problems with compressed loads?

What are the potential problems with a slightly compressed load?

Details: 7mm RM, Norma brass fired 1x, FL resized with .002 shoulder bump, .0015 nk tension, 68.4 H 1000, Fed 215, 180 berger VLD, bullet seated .035 out from lands, about 2930 FPS, no pressure signs

Seating dept test showed .035 out to be the most accurate ...but the loaded cartridge seems to be slightly compressed.

A second question. The best load with the same gun, NEW brass, is 69.1 H 1000 with a seating depth of .010 into lands. Velocity here is about 2965 FPS Is it fairly common for loads with new brass versus fired brass to favor different seating depths?

Thanks
Jerry

Not familiar with your cartridge or the powder you are using, but my .340 Weatherby loads are compressed (using RL19), I can hear the powder crunching when seating the bullet. I have read that having a compressed load is more consistent than having a powder charge that doesn't fully fill the case. Depending on the position of the powder in the case when firing, you could possibly get variations in velocity. If your load is listed as safe in the loading data you are using, and you have slowly and safely worked up to that powder charge without any signs of excessive pressure, you should be good.

Sorry, can't help with your second question.

a slightly compressed load should cause you no problems . a heavily compressed load can push the bullets back out a little causing your COAL to vary . if I'm using a heavily compressed load , I just run these through the seating die again the next day , and the COAL will stay where I wanted . I recommend you just checking your COAL the next day , if it's where you want it you should be good .

I'm not sure what to say about your seating question . I do know virgin brass will have a slower velocity than used brass that has been properly resized . I don't like to try to figure out anything with new brass . it acts different compared to used brass .

Tagging in

jlvandersnick said:

Is it fairly common for loads with new brass versus fired brass to favor different seating depths?

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Doesn't matter what new brass favors, -unless you intend only to use new brass.

A compressed load as dropped can be less filing while slowly trickled filled through a funnel. Slower fill = less case filling.

I tried compressing H1000 in a 270Win and they were very accurate when shot a couple days later but after a couple months of being in cool dry storage they were not accurate, and when bullets were pulled to look at the powder it had to be picked out of the cases, as it wouldn't dump. I might be the only reloader who has had this happen, I don't know. I switched to H4831 and didn't have to compress with this powder, but it didn't shoot quite as good as the freshly loaded H1000 although I can leave them for long storage time and they don't loose accuracy.

Gunpoor said:

I tried compressing H1000 in a 270Win and they were very accurate when shot a couple days later but after a couple months of being in cool dry storage they were not accurate, and when bullets were pulled to look at the powder it had to be picked out of the cases, as it wouldn't dump. I might be the only reloader who has had this happen, I don't know. I switched to H4831 and didn't have to compress with this powder, but it didn't shoot quite as good as the freshly loaded H1000 although I can leave them for long storage time and they don't loose accuracy.

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I use H1000 in a rifle . I have seen how this powder gets packed in the case . I've had to dig it out with a small screwdriver and dentist pick . it really gets packed in there . I think it's just one of the quirks of H1000 . I have not had an accuracy issue though . it will even clump together in the 8 pound jug .

Laelkhunter said:

Not familiar with your cartridge or the powder you are using, but my .340 Weatherby loads are compressed (using RL19), I can hear the powder crunching when seating the bullet. I have read that having a compressed load is more consistent than having a powder charge that doesn't fully fill the case. Depending on the position of the powder in the case when firing, you could possibly get variations in velocity. If your load is listed as safe in the loading data you are using, and you have slowly and safely worked up to that powder charge without any signs of excessive pressure, you should be good.

Sorry, can't help with your second question.

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I agree a slightly compressed load is OK but I steer way clear of highly compressed loads . A powder load that slops around in the case will have slightly changing ignition and burn characteristics due to being forward or back or laying flat in the case . I like a powder type and load that fills the case to a point that the bullet just sits on top of it close enough so it don't move anyplace inside the case .

I have grown to stay away from compressed loads. They typically do not seem to be as good as a load that is close to 100% fill without compressing. My goal when load developing is to find top end performance right at full load density. When I can find this combo it usually turns out to be a good load.

Steve

RockyMtnMT said:

I have grown to stay away from compressed loads. They typically do not seem to be as good as a load that is close to 100% fill without compressing. My goal when load developing is to find top end performance right at full load density. When I can find this combo it usually turns out to be a good load.

Steve

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I do the same as you and it seems to work good all else being accurate and correct .