338 WM Jump to lands... Old school

[Porker]

Hey, loading for 338WM with 200g Speer's. With the lead tip, I have managed to create a dummy round which gave me an avg COL of 3.315" ... I discarded 3 of the 8 measurements done. It does seem a bit short in there? Any 338 fans who can comment on their throat?

I know the lead tips are not accurate and I have no tool to measure ogive, so how would you go about setting a standard Lee seater to jump to the lands, and how much jump do you recommend?

 

[Lefty7mmstw]

why don't you drop a bullet in your bore, tap it to jamb with a cleaning rod (then go in from the muzzle and mark jamb), then kick the pill out and mark the bottom of the chamber with a closed bolt.
You will get a decent jamb measurement this way as long as your firing pin isn't sticking out and you have a flat end on your cleaning rod; I use a modded patch jag with a flat end myself...

 

[Porker]

Hi lefty, thanks for that... I'm comfortable with my COL, it's setting my seating die that has me stumped... Do I turn it down to rest on my dummy round and then give it half a turn down for a tad under max? ... What jump do you suggest? .02 or more?

 

[J E Custom]

Hey, loading for 338WM with 200g Speer's. With the lead tip, I have managed to create a dummy round which gave me an avg COL of 3.315" ... I discarded 3 of the 8 measurements done. It does seem a bit short in there? Any 338 fans who can comment on their throat?

I know the lead tips are not accurate and I have no tool to measure ogive, so how would you go about setting a standard Lee seater to jump to the lands, and how much jump do you recommend?

The best way to get this dimension is by using a Cartridge Overall length Gauge.

Case Gages & Bullet Comparators- MidwayUSA

They are very cheep and can be a very useful tool that works on all bullet designs.

To set your dies = I like to use a full length sized (Un Primed) case and take the bullet you intend to use, seat it shallow with the dies backed off. then using the COAL gauge or the chamber its self, start chambering the round by cranking down on the die 1/2 turn at a time until the bolt closes easy (Don't force the bolt to close or you will get a false reading and possibly stick the bullet in the bore).

Normally when done this way the bullet will engrave 4 or 5 thousandths so you have to tighten down on the dies just a little more. This is where the gauge comes in handy for precise measurements.

Lead tipped bullets can be very accurate if they are handled carefully.

Most big magnums like some free bore (It helps keep the pressure down) I normally just use the magazine length - .020 to .030 to start with, some bullets will like .090 to a .100 off the lands and the gauge will tell you where you are when you find the most accurate load.

These tools are made out of aluminum, Plastic and brass so they will not damage the bore or the chamber.

J E CUSTOM

 

[Porker]

thanks JE, will have a search for that tool down under, meanwhile I think I will subtract 0.02 from my avg OAL and see if it chambers ok and then take it to the range ... from your comments on jump measurements, it seems to me that its not that critical for accuracy or that is varies considerably from rifle to rifle...