iv been working up loads for my 7mmremmag using 175woodleighs and ADI 2225 powder iv got the group down to about 1.7" but id like it to be better, i currently seat them at .040 off the lands my Q is if i change the seating depth should i just use the best group so far or do i have to go through trying different weigh powder charges as well.

g'day. No use changing the powder yet, I'd start lengthening right up to almost touching the lands, eventually, if they'll still fit in the mag, but your PRESSURE may go up suddenly if and when you get to the rifleing.

Then from that best group, you could adjust the powder slightly to see what happens. Then there's primers, standard and mag. etc etc. all one thing at a time.

Sambar,

I agree with JAL.

Normally, I don't play with seating depth too much because I start with what I consider an optimum AOL. This is based on years of expereince and I have a tool (Stoney Point AOL Tool) that assists me in setting up the AOL with a specific bullet in the rifle's chamber.

Prior to purchasing this tool I didn't start playing with seating depth until after I had found a load that showed some real promise. Sorry, but IMHO 1.7" groups from a 7mm Rem Mag. with properly assembled loads & components just hasn't arrived yet.

While there are a whole number things that would influence your 1.7" group from a 7mm Rem. Mag., bench technique, how stable, distance, the rifle, barrel, scope, mounts, your ability, ect.

Again, I can't help with alot of these variables but from my perspective a real tack driving 7mm Rem. Mag. with resonably assembled loads should be giving you .75" 3-shot groups before I would consider beginning to tweak AOL.

OAL is usually the last thing I work on. I am normally loading hunting ammo so my OAL is usually determined by magazine function and whether or not I've got the bullet seated deep enough to hold it firmly. As Gerry said, at 1.7" I don't think you are at the fine tweaking point yet. I would change powder and/or bullets until I got it down to an inch. I don't know what type of rifle you have but two friends of mine that have 7mm Mags swear by Ballistic Tips and 4350 or RL22 for accuracy. If you can't get it under an inch by switching some components around, you may have to start looking at the rifle.
Good Luck

Different strokes, but I start with the Jump to Lands measurement before messing with powder changes. I find the Zero Lands point (where the bullet's ogive touches the lands), both with an RCBS Precision Mic, and by marking the bullet (with green marker, because I have one), then seating the bullet to a 0.030" Jump To Lands (JTL). I then adjust powder charges, and may or may not fine-tune the JTL by 0.003" at some time, depending on how interested I am in that particular bullet/barrel combination, but the 0.030" has proved to be a pretty good all around measurement. It works for me.

Jaywalker

quote:

Originally posted by sambar1:
iv been working up loads for my 7mmremmag using 175woodleighs and ADI 2225 powder iv got the group down to about 1.7" but id like it to be better, i currently seat them at .040 off the lands my Q is if i change the seating depth should i just use the best group so far or do i have to go through trying different weigh powder charges as well.

I don't know enough about your rifle but when you say I've got my group down to 1.7 ". I certianly think the load is not the problem. Woodleigh makes some good quality bullets I shoot them in a couple of my rifles. They shoot sub MOA for me. My gut tells me you shoud have been starting with an accuracy of 1.5" or better. Is this a new or used rifle? Has it been bedded? Does it shoot better with factory or other loads? Do you have other rifles that shoot better than the 7MM?

Just for another view, I am with Jaywalker, in that I start adjusting OAL pretty early. I do establish a max OAL based on the magazine, and start there and then start seating the bullets deeper. I have MANY rifles that shoot better with shorter OAL's--or said another way, with my bullets being seated deeper, farther from the lands.

I usually start with a known accuracy load, build some rounds a liitle on the high side and a little on the low side of that powder charge, and then start tweaking with the seating depth after that.

Jay Johnson has some good questions, I would think a good factory load would do you better than 1.7", so I'd check some of the things Jay suggested. Additionally, how does the brass you're using fit your chamber, is it virgin, or has it been fireformed in this rifles chamber--I've had rigs that shot significantly better just by reproducing the same loads, but with fireformed brass for THAT rifle, that had been partial full length resized so the shells had a slight crush fit upon chambering.

Good Luck--Don

the rifle is a new weatherby vangaurd with a 1:9.5 twist that has been bedded and floated. it shot remington 175gr factories at 1.5" but i can load 160 woodleighs and 154gr interlocks to put 3 shots into .6 at 100m.
the 1.7" group was the best one i shot going up by .5gr in powder(ADI2225) with the bullets seated at .040 off the lands. will changing the seating depth of this load give me the best accuracy or do i have to change seating depth and powder charges to acheive the best group?
I havent yet changed powders or primers to improve this load.
I think the 1:9.5 twist should stabilise a 175gr bullet but they are a very long bullet could this be the cause?

quote:

it shot remington 175gr factories at 1.5" but i can load 160 woodleighs and 154gr interlocks to put 3 shots into .6 at 100m.

I couldn't get the 175 grain bullets to shoot real well in my 7mm mag either, give them the flick and stick with the 160 grain woodleighs, there is no real advantage going to the 175's anyhow.

You have a large selection of bullets in the 150 to 162 grain region that are ideal for the 7mm mag just use whatever shoots well in your rifle.

Sambar,

Nice piece of kit yur Weatherby IMO - I'm sure your think so as well.

I've very little experience with Weatherby's and the one I did set-up for a friend was a .300 Weatherby.

I din't get great accuracy at first with reloads - the Remington Factoy fodder shot very well in it and that was with ammunition loaded with bullets that had a very short AOL. Those bullets had a huge amount of freebore to overcome to engadge the lands in that barrel.

I think those long 175 grainers ought to do just fine in this rifle. Like yourself I've also had good luck with the Hornady 154 grain bullets also.

Just goes to show every rifle & load combination is a law unto itself but if you're getting .6 with other bullets I'd be pleased with that.

quote:

sambar1: will changing the seating depth of this load give me the best accuracy or do i have to change seating depth and powder charges to acheive the best group?

It's hard to give rules-of-thumb about rifles, since each barrel's different. While it might be neccesary to do both, your barrel may not require it. I've found changing seating depth by 0.005" changes group size more than changing 0.5g of powder - in 30-06-sized cases, at least. YMMV.

For accuracy, you're trying to locate the vibration node that releases the bullet from the muzzle at the same point for each firing. Powder, bullet, seating depth, and even primer affect this vibration, so any change in them could affect your accuracy.

Jaywalker

What Jaywalker said!

As one other point, going from 160's to 175's would surely require you to reduce your powder charge by more than 1/2 a grain, so interpolate where your powder charge fell within a given range for your 160's, and then try the same with your 175's. --i.e. if your 160 gr bullet powder charge was in the middle of the range for that weight bullet, than pick a charge that is in the middle for the 175's

Good Luck--Don

quote:

Originally posted by sambar1:
the rifle is a new weatherby vangaurd with a 1:9.5 twist that has been bedded and floated. it shot remington 175gr factories at 1.5" but I can load 160 woodleighs and 154gr interlocks to put 3 shots into .6 at 100m.
The 1.7" group was the best one i shot going up by .5gr in powder(ADI2225) with the bullets seated at .040 off the lands. will changing the seating depth of this load give me the best accuracy or do i have to change seating depth and powder charges to acheive the best group?
I havent yet changed powders or primers to improve this load.
I think the 1:9.5 twist should stabilise a 175gr bullet but they are a very long bullet could this be the cause?

Some of the older 7MM (Sako) used a 1 in 10 and they would only stabilize 160's. Since your gun seems to shoot 160 Woodleighs very well it would seem to me the twist just isn't fast enough. The Remington uses a 1 in 9 twist. My own feeling is the 160 Gr. bullets in the 7MM are superior to the 175. The B/C is slightly lower but with much better velocity. I would either go with that 154 Interlock you seem to have had some success with or the 160 Woodleigh. .6 a Sub MOA group is hard to argue with in a game rifle.

I am curious though what are you shooting in Australia that you feel the need for a 175 Gr. bullet?

thanks guys i think ill just stick with the 154 and 160 they both shoot identical at 100m.
Jay this rifle is only used for hunting sambar deer i was after the 175gr just for that little bit extra not that i really need it its just one of those "i would like too" things