Jacket Wall Thickness Consistency (How Important it is)

[Desert Fox]

I have just finished reloading 45 rounds for my 6.5-284 (25 Sierra 142 grain SMK and 20 Berger 140 VLD Target) today. I'm still in a process of load development trying to squeezed more fps out of the 26" Lothar. By the way thanks to the kindness of Powerstroke for sending me the Berger all the way from Colorado. He even paid for the postage,.."What a guy". Thank you Mark. I hope I can return the favor someday.

Anyway, while at it, I started sorting the loaded round by measuring bullet run-out and I noticed that out of 25 Sierras that I measured only 8 made it into the .001" to.002" range and the rest between .003" - .007". I began to suspect the Lapua brass until I got to measuring the Bergers. Out of 20 loaded case, 13 are within .001"-.002" range and the rest measured no more than .004". Now the brass came from the same lot and I haven't measured the wall thickness yet. I'll do that after the first firing and neck sizing. So I assumed the cause of the extreme runout on the Sierra must have come from the bullet. What do you think Guys? DF

Here's the loaded round. The Berger on the right.

 

[Bruce Mc]

Sierra Match bullets are extremely consistent, I might suspect that your seating plug is shaped more closely to the Berger and is thus seating it more accurately. Unless of course you have a match type seater that centers the bullet, then who knows.

 

[Desert Fox]

You might be right Bruce. Right now I'm just using the regular Redding Die. I'm waiting for the Foster Ultra Micrometer Seater Die and a Redding Neck sizer bushing die. Anyway, I will be using the Berger exclusively.

 

[jtoews80]

It's pretty hardnot to like that 0.640 BC. If you could keep us updated on whether or not that is accurate I'd be interested. I've had a box of them sitting on my bench since spring and have only fired about 10 of them.
I haven`t had time to do more.

JT.

 

[Desert Fox]

It's pretty hardnot to like that 0.640 BC. If you could keep us updated on whether or not that is accurate I'd be interested. I've had a box of them sitting on my bench since spring and have only fired about 10 of them.
I haven`t had time to do more.

JT.

That's what I was hoping for JT. I'm really excited with this round. I run the Berger through my Ballistic program and I was amazed at the performance of this bullet... at least on paper. At a velocity of around 2900 fps, the sleek little bullet has enough energy to clobber an elk at 1000 yards. 25 MOA will get me to 1K at 2000 ft. level where I mostly hunt. There's a video at the Best of West website showing a guy dropping an elk with one shot using the Berger at a distance of 925 yards.

Here's the link

http://www.thebestofthewest.net/frontpa ... ideos.html

 

[coyotetrapper]

The only problem I have seen with bergers is bone hits!!! Let me know how it does if you hit bone! Remember where they are htting things on those long range best of the west shots too!

 

[Desert Fox]

The only problem I have seen with bergers is bone hits!!! Let me know how it does if you hit bone! Remember where they are htting things on those long range best of the west shots too!

I'm not worried about bone hit with these bullet since it's going to be primarily use for deer or goat. If I want to shoot an Elk, I have several appropriate rifle for that.

 

[GB300wm]

DF, I always at least true my brass with a neck turner. I find that brass thickness in the case walls of the necks to always be a little out. You'll find that you may take a little off one side and not touch the other. A little at the bottom of the neck and not at the top. Just true them if your neck tension is OK. It will help big time in runout, although .001-.003 is almost as good as it gets. You may also want to get a benchrest micrometer seater die. It tightened up my groups nicely at 400-600 yards. Really made a difference. :grin: :grin:

 

[Desert Fox]

Will crap, I'd just received my Type S neck die and two bushings from Midsouth and I already have to sent the bushing back to Redding. I run a .291 bushing on my once fired brass and instead of expecting a measurement of .292 or .293, I'm getting .288... way too tight for my liking. Talk to Chris from Redding and I was told to send the bushing back to them including two dummy rounds so that they can measure it and sent me the appropriate bushing. I also sent my die for honing to match my chamber. We'll see what they can come up with.

I think this is the best way rather than guessing and trying to figure it out your self. I followed Reddings instructions in choosing the right bushing and still I'm off. My reloaded round measured .294 to .295. so I figured a .290 or a .291 will give me .292 or .293 with .002 brass springback. Well, I didn't got the .002 springback instead I got a .002 spring forward :? I read somewhere on Redding Tech line also that if you have larger than normal neck chamber diameter, you will have this problem. My fired brass measured .296 to .297. I don't think that's the case here. Anyone can shade light on these.?

Thanks,
DF

 

[woods]

Hey DF

The best tool I have found in these type of situations is a set of pin gauges

http://www.cdcotools.com/index.php

click on measuring tools, pin gauges and the 3rd one down on the right - $55.00

You can check bushings and the inside of your case necks. They are useful for determining springback and looking for do-nuts also. I am extremely anal about outside neck turning

and even so the inside of the neck can vary after sizing with a bushing because of variations in the process of neck turning. All that effects bullet grip.

The most consistant ID of sized necks are with the Lee Collet which size the inside of the neck against a mandrel. Any die that sizes the OD of the neck will have slight variations in bullet grip because of the remaining variations in neck thickness. IOW if you are trying to outside turn to .012" you will some that are .0005" more and some that are .0005" less, unless you can turn a lot better than me. That will add up to .001" variation

 

[Desert Fox]

Thanks Wood,

I'll place an order for a set of those pin gauges. Looks like a real handy tool to have. The 6.5 drives me nuts. I can't remember having this problem when buying the bushings for my 338 Lapua. I'm all set to order either .293 or .294 when I decided to call Redding. I offered to sent my once fired brass but I was told that it's not necessary. I hope they'll send me the right bushing.

I'll wait til all the brass had been fireformed before turning the neck. I measured an average of .0145 - .0153 neckwall thickness on these batch of Lapua Brass. That'll give me .0008 to clean-up.

You're right about the Lee Collet die. I have one for my 300 Weatherby and I really like it. I might order one from Lee for my 6.5. The only thing though it will be a special order because the caliber is not a standard chambering.

 

[woods]

With the pin gauges you will find that you have to turn off a little more than the math indicates in order to get the ID you want. Don't ask me why, it just happens.

The operable dimension on the Lee Collets is the distance from the case head to the neck/shoulder junction. On the 6.5x284 it is the 1.902" and on the 6.5 Swede it is 1.852". You could find a washer that is .050" thick and place it around the case on top of the shell holder

or even if it were a little thicker (like .25") it wouldn't hurt much, just leave a portion of the neck fire formed size

which wouldn't be a bad thing.