Barrel throat depth question - Shilen

[mjphawk]

if your building a single feed rifle then id seat the bullet to where i had 0.020 or so of the boat tail/shank junction past the neck/shoulder junction and that would give you room to chase the lands and still have good neck tension as the throat burns out.

LongRange, thanks so much, this is exactly the information I was unsure of. The rest of clearly helpful as well in affirming that I was understanding what you were saying but I didn't have any concept as to how best to determine the seating depth.

Now I just need to wait for my shipment of Bergers to come in so I can load up some rounds and pick which I will be sending to Shilen.

Thanks so much for your patience and knowledge sharing.

[LongRange]

and so we are clear by 0.020 past the neck/shoulder junction i mean the bullet seated deeper by 0.020 past.

[homefrontsniper]

Nice!

[m12lrs]

LongRange, thanks so much, this is exactly the information I was unsure of. The rest of clearly helpful as well in affirming that I was understanding what you were saying but I didn't have any concept as to how best to determine the seating depth.

Now I just need to wait for my shipment of Bergers to come in so I can load up some rounds and pick which I will be sending to Shilen.

Thanks so much for your patience and knowledge sharing.

Berger hybrid or berger vld

Hybrids are about as sensitive to seating depth as a MK. Now I am not saying they won't shoot better when you find that magic spot. Just they are nothing like a VLD.

VLD's were designed to be shot jammed into the lands .001 to .002. Recently it was found that they would jump. If.interested read about how to get the greatest accuracy from your berger VLD. I know from experience it works.

If you are going to chamber a barrel especially for one bullet, if it is the VLD, how about a secant chamber. All chambers are designed around a tangent ogive. it would be a good experiment.

[mjphawk]

and so we are clear by 0.020 past the neck/shoulder junction i mean the bullet seated deeper by 0.020 past.

So I got my shipment of 168gr Hybrids so I could take some measurements. Based on discussions here, I will set my dummy round up to be seated 1-caliber length (.300) into the neck plus 0.020" to allow for erosion. At this length, the ogive of my bullet should be approximately 0.030" from the lands.

Based on these parameters I have the following choice to make:


If I use 175 SMK as my dummy rounds (most commonly used) then the 168gr Hybrid will be seated approximately 0.100" deeper than ideal with an COAL of approximate 2.695" (0.116" shorter than SAMI max and 0.206" shorter than mag length)
If I use 168 Hybrid as my dummy rounds then the 175 SMK will be seated approximately 0.100" shallower than ideal with an COAL of approximate 2.852" (0.042" longer than SAMI max and 0.049" shorter than mag length)


If I set for the 168 Hybrid then the 175 SMK would be seated with the bearing surface contacting 0.224" which may be reduced to 0.194" as the throat erodes. Seems to me like that might be getting seated a little shallow and maybe I am better off just living with the fact that if/when I use the 168 Hybrids they will be seated a little deep which would decrease case volume (i.e. increase pressure) and I may be giving up a little velocity. Thoughts?

[LongRange]

id use the bullet you plan to shoot for your dummys and not worry about the seating depths of the others or if one bullet shoots better than the other...unless your a bench rest shooter just pick a bullet and tune it to shoot...i only shoot 2 brands of bullets berger hybrids and sierra match kings and in 9 or 10 different barrels both bullets would shoot better than 1/4moa at distance and 1 hole groups at 100yds and im not that great of a shot.

[RC20]

I will disagree with you. Anyone that can shoot one hole groups at 100 is a good shot.

At some point the rifle is accurate enough to do it, its then the shooter that is the limiting factor.

1/4 MOA at distances is world class.

I have been working at it for some time, I believe I am capable of something below 1/2 MOA. I believe the gun is good to 1/4. The other day I put 3 into a hole at 108 yds, the other two were off and I got 5/8. One of my "happy" groups. It tells me I can do better and not a bad group by my standards which is sub 5/8 MOA.

This is recent. I finally got a rifle setup that is capable of it and my technique has improved. Before it was 7/8 MOA.