I am finding that when my loads are very compressed, it is hard to get the bullet to seat to a consistent depth and to stay there.

Is it generally better practice to try and avoid compressed loads when looking for accuracy?

In my experience, yes. I've never seen a "most accurate" load that was compressed to any great degree. Generally, best results are obtained with the very slightest compression, to minimize air gaps which might allow the powder to shift even slightly in the case.

Heavily compressed loads should be avoided at all costs. I witnessed an idiot one time who was standing there in the dark on the first day of deer season wondering why his 7-08 ammo wouldn't fit in the magazine. That was because I, errr, ummm, I mean, he had used a very heavily compressed load of H4350 behind the 145 Speers, and over time the bullets were actually pushed about .050" back OUT of the case, and the cartridge was now too long to fit in there. Ahhh, the lessons we teach ourselves sometimes.

R-WEST

I have never found a compressed load that shot well. I like to set the seating die to the seating depth to be used, make a dummy round, and take a measurement to the ogive. Then find a powder that will give as close to max load as possible without compressing the powder enough to effect the seating depth. In my experience, it doesn't take much compression to push the bullet and change the seating depth.

I have found in the one rifle I load most for and/or give most attention to, a 6PPC that the faster loads give me very good groups.

28grains of VV N133 under a Nosler B-Tip seated just touching the lands.

Sometimes I get the suspicion that the bullets have been pused out because one may be hard to chamber.

The other and main problem is that when seating, each bullet takes a few trys to get right (44.04mm C.O.L.)I measure each one with a digital caliper to between .03 & .05 if possible.

All the same this load gives groups in the .3's and on occasion .2's

I am considering trying VV N130 to see if the compression is considerable less and the seating problems go away, insomuchas the fact that the groups do not suffer.

Express; Stay with the VIT-133 and go to a flat based Sierra bullet for the 6ppc. Also; try loads in the 26.5 to 27.0 range. There will be a sweet spot down there that is usually VERY accurate.

[ 09-21-2003, 08:56: Message edited by: Old & Slow ]

My experience is the exact opposite of some of you folks ........I have seen many compressed loads that were very accurate.......many were the most accurate loads you could whip up for an individual rifle ........especially in some of the overbore rounds like 7mm mag .

Would have to agree with gunslinger. My most accurate loads whether they be slow or fast powder are compressed. Have had old timers tell me to see which loads filled the case more and then bet they would be the most accurate. Though I don't approach my powder selection this way, it makes sense if you think about it (uniform burn in case, bullets in follow up shots in magazine less likely to move back, etc.). Sometimes my complicated way of thinking has a hard time of believeing it though.

Deke.

I have some good shooting loads that are moderately compressed, and a couple of great shooting loads with very slow burning Ball powders in belted magnums that are HEAVILY compressed. And I used to shoot some very heavily compressed loads of 3031 under 400 grain bullets in 45-70. They shot OK, but I don't want to punish myself that way anymore.

I've also had some loads of H4350 with 150 grain PSPs in 30-06 that were heavily compressed (and still never got close to the max loads for this powder in the loading manuals, I just couldn't get it in the case. Had a hard time getting past 57 grains.) Those loads didn't shoot well at all, but for that matter I never found a load of H4350 that did shoot well in that rifle. So I don't know that the compression was the problem. I got low velocities and lots of unburned powder, too. Used up the 2 lbs of that powder I had and never bought any more.

I've read that very heavily compressed loads could fracture powder grains and cause inconsistency. Haven't seen it myself, just saw it in loading manuals. I'd expect that to be more of a problem with extruded powders. The problem with compressing Ball powders is that they compress very suddenly. They're already at pretty high density when the case gets full. And the pressure tends to climb pretty rapidly when you squeeze 'em past that.

To be a compressed load or not often is a question of seating depth and/or how the powder is filled into the case.

Express, I doubt 28grs N133 in a 6mm PPC case are able to push out the bullet: I've tried 29.6 grs behind a 66grs FB bullet in a Lapua case, and the bullet did only come out when fired.

When you use a long drop tube and trickle the powder into the case instead of throwing it in, you'll be amazed how much space is left - 28 grs will hardly touch the neck area !

One word to Express's OAL-measurement. As the ogive is not always the same and the ogive being the part touching the rifling (if set up to do so), you need a speacial seating gauge (Sinclair, Stony Point and others): calipers will yield irrelevant results.