.20 Vartarg barrel length and twist for lead frees

[Kiba]

Been running 223Als as my primary squirrel blasters for a while now, but feeling the need to build a .20.

The 20 practical would be the easy option, but being I do most of my squirrel hunting in CA I'm limited to lead free bullets. That leaves the Hornady 24 NTX and the Nosler 32 BTLF as my 2 top choices (if I can ever get a hold of the Nosler 32 BTLF, seems like they've been out of stock for 2+ years now.) The 20 practical and 20 tactical seem like overkill on powder capacity for the 24s or 32s, which is why I'm leaning towards a Vartarg build. Thought about the 20-222, but IMO the 20-222 is just too close to the 20 practical in case capacity to justify buying all new brass and dies when I could simply buy a different bushing and use my stockpiles of 223 components for the 20 practical. If I could use the 40gr lead bullets, I'd lean towards a 20 practical or tactical build for the extra case capacity for the heavier bullet, but since I can't the Vartarg makes the most sense IMO.

Since the Vartarg seems to excel with faster burning powders like AA2200, RL7, and H4198, is there a point where barrel length becomes too long for those faster burning powders and friction starts slowing things down? I was leaning towards a 26" barrel, but wondering if that might be too long for the Vartarg. Doing some searches it seems 22- 24" seems to be the most common barrel lengths for Vartarg builds, with a few outliers at 25-26". Haven't found any posts anywhere from someone who's tried a 26-28" barrel with the Vartarg. I'm not opposed to a 28" barrel provided it's not overly long and will start slowing things down with the typical faster burning Vartarg powders. Thoughts?

Still trying to decide on twist rate as well, since the lead free bullets are long for their weight they need a faster twist to stabilize-- especially if I'm using it on a cold morning 20' above sea level. I had that issue with my 17HMR with a standard off the shelf 9 twist Lilja barrel with the lead free NTX ammo. When the DA was under about 3000' the 15.5 NTX lead free would only manage 2-3" groups @ 50Y, but the 17gr Vmax would make tiny groups regardless of atmospheric conditions. Drive up to somewhere where the DA was above 3000' and suddenly the 15.5 NTX starts shooting tiny groups at 50Y. A couple stability calculators backed up my observations that the 9 twist wasn't adequate for the 15.5 NTX in all atmospheric conditions. I had Lilja make a custom 7 twist barrel and now it shoots both the 15.5gr NTX and 17gr Vmax into tiny groups at 50Y, even on a cold morning where the DA is -1200'. I have no desire to run into this issue with the .20 Vartarg build, so I'm leaning towards a 9 or 9.25 twist to ensure stability with the Nosler 32 BTLFs at around 3550fps on cold mornings at sea level.

Appreciate any input on both the length and twist, as I'm looking to order a barrel blank this week.

 

[Evan]

There is no practical length of barrel that will slow the bullet down in a 20 Vartarg. A 22LR has ~2gns of powder and slows down above 24” or so. A 20 Vartarg burns 18gns of powder with A LOT more gas expansion. Only downside to longer barrel is reduced maneuverability.

My 20 Vartarg has a 26” barrel and will sling 55gn Bergers at 3150fps. 9 twist really has no downsides.

 

[L.Sherm]

Don't overthink this, there's a million threads out there on the 20VT including recent one here just do some reading.

 

[Bill K]

Do not overthink the twist needed to stabilize the lead free 20 cal bullet. All my 20's still use the overall best twist of 1/11 and the lead frees work as well in them as the lead did. In fact some of my loads with the lead free are more accurate than the lead pills were.

 

[Kiba]

There is no practical length of barrel that will slow the bullet down in a 20 Vartarg. A 22LR has ~2gns of powder and slows down above 24” or so. A 20 Vartarg burns 18gns of powder with A LOT more gas expansion. Only downside to longer barrel is reduced maneuverability.

My 20 Vartarg has a 26” barrel and will sling 55gn Bergers at 3150fps. 9 twist really has no downsides.

Good to know. I might go 28" then as most of my other varmint guns used from the bench for ground squirrel blasting are 28", and that's what's this build is going to be. I have a couple of lightweight rifles for carrying type hunts, and this isn't going to be for that.

Don't overthink this, there's a million threads out there on the 20VT including recent one here just do some reading.

I have been doing quite a bit of searching and reading over the last week, but not finding much specific to recommended twist rates for the lead frees, which is why I asked. There is an old thread from 2013 where people were saying their 11 twists stablized the Nosler BTLF just fine, but I'm not sure what altitude they're shooting at as all the stability calculators (including JBM's which has an input for a plastic tip) say 11 twist won't work for the 32 BTLFs-- especially on cold mornings at sea level. My local squirrel spots are all about 20' above sea level, and when I head north once or twice a year that's about 4500' and up there conditions are a lot more forgiving in regards to twist rates.

As I mentioned, the change to having to use lead free for all hunting state wide bit me on my .17 HMR when the "standard" 9 twist Lilja that I used for years and worked great with the 17gr lead Vmax was too slow to stabilize the lead free 15.5gr NTX properly at lower density altitudes. Slow twist rates also influenced bullet selection on a couple of rifles belonging to a friend that had slower twist barrels and wouldn't stabilize the .224 Nosler 50 BTLFs and had to use the 40 BTLFs instead. Nosler says the .224 50 BTLF needs a 12 twist minimum, but one of his rifles was a 12 twist and the 50s didn't even make it to the paper at 100Y, and his other rifle was an 11 twist and it made about 4" groups at 100 yards. I loaded up some new stuff for him with the 40 BTLFs and both made tiny groups. So, the reason I'm (over)thinking the twist for this build is because I have several learning experiences with "borderline" twist rates with the lead free stuff, and I do not want to end up with a barrel that prints shotgun patterns on cold mornings at sea level with the 32 Nosler BTLF with this .20 VT build. Thus, I figured I'd ask for some input from other .20 VT shooters to see if I was on the right track.

I'm fairly confident going with the numbers from the stability calculator and not too worried about blowing bullets up with a 9 twist on this build; with the 32s at 3550 that's 284k rpm, and if I have to use the 24 NTX until I can find some Nosler 32 BTLFs, I'm guessing I can send the 24s at about 3900fps which is 312k rpm. A bit high, but as 2 other data points I'm sending the .224 50gr Nosler BTLFs at 3500 in a 7.5 twist in one of my 223AI's and that's 336k rpm, and I'm also sending Nosler 55 BTLFs out of my 8 twist 6 Dasher at 3850fps which is 346k rpm, and in both of those applications they hold together just fine, make tiny groups, and they all make it to the target. I know the .224 and 6mm Nosler BTLF's will handle high RPM and I'm hoping the .204 32gr BTLF will as well, just like I'm hoping the 24gr NTX will survive 312k rpm or so without coming apart.

Still deciding if I want to form my own brass from Lapua .223 or Starline 5.56, or just buy some already formed from Lake City cases off the classifieds here. I know Nosler makes .221 brass which is a much easier route than forming from .223 cases, but based on previous experience with Nosler brass in other calibers I have a hard time paying Lapua prices for Nosler brass when it isn't as consistent and hasn't held up nearly as well as Lapua for me. Be nice if Lapua was still making .221 brass...

 

[DiRTY DOG]

I've read the 204 Ruger optimal barrel length is 23". From Varmint Al I think. Meaning you don't gain velocity longer than that.

I also shoot lead free near sea level and up to 4500 DA. I am currently building a 20 Practical for 24/32gr bullets (the 32 NBT-LF are superior ballistically but not in production). I commented here recently that Berger's stability calculator seems to show 10 twist is equal or better than 11 or 12 twist for pretty much every bullet in the 20 cals. From the comments, it seems people here don't trust Berger's calculator on this and the common wisdom is 11 for everything. If I recall from the calculator, optimal twist was about 10.3 or similar, closer to 10 than 11.

I ordered an 11 twist Criterion prefit from NSS only because it was in stock. I'd go with a 10 if custom ordering.

 

[nmkid]

Could be overkill but have you looked at the Hammer Bullets? They have 3 bullets you could use from 31 grs. to 41 grs.

 

[Kiba]

I've read the 204 Ruger optimal barrel length is 23". From Varmint Al I think. Meaning you don't gain velocity longer than that.

I also shoot lead free near sea level and up to 4500 DA. I am currently building a 20 Practical for 24/32gr bullets (the 32 NBT-LF are superior ballistically but not in production). I commented here recently that Berger's stability calculator seems to show 10 twist is equal or better than 11 or 12 twist for pretty much every bullet in the 20 cals. From the comments, it seems people here don't trust Berger's calculator on this and the common wisdom is 11 for everything. If I recall from the calculator, optimal twist was about 10.3 or similar, closer to 10 than 11.

I ordered an 11 twist Criterion prefit from NSS only because it was in stock. I'd go with a 10 if custom ordering.

Berger's stability calculator definitely seems to recommend a faster than needed twist for any bullet with a plastic tip as it may not take into account the density change of the plastic tip which changes the moment of inertia, so it possibly calculates assuming a standard jacketed construction. (Since berger doesn't make plastic tipped bullets, I have a hunch this is the case.)

The JBM stability calculator on the other hand has an input for plastic tip length, and when the plastic tip length is input, the stability number it returns is much higher than the berger calculator for the same twist rate and parameters/conditions.

Since I don't have any 32gr BTLFs on hand to measure I found some pictures of them, and knowing the overall length is .745" it appears the tip length on the 32 BTLF is about 0.115".

There's a good paper out there by Michael Courtney and Donald Miller for a modified Miller stability formula for plastic tipped bullets, and I need to make a spreadsheet with it to double check what JBM is coming up with. There's also this thread with input by Bryan Litz with good info regarding plastic tips and stability: https://forum.accurateshooter.com/threads/sg-twist-rate-plastic-tipped-bullets.3861847/

And of course to make things more confusing, the Miller stability formula typically isn't accurate for flat based bullets, and the Nosler BTLFs are flat based... but nosler doesn't list a recommended twist rate for the 32gr BTLF, and I dealt with 2 rifles that wouldn't stabilize the. 224 50 BTLF even at and 1 turn faster than the nosler recommended twist rate...

I hear you regarding the nosler 32s not being in production. I had a very difficult time from 2020-2022 sourcing the nosler .224 40gr and 50gr BTLFs, and nosler told me since they're a low demand bullet made primarily for one market (California) that they didn't make them for a couple of years to focus on production of higher demand bullets, and when they do make the BTLFs it's typically only a single production run around January of every year.

The .224 40s and 50 BTLFs were available early 2023 and early 2024 and I stocked up, but I haven't seen the 32gr .204 or the 6mm 55 BTLFs in stock for a couple of years now. To be honest I'm a bit concerned about building the .20vt as I really don't want to be limited to only the 24gr NTX or the Barnes varmint grenades, as when I was doing load development with my 223s, 223AIs, 22br, 22-250, and 6 dasher, in every rifle the nosler BTLFs were by far the most accurate. The NTX did ok, and the varmint grenades were terrible when it came to accuracy.

Could be overkill but have you looked at the Hammer Bullets? They have 3 bullets you could use from 31 grs. to 41 grs.

Hammer and Lehigh both make copper monos in .204, and while I've had excellent results with the Lehigh 72CC in my 22br and 223AI and use them for squirrels on windy days where the extra BC is helpful, the copper monos are a bit hard on the wallet for sustained high volume use, lol. They may be a good temporary solution though until Nosler runs another batch of 32 BTLFs provided I'm not happy with the accuracy of the 24 NTX.

 

[DiRTY DOG]

What would you say is the ideal twist for the 24/32 lead frees?

 

[Kiba]

What would you say is the ideal twist for the 24/32 lead frees?

Based on the JBM calculator and the Miller/Courtney paper, and knowing the Miller formula underestimates stability for flat based bullets for a given twist rate, I'm now thinking a 10 twist will be plenty adequate for stability and quite possibly impart full BC at sea level on a 30F morning with the 32 BTLF at 3550, and the margins are even better for a 24 NTX at 3900, both of which are moderate vartarg loads-- but there are a lot of ifs and assumptions in there.

Would definitely need more in depth calculations and probably some time with a true doppler radar setup to confirm, but I'm already bordering on analysis paralysis, lol

The biggest issue at this time is simple component availability. Just based on my experiences developing lead free loads for my .22s, I really want to use the Nosler 32 BTLF, but they have been unavailable for about 2 years now and who knows how much longer they will continue to be unavailable. The selection of .204 bullets is limited compared to .224, and the selection of lead free .204 is even more limited. Some of the popular powders for the vartarg seem to be available (AA2200) while others are still hard to find (H322, H4198.)

I'm also considering going 20 practical to save the vartarg brass forming hassles and simply running lighter loads in it, even if a light 20 practical load uses more powder than a vartarg at similar velocity. Another nice thing about the practical is it has extra case capacity for the 40gr lead bullets when I go to Oregon or Nevada.

 

[DiRTY DOG]

I chose 20P only because my available action is a Savage, and 20VT won't mag feed from a Savage. A mag is a must for a walking varmint rifle. 24" heavy sporter. This is mostly for my kid, for now we'll shoot 24 NTX for squirrels and targets, 31 Hammer Hunters for coyotes and rock chucks, and if Nosler ever makes the 32 NBT-LF I'll buy a few thou of them and use those. I have a few jugs of 8208xbr that should do well.

But the VT looks pretty sweet doesn't it?

 

[Kiba]

I chose 20P only because my available action is a Savage, and 20VT won't mag feed from a Savage. A mag is a must for a walking varmint rifle. 24" heavy sporter. This is mostly for my kid, for now we'll shoot 24 NTX for squirrels and targets, 31 Hammer Hunters for coyotes and rock chucks, and if Nosler ever makes the 32 NBT-LF I'll buy a few thou of them and use those. I have a few jugs of 8208xbr that should do well.

But the VT looks pretty sweet doesn't it?

It does look cool, and I love how efficient it is on powder.

Regarding magazines, I managed to get the stubby little vartarg controlled round feeding in my ARC Archimedes action with a 223AI barrel using slightly modified plastic Ruger 223 AICS magazines. The plastic Ruger mags have the longest feed lips of any 223 AICS magazine I tried (mdt metal, mdt plastic, genuine ai, accurate with standard feedlip liner, accurate with extended feedlip liner) and the Ruger mags hold onto the vartarg case just long enough it feeds reliably as long as you run the bolt with normal or faster speed. The extractor even manages to pick up every round as it exits the feedlips. If you try and run the bolt really slowly the round will pop out of the mag and turn a bit sideways in the action, or even fall down the gap between the other rounds and the front of the magazine (I may shorten the front of the follower and 3D print a filler for the front of the mag.) Running the bolt at a a normal speed it fed and ejected 10 full mags with zero problems.

What's funny is while the Ruger 223 mags feed vartarg quite well, they will not feed 223 or 223AI in my action-- the feedlips are too long and act as as pivot point causing the cases to dip excessively at the back as the round is being stripped out of the mag, and then the bolt rides over the top of the case.

 

[Richard Jones]

A mag is a must for a walking varmint rifle.

For me, it depends on the varmint. I have quite a few single shot walking varmint rifles.

 

[rickiesrevenge]

I like short barrels. Ive been chambering a lot more 20" barrels for customers these days. Most are wanting to shoot suppressed.

 

[Gabe22BR]

22” barrel
1-11” twist
100yds
20-221AI

 

[snert]

I shoot a 20 VT HArt 22 inch, 10 twist. No issues with anything between 32 and 40 grains. Im sure it would stablize a copper bullet.

 

[searcher]

Been running 223Als as my primary squirrel blasters for a while now, but feeling the need to build a .20.

The 20 practical would be the easy option, but being I do most of my squirrel hunting in CA I'm limited to lead free bullets. That leaves the Hornady 24 NTX and the Nosler 32 BTLF as my 2 top choices (if I can ever get a hold of the Nosler 32 BTLF, seems like they've been out of stock for 2+ years now.) The 20 practical and 20 tactical seem like overkill on powder capacity for the 24s or 32s, which is why I'm leaning towards a Vartarg build. Thought about the 20-222, but IMO the 20-222 is just too close to the 20 practical in case capacity to justify buying all new brass and dies when I could simply buy a different bushing and use my stockpiles of 223 components for the 20 practical. If I could use the 40gr lead bullets, I'd lean towards a 20 practical or tactical build for the extra case capacity for the heavier bullet, but since I can't the Vartarg makes the most sense IMO.

Since the Vartarg seems to excel with faster burning powders like AA2200, RL7, and H4198, is there a point where barrel length becomes too long for those faster burning powders and friction starts slowing things down? I was leaning towards a 26" barrel, but wondering if that might be too long for the Vartarg. Doing some searches it seems 22- 24" seems to be the most common barrel lengths for Vartarg builds, with a few outliers at 25-26". Haven't found any posts anywhere from someone who's tried a 26-28" barrel with the Vartarg. I'm not opposed to a 28" barrel provided it's not overly long and will start slowing things down with the typical faster burning Vartarg powders. Thoughts?

Still trying to decide on twist rate as well, since the lead free bullets are long for their weight they need a faster twist to stabilize-- especially if I'm using it on a cold morning 20' above sea level. I had that issue with my 17HMR with a standard off the shelf 9 twist Lilja barrel with the lead free NTX ammo. When the DA was under about 3000' the 15.5 NTX lead free would only manage 2-3" groups @ 50Y, but the 17gr Vmax would make tiny groups regardless of atmospheric conditions. Drive up to somewhere where the DA was above 3000' and suddenly the 15.5 NTX starts shooting tiny groups at 50Y. A couple stability calculators backed up my observations that the 9 twist wasn't adequate for the 15.5 NTX in all atmospheric conditions. I had Lilja make a custom 7 twist barrel and now it shoots both the 15.5gr NTX and 17gr Vmax into tiny groups at 50Y, even on a cold morning where the DA is -1200'. I have no desire to run into this issue with the .20 Vartarg build, so I'm leaning towards a 9 or 9.25 twist to ensure stability with the Nosler 32 BTLFs at around 3550fps on cold mornings at sea level.

Appreciate any input on both the length and twist, as I'm looking to order a barrel blank this week.

That is interesting that your 24 NTX bullets weren't shooting well out of your 1-9" twist tube at lower elevations. My .17 HMRS shoot both leaded and the NTX equally well, both at sea level and at 6,500 feet. Maybe I got lucky or you got a slow barrel. Now, I'm curious to see how that NTX will shoot in my 1-9" Lilja .17 Hornet. I bought some of the bullets but haven't yet had a chance to do load development on them. That Hornet did shoot the 20 grain lead-free Lehigh Defense fairly well, so I'm hopeful.

Regarding those .20's, I can tell you that I have a couple of .20 Practical rifles that both shoot (as do those of my shooting buddies) the 32 LFBT's exceptionally well. They are all 1-12" twist, with three of them being Hart tubes. Three of the five are 26" long, the other two 24". I have read on this forum where some guys have had problems with the 1-12' tubes stabilizing the 40 V-Max. I think if I were to buy another barrel other than a Hart, there would be no downside to getting a 1-11" tube to be safe, as I use a lot of the 40 V-Max, along with the 32 LFBT. But because these calibers tend to perform best with fast powders like LT-32 and H-4198, I doubt you would gain much, if anything, going with a longer tube. Personally, I love long tubes to gain all the velocity I can - but for what little "might" be attained, I just don't think it would offset the unwieldy length and added pressure put on the tenon - and potential increase in bullet whip. Might need to bed several inches of the barrel as well. Seems a little sketchy going longer, but maybe someone on this forum has tried it. For the lead-free, you should do well with a 1-11" twist. Some guys have been using 1-10" twist, though I think that is a bit over-kill - and a 1-9" even more so. I see no harm in "over stabilization", but it can get to a point of negative returns in velocity loss. You won't get the bullets moving fast enough in the Vartarg to risk them coming apart in any case, regardless of the which of those twists you choose, I don't think. The lead-free bullets handle some pretty darned fast velocities. I know I haven't had any issues running the 32 LFBT's at around 1,000 altitude where I do most of my shooting - and they do great at 6,500 ft.

I'm also going to build a .20 Vartarg, and plan on a 1-11" tube with intent of also shooting the 32 LFBT or the Varmint Grenades, maybe. I was squirrel shooting with a few buddies a few weeks ago and one of them had another friend there shooting his Vartarg. His had no problem.

 

[L.Sherm]

Bedding in front of the recoil lug has more detrements than gains in my opinion, ive done it both ways and even on my 28" Varment conture on my 20BRA its not bedded in front of the recoil lug.

 

[Kiba]

Update…

Brass is ordered from a very nice member in the classifieds here (decided to order ready to go brass for now so I can be up and running sooner, rather than forming it myself from scratch since I don’t have a neck turning setup yet.) Dies arrived today. I’ll be ordering the 26” 10 twist barrel and 24gr NTX’s tonight. Figure I’ll start with the 24gr NTX until the Nosler 32 BTLF’s are available again (hopefully Nosler decides to run a batch of those as well as the 6mm 55gr BTLFs in spring 2025…)

The only thing left to get at this point is powder.

Based off searches here and on Saubier to get info from other Vartarg users, and also running numbers in quickload for the 24gr NTXs and the Nosler 32 BTLFs, it seems H4198, H322, AA2200, N120, and N530 are all a good match of case fill vs velocity vs pressure for the 24s and 32s.

AA2200 seems to have always been the “go to” powder for the Vartarg, but I’ve read AA2200 can be a bit temp sensitive and to work up your loads on hot days, or if you work them up on cooler days don’t pick an upper node so there’s safety margin in the load for hot days. Some suggest having separate cold and hot weather loads, and I’d like to avoid that. I haven’t used AA2200 myself, so going by what others have said regarding temp sensitivity. AA2200 looks to be readily available.

H4198 comes up frequently as a recommendation for the Vartarg but is pretty much unavailable right now and has been difficult to get for a while. Same for H322, but I do have 16# of H322 on hand for the Nosler 55 BTLF in my 6 Dasher.

Quickload shows N530 being a potential powder candidate, but it’s discontinued… however several vendors still have quite a bit of it in stock, some of them even have it on sale/clearance for a decent price. It’s a dead end powder though once I use it up if I buy any.

Going by Quickload, N120 looks like it might be about the best option for the 24s and 32s, and it’s fairly readily available. How is N120 for temp sensitivity, is it better than AA2200? Did some searching but can’t find much info on it. I’ve seen a few members here say they’re running N120 in their Vartarg builds with good speed and great accuracy, so at this time I’m leaning towards picking up N120. I’ve used N133 for probably 20 years for 40gr and 50gr loads in the 223s with great results and hoping N120 will be a similar experience.

Again, appreciate any input.

Might go back up for 4-5 days of additional squirrel blasting after the first alfalfa cutting in early June, and there’s a chance I might be able to have the build finished by then and be able to take it...

 

[searcher]

Bedding in front of the recoil lug has more detrements than gains in my opinion, ive done it both ways and even on my 28" Varment conture on my 20BRA its not bedded in front of the recoil lug.

I've got several heavy, long tubes I bedded the first 1 1/2" of the barrel. The only downside is when changing barrels - as need to re-bed. The recoil lugs get cut short, too.