Seating depth

[Quackaddict]

Hey guys,

Im working with a Remington 243 win running 70 gr Nosler BT's. I have been working with this rifle for a bit now but havent found that "magic" load that shoots bugholes.

I started with 70 blitzkings and varget, I got roughly 1 inch groups at 100 yards and about 3400 fps. I switched to Nosler bullets and got slightly better accuracy. I then tried IMR 4064 and that kept 3/4 -1 inch groups at 100 yards plus gave me velocity in the 3650 range.

My question now is all of my testing has been done with the bullet .015 off the lands. Do the NBT's have a known preferred distance from the lands that may improve the accuracy? Am I missing the boat on something?

I also plan on trying some RL-17 to see what that does.

Any help is appreciated.

 

[DCRYDER]

I would try some 87gr VMAX's and H4350 about .010" in the lands. May not fit in magazine but may shoot better.

It takes a GOOD shooting factory barreled rifle to shoot 1/2" or better 5 shot groups consistantly.

 

[artbosco]

Hey guys,

Im working with a Remington 243 win running 70 gr Nosler BT's. I have been working with this rifle for a bit now but havent found that "magic" load that shoots bugholes.

I started with 70 blitzkings and varget, I got roughly 1 inch groups at 100 yards and about 3400 fps. I switched to Nosler bullets and got slightly better accuracy. I then tried IMR 4064 and that kept 3/4 -1 inch groups at 100 yards plus gave me velocity in the 3650 range.

My question now is all of my testing has been done with the bullet .015 off the lands. Do the NBT's have a known preferred distance from the lands that may improve the accuracy? Am I missing the boat on something?

I also plan on trying some RL-17 to see what that does.

Any help is appreciated.

You appear to be jumping all over the map in an attempt to find the magic load. Unless you've covered most or if not all of the procedures below or something similar, you may never find it. Work methodically with one powder and one bullet at a time. Here's some steps that should help:

Working Up a Load …. by Lee Euber

1. Polish bullet with steel wool. Initial seating depth achieved when bullet is marked by all lands. Tony Boyer likes to see a “square.”

POWDER

2. Load 3 cases in a low grain load. Increase each 3 case load by .5 of a grain, and then shoot. Increase loads until primers show pressure.

3. Identify shots that grouped well, not so good, and then good again.

4. Pick load that shot the best. Load 3 cases with .1 grain less, and 3 with .1 grain more, for another comparison.

5. After picking charge for use, load 30 cases with the same powder charge.

SEATING DEPTH

6. Load the 30 cases in groups of 3, increasing the seating depth from touching the lands to jumping about .040 of an inch, in increments of .005 of an inch.

7. Shoot all 30 rounds without cleaning or clean after each 10.

8. Use ONE fouling shot after each cleaning.

9. Select load that shot best. Load 5 cases with that powder charge and seating depth.

10. Load 10 cases, 5 with seating depth .005 less than benchmark figure and 5 with .005 more.

11. Can compare more than once or change seating depth by .001 or .002.

12. Once you’ve picked the best seating depth, load 15 cases at that depth.

POWDER

13. Check first test by varying charge by .1 grain, for each 5 shot group.

14. Shoot in a medium wind condition, letting the gun do the work.

SEATING DEPTH

15. After picking the best load jumping the lands, compare it with the load that touches. Compare these loads again and again, on different days, in varying conditions, deciding which one is best.

16. If it doesn’t shoot to your satisfaction, restart with a different powder.

NECK TENSION

17. If you decide on the load that puts the bullet in the lands, be sure neck tension is tight enough to hold the bullet uniformly.

 

[SS427]

I think .015 off was a great place to start. I've found in a factory rifle bullets have the most impact on accuracy. I like to try 3 different bullets with one or two powders and find which bullets it likes best. Then I find which powder works the best. I start tweaking things like seating depth and primers last.

Could be your gun doesn't like light bullets, in which case you could waste a lot of time and components chasing the wrong weight bullet. I like DCRYDER's suggestion of trying the 87 grain Vmax and you might want to try the 80 grain Noslers BTs, especially if you have them on hand or someone you can swap with.

I use Outdoorsman's approach when I have a rifle I know will be very accurate.

 

[headhunter1111]

I seem to find that seating depth is more important than powder charge in my current rifles. Could just be me. I like what outdoorsman said about working up until you see primer flattening. I'd go that route, pick something that shoots well and tinker with seating depth. Try it from .040 jumped to .015 jammed. See what works. JMO

 

[Quackaddict]

To clear a few things up....

I worked up the powder charge (starting low) until I got to pressure with both IMR 4064 and Varget, and did that for each of the bullets I have tried. For whatever reason, the 4064 was just a faster powder. I picked 4064 for the current load because it was faster and it wasnt less accurate than the Varget.

I started at .015 because thats where my 308 seems to like the bullets.

The only thing I dont have repeated testing for is seating depth.

I have built something like 150 of the current load with 4064, it has been consistent since I developed it. I had hoped that running a few more rounds down the tube might make things better (break in, if it exists).


The 87 vmax is on my radar for future development.I am really trying to get the 70's to run. I like what they offer (speed/trajecotry/stopping power)

 

[RonAKA]

I would try the Berger 68 and 69 grain flat base bullets. They are the two that shoot the best for me in a 6BR. Also try 0.010" into the lands. I have not found much difference between 0.005 and 0.020" jump, and none of the jumps in that range shoot quite as well as the jam. But each gun is different, so all you can do is try it. Varget works best for powder in my 6BR, but your case is bigger. H4350 may be better. I like to see the case filled to the neck with a suitable charge weight.