SmallCaliberCentral

How much jump is too much? I've been reading everything I can on this forum since I got my new rifle. I have a Ruger Mod. 77 Mk II Varmit in .204. Please tell me if my thinking is flawed in what I have done. To find out how much "jump" I have in my rifle I did the following. The only measuring equipment I have is a micrometer and a digital dial caliper. I partially neck-sized a once fired case. Then I inserted a bullet in it and closed it in the rifle letting bolt seat the bullet into the barrel. I then measured the over all lenght of the cartridge. It is 2.473. A factory round is 2.260. That's .213 difference. That seems like a lot. I know there will be some difference because the ogives on the bullets are a little different. So, will seating bullets at .020, .030, .040 & .050 deeper than the 2.473 measurement be OK, or should I start at .030. Or am I just wasting my time and should go with e factory O/A length?
Thanks,
OtH

OTH.........some factory rifles like a little jump. My ruger #1 likes 39 sierras set at an COAL of 2.340. You can try this or 2.300 and work out. Factory chamber are cut a little on the long side. This is were I ended up with my factory ruger. Yes I agree factoy rounds are realy set deep in the case. You found out how long you chamber is but that doesn't leave much bullet in the case to work with. 26.0 hodgdon benchmark or 27.0 hodgdon H4895 with 39 grn Sierras do very well in my Ruger #1.
Hope this helps a little.
later
Ray P

Ray P. Thanks for the info. I agree there is almost no bullet left in the case if seated to anywhere close to the 2.473 o/a length. I'll use what you suggested and see how it works for me.
OtH

Here is what I discovered this week:

I've been working with the 26 grain Barnes Varmint Grenades in a .204 Ruger on a Savage PTA with a Shilen barrel. Thinking that the Barnes recommendation that VG's work best seated .020" off the lands that's where they were seated. RL 10x produced fair but inconsistent groups. I tried moving the bullet out to .010" and .015" off the lands. No brass ring, things became more inconsistent.

Then, I tried seating them to the standard factory OAL listed on the Barnes loading page, or 2.260" which placed them .082" off the lands. The groups shrank. Shooting at 100 yards in a gusty 8-15 mph cross wind, the 25.2 grain load of RL 10x produced a ten shot group where 8 rounds went through a .246" hole, with two wind fliers (the flags picked up just before the trigger released) that opened the group to .5" and 1". These little bullets do move around in the wind! Average velocity is 4,085 fps.

So, once again I had to learn the lesson that escaped my steel sieve mind, start with the factory depth and then experiment. Sometimes I just out smart myself.