullet 20+ thou then the measured 2 thou variance means nothing, based on my personal experience!

Ian

Ian, I believe you just made one!

Ian, those convinced against their will are of the same opinion still. So I'm not going to bother.

But some guys here know that I have my own 1,000 yard range, which allows me to do a lot of testing. I share my findings with guys who ask the right questions, since I have found that if I just share my findings I often encounter resistance from some shooters, so I let them be and help those that I can.

But if it's statistics and facts that you want, here it goes.
3 out of every 4 people make up 75% of the worlds population! ;D

 

[bozo699]

Does .002" seating depth variation matters?
Yes.

Do I achieve .000" variation in seating depth?
Yes.

Does it matter where your measuring tools contact the ogive?
Yes.

Does .000" variation help with accuracy?
No, it helps with consistency. If your gun is not properly tuned consistent seating depth will not make gun more accurate, but if your gun is tuned, it will shoot tighter with no flyers.

How can some shooters do so well without obtaining .000" seating depth consistency?
They might have perfect ammo, but their measuring tool is measuring at the wrong place. Also, this is where "good" bullet lots and "bad" bullet lots come into play.

Hi Erik, With respect what statistical data based on testing do you have to support your statement that 0.002" seating depth variance matters????

Its easy to make unsubstantiated statements and word them like they are facts. Its another matter providing the data you have based this "fact" on.

If your jumping a bullet 20+ thou then the measured 2 thou variance means nothing, based on my personal experience!

Ian

Ian, I believe you just made one!

Ian, those convinced against their will are of the same opinion still. So I'm not going to bother.

But some guys here know that I have my own 1,000 yard range, which allows me to do a lot of testing. I share my findings with guys who ask the right questions, since I have found that if I just share my findings I often encounter resistance from some shooters, so I let them be and help those that I can.

But if it's statistics and facts that you want, here it goes.
3 out of every 4 people make up 75% of the worlds population! ;D

;D
Fact!!
Wayne.

 

[Shynloco]

Boyd,
I am surprised you didn't finish your post! Gentlemen you cannot nor never will have consistent bullet seating depth unless you have consistent neck tension, you won't have consistent neck tension unless you anneal, sort brass, brush necks, properly fitted to your chamber f/l sizing die, etc,etc,etc. There is much more to consistent bullet seating then just your seating die, of course a quality inline die can't hurt
Wayne.

Martin,
Just a couple of comments based upon my own experiences. I've discovered via my own reloading after reading various expert comments and testing those suggestion, that neck tension IS the most important factor AFTER all else has been properly prepped with a casing. By properly I mean the FL resizing, flashhole deburring, primer pocket cleaning and the NECKS TURNED. For me, I use the Wilson Dies/Arbor Press for seating bullets because I can better feel the bullet being seated. (BTW- concentricity measurement with finished loads using the Wilson Seaters provided the least variances in runout of no more that .001.) I can tell (and measure) when I have a hardened casing or an inconsistent neck in terms of tension. As a side note, I tested 25 new Lapua brass pieces (all that were measured and weighed for consistency) and turned those necks and then took another group of 25 new Lapua pieces of brass without turning the necks. Both groups were fireformed and then reloaded. I was surprised by the number of pieces of brass in the unturned neck group that had a variation in neck tension when reloaded. The turned neck group were all consistent and produced the better group on the target when refired. That proved to me that Neck Tension is probably the most inportant factor that produced consistency. Guess it all played into the rule of consistency from start to firing. BTW, I end up turning the necks of the unturned original group and re-fired them and those variances went away, but for a few casing that I'm going to anneal to see if that helps. Just my thoughts.

 

[Nomad47]

I've been to Erik's personal 1000 yard range and I've seen him shoot. I also watched him shoot MY rifle better than I shoot it.
So I will take anything he says to the bank.