|
|
Post by herman on Mar 18, 2009 7:33:53 GMT -5
Richard sent me a copy of a report from berger bullets on finding the sweet spot for their VLD bullets.I had just gotten some bergers but they were the wrong ones and I had a bunch of 168 Hornady a-maxes.So I thought I would use their method to find the sweet spot for the a-maxes. I shot four groups of three useing col's as follows: 1- jamed into the lands 2-.040 off the lands 3-.080 off 4- .120 off. Now this is for a target rifle if you want to try it with a hunting rifle start out at .10 off the lands.You could possibly eject a round from the chamber and pull the bullet out of the case then you would have a action full of powder. You can see that the shots were pretty good with any of the col's but #1 and 4 were the sweet spots,#1 being the best of the lot.It tells me that the a-max will shoot good in a hunting rifle with a shorter col also.  |
|
|
|
Post by youp50 on Mar 18, 2009 18:08:41 GMT -5
When I work on a load the first thing I try is the different weights of powders. I go up a half of a grain at a time until I reach maximum. If it looks promising at one of the weights, I will reload at that weight and two tenths up and down. Again looking for the best group. After I have settled on a powder weight I start looking at the jump or COL.
Is there a better way?
|
|
|
|
Post by whyohe on Mar 18, 2009 19:21:29 GMT -5
herman that is some sweet shooting!! i was told to keep the bullet as close to the lands as possible. it makes for better transition (for lack of a better word right now) of bullet to lands. how i guaged mine wes like you said i put a bullet in a resized brass and put bullet in neck STREIGH AS POSSIBLE and chambered the round and SLOWLY eject it and take measurement. i looked to see if there where markes on the bullet as if it came up off the neck to make sure i got the right length. then i made some dummy rounds and made sure they would stack right and chamber properly and looked for marks on bullet to see if it hit lands.
|
|
|
|
Post by deadeye on Mar 18, 2009 21:37:21 GMT -5
When I work on a load the first thing I try is the different weights of powders. I go up a half of a grain at a time until I reach maximum. If it looks promising at one of the weights, I will reload at that weight and two tenths up and down. Again looking for the best group. After I have settled on a powder weight I start looking at the jump or COL. Is there a better way? youp,i do the exact opposite,i work the jump or col within one powder 1st, then proceed exactly as you decribe 2/10 up or down,if not working jump to another powder,i find the powder does not control the jump,probably more so action squaring etc, jmho |
|
|
|
Post by herman on Mar 19, 2009 5:09:47 GMT -5
I have been doing about the same as youp for around 50 years finding the best load.This was a proven load and I received the wrong berger bullets,so I had several different brands on hand,and I had tried the hornady match the week before so after measureing the a-max and found they measured closer to the bergers than the rest and I had just gotten the post from richard I decided to give the a-maxs a try to see if their tests would work on a different bullet.
This was the first time I tried this and it looks like it would save shots finding the sweet spot.If I was going to set up a hunting rifle I would start at fartherest col back from the lands.According to the test above.If you have ever ejected a round and the bullet pulled out and the powder dumped in the chamber you know what I mean.
Next week I will see what this tells me at 300 yds.
|
|
|
|
Post by olsmokey on Mar 20, 2009 17:41:04 GMT -5
Herman; What did you end up with for a OAL with the 168g A-Max? I have mine at 2.850 which is .015 off the lands. Been useing your load of 43.5 of H-4895 and shoots great. [3holes-5shots] Tried the varget but couldn't get them consistent, so gave up on it. If the wind ever quits blowing gonna try some 300yd shots and see how they do. By the way, ended up with a 6-20 Nikon Monarch for glass. Let you know how it works when I start doing some longer shots. Dave
|
|
|
|
Post by herman on Mar 23, 2009 6:22:36 GMT -5
I have one of the nikon 6 x 20's very good scopes.Am useing the 8.5 x25 luppy on the savage.
I didn't get to try any of the long col bullets tuesday because all I had of them was the 6 I used to test with.I did shoot a 3 shot group at 2.810 at 300 and got a 1.066 in group with the 168 a-maxes and 1.465 in with my 308 tikka.
I also tried the 150 berger jamed into the lands and got a .953 in group.
What I am going to do this week is run them at 2.860 and let them jam theirself and see what that gives me.
|
|
|
|
Post by mshm99 on Mar 28, 2009 11:25:20 GMT -5
Is anyone using a comparator. IMO this the only way to accurately determine bullet jump to the origin of the lands and grooves . Damage to the points of the bullets makes measuring from the point to the case head iffy. Measuring ogive to case head is totally consistant. It also makes it easy to swith to bullets with different ogives and maintain the same jump.
How bout it Richard?
mshm
|
|
|
|
Post by Richard on Apr 1, 2009 19:42:20 GMT -5
Actually what I do is to make up a "stub-gauge" or "gizzy gauge" for each of my rifles/long range pistols. This is a short piece of barrel (when you buy a barrel blank, there is always about one to two inches at the muzzle, the manufacturer recommends cutting off. I take this piece and square off both ends, then run my chamber reamer in just up to and including the shoulder. (this provides me with an exact mimic of my chamber) I now have a gauge that can do two things: First of all, I can check bullet to rifling engagement without ever having to chamber a round. I do almost 99% of my bullet seating with Wilson type hand seaters (used in a arbor press). These seaters have a very adjustable stem. I start with my bullet well out from the case. Insert it in my gauge and see how far it goes in, adj. my stem out longer and re-seat, then check in the gauge until I just start getting fine "nicks" (as seen with a magnifying glass). I then measure my seater stem length with a caliper and use this as my base line for "just touching the lands." When I go to the range to work up a load I then adjust the stem.......fire a group..........adjust the stem......fire a group and work either into or off the lands.
The second and most important thing I use the gauge for, is to measure the base to shoulder length. This is what determines your headspace. Too much sizing and you push the shoulder back further than it needs to be and you create excessive headspace. This will cause your brass to "extrude" or grow in length. That extrusion takes place just forward of the case head where the solid part turns into the thin wall. Several firing like this and you wind up extraction just your case head and the rest of the cartridge remains in your chamber. "IF" you adjust your die so you size just enough to let the round chamber without having to "crank" down on the bolt handle, your headspace will be maybe .0005" to .001" and you will not get that excessive stretching. Hence longer case life.
I NEVER, measure Cartridge Overall Length from the base to the tip of the bullet. It is totally meaningless. (just look at the tips of bullets with a magnifying glass and you will know why!) You need to measure from the ogive to the base. Sinclair makes a gauge that fits on your caliper ( they come in all calibers) that will do just that. They call it a bullet comparator, which it does, but can also be used with a loaded round. Of course, there is the Stoney Point also.
Richard
|
|
|
|
Post by mshm99 on Apr 4, 2009 10:07:53 GMT -5
Richard knows what he's talking about. I've used the Sinclair Comparator for twenty years as well as their Seating Depth Gauge. I can check my throat erosion and maintain the sweet spot OAL through out the life of my barrel. For most applications throat erosion is realtively slow , however with some overbore barrel burners ,you want to watch it closely. One thing for sure ,you can maintain accuracy for quite a long time by simply tracking erosion and increasing OAL accordingly. So finding the sweet spot is half of the battle, the other half is maintaining the COL in relation to the origin of the lands and grooves.
Just my opinion.
mshm
|
|
