Seating depth of my bullets...pros help me out.

[Darksith]

Question for the pros out there.

I have been told that I can have a COL that lets the bullet touch the lands when the round is chambered. Is this safe if I start at the min load and work up? Also, if this is safe, as long as the round will cycle through my magazine can I make a round with the bullet going into the lands/barrel? I would like to continue to use the hornady GMX bullet, but it is very long and seats quite far into the casing, which limits the amount of powder I can put in it. So if I can seat the bullet shallower but have it touch or go into the lands then I have more room in my casing for powder.

[SL1]

I don't know specifically about the GMX bullets. The original all-copper bullets are made by Barnes, and THEY say to seat THEIR bullets at least 0.030" off the lands. I would expect the same for the GMX bullets, which are slightly harder gilding metal. But, you really should ask Hornady:

Phone: 1-800-338-3220
Phone: 308-382-1390
Fax: 308-382-5761

Business Hours
Monday-Thursday 8 a.m. to 5 p.m.
Friday 8 a.m. to 4:30 p.m.
Central Time

SL1

[Crusty Deary Ol'Coot]

First off, will the loads fit your magizine?

If not, you are reduced to a single shot.

Many mags. and actions are not optimum for some of the rounds chambered there in. In these cases, many times bullets are required to be seated overly deep into the case which robs powder space in those rounds.

Common wisdom has said the bullet should be set just off the lands, but as all rifles are different, this to can be different rifle to rifle.

Awhile back, one writer did some tests which seemed to show that differing bullet seating depths gave an effect about like dialing in a B.O.S.S. on a Browning or Winchester so equipped.

Changing bullet seating depth changed the barrel vibration patterns and allowed for fine tuning for best groups.

Seating a bullet into the lands is said to be OK, providing loads take this into consideration.

During fireforming for a 300Gibbs wildcat, I seated the bullets long to maintain proper head space during the fireforming. No problem.

Seating the bullet into the lands, can raise chamber pressures, and must be factored into the picture during tests.

Keep em coming!

Crusty Deary Ol'Coot

[Darksith]

the problem I have is that my chamber is smaller than my mag, and the COL in my book is breater than my chamber allows without touching the lands.

I guess I will ask hornady and go from there.

[Crusty Deary Ol'Coot]

Yep, that can be a problem but -----------------

If your mag is longer then your chamber, it sounds (??) like you may have a longer action which has been set up for a shorter cartridge.

For example, some makers only had a couple action lengths, which required that they put rounds such as .243, .308 etc. in actions made long enough for cartidges like .270, 30/06. 300win. mag. etc.

If so, the mag. and longer action could allow for use of longer "COL" ammo.

Again if the above is true, a trip to a gun smith - pick a good one!!! -could be a real plus.

This would also depend on just how long your mag. and action is, but IF LONG ENOUGH the Gunsmith could lengthen the throat of you rifle which in turn would allow you to seat your bullets out beyond the listed "COL".

This would also allow for a bit more powder volumn then standard.

I had a RUGER #1 in 300 win. mag. which had a very long throat. This allowed me to seat the already long 200gr. Nosler Partition waaaaaaaaay out, far beyond standard COL.

The #1 had no mag. issues, but I think you can get the point.

Keep em coming!

Crusty Deary Ol'Coot

[Ky_windage]

I have a similar situation.

First, novice question, what is the land?

Second, I want to reload some spire point bullets on the Marlin .308 Express cartridge. I know, I know, you are not supposed to stack this type of bullet in a tubular magazine. I promise never to have more than one round in the magazine -- cross my heart and hope to die.

The information on this round is a little sketchy. But the COL is like 2.6" and loading the Hornady 3031 will exceed that by a wee bit.

What I hear you all saying is this might be a possibility?????

[woods]

Seating to the lands will increase pressure but seating jammed into the lands definitely does


In my experience, you have to have absolute control of seating depth with no variation in order to make seating to the lands effective. IOW if your seating depth varies by .005" because of bullet grip variation or press linkage compression differences then on one bullet you could be .002" off the lands and on the next one .003" jammed into the lands. Not good for accuracy and can lead to problems if you chamber a round and do not fire it and then extract it as sometimes the lands will grab the bullet and leave you with an action full of powder.

What caliber and bullet weight are you loading?

How are you determining how close you are seating to the land?

What powder are you using?

Personally I prefer to seat >.025" or more away from the lands and have yet to find where I could not get the accuracy needed by varying powder, powder charge weight, primer or varying seating depth deeper.

[jaybirdjtski]

I will defer to an expert.
http://www.larrywillis.com/

Left hand side of home page: "Reloading and Shooting Tech tips"
Then, under reloading tips, look @ #4...."The Best OAL for Accuracy"

The website does not allow me to simply put in the link but this article will answer your questions.

[SL1]

Ky_windage,

A "land" is the small-diamater part of the rifling, and a groove is the wide-diameter part. So when a bullet is seated so that it touches the rifling, it is touching the lands. The "throat" of the chamber is the section of the barrel where the rifling has been machined away so that whole circumferense is groove diameter. Beyond the throat, the edges of the lands are tapered to full diameter allow the riflng to smoothly engrave the bullet's surface when it is fired down the barrel. Before firing, the bullet sits with its full diameter in the "throat" of the chamber and with the nose of the bullet extending into the rifled section of the barrel. As you load the cartridge to longer length, it gets the full diameter section of the bullet closer the ramped part of the lands. At some cartridge length, it gets to the point where the part of the bullet just ahead of its full diameter (on its "ogive" or nose section) touches the ramped part of the lands just ahead of the throat. The cartridge length where the bullet just touches the lands is different for each individual rifle, and varies with the design of the bullet's nose.

With respect to using a spire point bullet in a lever action rifle with a tubular magazine, there is a question about whether it will feed from the magazine. The rifle is almost certainly set-up for flat point bullets (for the safety reasons that we aren't discussing here). The chamber throat of your rifle is probably set up so that a cartridge with a flat point bullet seated at normal length will have the bullet ogive close to, but not touching the riflng. If you imagine just adding the spire point section to a flat point bullet, you recognize that you will get a longer bullet. And, if it is seated in a case so that its ogive is the same distance from the lands as the ogive of a flat point bullet, the cartridge overall length willl probably be longer. But, lever actions with tubular magazines are set-up to feed cartridges that fall within a narrow range of lengths, so that might be a problem with feeding the longer spire point cartridge. You could try seating the spire points deep enough to make the COL short enough for the cartridge to feed. That can work, so long as the bullet does not have to be seated so deeply that its less-than-full-diameter nose section ends-up starting inside the case neck. But, that will leave a longer "jump" for the bullet before it touches the lands, and MAY make the cartridge less accurate. And, it surely will leave less space for the powder inside the cartridge case, so you will need to think about reducing maximum loads to compensate.

SL1

[Brian Pfleuger]

Originally Posted by Crusty Deary Ol'Coot

Changing bullet seating depth changed the barrel vibration patterns and allowed for fine tuning for best groups.

Changing the seating depth doesn't particularly change the barrel vibration patterns. It changes the point in the vibration that the bullet exits the barrel.

[Crusty Deary Ol'Coot]

Oh my peetzakilla you are picky-------------------

But correct to at least a point.

Keep em coming!

Crusty Deary Ol'Coot

[Darksith]

Not good for accuracy and can lead to problems if you chamber a round and do not fire it and then extract it as sometimes the lands will grab the bullet and leave you with an action full of powder.

What caliber and bullet weight are you loading?

How are you determining how close you are seating to the land?

What powder are you using?

Personally I prefer to seat >.025" or more away from the lands and have yet to find where I could not get the accuracy needed by varying powder, powder charge weight, primer or varying seating depth deeper.

The last thing I want is to unchamber a round and have it stay in my barrel and leave me with an action full of powder.

I am reloading/shooting 30-06, 165g Hornady GMX bullet, IMR 4350 powder, whatever primer I can get at the time I need more!

This is how I came to this little problem I am having. Being new to reloading and wanting to have the "best" I went to my local store and talked with Bob (he is used to me coming in and picking his brain) and asked what the best bullet was these days for hunting. He took me to the Hornady section and pulled their new GMX bullet off the shelves. Its not even in the hornady reloading manual its so new, anyway I bought a box to check it out. I called hornady and asked for the specs on the GMX, they gave me them and away I went. Now being so new and cautious/afraid of making a mistake, I reloaded 1 bullet at the min that the hornady tech gave me. Now b/c this bullet is so long, I had to readjust my dies to seat the bullet properly, and I used the COL in my book, measured the round and kept dialing my die down until I got the right length of cartridge. I then attempted to insert the bullet into my gun, and I couldn't lock the bolt down without resistance so I knew something wasn't right. I took the bullet out and noticed that the lands had scratched the bullet, so I knew my guns COL was different from the books. So I pulled that bullet, put in a new one and dialed my dies down a bit more, put the bullet back in the gun, still too long, so I kept doing this until I could lock the bolt down and then open it with no evidence of touching on the bullet. So I don't know how far off the lands my bullet is, but I know I was dialing my dies down a 1/4 turn each attempt.

Then I started to work my loads up until I had a decent group and enough bullets to do the job on my next trip.

[Brian Pfleuger]

This is how I came to this little problem I am having. Being new to reloading and wanting to have the "best" I went to my local store and talked with Bob (he is used to me coming in and picking his brain) and asked what the best bullet was these days for hunting. He took me to the Hornady section and pulled their new GMX bullet off the shelves.

No offense to Bob.... but the last person that you want to ask "what's best?" is the guy selling it.

That's like telling a used car salesman that you've got $10,000 and what car would he recommend.


Hornady's website specifically says, in regard to the GMX bullets, "Compatible with conventional reloading data"

Regardless, you should definitely call Hornady and ask them for load data for the appropriate bullet and cartridge.

[Darksith]

No offense to Bob.... but the last person that you want to ask "what's best?" is the guy selling it.
That's like telling a used car salesman that you've got $10,000 and what car would he recommend.

That can be the case most of the time, but Bob has a little store and he is the owner and a fellow reloader, and I trust the old guy.

The GMX might be overkill for what Im using it for, but it hasn't let me down yet.

Hornady's website specifically says, in regard to the GMX bullets, "Compatible with conventional reloading data"

yeah, but then when I call the tech he tells me that its not quite the same, and he gave me different numbers. The new hornady reloading manual coming out this year will have the GMX bullet in it Im sure.

[Crusty Deary Ol'Coot]

Darksith,

No need to keep pulling bullets.

Take an empty piece of sized scrap brass, seat a bullet.

Then take a black felt pen and "black" the bullet.

Chamber and attempt to close the action.

If the is possible without undue pressure, open the action, taking care to prevent the bullet from dragging on the action as the cartridge is pulled from the chamber.

Look at the bullet and any contact with the lands will show up a shiny spots on the jacket.

If you have marks and wish to adjust the deating die down, just recoat the black and use the same test cartridge again.

Keep em coming!

Crusty Deary Ol'Coot

[Unclenick]

I'll add to what Woods posted with another chart from some old pressure data. As you get near the lands the amount of gas bypass around the bullet is reduced. This raises pressure. If you seat too deeply, the amount of powder space is reduced. This raises pressure too. So there will be a pressure minimum seating depth, though how that particular depth will work out for accuracy is a toss up? The main thing, other than magazine fit and feed will be, does the increased pressure prevent you from using the additional powder you set out to use in the first place?

[Crusty Deary Ol'Coot]

Good post Unclenick!

In fact, VERY good.

Keep em coming!

Crusty Deary Ol'Coot

[under_dawg]

I posted a thread last week about the GMX bullet and compressed loads (it is posted a little farther down under .308 win and GMX bullet). I didn't get many resposes. Hornady required the bullets would use standard load recipes. It says on the box use with regular load data. I loaded my regular load data recipe up and as you mention due to the length of the bullet, it compresses the Varget. I haven't fired the compressed load yet, but I will soon. When I get the chance, I'm going to call Hornady and ask them about compressing Varget and other powders.

[mrawesome22]

A little compression is a good thing. It produces more consistent ignition because the powder can't shift in the case. If it's so compressed that it bulges the case... not good.

[Sarge]

Darksith,

I played with seating against the lands on a couple of rifles, years ago, both in 30-06. Pressure signs came early (I used faster powders in those days) and once that was resolved, I found myself custom-loading for each of our 30-06's- all for relatively small gains in accuracy. Short version is that for my purposes, the procedure brought more aggravation than benefits.

If I were to do this again I would determine max OAL for the specific rifle, by the methods outlined above, reduce OAL by 0.0015-0.0020 and then check again using several brands of casings. If no contact were evident I would hang with that OAL as being as close to the rifling as I needed to be.

You might save yourself some time & aggravation by contacting the tech division of the bullet manufacturer, explaining what combination you're using, and see what they have to say. Odds are that someone has run into the same conditions before and they may have just the answer you need.