Ran into a problem with 338 Lapua

[Nimrodmar10]

I'm working on new loads for a new Remington 700P in 338 Lapua Mag. I'm working on two different loads for the Sierra 250 gr. Match King and the Berger 300 gr. OTM Hybrid. I've got good loads for both bullets and am just trying to squeeze the last bit of accuracy out of them by trying different OALs. The dies I'm using are the Redding Type S bushing dies. The seating die is just a normal seating die, no micrometer. When trying to set groups of 5 shells to the same seating depth I noticed the OAL was varying up to .015" between bullets. I wasn't too surprised as I figured it was just small differences in the meplat. So I broke out the bullet comparator(six-sided nut with holes on each side). Still had the same problem. Shell length from base to bearing surface still varied 5-7 thousandths on the Berger and 10-15 thousandths on the Sierras. It's a little hard to change your OAL by .010" when you're getting. 015" difference between bullets. I even took the seating plug out of the die and used it as a comparator by placing a bullet in the recess and measuring the length of the two together. Had the same amount of difference.

The Sierra 250 gr. with a Max load of H1000 is shooting less than .5" and the Berger 300 gr. Hybrids with a Max load of Retumbo is shooting. 75" groups. Those are not bad groups but I wonder how good they'd be if the bullets were uniform.

Okay, here's the question, Has anyone else noticed this and does it matter with accuracy? Would it help to use a comparator and try to seperate them in groups of the same length from base to bore diameter?

You'd think that with what we pay for these premium bullets they'd be more precise. Just saying!

 

[Broz]

Well if it were me I would fix the problem. I think I know what it is.

What press?
What seating die exactly? ( is this the one that came with the redding "S" type die set?)

How are you adjusting the seating die in the press for depth?

Jeff

 

[D.ID]

I usually see meplat variances of .005 or less so .015 sounds like allot (can not believe I just said that) Look over your press and die real careful. bergers are typically better than sierra and sierra is usually only .005-........I sort my bullets bearing surface before loading so I can run right threw them.

 

[Nimrodmar10]

Well if it were me I would fix the problem. I think I know what it is.

What press?
What seating die exactly? ( is this the one that came with the redding "S" type die set?)

How are you adjusting the seating die in the press for depth?

Jeff

Jeff
The press is a new RCBS Rockchucker Supreme. As I said above the seating die came with the Redding type S dies. I'm adjusting the seating die in the press for depth by turning the bullet seating adjusting stem in and out. How would you suggest I fix my problem?

 

[Nimrodmar10]

I usually see meplat variances of .005 or less so .015 sounds like allot


........I sort my bullets bearing surface before loading so I can run right threw them.

I think I took the me plat out of the equation when I measured from the bearing diameter. I hate to sort them but I guess I will.

 

[green 788]

could be your bullet tips are touching before the ogive on some of the bullets...

 

[sp6x6]

could be your bullet tips are touching before the ogive on some of the bullets...

I have had that account for .002, vary, I clearnaced seater w/ drill for Berger, they sell different stems. If primers are not seated that can be another, .002-3. The brass can vary in sizing .002-3. Need your comparator to check this at shoulder. But adding all, still 1/2 where your at.

 

[Broz]

Jeff
The press is a new RCBS Rockchucker Supreme. As I said above the seating die came with the Redding type S dies. I'm adjusting the seating die in the press for depth by turning the bullet seating adjusting stem in and out. How would you suggest I fix my problem?

First, this may require the use of a Redding shell holder. But others can work if they are close to the same height on their floor.

Ok, back off the seating plug and run the die all the way down to contact the shell holder when the ram is up. Then go a little bit deeper to achieve a slight cam over feel at the end of the stroke. Die contacting shell holder. This will make sure that no matter how fast or with what force you push the handle down the ram and die are always in the same place (height) for seating. Use the seating plug adjustment on top the die to set the desired depth of the bullet.

The old way of backing the dies off is not the intended method with these dies. Although some of the instruction sheets do say to back off the die. Yes, they are wrong.

This process eliminated and variation in my seating depths. I use it on all my Redding bushing dies now.

Jeff

 

[Nimrodmar10]

I checked the seating stem for tip clearance. It has a hole drilled 1/4" beyond where the tip might hit, so that's not a problem.
I used the nut type comparator to measure the bullet from base to bearing surface. Out of a box of fifty Sierra 250 gr SMKs I found a difference from shortest to longest of 10 thousandths. The two largest groups that I measured and seperated into groups contained about 10 bullets each. The other 30 bullets were scattered to each extreme. I separated these into four groups of 5 each and loaded them. After I reloaded them I checked the comparator length of the shells and they measured the same. Conclusions: With the .005-.007" difference in the meplats (which I don't think matters) and the .010" difference in the bearing surface length (which I think does matter) it's hard to figure out what your COAL really is.

When checking the seating stem, I twisted the bullet several times to mark the bullet to see where it contacted the stem. It was contacting about half way between the point and full diameter. I think I'm going to use some scope ring lapping compound on a bullet to lap the stem to the correct contour. Anyone ever try this?

 

[sp6x6]

The meplat is the tip of the bullet, in match type bullets with full copper jackets, this area is prone to difference just from forming and shipping.They make a tool to uniform. The area you want to or are checking is the ogive, radius area between tip and bearing. I am surprised that your bullets are off that much, but know you know the biggest source of your problem.Now if you are trying to shoot minimum distance from lands this could be a problem, because you could go from off to jammed.But if you are well out then not a issue.

 

[Nimrodmar10]

First, this may require the use of a Redding shell holder. But others can work if they are close to the same height on their floor.

Ok, back off the seating plug and run the die all the way down to contact the shell holder when the ram is up. Then go a little bit deeper to achieve a slight cam over feel at the end of the stroke. Die contacting shell holder. This will make sure that no matter how fast or with what force you push the handle down the ram and die are always in the same place (height) for seating. Use the seating plug adjustment on top the die to set the desired depth of the bullet.

The old way of backing the dies off is not the intended method with these dies. Although some of the instruction sheets do say to back off the die. Yes, they are wrong.

This process eliminated and variation in my seating depths. I use it on all my Redding bushing dies now.

Jeff

Jeff
I've never used a Redding shell holder. They may be different than the others I've used. I like to never found a shell holder for the 338 Lapua brass. The RCBS #14 doesn't really fit. The case rests on the lips of the shell holder and sits off the bottom so much you can't seat a primer as deep as it needs to go. I'm using a Lee #8 now.

I'm not sure which dies you're using but they are not the type I'm using. You may be confusing your seating die with your sizing die. My sizing die has a crimping ring built into the seating die. You put an empty case in the shell holder and run it to the top of the stroke. You then screw the die in until you feel the crimp ring contact the end of the case. If you do not want to crimp your bullet you back the die out one turn. This leaves a gap about the thickness of a nickel between the die and shell holder. If you run the die down to touch the shell holder you will crush the case neck.
I do appreciate the response though.

 

[Broz]

Jeff
I've never used a Redding shell holder. They may be different than the others I've used. I like to never found a shell holder for the 338 Lapua brass. The RCBS #14 doesn't really fit. The case rests on the lips of the shell holder and sits off the bottom so much you can't seat a primer as deep as it needs to go. I'm using a Lee #8 now.

I'm not sure which dies you're using but they are not the type I'm using. You may be confusing your seating die with your sizing die. My sizing die has a crimping ring built into the seating die. You put an empty case in the shell holder and run it to the top of the stroke. You then screw the die in until you feel the crimp ring contact the end of the case. If you do not want to crimp your bullet you back the die out one turn. This leaves a gap about the thickness of a nickel between the die and shell holder. If you run the die down to touch the shell holder you will crush the case neck.
I do appreciate the response though.

Sorry, I guess the Type "S" Redding and the Competition dies are different then. Mine do not crimp and this is how Robin at Redding taught me to set them up. It works wonderfully on both the size and the seat die. I use the redding steped shell holders to control the amount of shoulder bump and tis method assures the die is set to the same depth each time.

Again, I thought you were having the same problem I cured a few years back. Sorry for the confsion.

Jeff

 

[flashhole]

Are your loads compressed loads? You may be getting a bit of push back from the powder column.

 

[Broz]

Are your loads compressed loads? You may be getting a bit of push back from the powder column.

Great point!!

I was wondering about inconsistant neck tension too. How many firings on the brass since annealed?