Obtaining Coal

[Bishop]

Trying to get the max coal to touch the lands using a once fired, unsized, unprimed case, just starting the bullet into the case and chambering the round.

So far i have gotten *measuring to the tip of the bullet*

3.435
3.568
3.521
3.462
3.516
3.482
3.504
3.396
3.421
3.452
3.560
3.551
3.435
3.515

My results don't seem to look to well?

Time to go get the hornady oal length gauge tool and bullet comparator?
Or should I just average these numbers and start loading?
Garn my head is hurting after all this.

Enlighten me please

 

[SBruce]

I never had much luck doing it that way either.

Seems like sometimes the bullet will "stick" in the rifling and COAL measurement will be longer because we pull it out of the case some when we pull the bolt back.

Seems like sometimes the ejector plunger isn't getting compressed fully, so the COAL measurement is shorter than it should be.

The ejector plunger can cause big issues when trying to do this, as can the extractor IMO.

I tried it by sooting the bullet with a candle, marking it with ink, split neck cases, neck turned minimal tension cases, thick neck bushing sized maximum tension cases, you name it...........inconsistant results, just like you're seeing.

I believe the best way to get it (if you want to use a real bullet and case and bolt is to remove the plunger and extractor, close the bolt, open the bolt and gently push the bullet and case back out with a cleaning rod. But that's too **** much work, especially since we need to check it often as throats get eroded from shooting.

So, long story short; I ended up getting an RCBS Precision Mic which has worked wonderfully for all my factory chambered rifles for many years now. Key Tip: if you use one, make sure the screw is as tight as you can get it with your fingers........I mean really tight. It's got to fully compress the ejector and slip past the extractor to get consistant accurate measurements. You want to feel alot of resistance when you push the bolt forward and compress the guage.

Hornady makes a tool, Sinclair makes a tool, as probably do others also. I use the sinclair model and comparators on the custom wildcat chambers now. Never have used the Hornady one. Regardless of which one you use/get, taking a reading off the ogive/bearing surface junction is the preferred method, rather than from the tip. You can seat two different type bullets to the exact same OAL (base to tip) and they will be different distances from the rifling because of the shape of the bullet (Ogive length, Bearing surface length, ect).

Not an expert on this by any means, but through trial and error I found a system that works well for me. Hopefully that helps save you some frustration.

 

[boomtube]

Few factroy rifles shoot their best on or in the lands, most do better from 20 thou off to as much four times that.

So, IF you want to start out to say 15 thou for intital load development, just average what you got and seat back from that.

 

[Bishop]

So averaging and taking .015 off of the average will give me a relatively safe starting point to work backwards from.

Im not actually "wanting" to jam or even be on the lands. Just wanted to try and only have one direction to play with. Reduce the coal till it shoots satisfactory. Instead of wondering if i left my optimal jump behind somewhere in the discrepancy's i observed with my measurements.

Ty both for your advice it is much appreciated to this "newbie"

 

[Bishop]

What really bothered me was when i looked at the coal listed in my manual compared to the numbers i was getting. My eyes bugged out of my head. But i take it from you guys its not unusually long?

 

[boomtube]

If you start at about 15 thou off (precision isn't really required for this, you just need a starting point) and develop your charge and then back off more in maybe 5 thou steps to find the best seating you will be fine.

Book OAL is only the length the book makers used to compile their data, it's just for our infomation and is not a law nor even a strong suggestion. I've been reloading since '65 and have never even considered using a book listed seating depth.

 

[Bishop]

Good deal, ill go ahead and continue onwards then tyvm for the information. Glad i dont have to shut down while waiting on a gauge to get here . Ill just use it to further refine if needed.

 

[SBruce]

As boomtoob mentioned, all you really absolutely need is a starting point. It's all relative anyway. No matter what distance from the lands you are, you might ultimately want to change that distance to find what shoots best in your rifle.

You can certaintly go ahead without waiting on a guage. But a guage will be helpful in the future. As I mentioned; the more you shoot, the longer the BF to Lands distance in the rifle gets. You will want to keep seating your bullets out further as the throat wears so your optimum seating depth stays relatively the same (relative to the rifle, not to a specific COAL measurement or "book value").

I agree with Boomtoob, most factory rifles I've had shot best with anywhere from .015 to .055 back from the PMR indicated Boltface to Lands distance. However, I wasn't shooting VLD type bullets in them.

Best o Luck

 

[Bishop]

Thanks, It seems i was being too critical of a measurement that didnt need that level of scrutiny.

I just am trying to proceed as carefully and safely as i possibly can. My wife and kids would probably be mad at me if i ended up with a permanent remington bolt imprint on my skull.

Hope I dont aggravate with my questions, i anticipate many more to come

 

[SBruce]

No worries, ask all you want.

There's alot of knowledge and experience on this site.