Is there a standard length for seating off of the lands?

[Dr. Tad Hussein Winslow]

Without specific data, what's a good starting point or standard, for seating the bullet back off the lands, to get good accuracy, but yet not spike pressure (and then to work up closer to the lands watching for pressure signs)? 1/10th"? 5/100ths? 1/100th? 5/1,000ths? This may be a dumb question, but sorry, I'm still newbie to rifle reloading. The books just show C.O.L. of course.

 

[1858rem]

The books just show C.O.L. of course

which is only a minimum too i think

 

[Jim Watson]

The usual number for things like SMKs is .020" - .030" but my setup came out at .012" and shot accurately so I have not seen a reason to change.

Solid copper Barnes bullets are recommended .050" the last I saw.

VLD profile bullets from JLK and Berger are recommended loaded "jammed" into the lands by about .010" with due care in working up loads.


If you want to shoot from the magazine, most bullets loaded to an OAL that will fit most magazines will be well short of the lands with little opportunity to fine tune. Not all, but most.

 

[gdcpony]

I like .001. Most will tell you from "kissing" the lands out to .01 I think. I used to go into the lands (kissing) but backed off.

 

[azar]

If I'm understanding your question correctly, the general rule of thumb is to start at 0.020" off the lands. It is commonly agreed that best accuracy will be attained between 0.015" and 0.030" from the lands, but it's something that has to be tuned to your gun & bullet combo (much like the powder charge) to find the most accurate distance.

Remember though that each bullet and gun combination will give you different measurements to the lands. Also, some bullets such as the all copper Barnes bullets recommend seating 0.050" off the lands to avoid high pressure spikes.

Basically, start at 0.020" off the lands (unless using Barnes bullets) and find the most accurate powder and powder weight for your gun. Then tune it buy varying the O.A.L. by 0.005" in either direction until you find what length gives you the best accuracy.

 

[NCsmitty]

I set my bullets .020 off the lands in rifles that I use for shooting bench groups. Each style/type of bullet will usually need to have a different COAL to achieve this. You absolutely need to keep records to be able to duplicate everything.

Rifles like my 30-30 and such just gets crimped in the factory cannelure.

NCsmitty

 

[USSR]

Dr.THW,

Assuming no magazine restriction, as is commonly found in short action rifles, I typically seat my bullets so they are .010" to .015" off the leade. I do not seat them less than .010" off for the simple reason that ogive location on the Sierra Matchking bullets that I sometimes use, will vary by .010". So, seating them less than .010" off the leade can result in some bullets touching or being into the leade. This is not conducive to accuracy. Just MHO.

Don

 

[mija]

Years back I asked this, the answer I got works well.
Seat a bullet to where it just begins to touch, it will leave impressions (faint) on the bullet.
Progressively seat it deeper, until the impressions are not noted.
.01,.02,.03 may be fine, but the less distance the bullet has to move unsupported once it leaves the case mouth the less wobble can occur.
Mija
Semper Paratus

 

[Birdhunter1]

I normally seat mine anywhere from .030" off the lands to jammed into teh lands.. provided I have a long enough bullet to do it. My Sierra Blitzking 55's in my .243 I have no clue where they are in relation to the lands as I worked with one seating dpeth with multiple powders adn when I found the load I had no reason to adjust or fine tune with the seating depth. Now on my 87 Vmax loads for the same gun I did jam them in the lands hard and it shoots just short of a good benchrest rifle (if shot properly).

 

[243winxb]

.010" or more. No standard that i know of. Clean bore/chamber compared to dirty/fouled bore would give diffferent readings if seating into the lands. The base of the bullet(full dia. not boattail) should be at the junction of the neck/shoulder area with the bullet just off the lands. This would be perfect setting if cutting a chamber on a new barrel, but not possible in many factory chamberings. There are to many bullet weights and lengths to have this perfect arrangement with factory.

 

[10 Spot Terminator]

Typical "rule of thumb"in most manuals is to start with a set back of .020 ,,, Those posts where folks are seating at or extremely near the lands tends to make more uniform what is refered to as the starting pressure . This is the point where the pressure builds enough when the powder is ignited to start the bullet to break away from the case and as it immeaditely touches the lands of the bore the pressure does not do a "double spike" when fired. If your magazine allows seating the bullets this far out and there is a sufficient amount of the bullet still inside the case "AND" you use this method from start to finish on your load work up you can achieve good results as long as you have the right powder and primer combination and the cartridge cases are sized "very close" to the full chamber dimensions. This is for the most part benchrest shooters style of reloading where bullets are single fed by hand to the chamber and will not work in all applications. In those that wont allow this then use the .020 seating set back and when you get to your best group with a particular load that tends to show good promise then load 5 rounds with the seating depth .005 longer ( if possible ) and 5 rounds with the seating depth .005 shorter and let the results lead you in the direction you need to go .

 

[lgbloader]

I do not seat them less than .010" off for the simple reason that ogive location on the Sierra Matchking bullets that I sometimes use, will vary by .010". So, seating them less than .010" off the leade can result in some bullets touching

I usually start at .025 off the lands and sometimes work in both directions. Strange but I have a M1A that likes his food .027 and I found this out by accident!!!!

LGB

 

[rg1]

With limited experience with only my rifles and the particular bullets I shoot in them, I've noted that manual overall lengths given puts the bullets near
.050" off the rifling in more than one bolt action rifle. One particular rifle that I've tested starting at .050" and working down in .010" increments shows that rifle with the bullet I use gives notably better accuracy seated 30 thousandths off the rifling. Closer and the group opens a little and farther it opens a little. For general hunting loads I'd load no closer than .020" but for match bullets and match rifles that is another story. Worth experimenting to find what your rifle prefers but note that pressure can increase greatly with bullets touching or jammed into the rifling.

 

[Zak Smith]

I never jam for safety and reliability. In my 308, I can't get closer than 0.12 or 0.15" to the lands and still fit in the magazine (yes, the decimal point is in the right place).

 

[Horsemany]

.020" is a standard starting point. You should fully read a reloading manual if you haven't already. They're full of usefull info just like that.

Also in your question you asked about hundredths and thousandths. I'd suggest always talk thousandths when reloading. I knew a guy who used to like to convert back and forth like that. It opens you up to mistakes if you don't convert it properly each time. One time he showed up at the range with a bunch of starting loads .002" off the lands. He was too stubborn to just always use thousandths and you could see the wheels turning whenever I gave him a measurement in thousandths. I think he thougth it showed how smart he was to be constantly converting. It's dangerous IMO.

 

[MCMXI]

In my 308, I can't get closer than 0.12 or 0.15" to the lands and still fit in the magazine (yes, the decimal point is in the right place).

I don't understand why rifle manufacturers do that. DPMS had the good sense to make the throat short on the .223 barrel (heavy, fluted, 24", 1:8) that I bought from them. I can seat a 77gr SMK HPBT 0.025" off the lands and it fits in the standard Bushmaster magazines that I use. POF decided to make the throat of their .223 upper long so with a Hornady 75gr BTHP seated to magazine length, the bullet is about 0.095" off the lands.

I recently experimented with a load for my .300 Win Mag by seating the 208gr bullet 0.005", 0.010", 0.015" and 0.020" off the lands. 0.010" and 0.020" resulted in tight groups but the other two loads didn't group anywhere near as well. I've read that there are "nodes" in bullet seating depth the same way there are nodes in the charge weight. Makes sense to me.

 

[41 Mag]

Depends on the rifle and the load....

Through they years, having loaded and shot MANY loads, I have found that some rifles have at least two sweet spots with regards to powders and seating depths.

With this I mean that sometimes you will find that using the .020" you might work up through the powders load range and hit a very tight group right off the bat at the very lower end of the range, then continuing up through the load you will see another very tight groups on the upper end of the range. Call it what you may, nodes, sweet spots, or harmonics, the results are the same. I have also found that some rifles will have a similar reaction to seating depth, in that one seating depth will shoot absolutely great, but not function through the magazine, however seating it in sometimes by up to .125" off will hit the same sized groups with the same load.

I however do not do this with top end loads, and some powders, with out backing down a tad and working back up, just to be sure of pressure issues. In my daughter refurbished 6.5 x 55, I cannot reach the leades with a 160gr bullet and it still be in the case. However using the 140's seated to function through the magazine, and somewhere WAY off the lands, it will shoot outstanding groups out at 200yds with several powders.

Having a starting point is good, and I used to try and get as close as possible. Nowday's, I generally use the length which will reliably feed from the clip or magazine as fast as I can ranck them through. This is my starting point and I work my loads up from there seating deeper as needed. This way I know up front that no matter what my loads end up, they will feed with no further work on my part. As a side note to this, I have a couple of rifles which even though the round will slowly feed through the magazine fine with the plastic tip bullets, when quickly running them through as in trying to get off a very quick second shot, the sharper tips will hang up in the very tiny gap between the magazine and the bottom of the action. Seating them just .005" deeper fixes this issue. It was however not nice to find this out while in a hunting situation. Now I check several times using a dummy round to be sure of feeding before loading a whole mess up for testing.

 

[Zak Smith]

I don't understand why rifle manufacturers do that.

In my case, it's not the manufacturer's fault- it's the fact that the barrel has over 5000 rounds fired. It still shoots great so I don't worry about it.