Seating depth advice

[JohnyRingo]

Where should I go from here? 300 H&H Mag. 180 grain Accubonds. 67.5 grains of IMR 4831. CCI primers and Nosler brass. 3.652" OAL to lands.

3.585" OAL. ES=100 fps. 1.5 MOA (3-shot group)
3.595" OAL. ES=25 fps. 0.9 MOA
3.600" OAL. ES=15 fps. 0.7 (2-shot group and a big flier)
3.605" OAL. ES=14 fps. 0.8 MOA
3.613" OAL. ES=47 fps. 0.6 MOA
3.625" OAL. ES=25 fps. 1.18 MOA
3.640" OAL. ES=14 fps. 1.15 MOA

Obviously, the 3.613" created the best group. I am surprised it shot so well with the ES being 47 fps. Should I try any other lengths to try to get better than 0.6 MOA? I am kicking around trying 3 shots at 3.610" and 3 shots at 3.620". I don't have a big surplus of reloading supplies to be messing with load development without eating into my supplies a little. This is the first time I have ever messed with seating depths as my other rifles seem to shoot great with advertised OAL. The advertised OAL for this load is 3.600", but I got a huge flier (2") out of it.

 

[VikingsGuy]

For a hunting load, my goal is less than 15 SD fps and 0.8 MOA for 5 shot group at 200y. If I get there I quit. From your data I would call 3.605 the winner. I would guess if you did a 10 shot group at 300 yards the perceived advantage of the 3.613 would melt away with 47 fps ES. There is no way 3 shot groups can distinguish mathematically between 0.6, 0.7, 0.8 or 0.9 MOA - they are scientifically essentially the same number at that "n". But have fun, I am sure any of your sub 20 fps ES will kill well if you do your job.

 

[pukeleeland]

For a hunting load, my goal is less than 15 SD fps and 0.8 MOA for 5 shot group at 200y. If I get there I quit. From your data I would call 3.605 the winner. I would guess if you did a 10 shot group at 300 yards the perceived advantage of the 3.613 would melt away with 47 fps ES. There is no way 3 shot groups can distinguish mathematically between 0.6, 0.7, 0.8 or 0.9 MOA - they are scientifically essentially the same number at that "n". But have fun, I am sure any of your sub 20 fps ES will kill well if you do your job.

Good advice. Thanks.

 

[cahunter805]

I would retest 3.600, 3.610 and 3.620 and see how they shoot. Also a picture of the groups would be helpful.

 

[Don Fischer]

For a hunting load, my goal is less than 15 SD fps and 0.8 MOA for 5 shot group at 200y. If I get there I quit. From your data I would call 3.605 the winner. I would guess if you did a 10 shot group at 300 yards the perceived advantage of the 3.613 would melt away with 47 fps ES. There is no way 3 shot groups can distinguish mathematically between 0.6, 0.7, 0.8 or 0.9 MOA - they are scientifically essentially the same number at that "n". But have fun, I am sure any of your sub 20 fps ES will kill well if you do your job.

Something no one seems to think about is no body has ever fired a .000" group, even with the smallest SD. I suspect if you fired three different ten shot groups at 300 yds every group would be different! I think group size has a lot more to do with the shooter than the SD! If this is a hunting load, I'd choose the best three shot group. How many animals are gonna give you more than three shots?

As for seating depth, seem[s everyone has their own idea on that. I like the bullet just off the lands and then again I like the bullet seated to the junction of the neck and shoulder if I can. The one that is right is the one you shoot best. Get factory ammo and all the bullet's are seated to ensure the round will fit any magazine the round is shot in! Go figure.

 

[VikingsGuy]

Something no one seems to think about is no body has ever fired a .000" group, even with the smallest SD. I suspect if you fired three different ten shot groups at 300 yds every group would be different! I think group size has a lot more to do with the shooter than the SD! If this is a hunting load, I'd choose the best three shot group. How many animals are gonna give you more than three shots?

First of all, maximizing performance can be fun - tinkering for some of us is fun. Second, the lower your fps SD and the better your groupings and the better your technique, the more room for error you have in the field when conditions are outside of your control. The odds of successfully and humanely shooting an animal in the field is a series of stack variances ("errors"). The more you choose to eliminate the less the chance of unacceptable error. Thirdly, fun.

 

[OntarioHunter]

I've had some problems with deep seated bullets since surgery a week ago. Picked up one of these tools yesterday. A pain in the ass to operate but it got the job done.

 

[antelopedundee]

First of all, maximizing performance can be fun - tinkering for some of us is fun. Second, the lower your fps SD and the better your groupings and the better your technique, the more room for error you have in the field when conditions are outside of your control. The odds of successfully and humanely shooting an animal in the field is a series of stack variances ("errors"). The more you choose to eliminate the less the chance of unacceptable error. Thirdly, fun.

All other things being equal how much will a 300 fps difference change the POI on a target 100 yards away? A half inch? One inch?

 

[VikingsGuy]

All other things being equal how much will a 300 fps difference change the POI on a target 100 yards away? A half inch? One inch?

Depends on bullet weight, bullet BC, elevation, etc. Don't have time to run the ballistics calculator on examples but I would guess more than an inch with some bullets and less than an inch with others. But in the field, if you have a 275yd shot but you are off on that distance estimate and you are at a low elevation and you tend accidentally put upward pressure on your stock when you fire under stress that 300 fps could make the difference between hitting a double lung vs hitting the brisket.

I have said a hundred times on threads like this - old 30-30 CoreLokt with horrible fps SDs have killed millions of animals so if that is what you like knock yourself out. If you like tinkering, if you like the science behind hunting and firearms, if you like to minimize risk of a bad shot, then it can be fun and useful to dial some of this stuff down.

 

[Don Fischer]

First of all, maximizing performance can be fun - tinkering for some of us is fun. Second, the lower your fps SD and the better your groupings and the better your technique, the more room for error you have in the field when conditions are outside of your control. The odds of successfully and humanely shooting an animal in the field is a series of stack variances ("errors"). The more you choose to eliminate the less the chance of unacceptable error. Thirdly, fun.

I agree that tinkering can be fun but, look at the op's chart and it say's you just might be wrong about SD! I doubt it has ever been proven that lower SD gives better groups, just in theory. Until you take out the human element, you can't prove much of anything. Look again at the op's chart. Best SD was 14, two times. Neither gave the best group. In fact one gave a group of .8 and the other 1.15. How can that be? I'd bet you could take the same exact load and fire it several time's and get a different SD every time! The best load is the one you shoot the best! Sure does give us something to talk about though huh?

 

[VikingsGuy]

I agree that tinkering can be fun but, look at the op's chart and it say's you just might be wrong about SD! I doubt it has ever been proven that lower SD gives better groups, just in theory. Until you take out the human element, you can't prove much of anything. Look again at the op's chart. Best SD was 14, two times. Neither gave the best group. In fact one gave a group of .8 and the other 1.15. How can that be? I'd bet you could take the same exact load and fire it several time's and get a different SD every time! The best load is the one you shoot the best! Sure does give us something to talk about though huh?

Groups of 3 shots do not prove anything of the sort (heck one of them is 2 shots as he declared a flier). There are competitive shooters that use 10-30 shot groups which clearly show the correlation between low SD and MOA. There is no serious doubt of the connection. But again, for hunting, it may not matter to you.

 

[cahunter805]

The OP listed ES not SD.
I like my ES to be below 20. For longer range shots it’s certainly a factor and one I can control so I will tinker with it.
The average hunter doesn’t need 1/2MOA loads or low ES but some of us want the most accuracy out of our rifles.

 

[VikingsGuy]

The OP listed ES not SD.

You are spot-on - shame on me for avoiding the caliber vs cartridge correction/discussion and just sharing my SD targets (as I don't use ES).

 

[pukeleeland]

I loaded up 5 rounds at 3.605" and 5 rounds at 3.610". I did adjust the powder charge to see how 67.3 grains will perform.

 

[VikingsGuy]

I loaded up 5 rounds at 3.605" and 5 rounds at 3.610". I did adjust the powder charge to see how 67.3 grains will perform.

Ideally, you don't change two variables within the same test - as seating depth and optimal charge are interdependent - but again, for hunting, likely all these will be fine.

 

[VikingsGuy]

At this point, I take it that JohnyRingo and pukeeeland are the same shooter . . .

 

[pukeleeland]

At this point, I take it that JohnyRingo and pukeeeland are the same shooter . . .

Yes. I don't know why switching to my phone has switched my username.

 

[pukeleeland]

Ideally, you don't change two variables within the same test - as seating depth and optimal charge are interdependent - but again, for hunting, likely all these will be fine.

I get what you are saying. Technically, the 3.605" batch is only changing the powder charge. The other batch is changing two variables but I wanted to compare the two batches with the same powder charge (67.3 grains).

 

[cahunter805]

I loaded up 5 rounds at 3.605" and 5 rounds at 3.610". I did adjust the powder charge to see how 67.3 grains will perform.

Why did you drop to 67.3? Did you already perform a powder charge test?OCW test? Ladder?
Also your seating depth test seems to narrow now to determine much of anything. Just curious if both test loads shoot sub MOA what then?

 

[pukeleeland]

Why did you drop to 67.3? Did you already perform a powder charge test?OCW test? Ladder?
Also your seating depth test seems to narrow now to determine much of anything. Just curious if both test loads shoot sub MOA what then?

I just wanted to revisit that charge now that I have settled into a seating depth range...more curious than anything.