How important is adhering to the COL in the manual?

[wombat13]

I would greatly appreciate any help. I don't want to keep adjusting by bullet seating die.

I'm working up a load for my .300WM (Ruger Hawkeye). I have three bullets, SGK, SST, Nosler Ballistic Tip. I set the bullet seating depth on the SGK to 3.338" (the Sierra manual indicates a max COL of 3.340"). When I switched bullets the COL for the NBT is 3.402" and for the SSTs is 3.418.

It seems to me that the seating die must be pressing the bullets in uniformly. That is, the distance from the base of the case to the part of the bullet that the die contacts must be the same for all of the bullets. It's just that the NBTs and SSTs have a long narrow point. The part of the bullet that the die presses is on is probably closer to the part of the bullet that seals against the bore. Therefore, even though the COL of loaded cartridges are different, there will be the same space between the bullets and the rifling of the barrel. Consequently, I should not have any pressure problems.

Am I wrong?

Second question: The Alliant website recommends a max load of 77 grains of RL-22 with a 180gr. bullet and a starting load of 10% less. I plan to load five rounds with each of my three bullets with the following powder charges: 70, 72, 74, and 76 grains. I plan to choose the best grouping bullet/charge combo and then load in half grain increments around that combo. Is this a good method for working up a load?

Thanks.

 

[Jim Watson]

You are close. I would check to see that the bullets really were off the lands (and would run through the magazine) before settling on a seating depth.

There are all sorts of load increment testing procedures out there. Yours will probably do OK or somebody might come along with something different that will help.

 

[Ol` Joe]

Always check the COL of the bullet to insure it isn`t hitting the lands, unless the books data has the COL for that specific bullet loaded to a length shorter then the SAAMI max. Different bullet geometry will make a big difference in how deep you can seat the bullet and stay out of the lands.
Sierra often develops their data with the bullet seated all the way out to SAAMI max COL as does Nosler, and at times others. That COL simply means the cartridge at that maximum length will fit any MAGAZINE in a factory rifle chambered for that cartridge. It means nothing as far as whether or not the bullet at that length will be out away from the lands or in them.
Plastic tipped bullets will vary a lot in their lenght. I always check when starting a new to me tipped bullet that the tip doesn`t bottom out in my seating plug. If it does I drill the cup out a tad deeper with a small drill bit. This allows the rim of the seating plug to be the only contact with the bullet as it is designed to be. Seating depth will appear to vary at the tip but, the depth to the ogive at the point of full diameter will be extremely close. They make OAL gages to measure your cartridges if you desire.

Here is a article on seating and the use of the gages to determine seating.
http://blog.sinclairintl.com/2009/03/26/determining-bullet-seating-depth/

 

[Captcurt]

Like Joe said, always check to make sure that the bullet isn't hitting the lands. Not only can it put your pressure over the top but I can also stick a bullet solid enough to cause the case and bullet to separate if you try to unload. Then you dump the powder into the action and have a bullet stuck in the barrel. Better have a cleaning rod handy.

Been there, done that.

 

[ranger335v]

"How important is adhering to the COL in the manual?"

I've been reloading both rifle and handgun ammo since '65 and have never paid any attention at all to book OAL.

 

[USSR]

COL in reloading manuals, is simply the COL that they used. As long as you have at least 1 full caliber of the bullet in the neck, and you are not contacting the leade with the bullet ogive, you are fine. Oh, and it's always nice to have them fit your magazine.

Don

 

[wombat13]

Thanks for all the responses. I did a little research online and found a little trick for estimating the OAL at which a given bullet will contact the lands in a specific rifle.

Take an empty, once-fired case and cut three or four slots in the neck with a Dremel. Slide a bullet into the neck until it just stays in position. Chamber the case and close the bolt. The lands push the bullet into the neck.

Here are the max OALs I found for my rifle using this method:

Hornady SST: 3.496"
Nosler BT: 3.540"
Sierra GK: 3.516"

So even with the SST, I've got nearly 0.080" of jump before the bullet contacts the lands (given the depth that the bullet seating die is seating the bullets).

I know this isn't the most accurate method, but I'm pretty confident that my rifle isn't going to kaboom.

I also checked the rounds that I loaded to make sure the feed in my rifle. They feed fine.

 

[1SOW]

So even with the SST, I've got nearly 0.080" of jump before the bullet contacts the lands

One thing you might want to keep in mind with this method: Your press isn't perfect. If the press varies +/-.0015, then you need to subtract .002 (rounded up) from your oal finding.

 

[wombat13]

One thing you might want to keep in mind with this method: Your press isn't perfect. If the press varies +/-.0015, then you need to subtract .002 (rounded up) from your oal finding.

Very good point. The press seems to be surprisingly consistent with variation in the range of less than +/- 0.001". Of course, it would still be safer to assume 0.002" less than the max OAL that I measured.

So, taking 0.002" off my measured jump I get 0.076" jump for the SSTs in my rifle. Is that enough? How much jump is necessary to be safe?

 

[azar]

So, taking 0.002" off my measured jump I get 0.076" jump for the SSTs in my rifle. Is that enough? How much jump is necessary to be safe?

That's more than enough. No worries there.

 

[wombat13]

That's more than enough. No worries there.

That's what I thought. Thanks for the confirmation.