Using a comparator to measure OAL

[Dombo63]

I recently treated myself to a Shooting Shed comparator in .308. Apart from being a truly exceptional looking piece of kit that wouldn't look out of place in a particle accelerator or space shuttle, it has also taken my reloading to a new level.
Loading for my Remington 700 I have in the past used a factory round to set the bullet seater and checked my hand loads OAL using a dial calliper, head to tip. However SMK bullets often have very slightly uneven tips, and as it's the ogive distance to the rifling that's important I thought a comparator might help. As a result, checking a box of previously loaded 155gn SMKs into Lapua cases revealed an average 3.828" OAL including comparator length (Unlike digital ones, dial callipers can't be reset back to zero), but with a 40 thou spread between the two outliers at 3.821 and 3.862. A dummy round that I made by closing the bolt on a loose-fitting bullet in an empty once-fired case had a 3.838" OAL including comparator. However the 700 has a very long chamber, probably for legal reasons, and so it's very difficult to make up a round with the bullet even remotely touching the lands.
I then tested a box of HPS rounds with 175 SMKs and found almost 100% consistency, with only a 3 thou spread between the highest and lowest, and a box of Prvi match rounds in 168 HPBT that had a 20 thou spread between the outliers.
One other point this exercise threw up was that the ogives on the different weight bullets are in different places, as the Prvis with their 168 gn bullets were on average a full 100 thou shorter OAL than my 155s, whereas the HPS rounds were in the same ball park, at around 3.800.
As for accuracy, my own squeaked in ahead of the other two, at just under 1/2 MOA, testing off a bipod on a bench at 100 yards. Hopefully, thanks to my new comparator, things might get a bit more consistent.

[Alpha1]

I have one of the shooting sheds comparators in .308 as you say they are a pleasure to behold I can just sit fondling it for hours.
Oh and it works a treat as well I use it all the time when building for my Steyr. If you have not got one you need to go over to the shooting shed web site and get one NOW.
I have just recently acquired one of there annealing cups in .308 another wonderful piece of machining I think he should run a completion with a day in his work shop as a prize.
its lovely and shiny. Oh and it works.

[Dombo63]

Well the comparator certainly works. I loaded 20 rounds of 308 yesterday, brand new Lapua brass straight out of the box, Winchester primers and 155gn SMKs. Powder was some N140 close enough to the Vihtavouri maximum load that suits my Rem 700. Shooting at 800 yards I converted my second sighter, which was a V-bull, then 6 more Vs, a 5 and a couple of 4s. Very happy.

[ovenpaa]

Good to hear feedback on our comparators, they are very popular although probably more so outside of the UK however we have a very loyal following over here as well. When we move we plan on putting a map of the world up on a pin board somewhere so we can mark all of the countries we have customers in

I have just recently acquired one of there annealing cups in .308 another wonderful piece of machining I think he should run a completion with a day in his work shop as a prize. its lovely and shiny. Oh and it works.

People are welcome to come and see us any time, the way we make things is not a secret, it is just down to care and patience and we are both really looking forward to getting everything under one roof at long last and adding some new machines and processes along the way.