A question on seating depth for varmint rifles.

vicvanb
When you seat your bullets keep them long on purpose.Now take your comparator mounted onto a caliper and measure them all into like groups of 0.001 and no more.Adjust your seater for the bullets that need the least amount of additional seating and seat that group.
All of those rounds should come out the same.If they don't those are the ones that have more or less neck tenson a bad chamfer or some other problem.
Doing it this way all of your loaded rounds will fall into a window of 0.003 or less.
The ogive variation on vld bullets is not as good as many would have you believe.
Lynn
 
Have you checked for this variation with other seating dies, a Wilson for instance? Friends have seen more of the variation that you speak of with their Redding competition seaters than with other types. One way to help this is to have the die body just kiss the shell holder. I am aware that this is against directions. The die body is unhardened, so easy does it. I have never gotten good results with my varmint rifles touching, or just off, and I have never pulled a bullet at .006 to .010 longer than touch.
 
Boyd
In another thread on the 1,000 yard forum I tried everything including 3-4 different presses,dies and neck sizes/tensions.
The problem is in the bullets ogive if measured at several different points.Even with the full blown custom vld's at $175 for 300 bullets you will see 0.003 variation.On the larger manufacturers 0.010 -0.015 is common place.
If you use a Wilson type seating stem to measure your loaded rounds the variations will be much smaller but the problem with that approach is your measuring way up on the bullets ogive not were the contact with the barrel is.
On a typical Berger vld bullet if you use a caliper mounted comparator and your getting 0.005 variation even though using the seating stem says all is well you will get trounced at a match.

If you can load up 25 rounds and head to the range to try this test and let me know what happens.
First make sure all of your loaded rounds measure the same length using a seating stem.Now using a comparator for that particular caliber(6mm most likely)sort them into like groups of 0.001 increments without any fudging.Now shoot some groups.
I will predict your seating depth has an optimal spot and that 0.001 on either side will still be okay but 0.002 - 0.003 will cause your vld's to show fliers.
Good Luck
Lynn
 
Interesting reading. I've noticed seating variations too. Since it was cold out I took my box of 500 generic bulk .224 50 gr varmint bullets (SP) and checked length with the Sinclair comparator until I had 50 of the same length (roughly 50 out of a 100+). These measured .297" and the rest measured up to +.006". I weighed the 50 I sorted by length and the weight was 50.1 +/- .2 grs. The distribution was roughly a Bell Curve. These bullets weren't seating to the same length; the seater stem contacts a different point than the comparator. I'll load them the way I sorted them and see how much difference there is now. They've shot less than impressive.

When I measure distance to the lands I typically measure at least 5 out of a box of 100 and average the measurement. If there is much variation I'll add 5 more. I mostly shoot Nosler, Sierra and Hornady and they are pretty consistent. - nhk
 
This is my latest sorting technique.

First I seated a FB bullet in a case base up, slightly above flush. Then I adjusted the stem of a Wilson seater so that when I dropped a bullet in the die, point to seater stem, and the case with the reversed bullet behind it, that the seater stem cap was off the die .020 or so (not critical). With this setup I can measure from where the seater stem contacts that ogive to the base of the bullet, by capturing the assembly between the jaws of a dial caliper, and subtracting the length of the case with the reversed bullet.

Wait, I'm not done yet:D

At this point I make a table with a column for bullet number, one for seater stem contact to base, and another for throat contact point to base. I can measure the latter with a caliper attachment. After putting a set of bullets in one row of a shallow loading tray. I start at the left (bullet #1) and measure,and each bullet both ways, filling in the information in the correct columns. After that is done, I can enter the difference between the two measurements in a fourth column. If there were no other factors, the differences in seating depth within that set of bullets should be the same as the variance in the fourth column. As a practical matter, I would guess that it would be greater, but I have no data...yet.

In one test of custom, short range , Benchrest bullets, I found a total variance of .002 in ten bullets. (seater contact to rifling contact) It would seem to me that the next logical question would be how much variation in seating depth is acceptable?

I have never looked at this before, but Bob Green has, and he makes a tool that has a floating seater stem at one end, that moves a .0001 dial indicator, and has the correct leade angle in the other. When a bullet is inserted in the tool, it stops on the leade and moves the seater stem to produce a reading on the indicator. When a double radius ogive bullet is used, technique get s a little tricky, but using the tool, one can quickly sort bullets in a way that no other tool will, in a single operation. He also makes a caliper attachment that contacts the bullet where the rifling will, for checking loaded rounds. I need to remember to start measuring every round this way, to see what shows up. How much variation in throat level ogive lenght of loaded ammunition do you think is excessive for the most demanding applications?
 
These posts really illustrate the differences between benchrest competitors and varmint hunters. I understand that the benchresters must split the gnat's eyelash, but most (not all) varmint hunters don't have the time, patience or inclination to use some of the techniques suggested here. And they wonder if they did use them whether or not it would be worth it given the other variables that affect accuracy when you're shooting in the field with all of the problems that occur when shooting there.

Many varmint hunters know that seating depth affects accuracy and they use trial and error to try to find the best depth giving smallest groups. But how many of them truly evaluate different seating depths by firing enough groups as opposed to settling on a seating depth after getting one tight group that might have been a fluke? If you are testing groups with 0.005 changes in seating depth, it takes a lot of groups to reliably know which depth is best. A lot of varmint hunters would rather send all those rounds down range at live targets.
 
Quite a technique! I've seen a difference in groups with as little as .003" difference in seating depth, so I would like to keep the variation at +/- .001" maximum. I don't think I'm capable of doing any better than that (IF I'm doing that good).

I'm mainly a varmint hunter but I work and size my brass like benchrest and weigh charges like long range in my factory rifles and am getting .5 MOA accuracy.

My Walmart .17 HMR shoots 3/8" at 100 yds; go figure.... - nhk
 
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He also makes a caliper attachment that contacts the bullet where the rifling will, for checking loaded rounds. I need to remember to start measuring every round this way, to see what shows up.

Boyd
This is were your accuracy will be found using vld type bullets.
Measuring the bullets ogive in two spots once using a 22 comparator and once using a 6mm comparator is eye opening but you absolutely have to seat the vld type bullets with a comparator tool on a caliper that contacts the bullet were the rifling will or atleast extremely close to it.
I used rounds this year at the nbrsa 1000 yard nationials and the total seating depth variation was 0.002 and this gave me first place over all until the match got thrown out.

Vicvanb
I am primarily a longrange hunter who doesn't really care to much for all the cheating and politics involved with the national organization I once belonged too.I really enjoyed beating the lying cheating shameless back stabbers but will now move on to something way more enjoyable.
We will be at squirrel wars this year and will be hunting several western states for mule deer as well.All of the bullets we will be using will be of the vld type and the seating depth will be held to 0.002 total variation.We will be using a simple caliper mounted comparator tool to check our seating depth and nothing else.
A trued up 700 Remington action with a Jewell trigger, Bartlien barrel and Shehane stock will shoot 2 inches at 600 yards in favorable wind and 3.5 inches at 1000 yards in the same conditions.It doesn't get much better than that.
Lynn
 
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Lynn,

If you can consistently get 3.5 inch groups at 1000 yards (even with zero wind) while shooting in the field (or even off a benchrest at the range) you are a way better man than me! The longest shots I can consistently make on prairie dogs with my 220 Swifts are at 450 yards. "Consistently" is the key word.
 
david dumas said:
hang on while I put on my fire proof underwear,,,,while I do have a couple of jam rifles, MOST of the time (but NOT all the tiime)I can keep working until I find a load/tune that works jumping, the problem with jamming is sometimes you'll get a pressure spike and miss a chance to go hotter(ie:faster/flatter) because of this spike,,,,,,,,, the main thing IMHO is that a rifle is like a woman, ya got to feed her what she likes and not two are just alike,,,,,,,,,,,,,,,,

the wind is my friend,,,,,,,,,,,,,,,,,

DD
Click to expand...

You got this post right, No need for fireproof undies from me. All of my factory rifles i.e rem, win, ruger, all like anywhere form 35 to 45 thou jump, my exceptions are my coopers that like between 3 and 15 thou depending on weight of bullet and velocity. My cooper in 220 swift likes 3 thou on 52s, and 10 on 55s, my #1V in 22-250 like 40 thou or more for the same bullet weights. The cooper in 223 likes from 2 to 8, so go figure.
Murphy , Good to hear from ya again.

DR
 
Seating depth variation

nhkuehl said:
Since it was cold out I took my box of 500 generic bulk .224 50 gr varmint bullets (SP) and checked length with the Sinclair comparator until I had 50 of the same length (roughly 50 out of a 100+). These measured .297" and the rest measured up to +.006". I weighed the 50 I sorted by length and the weight was 50.1 +/- .2 grs. The distribution was roughly a Bell Curve. These bullets weren't seating to the same length; the seater stem contacts a different point than the comparator. I'll load them the way I sorted them and see how much difference there is now.
Click to expand...

I seated the bullets with my Redding Competition Seater die and they were -.001" to +.002", so still .003" difference in seating depth. I checked run out on a few rounds and that was .002" or less. Now to the range. - nhk
 
What about built in jump like Weatherbys?

I have a factory Rem 700 in 7mmUltra that HAS to be loaded .350" OFF the lands in order for the bullets to fit the magazine...... I can only assume that Remington built "jump" into the 7mm RUM caliber so as to relieve some pressure just like Roy Weatherby did years ago.......................::confused:
 
I have shot cases of 748, aa2700, H335, Win 760. On all customs, they have zero freebore to begin with, and I seat the bullets to touch the lands, Factory rifles, same thing. I expect three shot groups of .375 and smaller.

If you shoot a 220 Swift, then AA2700 with a fed 210 with a 50g Nosler 44.0-44.5g will usually print sub .375 three shot groups, work up to that load.
 
Two thiongs here..........

1) I always replace the chamber return spring on any die that has one, (Redding or Bonanza Comp seaters) w/a spring that has about half the weight of its factory predecessor.

And,

2) Has anyone seated bullets shy of optimum for any of their rifle's 'sweet spot' then seated them a day or so later to the previously established depth, once they have had the opportunity to relax a bit?? :D

I've done #1, #2 I've thought about.
 
For my BR gun, this is my measuring technique... resize a case and seat a bullet very long (no primer, no powder!) , just deep enough to make it stay standing in the case. Load it into the gun and close the bolt, letting the bolt seat the bullet against the rifling, work the bolt once for good measure. Now hopefully the bullet will come out with the case and you will have a reference for exactly that make/model/ogive/lot box of bullets. You should be able to see the rifling marks on the bullet. I use a Wilson hand seater with a micrometer top, so now all I have to do is adjust the micrometer down until the seating stem just starts to spin and I know that I have a seater adjusted for exactly my "jam" length for that batch of bullets.
My PPC loves it just like that though I usually shorten it another .002 just so that I don't stick a bullet in the barrel if I have to eject a live round. If you don't have that style of seating die, you can still use one of those hex-nut comparators and your calipers to get your jam length and then make die adjustments from there.

Switch bullets? Start over - every lot could be a different die setup from the bullet maker. The same gun will like to jam one flavor of bullet, then jump the next. .010 - .015 is a good size step to find a tune. I like to put rounds in the magazines of my varmint guns and that usually means all the seating depth stuff gets thrown out in preference to overall cartridge length.

Rod
 
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