20P Bullet Seating

[Mike White]

After seating a 35 grain Berger HP in my 20P case, I noticed that there is not a whole lot of bullet in the case neck. I seated the bullet to 2.24" and I came up with approximately .120" of bullet that was actually in the neck.

Does this sound right, and do I have to worry about not having the "caliber" worth of bullet seated into the case?

 

[vmaxpro]

It could possibly affect runout, depending on your neck tension. Id say your probably fine.

 

[JASmith]

How much jump to the rifling do you have at that COAL?

The .120" is more than the length of shank for some of the lighter bullets.

The two principal questions are: "Where are the accuracy nodes in seating depth?" and "Will this load be used in an AR, bolt gun, or be single loaded?"

The AR is typically violent in stripping a cartridge from the magazine and chambering. I would want to keep at least a half caliber of shank in thie neck for the AR.

The bolt-action guns are gentler and the shoter has considerable control. I personally would be a tad nervous wih less than a half caliber here too.

Single feeding, on the other hand, means that the shooter has considerable control over the feeding process. So, as long as there is enough shank in the bullet to keep things aligned during normal handing, the best seating depth for accuracy should rule. Here I get nervous when the shank insertion drops much below 0.25 caliber.

 

[charlesasmith]

In my bolt gun using 39 gr Sierras @ 0,020 off jam results in the bullet shank seated into the neck shoulder junction. I do have a zero freebore chamber. You may want to consider a longer shank bullet.

Chuck

 

[Mike White]

The rifle is an AR that I'm assembling. I loaded that round just to get an idea of what the neck tension was going to be. I'm getting almost .003" tension.
All my parts are at the Cerakote shop right now, so I can't get a measurement to the lands.

I've done lots of reading, researching, and have asked lots of questions at this point, and have found that the Berger bullet is one of the more popular bullets for the 20 Practical.

I haven't seen a lot of listed OAL measurements, but have noticed that most rounds for AR's are loaded around 2.22"-2.26" depending on the mag length restrictions.

 

[hogpatrol]

I have both a bolt and AR in 20P and I load the bolt gun .010 off the lands and most of the 32s up to 40s have the bases at the neck shoulder junction. Here's my AR 32gr Vmax ammo, .010 off. Not sure what the exact freebore is in the AR. I'd say it was minimal. It's a 1-10 twist version from AR-X Enterprises and it loves these bullets.

 

[Mike White]

Here's a pic of the 3 bullets that I have available right now: 39 grain Sierra, 35 grain Berger, and a 32 grain Nosler.

I may work with all 3, but I fully intend to use the 35 on coyotes. I have seen way too many people loading this bullet for the 20P for me to believe that it won't work.

I just found it curious to see how much of the bullet was in the neck. Does anyone that loads this bullet seat to a different OAL?

 

[hogpatrol]

COAL doesn't really mean anything other than magazine fit. It's the bullet ogive to the lands measurement that counts. As long as you're under 2.260 AR mag length, and they feed ok, I'd see what kind of accuracy you get with your 2.240. They all look ok to load at that length.

 

[pacificman]

I'm perty sure the standard reamer for the 20 Practical has .233 neck and zero free bore.
This seems perfect compromise for 32 and 40 grain bullets. I also liked the fact that when
I ordered a chambered barrel I didn't have to buy a reamer as like said this is the standard
or SAMMI specs for 20P.

 

[hogpatrol]

I'm perty sure the standard reamer for the 20 Practical has .233 neck and zero free bore.
This seems perfect compromise for 32 and 40 grain bullets. I also liked the fact that when
I ordered a chambered barrel I didn't have to buy a reamer as like said this is the standard
or SAMMI specs for 20P.

My base to ogive is 1.772 on the Vmax, .012 longer than case length. A clarification, there is no SAAMI spec on this cartridge.

 

[pacificman]

hogpatrol...I wasn't sure about the 20p and SAAMI specs glad you could clarify. I guess Warren Brookman is the designer
and seems his specs are the standard for some barrel makers. Personally I am like the zero free bore but the neck
specifications could be a bit tighter. My specs for a bolt action are 2.845 from base to ogive.

 

[Mike White]

Thanks for the replies guys!

 

[RonS]

Pacificman, 2.845" base to ogive? For my bolt gun my base to ogive is 1.9060" and 0.020" off the lands. COAL is 2.2110" with a Speer 39gr TNT with a 0.2285" loaded neck. I single feed...the base of the bullet is at the neck/shouldeR junction.

 

[pacificman]

Pacificman, 2.845" base to ogive?

Yep... that is what I get using calipers adding the one inch with the stoney point (hornady) gauge.
Minus one inch it would read 1.845. I'm getting this measurement using 40 grain v-max with a 0.10
away from lands. The base of bullet does sit below the shoulder of the case a bit but I'm getting very
good accuracy ....in the 6's at 200 yards with 28 inch heavy pac-nor barrel on rem. 700 action. All this
at 3853 average velocity. I'm very happy with the 20 Practical for sure!

 

[pacificman]

Pacificman, 2.845" base to ogive? For my bolt gun my base to ogive is 1.9060" and 0.020" off the lands. COAL is 2.2110" with a Speer 39gr TNT with a 0.2285" loaded neck. I single feed...the base of the bullet is at the neck/shouldeR junction.

Sounds like you have a bit more free bore ...perfect for the speer bullets yer using.

 

[RonS]

My barrel is a 26" varmint contour stainless steel ER Shaw. I'm printing on a very good day .75 MOA at 200 yards using H4198. I have shot a few .2's & .3's at 100 yards using Benchmark.

 

[ratbuster]

I have two 20 Practicals. Base to ogive on one is 1.831" and 1.844" on the other. They both strongly prefer seating depth of bullet touching the lands