Weirdness setting up "template rounds" in 308

[pinne65]

I've been reloading straight walled handgun rounds in a single stage press for a couple of years now. And am just getting into bottleneck rifles, 308.

The first rounds I reloaded I fully resized with a coal of 2.805. They shot ok both from my 700 sps tac and my buddy's RR AR10.

Getting more into it, one of the things I read, was to create a template round, blank with a seated bulled just shy of touching the barrel, for reference.

I did this with fireformed brass from my factory rounds and Hornady bullets JHPBT 168 and 178 grains.

With the 168 grains I got a coal of 2.8095.

With the 178 grains I got 1.743 before the bullet didn't caught the barrel. And even with my limited experience from relaoding bottlenecks I find this difference extreme.

Before settling on this coal I narrowed the range down with new bullets and case just in case the old ones got deformed by chambering. However they would chamber without effort in every case from 2.810 and down.

The question is, how much attention should I pay to this? Stuipidly enough I didn't measure the coal on the factory rounds. My rifle seemed to like them - bunch of 3 shot groups at touchingf at 160 yds.

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[DieselScout]

How are you doing your measuring? What tools are you using?

 

[pinne65]

I'm using a caliper, setting the cartridge as square as possible on it, taking a bunch of measurements for each, kind averaging them out in my head. Admittedly its a cheapo chineese...

 

[DieselScout]

I would suggest getting the proper tool, being a bullet comparator and an OAL gauge. Having the right tools will give you better result and a proper measurement from the ogive of the bullet.

 

[pinne65]

Dengit - this gets more intrigiuing (allows me to flee from yard work and ha-ha tv shows) every day

Ogive - ok I'm off goolging and reading. What's the definition - fattest point of the bullet?

Ok, so for the 168 grain the fattest point was in the case or close to, whereas for the 178 grains it was 1/64" outside. Interesting new knowledge. So I need to know know where the ogive is from the tip/butt of the bullet. And a general purpose Hip-Ching caliper is not up to the job.

 

[DieselScout]

The Ogive is where the bullet is going to contact the lands of the rifling, or the part that puts the spin on the bullet. What your talking about is setting the bullet "jump" or the distance the bullet travel before it hits the lands. You have to have a bullet comparator to properly measure this, just guessing isn't going to get you close enough as your dealing with thousandths of an inch.

 

[pinne65]

Thanks! - Will have to get one asap

 

[Steve M]

With the 168 grains I got a coal of 2.8095.

With the 178 grains I got 1.743 before the bullet didn't caught the barrel. And even with my limited experience from relaoding bottlenecks I find this difference extreme.

The length of 308 Winchester brass is about 2.015" so I'm going to assume your OAL was 2.743" with the 178gr bullet. The length for the 168gr sounds good as the maximum length for a 308 is 2.800", but I'm suspicious of the 178gr and if it were me I'd try again, maybe even with a fresh bullet. You should be able to at least get the minimum OAL listed in the Hornady manual which should be around 2.800".

In case you didn't know, these measurements are specific to each gun and if you exceed an OAL of 2.800" based on these measurements then don't expect the cartridge to fit another firearm.

Buy bullet comparison gadgets if you must, but unless you're a competitive shooter the information you get from such tools may not be worth the price that you pay for them. There are probably other tools that you could buy first with better return on your money. Foremost in my mind considering this discussion would be the Hornady OAL gauge. Another good tool is the Hornady (formerly Stoney Point) headspace gauge.

 

[pinne65]

Thanks for the info. Yes 2.743 it was. I already bought the comparator. But haven't gotten back to trying again yet.

 

[FOWELKILLER]

do your self a favor and buy the hornady lnl o.a.l guage and the proper casing.its soooooooo much easier than using black marker or candle smoke on the bullet then trying to feed it without scraping the sides of the bullet.then use your comparator,for best results like the other gentlemen said the ogive is where you want to measure from,thats were the bullet contacts the rifling.another thing some bullets like to be stuffed into the rifling some like to be .20 off the rifling,some .60.you just need to play a little.i usually start at .15 and work my way down till i find what works,or up.for me i like a secant ogive.just remember its all about having fun and experimenting

 

[pinne65]

Ok - holding off on the jump set for a little while. I've had 100 rounds loaded in 5 different t powder weights that I haven't even gotten to shoot yet. Once that's done and I have gotten conclusive results I'll go on to the next step.

 

[Goosebrown]

Your comparitor is going to be your best friend. I assume you got the Hornady/Stoney Point?

I think I am about one year exactly in front of you. I encountered EXACTLY the same questions.

 

[pinne65]

Yea - got the Hornady bullet comparator. Not the OAL gauge yet.

I got to go and shoot but wasn't able to get enough me-time with the rifle. I'll have to go alone and dedicate a full day to the ladder shooting.