COAL Consistency

[LSOSGT1109]

I've found a load that my 700vs really likes, 175 SMK over 45 grains of rl-15, black hills brass, cci br2, seated to a COAL of 2.810 which is at the limit of the mag length. I'm trimming my brass precisely to 2.00 and I'm using a Foster micrometer seating die. I'm having a hard time keeping them all at 2.810. When I get the die set to load one at 2.810, they will range from 2.804 to 2.816. I even had one at 2.796 and one at 2.820. I've measured the current batch of 175 SMK that I have and have noted a difference in bullet length of up to .5". How can I get my COAL consistent?

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[TCKev]

Measure the Ogive length,to much variation at the tip of the bullet. Sinclair Intl sells one.

 

[kansas]

What he said. Sierra bullet points are not consistent. Ogive measurement is the right way.

 

[GUNZ n AMMO]

Measure the Ogive length,to much variation at the tip of the bullet. Sinclair Intl sells one.

+1 Hornady makes these BULLET COMPARATOR GAUGE but are made out of alluminum (affordable) Sinclair makes them too and of high quality which it felt and looks like milled steel.

 

[P7id10t]

Are these pulls or NIB SMKs?
I have the same setup and for the ones I'm plinking with I don't car about the 4mils. Part of it is I want to see if there is a discernable variation in my groups if my bullets COAL vary by 4-6 mils, and same with powder variations of 0-0.2 grains.
When I do want it dead-nutz, I back off the micrometer, press down part way, rotate (repeat a few times until at full stroke length), then measure and adjust the few mils needed to get to exact length.

 

[insight3b]

You can trim the meplats to the same length...since you are meauring for mag length trimming the meplats is the easiest and quickest fix
http://www.sinclairintl.com/reloadi...rming/sinclair-meplat-trimmers-prod36562.aspx

 

[LSOSGT1109]

Thanks guys. These are not pulls, they are an older batch of SMK, probably 6-7 years old.

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[gvanhyning]

You can trim the meplats to the same length...since you are meauring for mag length trimming the meplats is the easiest and quickest fix
http://www.sinclairintl.com/reloadi...rming/sinclair-meplat-trimmers-prod36562.aspx

Trimming the meplat properly is time consuming & will reduce bullet BC by 10%. Get a comparator to measure seating depth to the ogive. Once the seating die is set I check randomly and when I start a new box of bullets.
Good luck

 

[NoFail]

I find that even when I measure from ogive, which is now always with the Hornady comparator, the bullets I load, which are usually .30 cal AMAX, are not consistent and I can see variation of up to +/- 5 mils. I use new Forster Ultra micrometer seating die on 25+ year old 550B. I also seat 168 AMAX to 2.810" OAL. Should come out to about 2.180" at ogive but even that varies because of the tips. So I rely on just the ogive measurement and use the micrometer to back off and sink the bullet shy. Take new ogive measurement to determine amount on micrometer to dial back down. The Forster is fantastically accurate and makes this method very easy and consistent. I don't know what else to do and I won't be trimming no meplates I tells ya'.

 

[insight3b]

When done properly uniforming the meplats only reduces BC by 2% and if I'm going to measure to the tip I'm gonna make sure all the tips are the same if you have a Giraud the make a tool for it to.
http://www.giraudtool.com/meplat.htm