The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

Given the choice between H and IMR versions of powders, I start with H because of the temp stability. I started with h4895 and have now shifted to IMR because I could get it...

n160 was a sensible choice as it was available.

H4831SC was by far the best for me but can't find it atm.

Ah, I'd missed the earlier posts from Dromia somehow.

It's a shame that I am being considered 'dangerous' and 'cavalier' in my approach as I'm trying to be anything but. Hence joining this forum for advice. We all have to start somewhere.

Dromia, thank you for your advice to cross check, oh that I had seen it sooner as it tallies with what I found on the range. As I went up in the half grain intervals and reached 45.5gns. I noticed that there were small, shiny marks on the case head from the ejector pin. This is where I stopped.

So, tonight I cross checked data (bearing in mind that the seating depths between the two sets of data differ slightly, so that likely has a bearing on speed, pressure etc.). I'm using the seating depth or C.O.L from the bullet manufacturers for each type.

Here's the data for a Sierra 70gn Blitzking with a COL of 2.670"

START 41.6 (3000fps) 42.6 (3100fps) 43.6 (3200fps) 44.6 (3300fps and MAX)

and the Nosler data 70gn Ballistic Tip with a COL of 2.680" (which is what I'm using)

START 43 (3250fps) 45 (3430fps) 47 (3610fps)

Makes sense that 45.5 gave slight marks on the case head then so worth double checking before heading off!!!

And with this in mind, for a 100gn load I was going to use the Sierra data. Cross checked with IMR's.

Sierra state a COL of 2.650" (which is what I will use) and loads of 35.2 (2500fps) 36.8 (2600fps) 38.5 (2700fps) 40.1 (2800fps) 41.7 (2900fps)

IMR state a start of 38.5 (2760fps) and a maximum of 42 (2958fps).

So, I assume that I can work up from a base of 38 (I know just under IMR's start but well within Sierra's range) and go 38, 38.5, 39, 39.5 & 40, to see which is the best group and then bracket in .3 either side, so if 39 gives the tightest group go 38.4, 38.7, 39, 39.3, 39.6.

Given both manuals have data to 41.5 gr, I'd go at least that far, but probably to 42. So long as you're diligent when you work it up, shouldn't be a problem. You can always pull any that are too hot.

Your advice for the 100gn is appreciated

Been watching this with interest.
I don't load 243 or slot critters but Viht list many loads for it using 140/150/160 and the 5 series.
If I was loading for it I would opt for 150 or 160 or Ramshot Hunter.
I tend to stick to Viht and Ramshot as there always seems to be a regular supply.
Bear in mind that you could probably seat your bullet out further which may or may not improve accuracy.
Have you tried finding the lands?
Tony

Next time I'm at the range one of the other members is bringing an OAL gauge to measure the distance with all 3 bullets. I have ordered the part necessary for the verniers so I can get a consistent measurement from the ogive, rather than what I am currently doing and measuring the COL. I am slightly concerned that changing this will alter pressures, but I'm not totally sure if this id the case.

It will alter pressure.

Ah, one to watch then!