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I've been looking to buy some equipment to measure the correct amount of shoulder bumping during full length sizing and also measuring my Base-to-Ogive height rather than COAL (because sometimes I use different manufacturer bullets of the same mass but wish to keep the same amount of jump). So it looks like I need a bullet comparator and a headspace gauge for the calibres required. I stumbled across the Forster Datum Dial Indicator:
http://www.1967spud.com/shop/forster/da ... nt-system/

£132 does seem quite expensive, however, it does cover a large majority of my rifle calibres. I handload for .223, .308, .303brit, 6.5x47 and 8x57 IS. The aforementioned gauge covers Base-to-Datum length for all except 8x57 IS, and the Base-to-Ogive covers all except .303brit and 8x57 IS. It has the benefit of having everything in one package, so to speak. Searching around the net I found the following items to perform the same duty:

- Sinclair Hex Bullet Comparator £22.50 (.223, 6.5mm and .308)
- Hornady Headspace Kit w/Body £45 (includes .330, .350, .375, .400 and .420 bushings)
Total = £67.50

http://www.1967spud.com/shop/sinclair/s ... omparator/
http://www.sportsmanguncentre.co.uk/hor ... kit-w-body

This combo can then measure Base-to-Datum for .223, .308, .303 and 6.5x47, and measure base to ogive for .223, .308 and 6.5x47. This setup does exactly the same and is half the price?

I think the latter is all I need to do what I want. Any advice? Has anyone ever used either setups above and could comment?

Have you considered looking towards Ovenpaa and Shooting Shed? They do a two piece comparator that I use for exactly this purpose and it works very well.

I also use the shooting sheds. Good kit.

Thanks for the suggestions chaps. I had looked at Ovenpaa's stuff and don't get me wrong, I know it's excellent quality stuff, but for all my needs the final bill would be quite expensive! If I understand correctly, to have a bullet comparator and shoulder bump gage in one calibre would cost me £74. I'd like to have this for .223, .308 and 6.5x47 as a minimum so the overall cost is over £200.

As an aside, the description for David's Two Piece Cartridge Comparator says:

Please include details of your case size and make and choice of bullet

Does that mean the comparator only works with one type of bullet? Or am I missing something?

It depends how serious you are about your cartridge over all length and shoulder bump. It depends on the type of shooting you do and how far you want to go and how much you can afford to spend.
I can cope with out any of them for the type of shooting I do. I just need a set of callipers and a reloading manual. If I can close the bolt I'm fine. If I can knock down a figure11 at 400 yards I'm good.

Ovenpaa's a sensible chap and on good at getting back to e-mails. Drop him a line and have a chat with him, he may be able to give you some options.

I've dropped him an e-mail, let's see what he can do!

I added this to my Journal recently, it outlines the use of our Comparators and may be of interest, the previous article on the Journal covers the use of our Comparators in conjunction with our own OAL gauges.

http://shootingshed.co.uk/wp/2016/06/th ... mparators/

So I just received the following from the Shooting Shed:
* 2x piece 223 comparator;
* 223 comparator upper (case bump);
* 303brit comparator upper (case bump):
* 2x piece 6.5x47Lapua comparator; and
* 6.5x47Lapua comparator upper (case bump).

I had a quick play with them early and they are really cool. Excellent work by Dave he was really helpful and responsive via email for meeting my requirements, I'll get some pictures up of them in use when I find the time. I'm glad I went British and had these hand made for me Thanks again David!

Test results!

I went ahead and loaded some 6.5x47 Lapua bullets up to see if there was any velocity difference (average, ES etc.) when seating at different overall lengths. I used 39.9gr of Reload Swiss RS60 powder as this is a known good load I've developed and tried different base to ogive measurements with Lapua 123gr scenar's and Hornady 123gr A-max. Velocity measurements were made with a MagnetoSpeed sporter strapped to the barrel.

I had historical data with the 123gr scenar with a base to ogive of 2.120" so didn't load anymore, plus I didn't have any bullets left to load. I had loaded up some scenar's with a base to ogive of 2.099" by mistake (by dies hadn't been adjusted since the last time I used them so not sure how this happened) which shot fine the weekend before last, but nonetheless I wanted to test the velocity.

A known good A-max load for me was with a base to ogive of 2.110" so naturally I went 0.010" either way to see if there was any difference. I loaded up ten rounds at each length and shot two strings of five. I wasn't too fussed on accuracy because I was testing a new trigger which would have an effect on the group as I get used to it but won't have an impact on the velocity.

All results were shot on the same day, except for the 123gr scenar's at 2.120".

Hornady
I was actually quite surprised by these results. According to the data there is no linear relationship between average velocity and base to ogive measurement. The max velocity for the three depths have a total of 1fps variation. The average velocity deviates by 5fps across all three depths. This is most likely due to my Lyman Gen6 not throwing some slightly lower charges since the min velocity deviates by 11fps across the three depths. Grouping wise, the 2.110" (my historical load) shot better than the other two and this is confirmed with my historical results. Again, not going to disregard the other two sets of data since I wasn't focusing on accuracy at this point.

Lapua
There is a difference in velocity and ES, it seems the ones that I accidentally seated almost 0.020" deeper were causing more variation in velocity compared to the correct base to ogive depth. There's also a ~30fps gain in velocity - but I'm not putting this down solely to the base to ogive measurement. because both sets of data were shot on different days. Maybe it's the difference in loading conditions (e.g. was my shed more humid that day), shooting conditions or an accumulation of both, who knows.

To summarise, the new tool delivered by Dave is really useful for consistency. The overall length measurement can vary quite a bit due to inconsistent bullet meplats so unless you trim and point the meplat or sort your bullets by length you'll be hard pressed to keep consistent overall length. When using Dave's overall length gauge I found that the base-to-ogive measurement was ±0.001" within a batch of ten bullets without sorting or batching my bullets at all.