I'm shooting 208 Amaxs .100" off the lands, that's max mag length. What other bullets would get me closer to the lands at mag length? Don't say Round Nose bullets, something with good BC for long Range.
Seating depth
- Thread starter muleman
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Re: Seating depth
If you're out of magazine length then I'm guessing you need to either change the shape of your bullet, or find one that is more tolerant of shorter seating depth, or both. According to this article, the benefit of secant ogive shaped bullets like the Hornady A-max is they have high BCs but are finicky when it comes to seating depth. It goes on to say that tangent ogive bullets have greater bearing surface with the rifling making them less sensitive to seating depth, but at the cost of drag, resulting in lower BC. I assume you're shooting 300WM or 308 with a fast twist -- in that case, some Googling reveals that Berger has hybrid secant-tangent bullets in 185, 200, 215 and 230gr. The 215s are listed with a BC of 0.696, and 230gr with a whopping 0.711 BC. Right now, you're at 0.648 with the 208gr A-max.
FWIW I have no experience with anything heavier than the 175 SMK, but these heavy .30 cal bullets definitely have a following...
Edit -- just noticed that there are actually two variants of the 230gr Berger hybrid, the second having a G1 BC of 0.743. Damn!
If you're out of magazine length then I'm guessing you need to either change the shape of your bullet, or find one that is more tolerant of shorter seating depth, or both. According to this article, the benefit of secant ogive shaped bullets like the Hornady A-max is they have high BCs but are finicky when it comes to seating depth. It goes on to say that tangent ogive bullets have greater bearing surface with the rifling making them less sensitive to seating depth, but at the cost of drag, resulting in lower BC. I assume you're shooting 300WM or 308 with a fast twist -- in that case, some Googling reveals that Berger has hybrid secant-tangent bullets in 185, 200, 215 and 230gr. The 215s are listed with a BC of 0.696, and 230gr with a whopping 0.711 BC. Right now, you're at 0.648 with the 208gr A-max.
FWIW I have no experience with anything heavier than the 175 SMK, but these heavy .30 cal bullets definitely have a following...
Edit -- just noticed that there are actually two variants of the 230gr Berger hybrid, the second having a G1 BC of 0.743. Damn!
Re: Seating depth
What mag are you feedin these out of ?
What brand rifle/who did the chambering?
What mag are you feedin these out of ?
What brand rifle/who did the chambering?
Re: Seating depth
This is a factory Sendero 300 RUM. With the 208s I'm at 3.685 mag length, to reach the lands with the Amax It's 3.805. I want to be .020" off the lands which leaves .100". I'm looking for a shorter length from Ogive to the Tip of bullet, Tangent style, which is going to hurt the BC. I'd like to stay heavy 200-240GR.
This is a factory Sendero 300 RUM. With the 208s I'm at 3.685 mag length, to reach the lands with the Amax It's 3.805. I want to be .020" off the lands which leaves .100". I'm looking for a shorter length from Ogive to the Tip of bullet, Tangent style, which is going to hurt the BC. I'd like to stay heavy 200-240GR.
Re: Seating depth
Berger 210VLD (.708"), 240 SMK (.651"), 220 SMK (.672") versus your 208 AMAX (.777"). (meplat to ogive dimension)
I would go with a SMK as they are more tolerant to changes than a VLD. But what will you do when your throat errodes a bit more? I think if I invented a magazine stretcher I could quit my day job.
Berger 210VLD (.708"), 240 SMK (.651"), 220 SMK (.672") versus your 208 AMAX (.777"). (meplat to ogive dimension)
I would go with a SMK as they are more tolerant to changes than a VLD. But what will you do when your throat errodes a bit more? I think if I invented a magazine stretcher I could quit my day job.
Re: Seating depth
Squid284, +1 on the mag Stretcher!!! I can believe how deep Rem reams some of there throats, it's almost inferior craftsmanship.
Thanks for the measurements, that's exactly what I was looking for to pick another bullet.
Squid284, +1 on the mag Stretcher!!! I can believe how deep Rem reams some of there throats, it's almost inferior craftsmanship.
Thanks for the measurements, that's exactly what I was looking for to pick another bullet.
Re: Seating depth
I was at first suprised that you couldn't get it to the lands as I have plenty of room with my 7RM, then I realized you have a longer ultra mag. I recently tried the 7mm SMK's and am very pleased with the groups. My default jump is .020" off the lands and adjust from there. Got those dims from the Applied Ballistics book (thank you Mr Litz, you should be knighted). Good luck!
I was at first suprised that you couldn't get it to the lands as I have plenty of room with my 7RM, then I realized you have a longer ultra mag. I recently tried the 7mm SMK's and am very pleased with the groups. My default jump is .020" off the lands and adjust from there. Got those dims from the Applied Ballistics book (thank you Mr Litz, you should be knighted). Good luck!
Re: Seating depth
You could have your barrel set back and rechambered. Or.... why not just get your action trued and a new barrel smithed to your exact specifications. The accuracy improvement will be much improved over a factory set up.
You could have your barrel set back and rechambered. Or.... why not just get your action trued and a new barrel smithed to your exact specifications. The accuracy improvement will be much improved over a factory set up.
