Fast twist .223 throating question.

Dogleg

Dogleg

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This seems to be the place for this querry.
My VLS rebarrel job is about ready to go, it just needs the barrel beadblasted and screwed back on. The chamber was deliberately cut with a short throat so throating could be done as a separate operation. Barrel is a 1-8" Gaillard Palma contour, finished at 28".
As near as I can tell by looking at my pile of bullets and Bryon Lytz's book if I get the throat cut so the base (minus boattail) of the 69Gr SMK is level with the base of the neck then it is also very close for the 80 grain SMK as well. The 80 & 90 grain Berger, 77 and 90 grain SMK would need to be seated approximately .100" past the base.
The question is, do I cut the throat for the 69 and 80 SMK or move it ahead 100 thou for the 77 & 90 grain SMK and the 80 & 90 Bergers? Or am I way off base? Would deep seating the longer bullets make any meaningful difference?
 
I like to keep the bullet in the neck but this is really only an issue if you are neck turning. This is the problem with a short neck; it affects versatility. On the other hand, you might not need versatility. Cut the throat to fit the bullets you think you are most likely to use. If that is the shorter bullets, the longer bullets might not get a chance to perform their best but I can't say that uneqivocably. I think I would lean toward throating for the longer bullets since they are likely to be the better performers at long range anyway. People talk about throating shorter so they can chase the lands as the throat burns but I figure, if the throat's eroded that badly, I'd just as soom re-barrel. regards, Bill.
 
Case capacity is the big difference. With a short throat and heavy bullets in a short Rem mag, you will have lost about 2gr of powder capacity.

Does this matter? As always, it depends.

I have shot the 90gr Berger VLD with an OAL at 2.45" and it worked from the Savage mag. Looked goofy but there was enough room for Varget to get the job done.

I have also throated a barrel so this bullet can sit around 2.6ish". More case capacity, more speed, boattail right at the neck shoulder junction.

As was said, pick the bullet you want to shoot and throat accordingly.

Jerry
 
How much velocity do you think you gained by seating the Bergers right out? I'm leaning toward throating for the Sierras, and seating the Bergers deep if I try them at all. Fitting in the mag isn`t an issue.
 
Dogleg I have a new TruFlyte 30" that was chambered with a Pacific Tool 223 rem Match reamer. 80gr Bergers kissing lands is 2.418 OAL which is far to short even using a long drop tube you will cruntch 25.1gr of Varget which I don't like.
Good friend has a Krieger chambered with a Wylde reamer he seats his 90gr Bergers at
2.595 oal he shot this weekend at Connaught 3 days shooting 80gr VLD bergers my and did very well for conditions we had heat and wind, brothers Hart seats his 90gr VLD at 2.610 kissing lands he uses 80gr Sierras as well
I am waiting for throat reamer from Pacific and will lenghten mine to the 2.62 or 3
Hope this info will help you
Manitou
 
I had my 1:8 .308 throat cut to allow a 200 gr MK to engage the lands with only the boat-tail extending into the shoulder of the case. As a result I clocked the 200 gr MKs a hair under 2700 from the 28" pipe. The tradeoff is that if you ever want to shoot light (short) bullets, then by necessity you will have a significant jump to the lands, which cannot have a positive effect of accuracy.

I would be inclined to use the Sierra for your throat length. Due to its longer nose and shorter ogive, I doubt of the Burger would have to be seated deeper into the case.
 
I think I was making this harder than it has to be, mostly because I was trying to draw too much conclusion from the bullet diagrams.:redface: I was just looking at the cylindrical portion of the bullet and it never really dawned on me that that isn't the part that hits the rifleing. Since determining how far a secant or tangent pointed peg can go into a round tapered hole is somewhat past my math skills, I took the direct route of seating a 69 grain SMK level with the base of the neck, and doing the same with a 80 Berger.
Turns out that after I took the Stoney point comparator to the dummy bullets seated like this that the datum point was in almost the exact same place. So was the COL for that matter. I bet that there a boatload of other bullets bullets that will come close.
My trait of doing things the hard way is still alive and kicking.:redface:
 
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