Seating depth? Manual differences and effect.

[Zerk]

Hornady's 9th, over all lengths are shorter, then what I Lyman's 50th has for .243 win.

Deeper seated causes more pressure, and Hornady's max is less. Unfortunately I didn't catch this when loading 58 grain. I loaded 1.5 grains over. Haven't shot. Hornady 2.60 and Lymann 2.625. Lesson pay attention to length.

I am now loading 105 grn A-max, I have 1:9.25 twist. Again Hornady seats deeper. My question is, is it better to load longer, so closer to throat? Better accuarate and less throat wear?

Is Hornady just being conservative so it loads in all guns. I if I load longer, I will make sure it fits my magazine and loads.



Can I use a neck sided fired round to determine distance to throat? I read about coloring bullet with sharpie, sticking it in and chambering? Neck sizing to tight? Should I shoot one off in the backyard?

I am loading to try out when snow is gone. Thanks.

 

[AZShooter]

My impression from reading your thread is that you are simply choosing a random powder charge from the book and then shooting the rifle, it that correct?

The proper approach is to decide on the bullet seating depth, then you should work up a load. You didn't mention that you start low and work up progressively with more powder.

If you seat a bullet long and polish it with fine steel wool you can see the engraving from the rifling on the bullet. It the bullet is seated too long you will have difficulty closing the bolt. Adjust the seating die so the bullet is seated progressively deeper with 1/4 turns of the threaded shaft on top of the die. Polish bullet each time to see if you are still into the lands.

You decide if you want to have the bullet touching the rifling and how much. If the bullet is deep into the rifling there is the possibility you could leave the bullet in the barrel when extracting a loaded round.

If you read the threads here you will note most posters are seating the bullet with some distance from the rifling.

If you want to use the rifle as a repeater you will have to seat the bullet deep enough to allow the rounds to fit and feed from the magazine.

Once you have determined your seating depth work up the powder charge weight to see how the rifle responds. Shoot four or so of each powder charge noting the accuracy change.

In some instances powder charge changes are all you need to do to get an accurate load. Some rifles may require bullet seating changes to get the most accurate load. To do this manipulate the seating depth in small increments to further fine tune for best accuracy. Generally you can only seat the bullet deeper. I am talking .005" increments to try and find the best accuracy. It is up to you if you want to make this extra effort. The problem is how do you duplicate the seating depth when you just made up 5 or 6 loads with different seating depth? This can be a real pain if you don't have a seating die with a micrometer top.

To properly duplicate seating depth with a non micrometer topped seating die you will need a comparator. You will also have to make a dummy round for each seating depth as you progressively adjust the seater die deeper. That way when you find the best seating depth you can use the dummy and the comparator to duplicate the seating depth.

link showing comparator.
SINCLAIR INSERT STYLE BULLET COMPARATOR | Sinclair Intl

comparator use explained
https://www.youtube.com/watch?v=3wlsgGKfjfI

It is a pain to do but it will get you better accuracy in most instances provided the rifle is in good condition with no issues.

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Seating depth will not affect throat wear.

 

[Zerk]

My impression from reading your thread is that you are simply choosing a random powder charge from the book and then shooting the rifle, it that correct?

Using IMR4350, Varget, and H380.

You didn't mention that you start low and work up progressively with more powder.

ar.

Did I need to?


My question is, in the loads I am looking at, Lymann loads longer then Hornady. I am wondering if there is a benefit to one or other.

I am going to pick a length and load bunch of rounds. I will then take some of the better ones and I am may next summer try different depths. I do save dummy rounds, for setting dies quicker.

For the 58g I went with Hornady's factory length that matched their manuals. When I load Noslers, I do go by their length, since they are the manufacture. My Lyman books don't have Nosler bullets. But they do Hornady.

So I am wondering does the factory know better, or are they just avoiding clearance issues. I only have one 243, so I am not worried.

 

[AZShooter]

Sorry that thought you were just choosing a powder charge...my neighbor's son did that with a 6mm and a varmint bullet. AND he had it shooting bugholes. From then on my friends and I call it the Marvin approach to handloading. Hey you never said you worked up charge weights....

The OAL used by the various bullet manufacturers might be for what they think would fit in most SAMMI chambers. Who knows? I say seat the bullets out as far as possible so they fit and feed from magazine, may or may not touch the lands AND won't fall out of the case mouth.

I shoot a 55 gr ballistic tip from a 6mm-284 that had so little bullet in the mouth that I had to seat deeper. That is the only bullet I can say I didn't go with a maxed out OAL.

I will say that the Berger hybrid bullets tend to shoot where you seat them regardless of jump to the rifling. Only bullet that I have used that has that consistent quality.