Author Topic: Bullet touching rifling or not?  (Read 989 times)

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Offline MrJames680

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Bullet touching rifling or not?
« on: April 21, 2009, 09:40:42 PM »
OK! I am a beginner reloader, but I am technical so asking anyway.
I have read here and other sites about having the bullets seated into the rifling or not.
I know every barrel shoots different so beyond that....
Who does or doesn't do this and why or why not?


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Offline LaOtto222

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Re: Bullet touching rifling or not?
« Reply #1 on: April 21, 2009, 10:58:04 PM »
I usually start with the bullet touching the lands with varmint type weapons, if I can. When I say can, I mean if the throat is not so long as to keep me from touching the lands with a chosen bullet. I keep in mind that touching the lands causes pressures to go up, so I start with minimum loads and work my way up. As I work my way up I watch the velocity with a chronograph to make sure I am not going over the fps listed. Once I reach the max fps and I do not get an accurate load, I back off the lands and back off the powder and start over again using the same criteria I used before. When I cannot reach the lands in a rifle, I usually load to near the same OAL as recommended in the reloading books and work up a load, again, if I can not get an accurate load I work the bullet out some and start over again. In a hunting rifle, I do not want to touch the lands, making sure the bullets will function through my magazine and chamber easily. You not only want decent accuracy, you need total reliability. There are plenty of rifles that shoot well if the bullet does not touch the lands, but in some cases they do better touching the lands. You will just have to try it. I start into the lands for load development, because I seem to find good shooting loads quicker that way. Many times I have to be off the lands to get the best groups, but usually I am closer to the lands than I am to the recommended OAL when I find the best load. Some times it is kissing the lands, some times .020" off the lands and some times .040", it just depends on your rifle. I have seen factory loaded ammunition that shoots very well and it is well off the lands, but more than likely you will find that your rifle shoots best some where in between the lands and recommended OAL. Good Luck and Good Shooting
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Offline cwlongshot

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Re: Bullet touching rifling or not?
« Reply #2 on: April 22, 2009, 12:26:11 AM »
Please DO NOT follow loading manual data if your going to seat your bullets into the rifling!!!  All data published in these manuals was founded with bullets seated to a SAMMI spec for each cartridge that has the bullet far from the rifling. Having said this, seating closer or into the rifling DOES have its mettits, but you must be fully informed about the results and reason for doing so.

As a rule, I find my rifles shoot better with the bullets with in .005 -.007 OFF the rifling.

I will seat INTO the rifling when fire-forming brass.

CW
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Offline Steve P

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Re: Bullet touching rifling or not?
« Reply #3 on: April 22, 2009, 03:57:16 AM »
It depends on the gun and the bullet.  They are all different.  If you are shooting a jacketed rifle bullet, rule of thumb is about .010" short of touching the rifliing.

I shoot a lot of cast bullets.  Several of them are pretty long and have what is called a "bore rider" ogive.  They are made to be up into the rifling.  This increases the internal case pressure and also helps create a more uniform powder burn.  Most of these loads only run 1500-1800 fps.

I also shoot a lot of "wildcat" calibers.  "Wildcat" means the ammunition or brass is not readily available thru the stores or from ammo manufacturors.  There are some manufacturors that will pick up wildcat ammo for a while (Corbon is one of the best.) but usually reloaders have to make their own.   

Just last night I was making up some 6.5mmUS brass which is made from 30-30 brass.  I can run the brass thru the dies and do all of the trimming, but the brass will not be the correct shape until it is "fireformed".  Fireforming means I have to load the brass and shoot it in my gun.  The pressures created upon firing blow out the brass to form the same shape as the chamber.  For these "fireform" loads, I use a small amount of pistol powder and I seat the bullet way out so it is engaged in the rifling.  This increases the internal case pressures and helps the brass to form to chamber dimensions upon firing.  Once fired, I can now load normal book loads.

Some guns can be real finicky on the OAL or over-all-length.  You will see match dies on the market that are 3 to 4 times the cost of normal dies.  They actually have a dial indicator on the seating die so the reloader can seat their bullets to the exact length every time.  Some guys will actually come up with a good load for their gun, and then seat a number of bullets with "jumps" of .005", .010", .015", .020" etc to the rifliing and shoot these for group.  They will see which "jump" is most accurate in their gun and will load same "jump" every time.

Lots of information on bullet seating and OAL out there.  Without specifics as to throat length in the barrel, exact bullet, etc, it does not mean a whole lot.  I have captured some photos of Hornady 30 caliber bullets and have put them in below.  If you were to seat all of these bullets to the same OAL, you can see the difference in jump to the rifling they would have as the tip of the bullet makes no difference.  It is the ogive (bullet taper) that makes the difference because it is not until you get to near bullet diameter that you begin to engage the rifling.  Round nose bullets engage a lot faster than a long spitzer bullet.

I hope this helps some.

Steve :)
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Offline Catfish

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Re: Bullet touching rifling or not?
« Reply #4 on: April 22, 2009, 04:30:11 AM »
All barrels and chambers are different. Some guns shoot better with the bullets jamed into the rifleings, BUT this WILL INCREASE PRESURE. As you are just starting to reload I would recomand you DO NOT try seating into the lands untill you are sure that you can spot presure signs and then you start low and work up your powder charge.

Offline wncchester

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Re: Bullet touching rifling or not?
« Reply #5 on: April 22, 2009, 04:49:27 AM »
"I have read here and other sites about having the bullets seated into the rifling or not."

In my experience, factory rifles and factory bullets rarely shoot best in the rifleing or even close.  All I have ever actually developed loads for - that is, not just picked something from the book - shot best from .030" to as much as .125" off the rifleing. 

Loading into the lands is a Bench Rester technique.  Those rifles have tight chambers and short leades. Their ammo usually has soft bullet tension and precision made bullets.  It takes seating into the lands to allow them to build pressure properly for good combustion and, from that, good accuracy.  None of that's true for us so BR techniques are not relivant for us.   Okay?

Back off the lands maybe .010" at first and experiment to find your best powder charge with any given bullet and powder.  THEN back off in .005" steps until you find the best seating depth.  You'll be "home"!  IF you don't like the results, try another combo of powder and bullet.

You may want to test different primers too.  They don't often make a really great difference but they do vary some.
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Offline 1sourdough

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Re: Bullet touching rifling or not?
« Reply #6 on: April 22, 2009, 02:15:43 PM »
 After I account for magazine fit I am usually about .010 off the rifling. I measure the bullet for the chamber & compare my results to book COL. With tight measurements you increase the chance of a bullet stuck in the bore if your a touch to long. I've known of a few cases & it's not good on a hunting trip. I will admit once it was my own reloads, loaded for a partner where I couldn't measure his chamber. If you can believe it I had to go just UNDER book COL for his 30-06. 
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Offline cwlongshot

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Re: Bullet touching rifling or not?
« Reply #7 on: April 22, 2009, 02:38:36 PM »
 I forgot to mention, I have a nice tool that allows you to find out exact lengths of seated bullets. CRS must be setting in as I cannot for the life of me think of its name...  ;D
As its not the COL that you need look at. The length is bases off the ogive of the bullet and this will change with every bullet shape.

Hunting loads are best with about .0010 off the rifling. ESP if dangerous game is on the agenda.

CW
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Offline charles p

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Re: Bullet touching rifling or not?
« Reply #8 on: April 22, 2009, 02:47:00 PM »
Stoney Point?

Offline cwlongshot

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Re: Bullet touching rifling or not?
« Reply #9 on: April 22, 2009, 03:21:48 PM »
Stoney Point?

Charles, thanks!! THATS the one!!!!  I bought a couple modified cases and now I just make my own.  ;D It works great and allows for very exact measurements of individual bullets for your specific chamber. nice tool!!

Thanks to OR-E-gun Bill as well, for jogging my memory.  ;D

CW
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Offline wncchester

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Re: Bullet touching rifling or not?
« Reply #10 on: April 23, 2009, 03:16:38 AM »
"Hunting loads are best with about .0010 off the rifling. ESP if dangerous game is on the agenda."

CW - One thousanth off the lands is a bit tight for dangerous game agendas!
Just for accuracy, I think you probably meant to type that as .010" inches off the rifling?
 
The RCBS "Precision Case Mic" is another excellant tool to keep track of seating depth to the ogive AND for case headspace measurements.  The Mic does not require a dial caliper as the Stoney Point, now Hornady LnL, tool does. But you really need the caliper anyway so .... take your choice!  I have both tools and usually use the RCBS but only because it's a little faster.
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