Which should you find first --- charge weight or seating depth?

[Bob 964]

Until yesterday, everything I had read about load development testing was based on techniques (ladder and OCW tests) that first identify the proper charge weight and then identify the proper seating depth. I read an article by a Sinclair reloading technician (see link below), outlining a contradictory technique where you first identify the proper seating depth and then identify the proper powder charge weight.

The Importance of Bullet Seating Depth | The Reloading Press

I called Sinclair and talked to one of the reloading technicians, who explained why they focus first on seating depth and then on charge weight. It was explained to me that, if your optimal charge weight is at or near maximum, manipulating the seating depth is more likely to create unsafe situations. In contrast, if you begin with the start load and find a seating depth that produces good tight groups, then you can gradually increase your charge weight (and muzzle velocity) until your groups start to open up.

Has anyone tried the technique outlined in this article and, is so, how effective was it?

Thanks
Bob

 

[afrancke]

Personally I start at the longest depth (jammed or mag length, whichever is longer) and establish charge weight before playing with depth. I suppose it might be worth confirming you're still sitting on the node by testing charge on either side once you adjust depth, but I haven't made that a regular practice.

It seems to me that if you're going to test depth first, you still need to be close to a charge weight that gets you a node or the variance in the group due to depth may be hard to separate from the variance due to charge.

 

[JoshcBoucher]

Afrancke is "with me", on that. "Go to the lands, for your "charge weight/ Max load", then start to "Back off", and reduce your charge weight, to find your nodes.1/1000, at a time, for "back off". Backing off, will "reduce pressure". At least you know your "Max", as you proceed.Don't exceed that.

Personally I start at the longest depth (jammed or mag length, whichever is longer) and establish charge weight before playing with depth. I suppose it might be worth confirming you're still sitting on the node by testing charge on either side once you adjust depth, but I haven't made that a regular practice.

It seems to me that if you're going to test depth first, you still need to be close to a charge weight that gets you a node or the variance in the group due to depth may be hard to separate from the variance due to charge.

 

[Big Z]

I generally start my bolt guns in the lands and test charges & accuracy. If I'm not satisfied, I'll try a couple more lengths: lightly touching, and then off the lands.

 

[garandman]

I always start with the powder manufactuers specied COL, and work from a mid range powder charge, up to a max charge. So I don't see any danger of an over pressure situation.

Recently, with my 6.5C I exceeded the max powder charge (by half a grain) at the specified COL, and found a really good load (half MoA) Then I lengthened the COL to just off the lands, and the groups opened up signficantly. So I'm going back to the stated COL, with the half grain over max powder load, which shows no signs of pressure, and velocity is within specified range.

My best guess? Every rifle is different.

 

[Bob 964]

I appreciate everyone's input and the time it takes to provide it, but the original question attempts to better understand the merits of determining the proper seating depth before determining the proper powder charge weight. I would love to hear from anyone who uses the method (or one substantially to the method) described in the Sinclair article. Thanks.

 

[doc76251]

I would submit that the "tech" who wrote the article is pretty doggone familiar with the rounds he is using and probably has a good solid base from which he can tweak his loads from. In his instance with a relatively "known good" powder charge he can begin to play with seating first and then tune his loads. You will also note that he isn't experimenting with something new to him and he is not seeking max pressure or velocity (which he notes). You will also note that he begins his quest by "reaching the lands" as opposed to jamming them. This will provide a "zero balance" in load development. No increased pressure due to jamming and no decrease in case volume due to stuffing the boolet in deep. For the rest of us mortals I would submit that it would be folly to arbitrarily choose a powder charge for an unknown round/rifle/powder combination and fool with seating depths first. IMHO I consider seating depth to be the "fine adjustment knob" for a great round.

To add another variable to the mix "What about neck tension?" [Add evil laugh here]

Cheers,

Doc

 

[BobinNC]

Personally I start at the longest depth (jammed or mag length, whichever is longer) and establish charge weight before playing with depth. I suppose it might be worth confirming you're still sitting on the node by testing charge on either side once you adjust depth, but I haven't made that a regular practice.

It seems to me that if you're going to test depth first, you still need to be close to a charge weight that gets you a node or the variance in the group due to depth may be hard to separate from the variance due to charge.

Your advise, and that of the poster below you has to rank as some of the WORST I've ever read on Sniper's Hide reloading. Your "advise" completely ignores the number one rule for reloading from a magazine feed rifle, that is any load you develop must actually feed from the magazine!!!!! So your ideal seating depth for your initial reloads should be just touching the lands or your max magazine length whichever is SHORTER not LONGER.....

Further, consider the neophyte here that's loading for a stock Rem 700 in 308 WIN (the most common rifle used by newby posters here) whose throat is in the neighborhood of 3.0" and their mag box is 2.850"??

What earthly good is it to develop any load "jammed" that will only single feed, when your goal is to actually utilize your magazine?? Or how about the same guy trying to load 155 SMK"s (2155 or 2156)? Trying to load either of those numbers "jammed" in a stock 700 will have the bullet damn near falling out of the case.

So to the OP, you should always start with the longest possible seating depth, which is based on just touching your lands or your max mag box length whichever is shorter, but keep in mind the amount of bearing surface to keep your bullet secure in your case neck. Then work up your load. Then if you have to adjust your seating depth, you can only go shorter, not longer.....

 

[tobedell]

When loading for a magazine fed bolt gun, I have been limited in the seating depth area and had to taylor the powder charge to attain accuracy. Moving in .5gn increments the group will tighten then enlarge similar to changing seating depth.

 

[Huskerhunter]

When loading for a magazine fed bolt gun, I have been limited in the seating depth area and had to taylor the powder charge to attain accuracy. Moving in .5gn increments the group will tighten then enlarge similar to changing seating depth.

Who is taylor?

 

[Bob 964]

I would submit that the "tech" who wrote the article is pretty doggone familiar with the rounds he is using and probably has a good solid base from which he can tweak his loads from. In his instance with a relatively "known good" powder charge he can begin to play with seating first and then tune his loads. You will also note that he isn't experimenting with something new to him and he is not seeking max pressure or velocity (which he notes). You will also note that he begins his quest by "reaching the lands" as opposed to jamming them. This will provide a "zero balance" in load development. No increased pressure due to jamming and no decrease in case volume due to stuffing the boolet in deep. For the rest of us mortals I would submit that it would be folly to arbitrarily choose a powder charge for an unknown round/rifle/powder combination and fool with seating depths first. IMHO I consider seating depth to be the "fine adjustment knob" for a great round.

To add another variable to the mix "What about neck tension?" [Add evil laugh here]

Cheers,

Doc

Thanks Doc. Unless you advise differently, I am inclined to continue OCW testing, with the bullet seated at the depth at which the ogive touches the lands, to determine the optimal powder charge weight. Then manipulate the seating depths (starting jammed and working to jumped) to determine the proper seating depth.

 

[tobedell]

Who is taylor?

A good looking piece of brass.

 

[doc76251]

Thanks Doc. Unless you advise differently, I am inclined to continue OCW testing, with the bullet seated at the depth at which the ogive touches the lands, to determine the optimal powder charge weight. Then manipulate the seating depths (starting jammed and working to jumped) to determine the proper seating depth.

Concur with your methodology.

FWIW, IMHO, YRMV etc. etc. Jamming into the lands for a "regular" shooter creates issues in that if for whatever reason you need to down load the rifle (as in make it safe) you'd better have a cleaning rod and some compressed air handy. The boolet will still be in the barrel and the powder will be in your action. Other than "just to see" experiments I've never ended up with a load that was in the lands.

More things to ponder.

Cheers,

Doc

 

[garandman]

I love all the figgerin' / calculatin' / speculatin', but the powder manufacturers stated COL has given me half MoA in both my rifles, and that's good enuf fer me.

 

[Queequeg]

I do load development first then putz around with overall length. Advising noobs to jam the lands without a overall length gauge, or the means to accurately measure the distance of jump to them without one, is a whisker shy of being reckless for little appreciable gain of velocity or accuracy.

As a general rule, I have found anything Doc says to be helpful.

 

[JoshcBoucher]

Your advise, and that of the poster below you has to rank as some of the WORST I've ever read on Sniper's Hide reloading. Your "advise" completely ignores the number one rule for reloading from a magazine feed rifle, that is any load you develop must actually feed from the magazine!!!!! So your ideal seating depth for your initial reloads should be just touching the lands or your max magazine length whichever is SHORTER not LONGER.....

Further, consider the neophyte here that's loading for a stock Rem 700 in 308 WIN (the most common rifle used by newby posters here) whose throat is in the neighborhood of 3.0" and their mag box is 2.850"??

What earthly good is it to develop any load "jammed" that will only single feed, when your goal is to actually utilize your magazine?? Or how about the same guy trying to load 155 SMK"s (2155 or 2156)? Trying to load either of those numbers "jammed" in a stock 700 will have the bullet damn near falling out of the case.

So to the OP, you should always start with the longest possible seating depth, which is based on just touching your lands or your max mag box length whichever is shorter, but keep in mind the amount of bearing surface to keep your bullet secure in your case neck. Then work up your load. Then if you have to adjust your seating depth, you can only go shorter, not longer.....

His "point", is just, and well taken. My post should have stated that I feed "one at a time", and not from the mag, for "most" of my shooting. When I'm making loads, for the "mag", they change, and "may" not be the most accurate, for the gun. His comments bring up the bigger issue, which is why I just added a signature, to my profile. ANY advice, that I read here, is "taken" as "That's what THAT GUY DOES". IN THE END, when I "pull the trigger", It's my face,behind the gun, and I make my own decisions about that. I read all I can. I reload carefully. I have my own shooting style and "parameters". I think every guy here "does it" his way. Take any advice as an opinion. Take no mans opinion as "Gospel",except one, and HE doesn't shoot.Not on this earth, anyway, that I've seen.