Berger 75 gr VLD

[Mr.Snerdly]

Will it stabilize in a 223 with 1 in 9 twist? A 1 in 8 is recommended but the 77 gr Sierra will work with a 1 in 9 but that doesn't mean the Berger would. I am tempted to try it but don't want to waste time and money on something that won't work.

Any advice appreciated.

[Txhillbilly]

More than likely, you will need a faster twist for it. Your 1-9 will happily shoot Hornady 75gr BTHP bullet's and also the Sierra 77gr Matchking bullet's because they have a shorter bearing surface than bullet's like the Berger VLD's or the Hornady Amax / ELD-M's. The longer bullet's work very well in a 1-8 or 1-7 twist barrel.

[charlie b]

Mine shot the Hornady 75gn ELD's just fine. The problem for me is they had to be loaded long for best accuracy and would not fit in the mag. THey were loaded to 2800+ fps, just like the SMK's. The Berger length seems to be in between the Hornady and Sierra. If you have some, try them.

[Mr.Snerdly]

^^^OK, I will try enough for about 3 groups. Any suggessions on OAL? I got these for nothing so I won't be out of too much if they don't work and if the first group is terrible I can break them down and save the powder and primers on the remaining ones.

[Mr.Snerdly]

They aren't horrible but nothing to get excited about either. 2 groups, 7/8" and 9/16". Tried the Sierra 69 grain right after and 1/4". I think I'll stick to the Sierras. I wish the Sierras weren't so darn expensive but they shoot well. I guess you get what yolu pay for.

[charlie b]

The two Bergers in .308 I used did not group well until they were touching or even lightly jammed into the rifling. You may need to do the same with the .223 bullets.

I never tried them but I was going to test some of the RMR bullets to see how they did.

[Mr.Snerdly]

^^^I had them about .015 off. If you touch the lands, do you have to reduce powder charge? I normally don't load to the max but I did with these since I think it helps with stabilization and I knew I would be on the ragged edge with the stabilization.

[CFJunkie]

Don't be afraid to move them back.

I have always had trouble finding a jump that works for Berger bullets in at least three calibers.
I did manage to find their sweet spots, mostly all surprisingly different, but spent a lot of money on expensive Berger bullets in doing so.

When I found find their sweet spots, the group sizes are good but not necessarily better than with bullets that are a lot less challenging finding the right jump.

[charlie b]

My powder charges are determined in working up the load and usually are 100-200fps below book max. Chronograph results are checked to make sure I am in the right range. I still watch for pressure signs but have never seen any unless I know I am in the over max territory.

Normally you will see a bit higher pressure if you go from a jump to jam. If you are already at max charges then it will put you over. You can see this if you are using a chronograph as the velocity will change on you. Conversely if you go from, for example, 0.010 to 0.020 jump the velocity will not change enough to notice.

[CFJunkie]

It should change by about 6 fps. Decreasing the jump would seat the bullet deeper so the pressure goes up just a bit and the velocity rises.
As you say, not enough to notice and within the variation of the primer/powder burn from round to round.

[Whynot]

It should change by about 6 fps. Decreasing the jump would seat the bullet deeper so the pressure goes up just a bit and the velocity rises.
As you say, not enough to notice and within the variation of the primer/powder burn from round to round.


I've generally seen this backward- even though you are giving the powder less room by pressing the bullet in farther- it is still getting a running start at the lands. If at max load and then you jam the bullet into the lands you will probably be over pressure. But different bullets have different characteristics so very few things are absolute.

I am becoming a big fan of Berger bullets (and not only their supper high bc ones) because of consistency. Changing nothing in my reloading process except switching brand of bullet has resulted in better groups.

Go to the Berger web page and they have a bullet stability calculator- you just select the bullet and put in your info and it will tell you how stable it should be. Elevation plays a big part in it- so unless you live at high elevation they you will probably be marginally stabilized.

[CFJunkie]

Whynot,

You are right that being very close to the lands will increase the chamber pressure.
I was assuming that the bullet was not within 0.005 of the lands.
If you seat close to the lands, within 0.005, the pressure increases almost exponentially as you approach seating in the lands because the bullet has to overcome both the neck tension and the restriction of the lands before there is any pressure reduction caused by bullet movement out of the neck.

If the bullet is seated back from the lands, the pressure increases if you shorten the OAL, moving the bullet into the brass. That also increases the jump.
The pressure spike comes from buildup before the bullet begins to move out of the neck. Once the bullet starts in motion, the pressure drops from peak pressure unless there is more resistance encountered, like entering the rifling after the jump. If the entry into the rifling occurs after the bullet has started moving, the pressure has already begun its reduction and peak chamber pressure is reduced. But since the powder is still burning, added pressure when encountering the lands while the bullet body is still in the neck will probably cause a pressure spike.

Away from the lands by more than 0.005 inches, the pressure change caused by a seating depth change is very predictable and much less severe.
Turns out, that with most powders, given an equal trim length, a 0.002 decrease in the OAL will increase the velocity by 1 fps and the initial pressure will increase as well on the order of around 100 to 200 psi.
Pressure change will depend on the powder burn rate it is not predictable without choosing a powder and charge.
A corresponding increase in OAL by 0.002 will decrease the velocity by the same amount and the initial pressure will be reduced.