20 Practical 4443 FPS ....OOPS!

[Bill K]

I would sure love too see someone post some photo's of those 20 VT and 20 Tac loads showing 4000 FPS on their chrony. Bill K

[Oleman]

Originally Posted by Bill K

I would sure love too see someone post some photo's of those 20 VT and 20 Tac loads showing 4000 FPS on their chrony. Bill K

Well I don't have pictures but my 20 TAC did send some over the screens for an average of 4184 fps and the five shot group was a .184.

[20 EXTREME]

Originally Posted by Ratbuster

I will try some 32's at appreciably reduced powder levels...will go for velocity closer to 4150 fps so the brass will live. I expect it will shoot pretty good as even the overloaded rounds gave halfway decent accuracy....two of the four groups were in the 3's and one in the 4's.

Try some IMR 8208 with the 32 gain V-Max. I have a 20 Practical with Zero Free Bore and the bullet OAL is about 2.190" to the lands or 1.816" to a Hornady 20 cal (.193") comparator. If it had 0.050" Free Bore the bullet would seat properly in the neck and fit nicely in a 2.26" standard .223 magazine.

Start the 8208 at 26.0 grains and work up to 4000 + fps.My FL case holds about 26.4 grains of 8208, under the bullet, so you will have a nice case fill compared to H 4198. I do a FL size with a Forester Die set to just bump the shoulder, of a fired case, so it has less than 0,. 001" HS .It sizes the base, at the 0.200 " datum to 0.3735". The 20 Practical reamer is speced .3743" at that point so that is just about perfect. The shoulder is sized to 0.351" or about 0.0043" under chamber spec. I then size the neck, to the shoulder, with a 20 EXTREME die which gives it 0.0025" neck tension. If you keep the pressures down to where a new, or FL, brass does not expand more than 0.005" at the 0.200 datum then you will be running pressures that will not destroy brass and be safe to shoot under all conditions. As well you should find a very stable load that groups well.

I worked up this load for the 40 V-Max with H 4895 in Winchester 222Rem, FL sized, brass. The flier, in the 5 shot group, was likely shooter error.
[IMG][/IMG]

Ladder results with 8208 to follow.

[TAJ45]

You may want to edit your neck tension of .025".....or else I'm in for more education - which wouldn't be all bad.

[trotterlg]

My 20 Swift can run those 26gr bullets at 4,700fps out of a 12 twist. Larry

[GrocMax]

Either 32g varmint or the 34g VNE are very realistically 4200FPS capable in the 20 Prac. A wide variety of powders work.

[20 EXTREME]

Originally Posted by 20 EXTREME

Try some IMR 8208 with the 32 gain V-Max. I have a 20 Practical with Zero Free Bore and the bullet OAL is about 2.190" to the lands or 1.816" to a Hornady 20 cal (.193") comparator. If it had 0.050" Free Bore the bullet would seat properly in the neck and fit nicely in a 2.26" standard .223 magazine.

Start the 8208 at 26.0 grains and work up to 4000 + fps.My FL case holds about 26.4 grains of 8208, under the bullet, so you will have a nice case fill compared to H 4198. I do a FL size with a Forester Die set to just bump the shoulder, of a fired case, so it has less than 0,. 001" HS .It sizes the base, at the 0.200 " datum to 0.3735". The 20 Practical reamer is speced .3743" at that point so that is just about perfect. The shoulder is sized to 0.351" or about 0.0043" under chamber spec. I then size the neck, to the shoulder, with a 20 EXTREME die which gives it 0.0025" neck tension. If you keep the pressures down to where a new, or FL, brass does not expand more than 0.005" at the 0.200 datum then you will be running pressures that will not destroy brass and be safe to shoot under all conditions. As well you should find a very stable load that groups well.

I worked up this load for the 40 V-Max with H 4895 in Winchester 222Rem, FL sized, brass. The flier, in the 5 shot group, was likely shooter error.
[IMG][/IMG]

Ladder results with 8208 to follow.

The Hornady Manual show the 204R getting 3754 fps, with the 40 V-Max ahead of 27.3 grains of IMR 8208, and generating 56,000 PSI. As the 204 R holds about 2.9 gains more water, under the 40 V-Max, than the 20 Practical I thought stating at 25 gains. I shot the 5 shot ladder group shown over a MagnetoSpeed at 14 degrees Celsius. Shot #1 registered 3757, Shot #2 showed a 20 fps increase for 0.1 grain increase. Shots #3&4 showed no increase but piled on top of shot #2 which is what I al looking for when trying to find a good stable load. Shot #5 showed a significant pressure spike going to 3813 which resulted in a stiff bolt lift. I shot 3 More at the 25.1 grain load and they stacked on the second target. Buddy was estatic as his method of loading up to stiff bolt and backing off gave a "safe in my rifle load at an average of 3776. We tested the 39BK at 25.6 grains and got stiff bolt lift, at 3859fps, so went down to 25.2 grains and got 3782 which is about what I expected. It takes about .1- .2 grains more 8208 go get the 39 BK up to the same velocity as the 40 V-Max. Just trued the 40 Nosler BT at the starting load and pulled the rest of the bullets. These are awesome loads for the "safe in my gun" hand loaders but I would back down at least another 1/2 grain or about 3700 fps. I estimate that these loads would be running near 65,000 PSI, on a hot day, under sustained fire. Will likely back the H 4895 loads back to the next lower accuracy node.
[IMG][/IMG]

[trotterlg]

If you look at some of the temperature / pressure charts for 8208 you will find that in some cases the pressure goes down when the temperature goes up. I sort of found that interesting. Larry

[20 EXTREME]

Originally Posted by trotterlg

If you look at some of the temperature / pressure charts for 8208 you will find that in some cases the pressure goes down when the temperature goes up. I sort of found that interesting. Larry

Even before IMR 8208 was introduced at the 2010 Shot Show I had seen a report on tests done with it. I had been using the Hodgdon EXTREME 4895powder, Made In Australia, and found t]it a bit too bulky and slightly slower burning than optimal for the 40 grain bullets in My 20 EXTREME. When I discovered that it was nearly the same in kernel size and density as Benchmark and H 322, also EXTREME Powders, and just a bit faster burning than H 4895 I knew I it was the powder I had been dreaming about. I ordered 16# before it was released and took delivery in the summer of 2010. It is the perfect powder for the 39/40 grain bullets as a 95% load gets over 3500 fps and a near 100% load gets the 39/40 bullets to near 3700fps with no danger of over pressure under any condition.

I have had no need to compare pressures but I do have some loads that shoot slightly better on cold days or hot days as the case may be. While temperature may not be an issue with the 20 Practical loads the pressures are too high to be conducive to long brass life. And what the heck 3650/3700 fps with a 39/40 grain bullet is not enough to kill varmints?

[Oleman]

A lot of guys I know in BR shot 8208 the first year it came out. Its sure isn't Thunderbird. Most of them sold it after a short time or used it for BBQ starter.