What can I learn from this chamber cast?

[SlowBurn]

Hi all,

What can I learn from this chamber cast from my Husqvarna .308 Win?

https://c5.staticflickr.com/6/5462/30811594932_0e67632051_c.jpg

The previously fired cartridge is 1.998" long and is .3445" in diameter at the mouth. Measuring from the cartridge base to where the cast starts to step down from cartridge mouth diameter to bullet diameter is about 2.030". Based on this cast, what's the optimum cartridge trim length for this chamber?

As near as I can measure, bore diameter is .301" at the end of the cast, groove diameter is .308" where the rifling starts and about .3075 at the middle of the cast. Based on this cast, what diameter should I size cast boolits to?

I plan to use the rifle to shoot High Power Silhouette at a reduced range, between 200-400m. Any recommendations for cast boolit weight and profile.

Any other lessons/suggestions? Thanks!


Until I get an appropriate mold and sizer die, I'll try shooting Hornady 150 gr FMJ/BT; middle cartridge below.

https://c4.staticflickr.com/6/5577/25292456499_ebe71febe9_c.jpg

I seated the bullet (middle one above), by neck sizing a previously fired cartridge, partially seating the bullet on the press, chambering the cartridge in the rifle and closing the bolt, and finally returning to the press and adjusting the seater plug to contact the bullet plus 1/16 turn. Is this too long or too short? When reloading, I plan to add a light taper crimp.

Is there any problem leaving the cannelure exposed?

Thanks all.

[Tatume]

There is nothing wrong with leaving the cannelure exposed. Further, there is no need for a crimp.

There is no accuracy benefit to an "optimum" trim length. Trim cases to a length that will not interfere with the chamber; a few thousandths more or less won't matter unless the case is too long and gets jammed into the throat.

For cast bullet diameter you need at least groove diameter. A little more won't hurt. What is most important is concentricity of the loaded round with the barrel. This is mostly a function of the case, although the bullet can play a role. For 0.308" rifles I like 0.310" cast bullets. Some people like 0.311" cast bullets.

I suggest an empirical approach. Load some and shoot them. Predicting accuracy takes a back seat to demonstrating accuracy.

[SlowBurn]

There is nothing wrong with leaving the cannelure exposed. Further, there is no need for a crimp.

There is no accuracy benefit to an "optimum" trim length. Trim cases to a length that will not interfere with the chamber; a few thousandths more or less won't matter unless the case is too long and gets jammed into the throat.

For cast bullet diameter you need at least groove diameter. A little more won't hurt. What is most important is concentricity of the loaded round with the barrel. This is mostly a function of the case, although the bullet can play a role. For 0.308" rifles I like 0.310" cast bullets. Some people like 0.311" cast bullets.

I suggest an empirical approach. Load some and shoot them. Predicting accuracy takes a back seat to demonstrating accuracy.

Thanks for the advice.

Before I can "load some & shoot some", I need to buy a mold and sizing die. I realize that some of this is trail and error, but I'd like to start the trail off on a good foot.

With these cartridges, as best as I can measure, I could fit a 0.313" projectile in the chamber without having to turn the necks. But that seems over size for a 0.308" free bore; maybe a 0.311" mold sized to 0.310"? So, I guess I'm looking for 0.311" driving bands and a nose section that will fit in the 0.301" bore.

NOE has a 311-188-FN that looks like it should fit well:
http://noebulletmolds.com/NV/images/N.O.E._Bullet_Moulds_311_188Gr._FN__188_gr_Sketch. Jpg
Are there better choices to start off with? Am I approaching this the right way?

Thanks

[Edward]

Check out NOE 310 165gr FN(30xcb) that works in my Savage model 10 with a. 1/10 twist /Ed

[Tatume]

Thanks for the advice.

Before I can "load some & shoot some", I need to buy a mold and sizing die. I realize that some of this is trail and error, but I'd like to start the trail off on a good foot.

I repeat:

For 0.308" rifles I like 0.310" cast bullets. Some people like 0.311" cast bullets.

There will always be some trial and error on the trail to good shooting.

Take care, Tom

[runfiverun]

the 30 XCB bullet mentioned above is cut for the 30-06 throat but will work pretty well in the 308.
the rcbs 30-165 silh will shoot well at 1900 fps or so and your drop will be about 5 moa from 1-200 and another 5 moa from 2-300.
there is one more boolit that will work here and will work well since it is designed for the 308 throats and that is the 31-165A from accurate.
that's the one I would use if I wanted to get a bit more velocity and just use plain alloy.
sizing to 310 would be where I would start.

[popper]

31-165A from accurate works well in my 308s, sized 310 (2700 fps in 1:10). I have an Al 4x of it I don't use anymore, PM if you are interested. I PC so changed to the 'C' version. There is also a 31-186G for heavier. I don't know how fast NOE can turn a custom but Accurate does it in a week, you can specify dia. on any mould from them. For jacketed, I use the 168 Amax - not as good as a Nosler bullet but less $$. My brass is LC07 and I've never trimmed so far, however I FCD and just remove the bell. If you TC then probably need them all the same length for consistency. This is my hobby but I still want a good load that is better than my shooting skills.

[tomme boy]

Both the 311-188-fn and the 31-165A were made by me and for the 308 win throat. They both shoot very well with the 165 has a tad more edge for the speed factor. I was able to take the 188 up to 2200fps in a 10 twist and stay right at 1 MOA. It started to fall apart faster than the 2200 fps speed. I am just not as good of a caster as some here and the attention to detail was too great for me to push it faster.

[CraigOK]

You might try bartering for some sample bullets from other members then buy the mold that produced the results you wanted