Zane Shepherd,
The angle into the rifling, depending on how the throat is designed will effect how long you can seat teh bullets out.
For example, if you take a throat with a parallel diameter section(some call freebore) of say .110" in length and with a 1.5 degree angle into the rifling, you will be able to seat your bullets to a certain length.
If you take that same throat but steepen the angle from 1.5 to 3 degrees you will have a slightly shorter OAL because the steaper angle will engage the bullet sooner then the shallower angle.
As far as accuracy goes, I would say you would be hard pressed to prove a 1.5 up degree is more accurate then a 3 degree if both are set true and accurate.
What will be effected is the amount of pressure that will be required to start the bullet into the rifling. The steeper 3 degree angle will increase chamber pressure quicker then a 1.5 degree angle simply because full bullet engraving of the rifling will take place twice as fast as with a 1.5 degree angle.
This is also generally not a problem. It may be only if you have an absolute max load developed for a 1.5 degree angle and then had a barrel made with a 3 degree and used the same load.
Peak pressure would certainly occur quicker and may be higher as well but I would not expect anythign to get dangerous from this.
BAck to the accuracy issue. In high intensity rounds using thin jacketed match bullets, the 1.5 may produce tighter groups compared to the 3 degree simply because the 1.5 eases the bullet into the rifling in a less severe manor.
The thin jackketed match bullets would probably perform better with the 1.5 degree.
For big game bullets I would not expect to see much difference at all to be honest.
I am sure your throat is not 0.003" over bullet diameter unless you have an angled throat right from the leade into the rifling. This design is basically only a cone that guides the bullet into the rifling and often a larger starting diameter is used for these type of throats then with the type I discribed above.
Personally I do not like the conal throats, feel they do not compare in accuracy with the type discribed above but again you know what they say about opinions.
Your concentricities are running alright. I have shot some extremely tight groups with run outs in the 0.002" range. We are always looking to get sub 0.001" run outs but do not discard the 0.002 and 0.003 ammo unless your match shooting.
You really need to test your ammo run outs throughout the loading process. Size your cases and see what the neck run outs are before you do anything else. YOu need neck run outs in the 0.001" range or less if you want any chance at all to get at or under 0.001" bullet run out as generally the neck run out is magnified in the bullet run out.
If youare using an S type Redding bushing die I would highly recommend you get a Redding Comp Neck Bushing die. The S die is a great die but is does have one flaw, it does not support the case as the neck is being sized. While you have greater control with the bushing as far as neck tension goes, you have no more accuracy then a standard full length sizing die as far as controlling neck run outs in your case.
The Comp die from Redding hold the case perfectly centered as the neck is sized resulting in 0.001" or less neck run outs nearly all the time is you make sure to keep debris out of the bushing area of the die.
Another problem using the bushing sizing dies that most do not realize is that they make the outside of the case neck concentric but unless you turn your case necks, all the case neck thickness variation is transfered to the inside surface of the case neck. The outsides are nearly perfect but if there is any thickness variation in the case neck, it has all just been transferred to the inner diameter of the neck, Where the bullet will be held.
So unless you are turning your necks to get them perfectly even in thickness, do not expect to get sub 0.001" run outs a high percentage of the time because the neck thickness variation will be carried over to the seated bullet.
Once you have your cae necks sizing true its time to go to the seating die.
First though, you need to make sure your brass is trimmed square to the axis of the case and also that you have an even chamfer on the inside of the case mouth.
This is because if your case necks are not square, one side of the bullet will engage teh case mouth before the other and when the seating pressure is applied, the bullet will cant slightly until the entire bullet base contacts the case mouth, this means higher run outs.
IF it is square, the bullet will start to seat square and you have won half the battle.
The chamfer is also critical as an uneven chamfer will do the same thing an uneven case mouth will.
So now we have the case neck run outs under 0.001" and the case mouth square and chamfered squarely. Now its onto seating that bullet true.
Take a dumby case that as a know run out, preferably under 0.001" and seat a bullet in it as you would if you were topping a loaded case. Pull the bullet and check its concentricity. Generally, whatever your neck run out is, you can double that for your bullet run out or more if your necks are not turned.
Doing a few of these will tell you the consistancy of your seating die. If you get run outs all over the board something is not consistant with the seating process. Generally, as with the sizing operation, the case is not being controled and held in line as the bullet is being seated.
Again, teh very best system I have used is with either a Redding Comp seater die or a Forster BR seating die. Both use the sliding sleeve, in-line system as does the Redding Comp neck sizer.
The sleeve holds the entire case, not just the top half, the entire case length in perfect concentricity with the bullet as it is being seated.
With these dies, I have found that bullet run outs on turned case necks will often be equal to or even slightly less then neck run outs instead of being magnified using a stardard seater.
These dies do cost quite a bit more but once you use a set, you will forget about any price tags when you measure 100 rounds and the highest bullet run out you have is 0.002" and 80% are under 0.001" run out.
One thing that really concerns me with your problem is the fact that you are getting 0.002 to 0.0025" neck run outs on your fired cases, this is not acceptible at all.
Sometimes the Rem 700 can be a little rough on the case mouths during extraction and ejection leaving a flattened area on teh case mouth. Are your cases doing this and your picking up the run out from this?
If not your chambe is dramatically off. Perhaps not off axis but either it is off axis or your chamber is egg shaped.
Was your chamber cut with a reamer that used a live pilot bushing design or a solid pilot? THe only way to cut a match grade chamebr is with a live piloted reamer that has interchangable pilots so youcan perfectly fit the pilot to the bore diameter. Thes come in different sizes for each caliber.
For instance my sets have 9 different sizes for each caliber, each 0.0002" larger then the one before. When chambering or crowning a barrel, I use the pilot that perfectly floats on the lands. Using these correctly, there is no way to get a chamber off center if everything else is also done correctly.
TO check to see if your chamber is off or egg shaped. Use your concentricity guage to measure the concentricity of your case body right at the body-shoulder junction as well as at the rear of the case, but make sure it is above the expansion ring or you will get false reading.
IF these measurements are true, I would say your getting the run out from the ejection process. IF your chamber is egg shaped, youwill see this in the variation in these two measurements. If it is egg shaped, you will either need to live with this rifle as is or have it either set back and rechambered or rebarreled.
As far as the Bersin tool is concerned, for the money by a set of Redding Competition dies and true your necks and forget about run outs being a problem.
Hope this helps some,
Kirby Allen(50)
