Help a newbie find the to-the-lands length

[fattybinz]

I'm new to handloading and I'm having a difficult time finding what my maximum length is, both for my hunting rifle (Tikka t3x in 7 mag) and my for-fun range rifle (Ruger American Predator in 223 rem). I'm developing a load for the Ruger. I'd like to find out what the length to the lands of this rifle is so that I can play with my seating depths after finding a good chargeweight. I'm really confused about how to go about that. I'm using once-fired norma brass (resized and trimmed) and hornady 50gr vmax bullets. I bought a hornady lock-n-load length gauge with a 223 rem modified case. Followed the instructions of the gauge and watched a few youtube videos on how to use the gauge, including panhandle precision's. When I follow the instructions and push the gauge's rod in very lightly and slowly, I get measurements around 1.811-1.813 (I 'm measuring CBTO using a hornady comparator). When I apply more pressure to the rod, I get measurements between 1.825-1.828. I'm guessing the shorter measurement I got when pushing in gently is the one I should use, right? Here is where I get confused though. I also measured using another method...denting a fired case neck so it will put resistance on a bullet, putting a bullet in, chambering it, and then measuring the length. When doing this I consistently got lengths around 1.856. I tend to think the hornady gauge results are more reliable, but then I measured the cbto of some factory ammo (Norma Tac-223 55gr) that shoots .5" to .8" groups out of this rifle and the cbto of those rounds is about 1.848. If the hornady gauge is giving me the cbto to the lands (~1.811 or ~1.825), then how is this factory ammo longer than that? I thought factory ammo was made very short so that it wouldn't run into problems with any rifle's throat length. Does all of this suggest that the 1.856 length that the dented case neck method gives me is more reliable? I'm wondering if I should just not worry about it so much and do the chargeweight portion of the load development using the Norma tac-223 length since that factory ammo shoots so well.

No one told me this would be so difficult Enjoying the challenge though. Any advice would be appreciated.

 

[Brian in Montana]

I went through this a while back. What you'll find is that regardless of what method you use lots of hunting rifles don't have a design that makes it easy to get real close to the lands. I too have a Hornady OAL gauge, but you're going to be limited to what fits in the magazine. One of my rifles I reload for is a Tikka. I've stared just seating a bullet in very small increments and testing to see if it fits. Then measure it from the olive using a comparator and start load development measuring them all the same. I've pretty much shelved my OAL Gauge at this point. My wife's .270 is the only rifle I have that's long-throated enough for the gauge to even be relevant.

 

[SD_Prairie_Goat]

From what I have seen personally finding where the lands are hasn't made much difference in my accuracy. But with that being said, I did the second method you listed and found that my bullet would be very long, and decided to just load the bullet to a reasonable length and moved on. I found that by tweaking the powder I got better accuracy. But once I get my favorite powder figured out I may start playing with the seating depth for fun and see if it makes a difference.


I wonder, do you think your hornady length gauge is getting caught up on something (I remember when I researched them people said they has to sand the device to get good readings because it would give false positives)? Or maybe your chamber has some blemishes in it the bullet is getting falsely caught on? I'd maybe look into something like that and trouble shoot down that path to see if the issue lies somewhere there?

 

[Don Fischer]

I'm pretty much in Brian's camp. I don't even own one of those OAL gauges, never have. I fool with the same bullet till it fit's the chamber without touching the lands. Then I also dedicate a set of dies to one particular rifle and I don't fool around with loading different weight bullet's. each rifle I have shoot's only one bullet which is no problem for me. If I only had one or two rifles and fooled with different weight bullet's it could be bothersome, but I don't. But even then I could use my calipers and load to overall length with them and be alright. Everything would still fit but also be farther off the lands. Adjusting that length for accuracy sake seem's like a waste of time to me unless you have a custom made bench rest rifle and compete. Is your deer rifle is grouping 3/4" at 100 and you can just get it to 1/2" at 100 by adjusting the jump, what have you really gained other than bragging rights? Most my rifle's will go that 3/4" and a few down to 1/2" without all that trouble. When the target is 12", you really don't need a 1/2" rifle. Bragging right's only!

Ya know, rather than fooling with that, learn bedding the rifle. That has made really good difference's in most the rifle's I have ever had.

 

[fattybinz]

I wonder, do you think your hornady length gauge is getting caught up on something (I remember when I researched them people said they has to sand the device to get good readings because it would give false positives)? Or maybe your chamber has some blemishes in it the bullet is getting falsely caught on? I'd maybe look into something like that and trouble shoot down that path to see if the issue lies somewhere there?

Panhandle precision's video on how to use the gauge covers this. He suggested tapping the modified case forward so that you can hear the shoulder hitting against the end of the throat, confirming that the modified case was fully "chambered." After I started doing that I did get more consistent result and longer results...but that is how I got the results I posted. Before I started doing that, the measurements were even shorter.

 

[VikingsGuy]

My 3 tikkas, shooting TTSX bullets, lack magazine length to make meaningful seating depth changes, so I just seat to max magazine length minus 5-10 thousandths to give a little breathing room. All of them shoot 0.75 MOA or less with single digit SDs - plenty good for hunting under 450y. I do optimize seating depth on my drop floor rifles, and my benchrest rifles that I load one round at a time, and that can at time squeeze out more accuracy (the benchrest ones are fiddled with 'til getting to sub .3 MOA). So, I do like optimizing seating depth when I can, but in my experience tikka's lack sufficient mag length to allow meaningful effort with long bullets.

 

[antelopedundee]

Seat a bullet that's out to far and try to chamber it. Turn the seating stem in in small increments until the round [using an UNPRIMED CASE] just chambers and you should be close enough for state work. Hopefully it will fit in the magazine too. Set this aside and label it as a seater dummy round.

 

[Scott85]

I use a very simple approach, maybe not a simple as some by not worrying about it. Take a spent case and bend the neck in enough to hold a bullet in place. Then take the round and load it in the weapon and chamber it being careful when extracting the round. I normally do this about a dozen times measuring after time. I then take an average and back off .001" or whatever you want to start with. After I load up the first round I make sure the load round chambers smoothly with no force and then I would start to mess around with distance from the lands while looking for pressure signs.

 

[HiMtnHntr]

As noted above, the tikkas generally don't allow one to chase the lands. Most commonly you'll find yourself seating to mag length or there abouts. In rifles that allow for it, getting nearer the lands can really help. In these cases, I recommend the OAL gauge and the modified case, or even better is a modified case made from a case fired in that rifle, because dimensions will be more precise. It seems like bullet manufacturers are really attempting to produce bullets that aren't all that seating sensitive, given the current craze of lightweight rifles and short mag boxes.

 

[El Jason]

I use a very simple approach, maybe not a simple as some by not worrying about it. Take a spent case and bend the neck in enough to hold a bullet in place. Then take the round and load it in the weapon and chamber it being careful when extracting the round. I normally do this about a dozen times measuring after time. I then take an average and back off .001" or whatever you want to start with. After I load up the first round I make sure the load round chambers smoothly with no force and then I would start to mess around with distance from the lands while looking for pressure signs.

This is what I do as well. If you work slowly, I’ve gotten very repeatable measurements. I do this about a dozen times and look for the most consistent results.