20 Practical 40 V-max COAL???

[Bachekermooni]

I just got my CZ 527 re-barreled to 20 Practical. When using the Stoneypoint and a modified case, the COAL with a 40 V-max is 2.200". Does this seem right? How far back should I seat the bullet? Running Hornady cases with TAC.

Cheers.

 

[Coyotefurharvester]

If you have a short/zero freebore those numbers seem "ballpark". My BHW AR runs longer, by 0.02+ depending on bullets. I haven't loaded any 40 gr vm only the 32's. I think the Wheeler method is easier to find bolt face to lands distance,at least for me.

 

[Bachekermooni]

I just tested the 32 vmax. It is 2.22" to the lands.

 

[pdhntr]

I just got my CZ 527 re-barreled to 20 Practical. When using the Stoneypoint and a modified case, the COAL with a 40 V-max is 2.200". Does this seem right? How far back should I seat the bullet? Running Hornady cases with TAC.

Cheers.

I believe my reamer is a zero freebore from PTG, and the 40 gr. V-max COAL is 2.190.

You really have to use a bullet and check your chamber to know for sure. Too many variables.

If you are surprised at how far the 40 gr. V-max is pushed into the case, you probably got it about right. They are pushed way in with a zero freebore.

If it is a hunting rifle, I would load to .005-.010 off the lands (shorter than COAL) to start with.

Jim

 

[TheCZKid]

I just got my CZ 527 re-barreled to 20 Practical. When using the Stoneypoint and a modified case, the COAL with a 40 V-max is 2.200". Does this seem right? How far back should I seat the bullet? Running Hornady cases with TAC.

Cheers.

Since you just got the new barrel, I'd ask the maker of the barrel for information / specs on the reamer that was used for that barrel. I asked White Oak Armament, and they sent me the drawing of the chamber with all the dimensions on that reamer. I think it's a pretty normal thing to ask, they sent it to my email. Mine has .020 freebore, many others have zero. It would be good to have that info.

Then, if you start to measure base to ogive length, rather than COAL, you will be able to use those dimensions for various bullet weights and profiles, and have a better idea of how far off the lands you are, as compared to the tip of each bullet.

here's Pacific Tools reamer, not the dimensions of Lead and Throat are the same, zero freebore


Here's what WOA uses, JGS it appears.

 

[hogpatrol]

I just got my CZ 527 re-barreled to 20 Practical. When using the Stoneypoint and a modified case, the COAL with a 40 V-max is 2.200". Does this seem right? How far back should I seat the bullet? Running Hornady cases with TAC.

Cheers.

Five 20Ps chambered, zero freebore, trim to 1.755. BTO 1.760 on most all bullets for .010 jump.
COAL is a magazine fit reference length.

 

[Bachekermooni]

Ah, 1.755"???

 

[hogpatrol]

Ah, 1.755"???

Fat finger typo. Yes, 1.755 & 1.760. Fixed it.

 

[Coyotefurharvester]

The 20p seems to be similar to the 204R, tolerates jump. So bullets tend to appear seated deep.

 

[TheCZKid]

Five 20Ps chambered, zero freebore, trim to 1.755. BTO 1.760 on most all bullets for .010 jump.
COAL is a magazine fit reference length.

With the WOA chamber, which has .020 freebore, my BTO length with 40 Vmax is 1.852" for best group. And with 32 Vmax I find 1.848" to 1.850" best. So far, it seems to like 40's over the 32's for accuracy, but I'm not done testing yet.

 

[Bachekermooni]

I used COAL because the BTO depends, to some degree, on the 20 cal insert for the Hornady (Stoney Point) tool.

Here are the number anyway:
Vmax 40 - BTO 1.832", COAL 2.201"
Vmax 32 - BTO 1.831", COAL 2.203"
Practically identical.

I am running 0.010 - 0.012 off lands. 0.5 - 0.9 results with TAC. Will try AA2230 next.
Cheers

 

[Bachekermooni]

Since you just got the new barrel, I'd ask the maker of the barrel for information / specs on the reamer that was used for that barrel. I asked White Oak Armament, and they sent me the drawing of the chamber with all the dimensions on that reamer. I think it's a pretty normal thing to ask, they sent it to my email. Mine has .020 freebore, many others have zero. It would be good to have that info.

Then, if you start to measure base to ogive length, rather than COAL, you will be able to use those dimensions for various bullet weights and profiles, and have a better idea of how far off the lands you are, as compared to the tip of each bullet.

here's Pacific Tools reamer, not the dimensions of Lead and Throat are the same, zero freebore
View attachment 1290504

Here's what WOA uses, JGS it appears.
View attachment 1290505

Upon close review, there is a lot more diff than just the 0.020" of lead. The case length is also longer in the WOA version. Also, base to throat is quite different. Am I missing something or just inexperienced!?

 

[L.Sherm]

Looks like that JGS print is set up for Lapua 223 brass

 

[TheCZKid]

Upon close review, there is a lot more diff than just the 0.020" of lead. The case length is also longer in the WOA version. Also, base to throat is quite different. Am I missing something or just inexperienced!?

It does look like there are various differences, and the trim length on the JGS could be .012 longer. Also, the ID on the neck part of the chamber is .233 vs .236.

Looks like the JGS is cut larger on both. Reminds me of the differences you find with from chambers cut for 5.56 and 223 or Wylde.

 

[L.Sherm]

Its just like the difference between the 20VT reamers. Remington brass vrs Lapua

 

[Coyotefurharvester]

Seated some Nosler 40 gr BT to 2.203 +,- 0.001, shot very well out of my BHW AR barrel(1/10 t). Already shot a couple coyote with them, don't have any Hornday 40's will watch for some to try.

 

[Bachekermooni]

Seated some Nosler 40 gr BT to 2.203 +,- 0.001, shot very well out of my BHW AR barrel(1/10 t). Already shot a couple coyote with them, don't have any Hornday 40's will watch for some to try.

Midway has them. I usually use ammoseek.com to look for things. Note: vmax and v-max (not case sensitive) will return diff results. Use both when searching.

 

[Coyotefurharvester]

I haven't ordered any components for a couple years, shipping+ marked up prices. Bullets/powder have started showing up locally.