Consistant seating depth...

[David Christian]

@20PPC I have not read all 4 pages of comments, my bad. Has anyone asked what neck tension you are running? What is the neck diameter of a loaded round? What size bushing or sizing die are you using? Do you use an expander mandrel?

 

[William Vogel]

@gunsandgunsmithing yes Mike I did try another VLD stem, nothing changed.
I've got some Berger 108 targets I'm going to try.

Are you running a mandrel through the necks after sizing and using a FL bushing die for sizing?
My process is to decap, clean exterior carbon from neck, clean primer pocket, anneal, trim, FL bushing resize, lube neck with lockeze, mandrel neck, tumble, store or load after identification with length and date.

 

[Fire Dog]

Consistent seating depth almost always comes down to brass prep in my experience. I don't sort my bullets and my seating depth is rarely more than .0005 variance. If your brass necks aren't consistent, there will be variations in drag/pressure as the bullet seats which will cause inconsistent seating depth. This is something I've spent a lot of time working on. In my experience, these are the things that help with consistent seating depth.

1. Anealing
2. Consistent chamfer with slight bevel
3. Graphite or Neolube inside of neck
4. Mandrel as last step before seating. Use the mandrel just before seating

I was about to load some up so decided to record it and put my money where my mouth is....I can do this all day and get an extreme spread of .0005. I can't express enough how much difference it makes to use the mandrel right before seating.

What brand of comparator are you using on the vernier? I like the flat surface for the base of the cartridge.

 

[Fire Dog]

This has been more help in seating depth consistency than anything I've tried so far. Pressure on the press handle and no bounce at the bottom of the stroke is key at least with my Rockchucker.

Same for my Co-Ax

 

[6Creed73]

What brand of comparator are you using on the vernier? I like the flat surface for the base of the cartridge.

The comparator is Short Action Customs. That base is actually from a guy on this site...I got it from the classifieds here. I'll try to find the ad.

Edit: @Fire Dog here is where I got the base.

SELLING - Caliper Bases - $23.00 Shipped

Updated - 10.20.2025 - Current time from purchase to received - 3-4 days. Ensures consistent and repeatable measurements during the bullet seating process. See forum comments, reviews and feedback. PM me for additional information. 6061 Aluminum - Hard Anodized Black. Use in conjunction with...

forum.accurateshooter.com

 

[J_idaho]

In my experience varying neck tension does have an affect on seating depth consistency.

What Bill said:

 

[wkdickinson]

Nomex underwear on so I can throw in my pre inflation $ 0.02.

My experience with a load shooting well as the throat erodes ( not chasing the lands ) has led me to sort bullets by BTO (base to comparator touch point ) and then control the CBTO of the loaded rounds under 0.002”. This keeps the base of the bullet at the same location in the case neck and this seating depth control has shown to be more indicative of controlling a loads tune than jump to touch point.

YMMV but this seems to be working for me.

I have wondered for a long time whether when we tune using "jump" if we aren't really tuning with the depth of the bullet base in the case.

 

[William Vogel]

I have wondered for a long time whether when we tune using "jump" if we aren't really tuning with the depth of the bullet base in the case.

I think you’re on to something but I’m also thinking it’s about the pressure “knock” that forms every time an obstruction is overcome. What I mean is there’s a pressure rise and fall when the bullet first moves in the case, the neck is expanding and the bullet reaches the lands. Pressure rises again as the bullet is forming into the bore/grooves. Of course this pressure rise is much greater but it’s a succession of events. I’m continuing to imagine the pressure events and bullet accelerations in the barrel along with the barrel deformation with travel and the release of pressure at bullet exit.

 

[Fire Dog]

I started off with finding the sweet spot of my new barrel and have never changed the COAL over the life of the barrel.
Seem to be working for me and I have read other items written saying Do Not chase the lands...
A bit along the lines of "If it ain't broke.... Don't fix it"

 

[20PPC]

@20PPC I have not read all 4 pages of comments, my bad. Has anyone asked what neck tension you are running? What is the neck diameter of a loaded round? What size bushing or sizing die are you using? Do you use an expander mandrel?

@David Christian I am not running a mandrel, my necks are turned to .112 with a .262 bushing in a .268 chamber .
My loaded rounds measure .2650 - 265, I'm sure all my neck thickness have some variance to them.
I'm using a Harrels fl bushing die and haven't been able to anneal because my Annie is in for repair.
I'm sure a set of mandrels would be of benefit.

 

[jelenko]

seater stem makes contact any where on the ogive a very slight change in the diameter at the point of contact

I asked Forster about whether their seater 'compensated' in any way for small changes in the shape of the ogive.

Their response:

If using a bullet comparator measuring O-give to base you should find your bullets to be extremely consistent. It is important for bullet manufacturers to maintain this distance as being consistent as this will determine how consistent your bullet encounters the lands of your rifle. By keeping this profile extremely consistent, even with your comparator hitting at one spot, your seating stem hitting at a slightly different spot, and your rifling hitting a slightly different spot, we should see this stay consistent.​

​

My take => The variation in the shape of the ogive is consistent enough that variations in base to ogive measurements are small enough to ignore.

 

[jelenko]

bullet nose length can have a significant impact on consistent seating depth because the two contact points critical for maintaining consistent seating depth are located on the bullet ogive.

Ned - I asked Hornady if sorting bullets from the same lot would improve the consistency of the base to ogive measurements. Here's their response:

The base to ogive measurement is a more consistent method for comparing bullets than overall length, as the ogive is the most consistent place to measure. Variations in the bullet tips can lead to differences in overall length, but the base to ogive measurement tends to remain more uniform. Sorting bullets by overall length may not necessarily result in more consistent base to ogive measurements within a sorted group, as variations can still occur due to manufacturing processes and material differences. It is recommended to use a bullet comparator to measure from the base to the ogive for more consistent results. If you are experiencing significant variances and it is affecting your accuracy, it may be worth examining the bullets more closely or contacting the manufacturer for further assistance.​

My understanding is that the length of the tip is essentially independent of the process that forms the ogive.

What do you think?

 

[Bill Norris]

jelenko​

My take => The variation in the shape of the ogive is consistent enough that base to ogive measurements are small enough to ignore.

On most bullets I believe this is true but there are some exceptions where the ogive is not consistent enough to ignore.

 

[jelenko]

jelenko​

My take => The variation in the shape of the ogive is consistent enough that base to ogive measurements are small enough to ignore.

On most bullets I believe this is true but there are some exceptions where the ogive is not consistent enough to ignore.

Bill - Do the exceptions come from certain manufacturers?

 

[barefooter56]

I just started shooting mid range 600 yards and am experiencing problems getting consistant seating depth in the case.
I'm shooting a 6BRA chambered by Ronnie Long, Lapua brass, Varget, Federal primers and 105 Berger Hybrids.
I cannot get 2 bullets in a row to seat the same depth, I sent the Wilson seater stem to Ronnie because it was was not making the consistant proper contact on the bullet.
He opened it up a slight amount and polished it to what now appears to be perfect contact with the tip of the bullet.
I've measured BTO on the bullets and all of them appear to be within + - .0015 yet when seating I'll get .004 - .010. difference.
Needless to say 2 1/2 hrs later " actually longer " and only 75 rounds loaded is getting to the point the hassle of loading is outwaying the enjoyment of shooting.
Any advise would be appreciated.
Dave

Dave,
You don't want to seat rifle bullets off the tip of the bullet. The seating stem should 'cup" or make contact somewhere on or close to the ogive of the bullet. The two dimensions we track in A LOT OF BULLETS. Are the bullet base to ogive and weight. Thats all. You should have had the stem drilled DEEPER instead.

 

[Straightshooter1]

Ned - I asked Hornady if sorting bullets from the same lot would improve the consistency of the base to ogive measurements. Here's their response:

The base to ogive measurement is a more consistent method for comparing bullets than overall length, as the ogive is the most consistent place to measure. Variations in the bullet tips can lead to differences in overall length, but the base to ogive measurement tends to remain more uniform. Sorting bullets by overall length may not necessarily result in more consistent base to ogive measurements within a sorted group, as variations can still occur due to manufacturing processes and material differences. It is recommended to use a bullet comparator to measure from the base to the ogive for more consistent results. If you are experiencing significant variances and it is affecting your accuracy, it may be worth examining the bullets more closely or contacting the manufacturer for further assistance.​

My understanding is that the length of the tip is essentially independent of the process that forms the ogive.

What do you think?

I've been sorting my bullets by base to the seating stem contact point on the ogive and it gives me very consistent seating, even when the seating is measured by a typical caliper insert (seldom seeing any significant variation between the two contact points). When comparing those sorted by seating stem contact point with their OAL, I find a significant variance in OAL's. That distance from seating stem contact point to the meplat varies quite a bit. These bullets I've measured are the Bergers and SMK's. The most consistent bullets I've measured this way are my 6.5 Hornady A-Tips, where these measurements hardly varied at all. Since I've sorted based on seating stem contact point, I get VERY consistent seating depths . . . and with the annealing, the consistent seating resistance helps.

 

[jelenko]

I've been sorting my bullets by base to the seating stem contact point on the ogive and it gives me very consistent seating, even when the seating is measured by a typical caliper insert (seldom seeing any significant variation between the two contact points). When comparing those sorted by seating stem contact point with their OAL, I find a significant variance in OAL's. That distance from seating stem contact point to the meplat varies quite a bit. These bullets I've measured are the Bergers and SMK's. The most consistent bullets I've measured this way are my 6.5 Hornady A-Tips, where these measurements hardly varied at all. Since I've sorted based on seating stem contact point, I get VERY consistent seating depths . . . and with the annealing, the consistent seating resistance helps.

Just to show again what those two contact points are, here's Ned Ludd's illustration:
View attachment 1517940

Interesting. The contact point for my Forster on a 223 68gr HPBT is about 1/3 the way from the Seating Die Stem arrow to the Caliper Insert arrow - so significantly further away from the meplat.

 

[marine52]

I have a hard time believing that the Berger bullets are the problem. I shoot the 105 Hybrid Target and I have several thousand. I’ve never gotten these inconsistent seatings from my 6Dasher loads. I also shoot Hornady ELDM in 223AI, 6.5 Creedmoor and 308 and also get very little inconsistent seatings. I don’t know what might be happening here.

I agree. I’ve never had this much seating variation (0.010) with Bergers. A lot of good advice above, especially @Ned Ludd on bullet ogive/nose profile.

The OP is obviously using an Arbor press since he is seating with a Wilson. When I recently started using the arbor press, I had to learn the “feel” of the press. the press would show a jump in pressure (using attached pressure gauge), indicating I had hit bottom with full seating. However, close inspection showed the top of the arbor die stem not fully down. It took me a while to learn the “feel.” With a threaded die on a rockchucker type press, the leverage is very high. However, with the arbor‘s lower leverage, you have to continue til you feel the definite bottom. As others have mentioned, inconsistent neck tension/lubrication leads to changes in required seating force.
It’s a learning curve.

Dave, @20PPC, you may have much more experience with the arbor than me so forgive me if that’s the case. but, if your seating variation is always on the positive side—in other words, you’re finding the seated cartridges longer in CBTO when compared to your base goal—this would imply your seating stem not fully extended. Do a visual inspection of the top of the die after completion of the arbor stroke and make sure the stem is fully extended.

 

[20PPC]

Dave,
You don't want to seat rifle bullets off the tip of the bullet. The seating stem should 'cup" or make contact somewhere on or close to the ogive of the bullet. The two dimensions we track in A LOT OF BULLETS. Are the bullet base to ogive and weight. Thats all. You should have had the stem drilled DEEPER instead.

@barefooter56 I sent the seating stem to my gunsmith Ronny Long and he did drill the stem out and polish it, the stem is contacting the sides not the tip.
I spoke to a tech at Berger and he said " it had to be from a compressed load or the seating stem is cracked. "
I'll try seating on an empty case and double check for a crack when I get home tonight.

 

[Ned Ludd]

Ned - I asked Hornady if sorting bullets from the same lot would improve the consistency of the base to ogive measurements. Here's their response:

The base to ogive measurement is a more consistent method for comparing bullets than overall length, as the ogive is the most consistent place to measure. Variations in the bullet tips can lead to differences in overall length, but the base to ogive measurement tends to remain more uniform. Sorting bullets by overall length may not necessarily result in more consistent base to ogive measurements within a sorted group, as variations can still occur due to manufacturing processes and material differences. It is recommended to use a bullet comparator to measure from the base to the ogive for more consistent results. If you are experiencing significant variances and it is affecting your accuracy, it may be worth examining the bullets more closely or contacting the manufacturer for further assistance.​

My understanding is that the length of the tip is essentially independent of the process that forms the ogive.

What do you think?

For the record, I never stated that sorting bullets by OAL would lead to more consistent BTO measurements. I never said anything like that, so I don't understand why you would be asking Hornady about it. In fact, I don't recall anyone else making such a claim in this thread or in others like it, either. The whole point of my earlier post was quite the opposite. If someone is looking to minimize length variance within the ogive region of the bullet (i.e. between the two critical contact points in the nose region), they're not going to accomplish anything by sorting based on a region that lies outside of those two points; i.e. BTO. The point here is simple: the BTO region lies outside the nose region. Sorting by BTO will not improve nose length variance, nor is sorting by OAL likely to improve BTO consistency if the majority of bullet length variance lies in the nose region, which it does. In my hands, bullet base-to-ogive measurements are generally far more uniform/consistent than either OAL or nose length measurements, and vary little, if at all. If you want to sort bullets to improve length variance in the nose region, you have to sort them by the length of the nose region, or possibly by OAL as a surrogate for the nose region, but only when the BTO dimension is very uniform. Further, when bullet BTO measurements are very consistent, any variance in OAL measurements must therefore lie mainly in the nose region. This is simple geometry. That is the region where the two critical contact points also lie. Collectively, these observations support the notion that sorting bullets by OAL that already have consistent BTO dimensions will result in more consistent measurements within a single OAL group between the two critical contact points. Again, this is simple geometry.

My understanding is that the ogive of the bullet extends from the top of the bearing surface all the way out to the edge of the meplat. In other words, the ogive encompasses the entire curved outer surface of the bullet nose, from the top of the bearing surface to the meplat. That definition is also consistent with the term "ogive radius", or the curve defined by the outer edge of the bullet nose from bearing surface to tip. On numerous occasions, I have lined up bullets from the shortest and longest length groups within a single Lot #, short in front, long in back. It is often possible to observe with the naked eye that the ogive radii of the two bullets are not the same. If the [centerline] nose length varies between two bullets, by definition their ogive radii should be different, and they are. This observation provides further support for the bullet nose geometry I described above and the effect of sorting bullets by OAL on length variance between the two critical contact points. I seriously doubt someone like Bob Green would make and sell a tool to sort bullets based on the region between the two critical contact points specifically to improve the consistency of seating depth if the bullet geometry didn't support the notion that it would work.

I posted the bullet image above with the critical contact points in order to better illustrate concepts of bullet geometry that occasionally seems difficult to grasp for some. There was no other reason or agenda behind that action. Nonetheless, I would urge anyone not to simply take my statements on an internet shooting forum as gospel or fact. Quite the opposite. I would urge anyone curious about details in the reloading process such as bullet geometry and length sorting to start taking measurements for themselves. Test things, measure things, and then draw your own conclusions from your own observations and recorded data.