Seating Depth?

Matt N.

Matt N.

New member
Several times over the years I have heard that bullets should be seated at least 1 caliber deep to obtain satisfactory concentricity and adequate tension. In my experience this does not typically get the bullet as close to the rifeling as many other sources suggest. So... I see some contradiction here. Is there really a minimum depth that bullets should be seated? Or, is getting the bullet the proper distance to the lands a priority?

Thanks.
Matt
 
Seating depth depends on the rifle and the bullet used, Bench Rest Shooters may seat their bullets close to the lands,Hunting rifles may not shoot well with the bullet close to the lands and like a jump. Hunting loads a Caliber shooting depth is a good starting point and then work both ways, keeping in mind that seating deeper will increase pressure.
 
I aggree with Matt, a bullet should be seated no less than there diameter, plus some for boat tails. Just measured off some .224 bullets for my 22-250 up to 60g, and not one could be seated to .020 off using this critera. Thats shooting.
Jim
 
With the loads I'm shooting now, I took a brass that had been shot, but not resized yet, and put a bullet in it and wrenched it in my gun. Then carefully took the round out, then seatet it about a 16th of an inch deeper. Have had no problems with that load.. however I did try to load some 68 grain match bullets, and no matter how I loaded or seated the bullet...every single round tumbled! My gun did not like them at all!
 
In all my factory and custom rifles from 17 Ackley hornet to 7 Mag I found the rifles to shoot tiny groups with the bullet seated -.005 to a jam of .003. A jam of .003 will not pull the bullet out of the case.

I have two exceptions, a 25/06 that likes a .040 jump and one particular 270 that likes a .040 jump.

I started off benchrest shooting in the late 60's as a kid and transfered that technology to my hunting rifles. I had never heard of the caliber deep thing till I started reading the internet....it's pretty much hog wash.

Accuracy is pretty much a relative thing. To one guy, one inch groups are fantastic and to aother it is time to re-barrel. For your gun's best accuracy, play with seating depth starting off with the bullet just barely touching the lands. After you have worked up your load, then go into the lands .003 then shoot 3 shot groups, jumping the bullet in .015 increments. You can then micro manage the .015 interval as accuracy shows improvements.

It is darn RARE that any gun that I have owned did shoot groups with all bullets touching(groups from 0.200-0.375 or less) with OAL's where the bullets were not touching the lands, no matter what the caiber.

If I happend to get a rifle that had a long throat, I was taught by a world famous gunsmith in Ca that shooting a Semi Point bullet will probably achieve the best accuracy (Sierra 50 & 55g Semi points). In other calibers, if the barrel has a long throat, then a bullet that has a lot of bearing surface Vs a VLD type of bullet MAY get the best accuracy. The Sierra 55g Semi point is an unreal accurate bullet. Longest shot that I have ever seen on a ground squirrel was at 800 yards with that bullet. Plastic tip bullets as a general rule of thumb have less beaing surface.

There is a relationship in how far a bullet has to jump to engage the lands and grooves in the barrel and ACCURACY. It was explained to me that the further a bullet jumps, the more apt it is that the bullet get started crooked in the barrel, thus shaving off more of one side of a bullet or making it egg shaped...unbalanced.

Also, as brass work hardens, brass will work harden differently from piece to piece. As bullets are seated deeper in the case neck, there is more "grip" on brass that is harder vs brass that is softer. Work hardening will have more effect from loaded round to loaded round, so pay attention to the force needed to seat a bullet.

As guys get started reloading, there seems to be so many details to remember that it takes all the fun out. As a guy gets more experienced and wants to take accuracy to the highest level for his rifles, then learning to accuratly measure the seating depth to the lands and adjusting his test loads accordingly is the next step. Individual rifles are unique to themselves, and I don't assume that any of them will like the bullet touching the lands, I just always start off there...letting the rifle tell me what it likes.

On calibers that kick so hard that it knocks your ear muffs off side ways on your head such as a 300 Weatherby on up, then the bullet is going to be seated deep in the case due to magazine length constrictions.

On some dog rifles, the seating depth became very long as the barrels became worn from hard shooting. I learned that in varmint calibers up to a 6mm AI, that if you can't pull the bullet out of the case by hand, it will not move due to recoil....seating caliber deep is not necessary. If you carry a lot of rounds in your pocket, or transport loaded rounds loose in a coffee can, then seating depths can be be a challenge for you.

Everytime I read the issue on seating the bullet a caliber deep, my head wants to explode. Every benchrest shooter of any discipline knows that the "caliber deep" is some very ill informed technology to pass along.

All advanced reloaders should educate themselves on the issues of establishing the seating depth that their particular rifle likes. There are some very knowledgable benchrest shooters and varmint hunters that hang out on www.benchrestshooters.com and the 6 Br board, they are always willing to help a guy out on his learning curve.
 
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I dont have a ton of experience, but I use the hornady lnl seating depth gauge. Use a known load that shoots well and then adjust seating depth in increments of .005 or less with the known powder charge until you are shooting satisfactory groups.
 
"After you have worked up your load, then go into the lands .003"

Does this not jump pressure up to the point to where it may be a good idea to reduce heavy powder charges a bit?

Thanks.
Matt
 
Well there's your answer. There is no definitive answer.

It depends on your rifle, magazine, cartridge, chamber, and your ability to measure any and all of the components; let alone your ability to shoot.

But don't let that stop you from experimenting.
 
I feel the need to say thank you for your reply. Being a new reloader, this has answered a couple of things that I have been asking myself and researching. This is really proving to be a great site to hang out on.....
 
Here may be a monkey wrench. I load .223 with Hornady 68 gr. I however load them to a 2.220 instead of the suggested 2.260 for AR-15's. Or the 2.250 it says in the manuals. I have found that I have better accuracy putting them shorter. I do not know why. Any ideas? The only thing I can figure is it is increasing pressure making the projectile go a bit faster.
 
Originally Posted By: huntin4emWith the loads I'm shooting now, I took a brass that had been shot, but not resized yet, and put a bullet in it and wrenched it in my gun. Then carefully took the round out, then seatet it about a 16th of an inch deeper. Have had no problems with that load.. however I did try to load some 68 grain match bullets, and no matter how I loaded or seated the bullet...every single round tumbled! My gun did not like them at all!

If they are tumbling, you probably don't have enough twist to stabilize that bullet.
 
Mgysgt,

Oddly enough, I was told that same exact thing today at the sporting goods store, met the guy in the reloading section and sparked up a conversation, and that's what he said. I never really put any thought into it at the time, I just knew I couldn't do anything with them.. I have a remington 700 adl, 22-250, what is the twist ratio for it?
 
Originally Posted By: ackleymanThere is a relationship in how far a bullet has to jump to engage the lands and grooves in the barrel and ACCURACY. It was explained to me that the further a bullet jumps, the more apt it is that the bullet get started crooked in the barrel, thus shaving off more of one side of a bullet or making it egg shaped...unbalanced.

So True...
A bullet starting into the barrel crooked, comes out crooked!









 
Huntin4em, it's not surprising that 68gr match bullets are tumbling in your 250. Standard twist is 1:14 and it would be unusual indeed to stabilize a long 68gr bullet.

Try 55gr and shoot like a laser.

Most folks find that seating app .010 off the lands is a good place to start tweaking for accuracy.

If you are loading near max pressures, moving onto or into the lands can cause a sharp pressure spike.

Moving off the lands will cause a decrease in pressure, except that again if you are loading near max loads and still have room in the case, you can cause an an increase in case pressure by seating deeper in the case.

There's just about nothing you can do in ballistics that doesn't affect something else. Proceed carefully.
 
Here's what I'm shooting,

35 grains of varget powder
55 grain sierra soft tip bullets
Winchester primers.
How can you tell how far off the landing, and where exactly does the landing start/stop?
 
Originally Posted By: huntin4em How can you tell how far off the landing, and where exactly does the landing start/stop?
Here is one idem that you can use - Here , I have been using these for probably 15 yrs and they are very simple to use.
 
The one bullet that I have found that likes a jump is the Barnes, in my 243 and 2506 could not get a decent group until I seated them deep, may just be my Rifles but if you are having troubles with the bullet close to the land try seating deeper. cc
 
I think I found a lot of the problem in my cases, and my powder scales had got off from being moved around, and I hadn't calibrated it in a long time. I pulled all of my bullets, and reloaded them after working on my cases, and re calibrating my scales. My new groups are now 1/2 inches at 100 yards, and 1.5 inches at 200 yards. I also got my barrel freefloating. I think I fixed the problem. By the way Matt, I hope you don't think I have stole this threas from you, I didn't mean to, just trying to figure out if mine had problems with this too. Thanks for the info!
 


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