I ran across an old article (Nov 2000) in Shooting Times by Rick Jamison. He showed how to develop a precision load for a rifle (he went from 2" to 0.75") by simply varying the depth the bullet was seated. Starting at some nominal seating depth and then lengthening or shortening it by about 0.020" at a time he tuned in and got great results. Same powder, bullet, case, charge only seating depth changed. Has anyone tried this approach and did it work? I have a 7600 in .30-06 that consistently hits about 2" with reloads or factory. If this works, it would be a nice experiment to see if I can improve the precision.
Reloading for precision groups
- Thread starter Oldnamvet
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Yes, seating depth does make a differance.
I`ve seen seating depth vary the groups ~0.5" in a rifle or two but never over a inch as stated. I can`t say it never will alter the groups that much, just that I haven`t seen it.
I normally seat mine to the lands when working up a load then vary it by .005" increments until I hit a "sweet" spot, usually about 0.010"-0.015" from the lands, but I have a old 6.5 Swede that likes them close to 0.10" back. You just never know you just have to keep playing with them.
I`m not trying to knock your M7600 but it never will likely shoot like a bolt . The 2" you report getting is probably close to as good as it will do. I`d still try varying the seating depth. I don`t doubt you`ll see some inprovment, but if you get to 1.5" you`re probably as good as you`ll get. Don`t start flaming me, I know someone has a <0.5" M7600, but on the average I`d be very happy with a repetable 1.5" and not expect .75" from one.... JMHO
I`ve seen seating depth vary the groups ~0.5" in a rifle or two but never over a inch as stated. I can`t say it never will alter the groups that much, just that I haven`t seen it.
I normally seat mine to the lands when working up a load then vary it by .005" increments until I hit a "sweet" spot, usually about 0.010"-0.015" from the lands, but I have a old 6.5 Swede that likes them close to 0.10" back. You just never know you just have to keep playing with them.
I`m not trying to knock your M7600 but it never will likely shoot like a bolt . The 2" you report getting is probably close to as good as it will do. I`d still try varying the seating depth. I don`t doubt you`ll see some inprovment, but if you get to 1.5" you`re probably as good as you`ll get. Don`t start flaming me, I know someone has a <0.5" M7600, but on the average I`d be very happy with a repetable 1.5" and not expect .75" from one.... JMHO
Steve in PA
Member
Yup, I've tried it and it worked.
When working up a pet load for my hunitng .30/06 I would decide on bullet/powder combo then work up a load to find the best accuracy (using a standard OAL).
After finding the best powder charge I would then play with the seating depth of the bullet. I used the RCBS Precision Mic when doing this.
When working up a pet load for my hunitng .30/06 I would decide on bullet/powder combo then work up a load to find the best accuracy (using a standard OAL).
After finding the best powder charge I would then play with the seating depth of the bullet. I used the RCBS Precision Mic when doing this.
To Ol' Joe
Why would I flame you for stating the truth? The 7600 is a good gun for hunting but it is not a target rifle. I like pump shotguns and rifles. For me, they are as fast as a semi-auto for aimed second shots. Besides, I love the sound of them racking.
But, just for curiosity, I will have to try and see if I can squeeze it a little for a tighter grouping. Any excuse to load and shoot more.
Why would I flame you for stating the truth? The 7600 is a good gun for hunting but it is not a target rifle. I like pump shotguns and rifles. For me, they are as fast as a semi-auto for aimed second shots. Besides, I love the sound of them racking.
But, just for curiosity, I will have to try and see if I can squeeze it a little for a tighter grouping. Any excuse to load and shoot more.
Lennyjoe
Member
My Savage 110 is putting out quarter size groups at 100yds with 165gr Sierra Gameking HPBT over 59.5gr of IMR 4350 and WLR primers in Winchester brass seated at .010 off the lands.
On that note, my Savage 22-250 likes the bullets .015 off the lands. At .005 off the lands I got high pressure signs so I had to seat them deeper.
On that note, my Savage 22-250 likes the bullets .015 off the lands. At .005 off the lands I got high pressure signs so I had to seat them deeper.
You will need to change more than *just* seating depth for true "precision" shooting.
You need to get your load, then mess with OAL to fine tune it. If you are getting 2" and by simply changing OAL you get 0.75" you never got your load in the first place.
You need to get your load, then mess with OAL to fine tune it. If you are getting 2" and by simply changing OAL you get 0.75" you never got your load in the first place.
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bogie
Member
0) Put wind flags out, and only shoot when they show a consistent pattern for each group.
1) Adjust your seater for maximum magazine length, unless you wanna feed it like a single-shot rifle.
2) Work up a load, going up about 1/2 grain each step, changing nothing but the powder charge. 3 shot groups are fine.
3) Look for the accurate loads - this ain't a speed race, and Bambi will be just as dead with 2650 fps as with 2800...
4) Now, with the accurate load, start moving the bullet into the case, about 0.003" at a time, firing a 3 shot group for each, again waiting until the wind flags are consistent in "your" condition.
You'll know when you get it dialed in.
1) Adjust your seater for maximum magazine length, unless you wanna feed it like a single-shot rifle.
2) Work up a load, going up about 1/2 grain each step, changing nothing but the powder charge. 3 shot groups are fine.
3) Look for the accurate loads - this ain't a speed race, and Bambi will be just as dead with 2650 fps as with 2800...
4) Now, with the accurate load, start moving the bullet into the case, about 0.003" at a time, firing a 3 shot group for each, again waiting until the wind flags are consistent in "your" condition.
You'll know when you get it dialed in.
Sunray
Member
Yep, once you have a decent group, you can tweak it by changing the seating depth. The problem is that it's done entirely by trial and error like Ol` Joe says.
Part of the fun of reloading is doing stuff just like this. I doubt you'll ever get sub-MOA groups with a 7600, but you'll have fun trying and you'll still have your hunting load.
Part of the fun of reloading is doing stuff just like this. I doubt you'll ever get sub-MOA groups with a 7600, but you'll have fun trying and you'll still have your hunting load.
Big_R
Member
There is no reason your 7600 shouldn't be able to do just as well as a factory bolt rifle. The 760/7600's are good rifles.
To most everyone's point, though, seating depth is just one factor in making accurate loads. Volumes of books have been written on that very topic and on several points, they agree. Most of them say that seating depth should be the last variable adjusted. I always start with a chronograph looking for consistent velocity, shot to shot. Once I have that, then it's time to tweek.
Ryan
To most everyone's point, though, seating depth is just one factor in making accurate loads. Volumes of books have been written on that very topic and on several points, they agree. Most of them say that seating depth should be the last variable adjusted. I always start with a chronograph looking for consistent velocity, shot to shot. Once I have that, then it's time to tweek.
Ryan
bogie
Member
It is NOT trial and error. Start at max magazine length (as close to jam as you'll get), and work up your load.
KEEP RECORDS.
3 shot groups are enough.
If you bump up in half-grain increments, you'll notice spots where stuff tightens. Those nodes are what you're looking for. Pick the fastest tight node.
Now, after you have that, seat the bullets 0.005" deeper into the case. Shoot 3 shots. Measure.
Repeat until you've got about 0.030 into the case, and then pick the best load from there.
Use wind indicators.
KEEP RECORDS.
3 shot groups are enough.
If you bump up in half-grain increments, you'll notice spots where stuff tightens. Those nodes are what you're looking for. Pick the fastest tight node.
Now, after you have that, seat the bullets 0.005" deeper into the case. Shoot 3 shots. Measure.
Repeat until you've got about 0.030 into the case, and then pick the best load from there.
Use wind indicators.
stallard
Member
Lennyjoe
Lennyjoe,
What caliber is the savage you are refering to ? I own a couple of these bluecollar shooters (30-06, .308 win). Savage is top notch without top dollar.
Lennyjoe,
What caliber is the savage you are refering to ? I own a couple of these bluecollar shooters (30-06, .308 win). Savage is top notch without top dollar.
Lennyjoe
Member
The 110 is a 30-06 and the 12FLV is a 22-250.
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