Bullet seating consistency? F-Class Standard - .308

[ReneZ]

Hi, I have been reloading for quite some time and have tried to get better (more precise/consistent) going through the usual upgrade treatmill. I reload for F-Class Standard (Australian) in .308 and have noted some issues that I would like to request your experience or knowledge about.
Seating bullets with a Forster Ultra Micrometer die I noted that the bullets were not all seated at the same depth as verified with calipers using Hornady and Sinclair comparaters. Using both there is a slight difference between the absolute measurement results of the two bits for distance between base and ogive, which I think is due to the difference in internal diameter of these two comparaters; they sit on different points on the ogive of the bullet.
Having noticed that and the little rings sometimes left on the bullet ogives by the seating stem (loading Sierra 2156 Palma with .0015/.002 tension) I measured the inner diameter of the comparaters and the seating die stem, which all showed different values. If a bullet would be always exactly the same shape this shouldn't give any differences necessarily, but that doesnt seem realistic. Variations will occur with the manufacture, however minimal.
All this brought me to the following: If we want to make sure we reload precise consistent rounds why are the relevant parts not sized to where it matters? With the reloading you try to be consistent with your seating depth to the part of the barrel where the bullet would hit the rifling when discharged, correct? I'm not refering to "chasing the lands", but the distance of the bullet ogive to the part where it will hit the rifling. In order to do so and appreciating that minor inconsistencies in bullet manufacture and therefore shape is unavoidable I would expect (or better prefer) that the diameters for the seating stem and comparaters would tough within the lands 'height' area (between .305 and .308) instead of the .298 and .295 of the comparaters and even smaller for the seating die stem.
Where it would be possible to clean up the inner diameter of the comparater bits with a .308 reamer and kissing the beginning with the 1.5 or 2 degrees land part of the reamer the seating die internal diameter around the seating stem is too small to allow a larger diameter seating stem.
I'm probably showing my OCD here and should go out shooting more, but the question remains. I'm not aware of a seating die that touches the bullet in the 'lands area' but hope to learn more here! Thanks!! Brgds, Rene
PS I'll try to attache a picture that shows three markes (of the seating stem and the two comparators) on the seated bullet for illustration purposes. Haven't been able to zoom in clear enough....

 

[NZ_Fclass]

From my experience, the Forster seating stem is a little dodgy. I had to polish an angle into the cup to stop the marking and even jamming of bullets. There's a lot of mentions of this issue on the forum. I'm planning on changing the seating die ay some point, but funds being limited...

Why 2 comparators? It doesnt matter where on the projectile it measures from - so long as it is the same place each time. It does not need to be an absolute.

There are other factors that will cause variation in seating depth - the most obvious being contact with the powder, when the neck tension is insufficient to hold the bullet in compressed loads. I know that we like to move those 155's quickly and 2208/Varget will touch is base of the bullet and push back after leaving the die. You may need to look at your recipe/ case volume. Have you tried seating bullets into an empty new case?

 

[piie]

I guess that is why - for the folks with the OCD - you measure and sort your bullets before seating. As you discovered, the comparators (at least the ones I can afford) has no “standard” , but as long as they, and you, stay consistent, it should not matter. Just dont mix or try to compare measurements when using different comparators. Many reasons exist for measurements to differ- even the slightest difference in where the bullet ogive/curve starts can cause a large difference in your length measurement- but does that matter? I’ve watched alot of videos from Erik Cortina, F-class John and many others, and none of them seem to fuss too much about this- or maybe I just missed that video???

 

[ReneZ]

From my experience, the Forster seating stem is a little dodgy. I had to polish an angle into the cup to stop the marking and even jamming of bullets. There's a lot of mentions of this issue on the forum. I'm planning on changing the seating die ay some point, but funds being limited...

Why 2 comparators? It doesnt matter where on the projectile it measures from - so long as it is the same place each time. It does not need to be an absolute.

There are other factors that will cause variation in seating depth - the most obvious being contact with the powder, when the neck tension is insufficient to hold the bullet in compressed loads. I know that we like to move those 155's quickly and 2208/Varget will touch is base of the bullet and push back after leaving the die. You may need to look at your recipe/ case volume. Have you tried seating bullets into an empty new case?

Hi, thanks for that!

I understand the seating stem comment and indeed could polish the internal with a bullet and some grinding paste, however the outside diam of the cup of the stem is less than .305, so you're still not touching the bullet where it matters (possibly).

I'm certain my powder load is not a compressed load, so am not concerned with 'push back'.

Brgds, Rene

 

[ReneZ]

I guess that is why - for the folks with the OCD - you measure and sort your bullets before seating. As you discovered, the comparators (at least the ones I can afford) has no “standard” , but as long as they, and you, stay consistent, it should not matter. Just dont mix or try to compare measurements when using different comparators. Many reasons exist for measurements to differ- even the slightest difference in where the bullet ogive/curve starts can cause a large difference in your length measurement- but does that matter? I’ve watched alot of videos from Erik Cortina, F-class John and many others, and none of them seem to fuss too much about this- or maybe I just missed that video???

Hi, thanks.

I included the comment re the different comparators as they showed differences (as expected) and therefore brought me to the query of having comparators and seating stems with a diameter greater than .305, in the same area of 'relevance'.
I probably have watched the same videos as you and appreciate there might be little, incremental improvements or none at all, but that doesn't take away my query . Quite possibly they use different bullets that have better consistency or are currently concentrating elsewhere. Or have determined that the difference doesn't matter.... Or have dies and comparaters that have been finished with the same final reamer their rifles were manufactured with. I hope one of them or other accomplished shooters would comment (not saying you're not!), would be interesting.
Brgds, Rene

 

[PopCharlie]

I have tried a few different seating dies. Forster, Whidden, Redding and Wilson in-line. By far, the best, most consistent is the Wilson in-line micrometer die, used in conjunction with an arbor press. The next most consistent is the Redding micrometer.
I have also tried the Sinclair, Whidden and Short Action Custom comparators (uses caliber specific inserts). I like the SAC tool because the diameter of the insert is the rifling land diameter. It also has a very slight radius to prevent marking the bullet.

PopCharlie

 

[piie]

Hi, thanks.

I included the comment re the different comparators as they showed differences (as expected) and therefore brought me to the query of having comparators and seating stems with a diameter greater than .305, in the same area of 'relevance'.
I probably have watched the same videos as you and appreciate there might be little, incremental improvements or none at all, but that doesn't take away my query . Quite possibly they use different bullets that have better consistency or are currently concentrating elsewhere. Or have determined that the difference doesn't matter.... Or have dies and comparaters that have been finished with the same final reamer their rifles were manufactured with. I hope one of them or other accomplished shooters would comment (not saying you're not!), would be interesting.
Brgds, Rene

Yes, I certainly would also be interested in seeing the "pro" shooters weigh in - that's about the only thing I know for sure - I'm no expert

 

[Ned Ludd]

I ran into the the issue of differing comparator insert hole size between Hornady and Sinclair caliper inserts several years ago when I started working up a load for a .223 Rem bolt rifle that had a zero freebore chamber. The [long] bullet I had selected needed to be seated relatively deep in the neck to maintain the relationship with the lands I wanted (i.e. jump). As a result, the point on the bullet ogive just above the bearing surface where the Sinclair insert with its larger hole wanted to seat was just slightly below the case mouth. As a result, the Sinclair tool was actually seating on the mouth of the case, not quite all the way down on the ogive where it should have been, because that site was situated just below the case mouth. I had some Hornady inserts for .223 Rem and tried them. Because the hole was slightly smaller, they seated slightly farther out on the bullet ogive, above the case mouth, and worked perfectly. Since that time, I have used the Hornady inserts almost exclusively.

As long as you use the the same insert every time, the results will be consistent. However, attempting to compare the measurements taken with the two different inserts may not provide consistent or readily interpretable results, because they seat at different points on the bullet ogive. As shown in the cartoon below, the two critical contact points for achieving uniform and reproducible seating depth are the the point at which the seating die stem contacts the bullet ogive out near the meplat, and the point just above the bearing surface where the caliper insert contacts the ogive when we measure CBTO with calipers. Bullet length variance between these two points can introduce seating depth variance, as well as variance between the measurements taken using two different inserts. Because the two different inserts seat at different points on the bullet ogive, any length variance in that region of the bullet may cause apparent variance in CBTO measurements taken with the two different inserts. In other words, the two measurements may differ because because bullet length variance in the nose region may differentially affect bullet diameter where the two inserts seat.

One can remedy this to some extent using a few different approaches. As I noted above, using only one of the inserts exclusively will probably help. Also, tools such as Bob Green's Comparator allow one to sort bullets by length variance between the two critical contact points. Finally, measurements taken from the bullets I typically load over years of reloading suggest that the majority of OAL variance resides in the nose region, much less so in the bearing surface and boattail regions of the bullets. Thus, sorting these bullets by OAL is sort of a "poor man's" Bob Green Comparator. I started length-sorting bullets by OAL many years ago for the purpose of obtaining more uniform points with a pointing die. It was only afterward that I noticed it also seemed to improve the seating depth consistency. It is a relatively painless exercise to take a few bullet measurements to determine whether the majority of OAL variance for a specific manufacturer's bullets resides in the nose region. If it does, one can easily sort a few by OAL and determine whether that produces more uniform seating depth with the seating die micrometer left on a single setting (i.e. not having to adjust the seating die micrometer to generate uniform seating depth).

 

[ReneZ]

Hi Ned, thanks for that. As described above I was expecting some differences between the comparaters and that was the case. If the seating comparater sits on the brass you were seating deep!
I'm not too much bothered by the length variations OAL (should I), but am wondering about the distance to the lands and if the comparater bits actually properly (consistently) represent that distance if they are not touching the bullet in the area where it would hit the lands once fired.
Re bullet sorting; I'll have a go at checking them with the comparater body as well as OAL on my left-over, see what it gives.
Cheers, Rene

 

[ReneZ]

Yes, I certainly would also be interested in seeing the "pro" shooters weigh in - that's about the only thing I know for sure - I'm no expert

Same here mate!

 

[CharlieNC]

If you get a new barrel turned, have the gunsmith chamber the stub which is cut off the muzzle. At roughly one inch long, you can use this as THE comparator.

 

[Ringostar]

Here’s an idea, since the comparitors don’t contact the bullet where is touches the rifling, or where the seating stem touches. Why use them? A big enough hole to match the rifling might not be practical either, because it’s so close to the actual bearing surface. So why not use a smaller hole that matches where your seating stem contacts the ogive? This should give more consistent measurements.

 

[ReneZ]

If you get a new barrel turned, have the gunsmith chamber the stub which is cut off the muzzle. At roughly one inch long, you can use this as THE comparator.

Cheers mate, thought about that, buit it'll only happen when I rebarrel and I'm quite a way off

 

[ReneZ]

Here’s an idea, since the comparitors don’t contact the bullet where is touches the rifling, or where the seating stem touches. Why use them? A big enough hole to match the rifling might not be practical either, because it’s so close to the actual bearing surface. So why not use a smaller hole that matches where your seating stem contacts the ogive? This should give more consistent measurements.

This would work if you want to get the comparator and the seating stem in the same 'plane' and don't care about the rifling. I'm thinking along the lines of that 'big hole' idea; why do you think the closeness to the bearing surface might be a problem?
Cheers, Rene

 

[Ringostar]

I haven’t tried to measure bullets closer to the bearing surface. I think that you could potentially get bullets sticking in the comparator, and very inconsistent measurements there also. As Greg @Ned Ludd mentioned, he had cases that would touch the comparator. The guys that have mentioned sorting bullets by over all length, do it to actually find variations in there sorting. This it what makes me think of measurements where the actual seating stem makes contact. You can sort your bullets measuring closer to the tip. Then find your land touch point with a seated bullet, but take your measurement where the seater is contacting vs an imaginary spot lower down.

 

[Dog Breath]

I did 2 things that helped a lot.

1) Bought half a dozen seating stems from Forster. For each style of bullet I hone a stem out a bit, put a dab of JB Weld in the end and with stem pointed up in a vise place a waxed bullet in the stem. After it sets up knock the bullet out, drill the centre out, clean up the edges to leave a nice band to contact the bullet. Custom seating stem.
2) As per Mr. Cortina's advice, I gave the Hornady comparator thingy to a friend with a lath and he honed it to .308.
A drill and sand paper wrapped around a screw driver or something round would work too.

 

[ReneZ]

Good one, thanks! Time to experiment a bit

Cheers, Rene

 

[D-4297]

I may have missed it while reading all the comments , but some of the seating stems are not machined deeply enough , and some bullets may actually touch the top of the stem , when being seated . That will cause seating depth inconsistencies ,with no real , how did that happen , answer .

Since I'm only loading .308 in rifle , and using primarily Berger bullets , I took the seating Die I had from when I started out , and drilled the hole .075 deeper and radiused the angle to reduce the possible bullet marking when seating . I've used this same seating Die now , for over five years , and literally over 100,000 rounds . It seats my rounds within + or - .001 , and for a F-Class round , I think I can live with that . And BTW ; The Seater Die is the old standard Lee .308 cheapo Seating die . When it wears out , if it does , I'll probably get another just like it , and switch the stem to the new one .

 

[ReneZ]

Regretfuilly I don't have time to watch all the relevant YouTube content, but I just found this gem

from Eric Cortina, who goes into detail on what I was wondering about. Great video and it closes the subject for me. Cheers all, Rene

 

[paulT]

Try batching your bullets from base to ogive then overall Length, I use a Fotester micro seater with the seating stem factory honed for my bullet of choice and my seated rounds measure the same with the odd one measuring 0.0005 to 0.0010 thou out
Also i find more consistant bullet seating measurements when not loading compressed or close to compressed charged loads.