More 20 Practical Q's

[Bachekermooni]

Q1: what FB should my GS use? My understanding is that the default is 0.000". At this FB, the COL length with a 32 VMax is what? Should I have a different FB? What? I will be shooting 32 VMax and 34 Dogtownn - the only ones I could find and already bought. With a 2.250" COL, the base of the VMax is at the neck-shoulder junction. I know COL is not as good as the ogive measurement.
Q2: This rifle will be used mainly for PD eradication. What magnification range should I use? Also, I prefer an FFP, MOA, X-Mas tree reticle. Thoughts?

Thanks in advance.

 

[TAJ45]

From reading on here re scope, magnification is seldom above 20x. Too much mirage. Some will say you can always turn it down but never past "full up". ;-) That really depends on pocket depth$ awa how much paper do you plan on punching "back home". HTH

 

[RegionRat]

I like wide variables, and if possible I like higher mag than 20X.

I run 32X and 36X when required. PDs are small targets and fine shot placement is required. 20X is absolutely fine for many places especially when the shots are all inside 300 yards.

Once you start getting out past a few hundred yards, you are going to want some magnification. Once it gets hot, yes the mirage becomes a factor, which is why I recommend wide variables. But these choices are to suit your own tastes, not like laws of physics.

I knew guys that stuck to their Leupold 6.5-20X scopes like religion for years. Then I put them in my long range bolt rig and had them popping PDs at 600 yards using an NF NXS 8-32X and they showed up the next year with higher mag scopes.

Once you have the rig in your hands, it is easy enough to go test at range and decide how much magnification you will want and scope up accordingly. Higher mag scopes are not for everybody, so YMMV.

Take a look at a nice wide variable like a NF NX8 C624 and see what you think.

 

[Cemetery21]

It may depend on where you shoot. In SD and NE rolling hills, we could use 24X or greater. In NM high flatland off a bench, 12X or lower to see thru mirage out to 400. If you can get higher - a bench on a truck bed - you could probably use higher X.

 

[Coyotefurharvester]

2.250 col so you are building an AR 15 upper in 20p? FB no more than 0.025, no freebore is fine. Even though you state low 30's bullet weight go with a 1/11 twist. I usually run 20x max variable scopes on 17,20's, and 223's. Ramshot xterminator, IMR 8208 work well for me.

 

[Bachekermooni]

2.250 col so you are building an AR 15 upper in 20p? FB no more than 0.025, no freebore is fine. Even though you state low 30's bullet weight go with a 1/11 twist. I usually run 20x max variable scopes on 17,20's, and 223's. Ramshot xterminator, IMR 8208 work well for me.

Thanks. It is for a CZ 527 getting a Lilja 3 twist varmint profile in 20 Practical - 22" finished.

 

[L.Sherm]

ZERO FREEBORE

 

[redrockranger]

Q1: what FB should my GS use? My understanding is that the default is 0.000". At this FB, the COL length with a 32 VMax is what? Should I have a different FB? What? I will be shooting 32 VMax and 32 Dogtownn - the only ones I could find and already bought. With a 2.250" COL, the base of the VMax is at the neck-shoulder junction. I know COL is not as good as the ogive measurement.
Q2: This rifle will be used mainly for PD eradication. What magnification range should I use? Also, I prefer an FFP, MOA, X-Mas tree reticle. Thoughts?

Thanks in advance.

This site has a cartridge guide. The 20 cal is a section. There is a article on the 20 Practical A shooter named Fireball and a smith put together the specs . A very detailed summary. I use the reamer they designed. 0 freebore if i remember correctly. Check it out a good read.

 

[searcher]

Regarding scope power (assuming shooting from bench and not a carry gun), the bigger the glass the better and going up above 30X makes a lot of sense when one can use it. The higher the quality glass and the larger the objective, the lower the power one can use and still get a great picture. A compact Nightforce set at 10x will give you a far better picture than 15X or even 20X on some lesser quality scopes, for example. If you use a second focal plane scope, you will want to do all of your come-ups based on the power setting of the scope when you shoot the different yardages to make up your dope sheet. Fine cross hairs or 1/4" MOA dots ensure your target is not obscured. If you detect big, repeatable impact shifts when going from 15 to 30 power, for example, you would do well to make up two dope sheets, based on impacts fired at 15X and another for 30X, for example. Just depends on how serious you are about hitting them the first time. The better quality the scope - the less this occurrence is present. Mirage will often force you down to a lower power setting than you might want to use - sometimes all the way down to 10X. I'd strongly advise using a dial-up system for elevation changes - as the x-mas tree reticles are not accurate enough when firing way out there. Once you get out there around 400+ yards with the 32-grain bullets - they start dropping quite quickly - and it is imperative to know the distance quite accurately - and to dial in for that distance. Trying to aim 3/4 of the way up between the third and fourth horizontal stadia -for example - is tough to do. You pretty much have to try both systems to see what I'm saying. I used to think the Horus and many of the x-mas tree reticles were the bomb. I don't own any of them anymore. When you make up your dope sheet, it is also a lot easier to put "5.2" next to a yardage instead of "about 3/4 of the way up from the 4th stadia wire". Best method in my experience is to shoot your actual load at 100 yard intervals and dial up until you are hitting right on the money at each distance. Record the settings. Then I take 62% of the difference between each of the settings to arrive at my 50 yard in-betweens - then split those in half for my 25 yard intervals. This is a pretty quick, but accurate way to dial in your load with your rifle. 1/8" MOA is better than 1/4" MOA on the dial. When you get out there 500 yards - having 25-yard increments on a 32 grain bullet will make the difference of a hit most often. I also record the temperature when I fired my test loads, and mark the elevation change for each 10 degrees. A 40 degree change at 500 yards can cause a miss if you don't account for that (it WILL on a small ground squirrel). It is common to start shooting at 60 degrees in the morning and have it going 100+ in the afternoon. Then I put in wind drift numbers next to each come-up, taken off the internet. Good Luck!

 

[Bachekermooni]

Thank you for your insightful advise. I totally agree and heed your advise. My 308 Kimber Monatna re-chambered in 6 creed wears a Leupold VX6 HD 2-12x - awesome for dialing. The problem here for me is that my "close" rifle range going out to 880 yards is at 250-300 ft elevation. I built this rifle for an upcoming, and now canceled :-( Canadian sheep hunt. It would have been at 6k-7k ft elevation. So will be my PD shooting which will be in WY at 5k-5.5k ft elevation. So I have to compare my actual drops at the range with the JBM tables and then make adjustments for the elevation I will be hunting. Getting on a sheep at 500 yards is not as bad as hitting a PD at the same distance. Of course a miss will be extremely costly during the sheet hunt.

 

[jepp2]

At this FB, the COL length with a 32 VMax is what?

For 2 of mine 2.22 to 2.24 COAL

What magnification range should I use? Also, I prefer an FFP, MOA, X-Mas tree reticle. Thoughts?

Went through several different scopes before I finally settled on the Vortex Viper HS LR 6-24. I have 5 of them and that is all I use on my PD rifles. Here is what the reticle looks like. Too busy for some but gives me what I want.

 

[jepp2]

and 32 Dogtownn

I've only seen the Dogtown bullets in 34 gr. Where did you find the 32's? I have never gotten the 34's to shoot to my satisfaction for PD's.

 

[L.Sherm]

I've shot 1,000's of the 20 cal 34's in several different 20 cals and all have been able to achieve atleast 5 m.o.a accuracy, granted they aren't a Berger or Sierra BK but the price reflects it.

 

[Bachekermooni]

I've only seen the Dogtown bullets in 34 gr. Where did you find the 32's? I have never gotten the 34's to shoot to my satisfaction for PD's.

apologies. A typo. corrected.

I also just bought some 40 V-max as well. I liked their BC for longer than 300Y shots.

 

[searcher]

Thank you for your insightful advise. I totally agree and heed your advise. My 308 Kimber Monatna re-chambered in 6 creed wears a Leupold VX6 HD 2-12x - awesome for dialing. The problem here for me is that my "close" rifle range going out to 880 yards is at 250-300 ft elevation. I built this rifle for an upcoming, and now canceled :-( Canadian sheep hunt. It would have been at 6k-7k ft elevation. So will be my PD shooting which will be in WY at 5k-5.5k ft elevation. So I have to compare my actual drops at the range with the JBM tables and then make adjustments for the elevation I will be hunting. Getting on a sheep at 500 yards is not as bad as hitting a PD at the same distance. Of course a miss will be extremely costly during the sheet hunt.

Yes - that elevation change does affect things a lot. I tend to do most of my ground squirrel shooting at two places. One is at 500 ft. elevation - and the other about 4,500 ft. I use two different drop charts.

 

[Hohn]

For small targets that don’t move and can’t hurt you, I recommend favoring more magnification. I’ve found my Golden eagle, while not useful at 60x, sure is great in that 35x-40x range. You’ll want mirage countermeasures with any good PD rifle. PD shooting isn’t all that different from F class.

 

[searcher]

I've shot 1,000's of the 20 cal 34's in several different 20 cals and all have been able to achieve atleast 5 m.o.a accuracy, granted they aren't a Berger or Sierra BK but the price reflects it.

I bought a boat load of 34 grain .20 caliber bullets several years back which were advertised as "surplus" or possibly seconds made by Speer. Speer currently only currently lists a 39 grain bullet on their website. They shoot fairly well - but not as good as V-Max or Bergers in the rifles I tried them in. Big air time, though.

 

[L.Sherm]

I'm pretty sure Nosler makes them.
Few months back I bought 5,000 from. Shooters Pro Shop

 

[searcher]

Yes - Shooter's Pro Shop sells Nosler products - but those I bought don't resemble the Nosler bullet at all - as I have both. I guess it matters little though.