Measuring cartridge overall lentgh.

[John25]

You will of course let us know how the 'new' rounds shoot in comparison with your 'old' ones?


Thinks to self - another one hooked! :shakeshout:

[Dougan]

I haven't gone as far as the F class boys yet, but would certainly be looking at measuring bearing surface etc. if I was shooting that discipline - That said, I do believe a little extra care with loading, even at my end of the game pays off...

...since reloading, my classics shooting has really improved - The amount of case prep I do depends on if i'm practicing or competing; but I always make sure the powder is within 0.1 gn, the bullet weights are within 0.3 gn and the seating depths are as consistent as I can make them - this means that I never 'plink' anymore, but carefully aim each shot...and even with cheap bullets can be quite competitive with my SMLE.

Your enthusiasm is contagious Alpha ...I think I'll get my reloading stuff in order tomorrow for the upcoming season tongueout

[Alpha1]

Just one more question well there might be another one depends on the answer I get.

My Comparator over all length measurement to the bullet ogive is 2.2360 I am going to start with my bullet ogive twenty thou of the lands 2.2560.
(25.6 inch barrel 168g Sierra match Kings 41grains of N140)
Does this make sense or should I start with a shorter comparator over all length and work up I was thinking of going up in .003 steps. This is new territory for me I am stepping off in to the dark side don't want to fall at the first hurdle.

[zeroveez]

Looking at the new Berger reloading manual, (a Christmas prezzie), Brian Litz talks about "cartidge base to ogive" CBTO, which is the thread of this topic? Can I ask what sort of tolerance you guys are getting using, say, the Stoneypoint guage? If it's of the order of plus or minus two thou, what sort of difference does this make in the results down the range? My feeling is that it makes b----r all.

[ovenpaa]

Firstly loose the last digit, you cannot measure to a tenth or even five tenths of a thou in a chamber, this is down to limitations in the process. Secondly you have gone the wrong way, you should be starting with a reduced OAL.

If your average COAL is 2.236" start at say 2.200" and move forward in .005" jumps, if the groups start to close at one point and then open afterwards that is the area to concentrate on. So if the group tightened slightly at 2.225" go back and test again in +/-.002" increments.

My concern would be the constancy of the bullets.

[Christel]

Looking at the new Berger reloading manual, (a Christmas prezzie), Brian Litz talks about "cartidge base to ogive" CBTO, which is the thread of this topic? Can I ask what sort of tolerance you guys are getting using, say, the Stoneypoint guage? If it's of the order of plus or minus two thou, what sort of difference does this make in the results down the range? My feeling is that it makes b----r all.

I used to think that. That it was all down to me to shoot well. Then Ovenpaa sat down and explained it to me, that took many hours because mathematically I am not a genius. I still struggle with it all and do not ask me to explain anything from Brain (!) Litz because I do not understand the language he is speaking. However in a nutshell, it does matter. It does make a difference.

The more you put into reloading the more you get out

[Alpha1]

Firstly loose the last digit, you cannot measure to a tenth or even five tenths of a thou in a chamber, this is down to limitations in the process. Secondly you have gone the wrong way, you should be starting with a reduced OAL.

If your average COAL is 2.236" start at say 2.200" and move forward in .005" jumps, if the groups start to close at one point and then open afterwards that is the area to concentrate on. So if the group tightened slightly at 2.225" go back and test again in +/-.002" increments.

My concern would be the constancy of the bullets.

You are spot on my friend I looked at the numbers and added it on instead of subtracting. I would of had a problem chambering them so and so,s. Just goes to show how important it is to check every thing. Only consolation is its easier to make them shorter than it is to make then longer.
Lesson learned high light plus and minus figures in my spread sheet.

[ovenpaa]

I always start by building over length, maybe 4-5 a few thou over and then reset the dies and bring them all down slightly and I always look for a repeatable figure across the 5. Once I am happy I have arrived at my chosen length I build the rest to suit. It is easier than having to pull them... I also seat some of my seaters on nitrile O rings with timing marks on my dies so they always go back in the press in the same position.

[Alpha1]

Interesting.
I am using a Le Wilson seating die with a arbor press to seat the bullets. I wish I had got the micrometre seating die now that I have used them.
Never mind I will know next time.

[zeroveez]

Christel, I have just measured the case head to ogive using a Stoneypoint system and Mitutoyo caliper; these rounds are 6.5mm 140 grain Sierra Game Kings loaded with sensible care using RCBS dies. Nine of the rounds measured to plus or minus one thou, with the tenth spoiling the measurements by a half of one thou. Using a Norman Clark Sako/Krieger barrelled sporting rifle, this ammunition shoots to better than half an MOA, admittedly at 100 metres. As Robert Chombart pointed out in a recent post on this forum, discussing the last TR World Championships, the Champion won with a better lateral dispersion of shots, and not a better V bull count. From this I infer that wind reading skills are more important than the absolute accuracy of the ammunition. Certainly in TR, if not in Bench Rest, ammunition that performs consistently to better than half a minute of arc will bring home the bacon, or venison, if you prefer. This consistency of ammunition can be produced using Stoneypoint, for example. To repeat my question, what sort of spread on the case head to ogive measurements are you looking for?