RCBS Precision Mic Question.

[fla9-40]

Hello,
I’m new here on THR so be easy on me!

I have a question on the RCBS Precision MIC. It is my understanding
this will tell you where the ogive/ojive is in relationship to your lands, thus
giving you a setting to set your bullet jump.

I cannot understand this if ALL bullets ogive are different from mfg to mfg and weights.

I have these ogive measurements checked with Hornady Comparator tool:
1) Sierra 168gr HPBT Match = .592
2) Mfg Un-known 190gr SP = .771
3) Mfg Un-Known 180gr SP = .616
4) Hornady 178gr AMAX = .699

Am I not comparing apples to apples or how will the RCBS tool be a “Use for All” tool when you have a difference in all bullets?

 

[brickeyee]

It is a comparison tool but you have to measure with every bullet type and brand you use.

 

[USSR]

I use the RCBS Precision Mic for it's case headspace function, but the tool for bullet seating ain't worth the powder to blow it to h3ll. For that function you are better served by the Hornady O.A.L. tool. Just MHO.

Don

 

[rg1]

The Precision Mic is touchy and not easy to get consistent measurements. It will give you a measurement from your bolt face to the edge of the barrel lands. Getting the friction right on the dummy bullet takes some trial and error. Having to put the dummy case under your extractor and holding it straight guiding it into the chamber and overcoming the ejector spring pressure at the same time takes patience and you need to take several measurements to make sure you get consistent readings. Then you can use the tools graduated dial to measure bullet ogives. I really like the Mic for measuring headspace and setting my sizing dies.

 

[rcmodel]

Save yourself a bunch of money and buy a $1.19 black Magic-Marker.

Seat long, color the bullet, and try to chamber it.

Where the ink rubs off, it is touching the rifling.
Seat shorter and keep coloring until it doesn't.


BTW:
(We used to use soot from a candle flame before they invented Magic Markers!)

And WAY before they invented $50 tools to sell us do to it less perfectly, and with less precision in any barrel.

(You can do the math on how much 1/8 turn of your seating stem seats the bullet deeper in the case.)

They vary by brand of dies, or I would tell you.

rc

 

[bainter1212]

Save yourself a bunch of money and buy a $1.19 black Magic-Marker.

Seat long, color the bullet, and try to chamber it.

Where the ink rubs off, it is touching the rifling.
Seat shorter and keep coloring until it doesn't.


BTW:
(We used to use soot from a candle flame before they invented Magic Markers!)

And WAY before they invented $50 tools to sell us do to it less perfectly, and with less precision in any barrel.

(You can do the math on how much 1/8 turn of your seating stem seats the bullet deeper in the case.)

They vary by brand of dies, or I would tell you.

rc

Yep this is my method.

I do it because I am poor, not because I am old like RC haha.

It works. If I had lots of cash I would buy the fancy gadget that doesn't work LOL.

 

[dirtman]

i am with ussr on this one... the precision mic is a good tool for head space.... and the stony point or now Hornady tool for oal to the lands has worked very well for me..... have used them both together when working up my most accurate loads.... in all rifles that i want tight groups.... all the best, dirt

 

[dirtman]

yes different bullets will have different oal to the ogive..... i usually start at about .004 off the lands and work back from there.... and u will have to work up different loads and oal for every different type of brand of bullet you plan to use, unless they are exactly the same....
depending on what cal we talking, i have certain bullets that i like for various purpose. example hornady 165 grns for 308 have been great and resonably priced... your on the right path..... so have lots of fun all the best dirt

 

[GW Staar]

i am with ussr on this one... the precision mic is a good tool for head space.... and the stony point or now Hornady tool for oal to the lands has worked very well for me..... have used them both together when working up my most accurate loads.... in all rifles that i want tight groups.... all the best, dirt

Ditto....I like the tool to measure headspace. Very accurate way to make sure you don't bump the case shoulders back too little (dangerous) or too much (overworks brass).

Also agree that the Stoney Point/Hornady tool is the most elegant simple way to measure bullets against the lands. I don't use the RCBS tool for that either.

RC's way works great too and I did it that way for years, being what we were all taught back in the stone age.....it's just bit harder to be quantitative if you think you need to know the difference between .002" and .004".

 

[rcmodel]

But, I do know the difference.

And it may surprise you to know when it comes to seating off the lands.
It doesn't matter anyway.

The most accurate ammo you can get is factory loaded Match or Varmint ammo.
Loaded to standard length.

With no regard to where the lands are.
Records are won with it all the time.

Rc

 

[MEHavey]

(^^^) Uhhhh..... not my experience.
(Please see http://www.thehighroad.org/showpost.php?p=6726733&postcount=24)

The OAL for any bullet's distance from the lands...
..... -- AND --
The most accurate distance off/into the lands...

very definitely varies with each bullet design/weight/shape.

 

[Reloadron]

I have and use the RCBS Precision Case Mics in some popular calibers like 223 Remington, 308 Winchester and 30-06 Springfield but for looking for the lands to determine seating depth I use the old tried and true method used by many. The following is from our friends at Nosler for those who may not be familiar with the method.

The following instructions were taken from the Nosler website FAQ section.

How to measure your rifle’s seating depth.

Step 1: Insert the bullet into the neck of the fired case. It should fall freely into the case with no resistance.

Step 2: Remove the bullet from the fired case and press the case neck lightly against a flat surface to create a small indentation in the case neck so that it will grip the bullet.

Step 3: Insert the bullet, base first into the case so that the case just grips the bullet by itself. Just get the bullet started into the case, don’t seat it too deeply.

Step 4: Completely color the bullet with a felt marker.

Step 5: Gently insert the case and bullet into the chamber of the firearm and close the action. Do not pull the trigger.

Step 6: Carefully open the action and gently remove the case.

Step 7: Retrieve the bullet. It will either be stuck in the lands of the barrel or still in the case. If the bullet is stick in the lands, it can be removed with a cleaning rod. If the bullet is still in the case, gently remove it with your fingers taking care not to mar the ink and proceed to step 8.

Step 8: During Step 5, the lands will have contacted the bullet and pushed it back into the case neck to scrape the ink off of the bearing surface of the bullet. Simply push the bullet into the case until the edge of the case neck is just to where the ink has been scraped off.

Step 9: Carefully measure the overall length of the dummy cartridge. This overall length is called your “rifle seating” depth. It is where the bullet contacts the lands of the barrel. This length is different for every type of bullet depending on ogive, meplat, etc. This process should be repeated three to four times to obtain a consistent average.

Step 10: Set your seating die to seat at a depth between .015” and .03” less than your rifle seating depth.

When loading E-Tip® bullets, seating them .050” - .100” away from the lands typically produces the best accuracy. Lightweight bullets may need to be seated further from the rifling. A depth of one bullet diameter inside the case neck gives good neck tension for ignition. The overall length must be short enough to function through the magazine.

Ron

 

[fguffey]

The distance from the bolt face to the beginning of the rifling's does not change on a rifle.

F. Guffey

I drill out the flash hole/primer pocket to a diameter that will accommodate a cleaning rod, I select a case with good bullet hold then I seat a bullet that will not reach the lands. After I seat the bullet I chamber the transfer without the bolt, 'then' I push the bullet out of the case with a cleaning rod until the bullet contacts the lands THEN! I stop pushing and remove the transfer test case.

After removing the transfer I use the transfer to transfer the dimensions of the chamber to the seating die. I adjust the seating die to 'ZERO' off the lands.

When adjusting the bullet off the lands I lower the seating stem and keep up with the numbers with a height gage. All of my seating dies are micro adjust, the micro is built into my dial caliper, height gage or depth gage.

I want all the hold I can get when seating bullets. Some choose to shred the neck of the case, some purchase cases that have threaded case heads, I don't, I want all the bullet hold I can get.

F. Guffey

I do not want my bullet setting at the lands when the trigger is pulled, I want my bullet running when it hits the lands I want bullet jump.

 

[dirtman]

The thing about the stony point is that it is just so easy to use and when used right, so accurate.... you really know where that bullet sits with regards to the lands....

MEhavey great shooting.... lotta work and great results.... thank you for sharing....
when you can take a rifle off the shelf and make them shoot like that..... humm... baby
you just gotta love it..... been there done that.... all the best dirt

 

[Blue68f100]

I use the RCBS Precision Mic as an aide in setting up the seating die. I use the old school method on determining where the lands start. I do use the PM to measure this as a reference. So I can check my distance jump to the lands. The tool supplied with the kit is not very good and is very hard to keep the bullet/plug from moving. Beside it does not have the same profile as the bullets you use. I take a reading for every type/weight/brand of bullet I use.

 

[fla9-40]

I use this method but I measure it with the Hornady Comparator tool. I do this measurement 5 times and use the average.

http://www.youtube.com/watch?feature=player_embedded&v=kaA3GECbbVA

I keep a log for each rifle and bullet I shot .

I was just question how the RCBS tool could tell you this using the supplied "dummy" round they gave

 

[Reloadron]

I use this method but I measure it with the Hornady Comparator tool. I do this measurement 5 times and use the average.

http://www.youtube.com/watch?feature=player_embedded&v=kaA3GECbbVA

I keep a log for each rifle and bullet I shot .

I was just question how the RCBS tool could tell you this using the supplied "dummy" round they gave

OK using a 308 Winchester cartridge just as an example.

Am I not comparing apples to apples or how will the RCBS tool be a “Use for All” tool when you have a difference in all bullets?

Working from the bullet tip down the bullet we will reach a point in the increasing bullet diameter where the bullet diameter is 0.300" and it is at that point the bullet will engage the rifle barrel lands. A 308 or 7.62mm rifle barrel has a bore diameter of 0.300" as measured land to land.

The dummy cartridge included with the RCBS Precision Mic kit includes a dummy bullet and just like a regular bullet working down from the tip we hit a point where the dummy bullet diameter crosses that 0.300" diameter point. The dummy cartridge in this case is called a freebore tool.

Now if I just start the dummy bullet into the dummy cartridge and place the dummy cartridge in my rifle and allow my bolt to finish seating my dummy round and then carefully extract my dummy round from the chamber it will tell me something. The precision mic has a threaded barrel with a 0.300" hole in it. I can place my dummy round in the mic and measure the distance from the case head to that 0.300" point where the dummy bullet engaged the lands in my barrel. It matters not how much bullet is above or below (bearing surface) that 0.300" point of my bullet diameter. The number I get is a reference point. That is all it is.

Now I can take an unprimed and uncharged actual cartridge case and seat a bullet and slowly work to seat the bullet to obtain the same reference number I just got. Regardless of bullet shape or length I know that the bullet I just seated will be right on the lands. I can now measure the cartridge OAL using my selected bullet. I can now start loading live ammunition using that bullet and move my seating depth back to where I want it till I find the sweet spot in my seating depth.

I can do the same thing using the method I outlined above.

Ron