Bullet touching the lands or 2000th back?

[Timeee123]

When I got my 28 nosler I loaded according to factory length. 3.340 found a load and it shot great. Started playing with seating depth. Grouping spread real fast and it seemed recoil increased. The assumption of .020 to .050 is just that. My 28 nosler is just one example. Of the 7 rifles I have or still reload for none of them shot well with the bullet stretched out. I dont know why. I've had way better luck staying close to reloading info length recommendations. However maybe I'm doing something wrong.

 

[LR65Pb]

I have a 300 WM and 338 Lapua, both in Armalite's AR30. I reload both at .001 off the lands. Neither one of them like more than .003 jump.
Added: 300 Bergers on the 338, 208 Amax in 300 WM since I had a stock of them before they were changed.

 

[FEENIX]

I always try to find the best compromise between COAL and CBTO with seating depth in mind. For instance, when I started reloading 215 Berger in my .300 WSM, I started at .020" off the lands but ended up at .160" off the lands for the best velocity and grouping.

 

[unleashed]

The main function of tuning seating depth is to change how long the bullet is in the barrel. Once you find the optimum charge weight and the harmonics in the barrel are predictable, you tune the seating depth to ensure the bullet is leaving in the center of the barrel vibration. There are caveats with chamber pressure differences, bullet design, etc. I am jumping my 260AI .080" and it shoots bug holes while my .308 is at .005" off and it performs just as well.

 

[FEENIX]

I have a 300 WM and 338 Lapua, both in Armalite's AR30. I reload both at .001 off the lands. Neither one of them like more than .003 jump.

WOW! That's way too close for comfort for me.

 

[Tikkashooter]

I like to not be touching the lands on a hunting rifle, expecially if you are chambering and unchambering a live round a lot. A good compromise ive found is to start somewhere between .010-.030.

 

[Greyfox]

With my hunters, I generally try to avoid seating bullets any closer then .015" off the lands. Most of my loads are seated .020'-.070" off the lands. I have rarely, if ever found myself not being able to develop a solid hunting load In this range. At, or in the lands under hunting condition, and the frequency of clearing live rounds, reduces the risk of bullet getting stuck in the lands. Even with the Berger's, I have experienced the errant bullet that was off spec in BTO. If a new lot has a variation in BTO, there is usually enough breathing room should the new lot be longer by a few thousanth's....... this is not uncommon! Lastly, I like as much neck contact as can get given the frequency of handling cartridges, and the possibility of knocking a tip out of alignment. IMO.

 

[Steve Sheasly]

.002.. thank you sorry

Recently I have developed loads for the following calibers and manufacturers:
340 Weatherby Mark V USA --- 300 gr. Accubonds 78.5 of IMR 4831 .040 off lands 1/2inch groups at 100 yards**
.338 Lapua Savage 300 gr. Accubonds Max load of H1000 .040 off lands 1-inch groups at 300 yards
300 win mag Browning Xbolt 200 gr. Eld-X max load IMR .020 off 1/2 inch groups 100 yards
264 win mag 140 gr interlock 57 gr. H-1000 1/4 groups at 100 yards. ( the .264 is a 1:10 twist VLD high BC long bullets will not stabilize shoots interlocks well if I wanted this gun to compete with a 6.5 Creedmore I would re-barrel to 1:9.25)

So it depends on the powder, bullet, and gun. Accubonds typically like more jump but

**Note: on the 340 I used the IMR for H 4831( the powders are not interchangeable!) I just read 4831 my mistake for sure, I wish there were not two 4831, 4350 and 1000s number designation but there are. A very dangerous and stupid mistake on my part but it happened. There is not a load listed for 78.5 grains of IMR with a 300-grain bullet. This was a mistake I will not make again but the cases showed no stress easy to eject and was very accurate. IMR is a faster burning powder so the pressure will build faster but should be less than H4831 for a shorter time). I shared this so maybe someone else will not make the same mistake.

 

[Rhovee]

I run the 184's .003 in the lands for a couple 7 Saums. There is a consistency in what bullets tend to like. My experience is:
195 EH .015-.020 off
180 Hybrid. .020 off
215 Berger. .025-.030 off
184 Bergers .003 in the lands
300 EH- .003 in or .025 jump

Most all the vld bullets I have tried work good .010 off and closer. Keep in mind that there are multiple seating depths for one bullet. And your best group at 100 won't always be the best at distance.

 

[beaver hunter]

i would love to try getting close to the lands , but i have tried most every bullet available for the 7 STW , with max COAL for my mag. at 3.645,,,, many are at least .200 off the lands , some are .250 ,, that is 1/4 inch !!!
do you think i should get a barrel custom made >????

 

[LR65Pb]

WOW! That's way too close for comfort for me.

What comfort?

 

[BigJohnH]

Touching. I don't like any movement that isn't straight down the pipe!

 

[jshepherd61]

There seems to be a question of varying opinion on whether to have a 2000 th jump to the lands and option of bullet touching the lands for best accuracy. What's everyone's thoughts here?

You will find a hundred answers to this question as there are that many correct answers! This is a three part equation; it all depends on what your chamber likes, each gun and projectile is different and even different with each load. Example I have three 7mm STW's have tried the same bullit and load in all three each one likes a different seating depth to get optimal accuracy. One thing to watch if you are loading on the edge, is pressure increases with loading closer to the lans! No chamber is exact! In the afore mentioned rifles they all have Bartlien barrels, all chambers were bored with the same chamber bore but each is a little different!

 

[robpiat]

In a tikka 6.5 C i found nodes....One at 2.8" and 1 at 2.925. It looked similar to a powder charge test where it grew then shrank.