Drop in Velocity?

[bcraft1111]

Thanks Kirby.

 

[bcraft1111]

I had a little time to spend this afternoon so I got out my old journal that I write all my reloading data in and found the page where I measured the aol to the lands for the 180 noseler partition I originaly loaded for my gun.
The original measurement was 3.632 to the lands the new measurment to the lands for the 180 is 3.750
Is this Throat erosion and could this be my problem.

 

[Fiftydriver]

Bcraft1111,

Yes this is throat erosion and yes this will dramatically lower your velocity and accuracy. Generally you can get some of both back by seating your bullets out farther to get them closer to the eroded origins of the lands.

You will never get all the velocity back but sometimes, accuracy does improve quite a bit.

For a large round like this I would highly recommend a 3 groove rifling design simply to increase barrel, throat life as long as possible. They also produce a bit more velocity as well compared to a traditional 6 groove.

Good Shooting!!

Kirby Allen(50)

 

[bcraft1111]

Thanks again for the info. I am going to call Gary Schneider in the morning and get me a new barrel on the way. I spoke with him the other day and he mentioned that he might would use a octogon rifeling ( I think this is what he said ) He did recomend that I put the largest barrel that my stock would hold to get the most out of my groups. I looked up the Mcmillian stock and they say up to a #7 contur barrel.Do you think I should lengthen the barrel from 27 to say 30. Would I see any signifigant improvement or should I stay with the 27. He did say to flute the barrel if I wanted to take some weight off. About how much weight would I add to my gun if I went to this #7 barrel. My gun has a #4 on it now.

 

[Fiftydriver]

bcraft1111,

Your big Warbird will certainly benefit from both added length an diameter on the barrel. This will give you mroe velocity and a stiffer barrel.

I #4 contour is pretty light at 27" for the Warbird. I would personally use nothing lighter then a #5 at this length and would prefer a #6 contour.

I use 30" #6 contours on my Extreme Sporters in the Allen Magnums and accurcy is excellent with the Lilja barrels.

The #7 will only add more barrel stiffness which is a very good thing for accuracy.

I am not sure what Gary's contours measure compared to Lilja barrels but they will be similiar I am sure. Comparing a Lilja #4 and #7 contours both with 30" finish lengths, here are the barrel weights.

#4 contour: 3.8 lbs at 30"
#7 contour: 5.5 lbs at 30"

Thats +30% more barrel mass for the #7 contour. This is significant and will show up on target.

This is a heavy barrel though for a sporter rifle with a composite stock. May feel a little muzzle heavy. I would certainly recommend fluting a #7 contour barrel and I would have it fluted with a large diameter flute in the .312" wide range.

This is how I have Lilja flute my barrels and over a 30" barrel length you will loose 3/4 lb of barrel weight while not loosing any stiffness or accuracy potential. Plus you have the flutes to aid more rapid barrel cool down.

I will be honest and say I have not played with the octogon and polygonal barrels much and certainly not enough to tell you I recommend them. Gary is the one to ask that question to find out the benefits of this system.

I use Liljas 3 groove system and have never had a reason to change, amazing accuracy, great throat life and higher velocities then conventional rifling with less bore fouling as well. Well, bore fouling is simply not an issue with any Lilja barrel if they are broken in properly.

So yes I would certianly go with a longer heavier barrel. I just got in my personal Lilja 30" 257 barrel for my 257 Allen Magnum rifle. This rifle will be a project in seeing how light I can build one of my extreme sporters in the round without loosing any balancing qualities or performance in velocity or accuracy.

The barrel is still a #6 contour but I had it fluted with the heavy .312" wide flutes which bring the barrel weight down to an even 4.0 lbs! Quite light for a 30" #6 barrel.

I will be using a McMillan BDL stock with their lightest fill and expect to get the rifle weight in the 8 1/4 lb range relatively easily. I will be using a full accurized Rem 700.

This rifle will easily play with the 1/4 moa range at 100 yards and sub 1.5" groups at 500 yards with a point blank range nearly out to this range!

Good Shooting!!

Kirby Allen(50)

 

[Fiftydriver]

Bcraft1111,

Well that took longer then I expected.

Here is the load data for the 7.82 Warbird using Retumbo and the 180 gr Accubond.

Case: Lazzeroni(new lot) old lot would not handle loads over 3475 fps without loosing the primer pockets.
Fed-215
180 gr Accubond
OAL: 3.692"
H-Retumbo

Starting load 94.0 gr

This rifle a Sako, topped out at 104.0 gr with an average velocity of 3511 fps in the 26" barrel. Extreme spreads were in single digits.

Your seating depth will lickly be different so start at the 94.0 gr level and find your correct seating depth and then work up from there to what your rifle produces as a top load.

Hope this helps, sorry it took so long.

Good Shooting!!

Kirby Allen(50)

 

[bcraft1111]

Thanks for the info. If it helps anyone else I called Lazzeroni they said to use the retumbo like RL25 with the Accubonds.

Thanks again Kirby