Build advice on first 6.5G bolt gun

[Rteague77]

Hi guys, need some advice and help!

I already have a 6.5G gas gun (AR platform). I like it and it’s pretty good out to 600 ( 1.0-1.25 MOA @ 600). But I’d like to really see how far I can push it with a bolt gun.

If you could go back and build from scratch With all the knowledge you have now, what would you build and how would you build it?What parts would you use and why?

I’ve looked at the HOWA and the CZ, can’t find a CZ barreled receiver, and don’t want to waste the money on a complete gun just for barrel and receiver.

I know I left this vague, but I’m looking to use all of you guys experience so I don’t run into the pitfalls of a first time build.

I want to see if I can get one to hold 1MOA out to and beyond 1000yrds.

I have built many Guns, I reload my own ammo and I am a long range competitive shooter already. So I have the base knowledge, just not much with the 6.5G. (Usually shoot a .300win mag or .338 Lapua).

[Lemonaid]

I aspire to be a long range shooter but do mostly bench rest target shooting at 100 to 300 yards. My experience with the Ruger American Predator has been great, fairly easy to get sub .5 groups at 100 yards. I went with a bench rest style stock of my own devise but I would think the Boydes at one stock would be superier to what I have and the oryx chassis better than even that.
From what has been posted here owners are equally pleased with the accuracy Howa or the CZ. I like the RAP since you can use the same mag that the AR Grendels use and also it's base price is lower.
No direct experience but the Uintah Precision AR style bolt action rifles use premium barrels and they are priced accordingly. Might be a good choice if you can afford one.

[Harpoon1]

The Ruger Predator probably has the most after market options, followed by the Howa, then CZ. I have all 3 and prefer the CZ, then the Howa, then the Ruger. Just prefer metal mags and control round feed and the CZ trigger was the best right out of the box, IMO.

Anyway, have to ask......if you handload, why not just get one of the CZ Varmints models with the 24” barrel and see what you can do with that first? Maybe you’ll get lucky and win the barrel lottery right from the factory. Then learn what the cartridge can do with Handloads. That would be the cheapest by far. IMO?

The problem with the Grendel is it’s short stubby case. And I think trying to convert other conventional short action rifles You can run into feeding issues with the Grendel. At least that was my experience trying to convert the Ruger over in the MagPul stock and using AI mags with the Primal Rights mag conversion. I finally gave up and just went back to the factory configuration and then just purchased the CZ and never looked back.

Of course, with deep enough pockets, you can eventually get what works for you.

[kmon]

From what A5 has said about his I would consider https://cz-usa.com/product/cz-527-varmint-mtr/

[Laman]

Go custom action, one of the Rem clones or my preference Bat. Put in a real benchrest stock and a 26 in Bartlein or Krieger barrel and have fun.

[Klem]

Hi guys, need some advice and help!

I want to see if I can get one to hold 1MOA out to and beyond 1000yrds.
.

RT,

Unfortunately you are going to be disappointed. While the Grendel will make 1,000yds and still be (just) supersonic it drops below 1,350fps/transonic at about 800yds. Your neat 1MOA groups start ballooning out after that like cross sections of a trumpet and unless you can speed the bullet up there's not a thing you can do about it.

With a bolt gun's sturdier action you can load above SAAMI without anything breaking (unlike an AR). If you put a long barrel that helps too. You can go up to 30 - 31" and take advantage of slower powders. Everything will be at the extreme edge however, whereas a Creedmore will be able to do this without breaking a sweat. The small boiler room of a Grendel is just not suited for the magic K and you will end up compensating for this in every other way.

One solution is to get a switch barrel system happening with a Rem or clone. have the heavy stock and long heavy barrel for 1K shooting and unscrew the barrel and swap out the stock for lighter closer range shooting or hunting. So, you have the same action, scope, bolt and mount for two guns. You will need a barrel vise and action wrench to switch barrels - takes about 10-15 min plus a re-zero. That'll save a lot of money and you will be familiar with one scope. Or with the same system you can have two bolts with one barrel a Creedmore for long range and the other a Grendel for short range. The Creedmore, 260Rem, 6.5*47 and Grendel use the same Short Action.

[Stinky Coyote]

Build a 6 arc instead.

I only care about hunting. My do over is a cz American base, stainless barrel swap maybe 20” same contour, warne medium rings with a short eye relief Leupold like a used 3-9x33 ultralight custom with cds-zl turret and wide duplex reticle or a Vx3i 2.5-8x36. Pillar and glass bedded. Possibly the McMillan m040 but I will Hunt mountains etc and love how the walnut stock feels too.

I’d grab the varmint for a bench rig to play at distance

[jason miller]

I had good accuracy with 140 Berger hybrids at 2440 FPS from my 20” Howa when I tried them a few years back. Should be doing over 1300 FPS at 1K yards here at ~1,000 feet ASL on a mild summer day.

If I were building from scratch for my own preferences, I’d buy a 22” standard weight Howa barreled action and have Wayne York put it in a blind magazine stock for a ~6lb scoped hunting rifle.

[Klem]

I had good accuracy with 140 Berger hybrids at 2440 FPS from my 20” Howa when I tried them a few years back. Should be doing over 1300 FPS at 1K yards here at ~1,000 feet ASL on a mild summer day.

If I were building from scratch for my own preferences, I’d buy a 22” standard weight Howa barreled action and have Wayne York put it in a blind magazine stock for a ~6lb scoped hunting rifle.

How'd they do grouping at 1K?

Your bullets go transonic (1,340fps) at 960yds.

[Stinky Coyote]

1126 fps is speed of sound

And my cz American in retrospect would likely get a contour heavier than stock and go 21” and fluted stainless barrel with a beadblast finish. To keep balance and weight near factory American spec. They already a tad tail heavy so keeping scope minimalist and under 12 oz would help. Wish Talley people warne had some .440 high mediums like the warne but in aluminum, these 5.5 oz rings too heavy, I run Talley on everything worse and they 2.5 oz

[jason miller]

How'd they do grouping at 1K?

Your bullets go transonic (1,340fps) at 960yds.

I never shot them at 1,000 yards, just like I bet you haven’t. But just because a bullet is slipping into the transonic zone, or even past the sound barrier and out the other side, doesn’t mean that they always lose stability and/or accuracy. Besides, 960 yards is damn close to 1,000- and this was with a short barrel at fairly low elevation. Add 4” of barrel for ~100 FPS on a custom build, as the OP mentioned, or move back to 7,500 feet ASL where I lived when I originally bought this rifle, and it’s a whole new ballgame.

Since you like to post about what the Grendel can and can’t do at long range, I wonder- do you have any actual experience at 1K and/or with heavier 140-class bullets?


Edit to add- the speed of sound is variable depending on air density. Keep in mind that at 1,000 feet and 75-95 degree temperatures, the speed of sound will be lower than the 1,116 FPS “standard”, and therefore so will be the upper threshold of the “transonic zone” mentioned.

[Oso Polaris]

The mini actions are fantastic... compact, portable, and easy in the field. I am broad shouldered, which means that mini actions feel a bit like a 22lr. For me this just isn't the right-size for serious bench rest or long distance. The larger footprint and mass of a Rem700 action or similar size (pick your make or model) and corresponding stock size make for a better foundation for long range rifle.

The 6Arc (ie 6mmAR...6mm Grendel) will stay supersonic further (higher BC) compared to 6.5 Grendel for similar weight bullets. If you don't want to step into a mid-size cartridge such as Creedmoor then you may consider the 6mmBR, which has more power than a Grendel-based cartridge. The 6BR case will have enough powder to keep you supersonic past 1000 yards and utilizes a more efficient case design then Creedmoor so less powder = less recoil.

Either way, if I was serious about distance then a bigger rifle (full size with longer heavier barrel and full size action) will be better. Downside... no one likes carrying a 13-15lbs rifle very far in the field for very long.

[Bfglowkee]

Klem is just saying that when a bullet slips below sound speed the chance and consistency of it performing admirably diminishes and is a crap shoot. Obviously if you live at high altitudes you will fair better then those at sea lvl etc. Can it do it....yes. Are you going to get consistent results of 1MOA or below....unlikely. I have tried shooting the Grendel out to 1k. After 700 yards its a challenge. If you are doing it for that challenge then have a blast and enjoy the the ups and downs it will bring you. If you want to ring steel with regularity with it you will need to curb your expectations. Its just not the tool for the job. That is what Klem was getting at.

I use a Howa Short Action 20" Heavy barrel action from Brownells in a Boyds At-One stock bedded. Its topped with a Nikkon BLACK F1000 6x24 when i am trying to stretch it out, and a Vortex Strike Eagle 1x6 for simple hunting. 129 ABLRs are the pill i tried to shoot 1k.

[jason miller]

Why is it not the tool for the job? The OP said he wants to build a rifle and has experience handloading. I was simply taking the counterpoint that with diligent handloading and an accurate rifle, a Grendel is absolutely capable of staying above bother the sound barrier AND the upper threshold of the transonic zone, if those are to be used as guidelines of what will work.

If you really just want to build a dedicated 1K gun, then no 6.5mm is ideal anyway. I was just trying to give real data to show the OP that it doesn’t have to be the crapshoot that everyone seems to think it is based on their results shooting lighter bullets.

[Klem]

Jason,

Settle down mate.

Correct assumption, I have no experience shooting Grendel at 1K. I do however have a decade shooting F-Class 223 at 1K. Those of us doing this noticed that after 800 the group sizes blew out like cross sections of a trumpet. Your ability to drive rounds around the target also became elastic, like the bullets were drunk. Even though still supersonic at 1K 223 would rarely win against the 308 guys. Less than 800 and it was a level playing field. Regardless, no-one keeps a 100yd 1MOA group all the way to 1K; there is always wind at long range.

960 yds is still enough distance for the group to expand so I am genuinely interested by how much.

[Stinky Coyote]

Ya not sure why if you wanted to shoot well at 1000 you wouldn’t be all about the 6-dasher. What was the Grendel designed for again? 2-800 yard improved lethality and performance over the .223. If you’ve never seen what a 6-dasher can do then you’re welcome for the intro...that’s your single digit ft/lbs recoil energy 1000 yard king right there.

[Old Bob]

Heh, heh... try shootin' a 45-70 blackpowder rifle in a 1000yd match. That'll humble you big time. :p Talkin' about peep sights & a mid range trajectory arc of 47 to 49 feet! :eek:

[JSH]

An interesting thread gents.
I have little to add that has not already been mentioned.
In my findings, going transonic made little difference of what caliber or of what distance. The transition seemed to have no given ending. One day it would look promising, only to have the next outing be 180 degrees different. Lesson in frustration at least for me.

[LRRPF52]

Twist rate will have an important role in keeping the projectile stable as it goes through the Mach 1.2 to Mach .8 speed region, often called the transonic flight region in aerodynamics, due to the anomalies associated with shock wave formation.

Some supersonic aircraft will stagnate/slow down their acceleration as they try to push through the transonic region (the F-14 was one that did that), while others will experience smooth transition and only see their Mach meter do a strange skip due to pitot tube and Venturi effect, like with the F-16. Aerodynamicists pay a lot of attention to the effects of the shock wave formation on a design so they can optimize it for certain behavior through and above the transonic zone.

Bullets share some challenges and benefits from these studies, but rifle bullets do something that aircraft don’t, namely spin at over 200,000 revolutions per minute for gyroscopic stability, since they don’t have wings or aerodynamic planes to guide them.

With tighter twist rates, you can help control stability nicely through the transonic region where the shockwave behavior starts to change.

The mach cone (supersonic shock wave) starts to alter its shape and location as the bullet decelerates. If the twist is looser, it’s easier for the projectile to suffer from gyroscopic wobble, resulting in erratic and unpredictable point of impact.

1/8 twist or tighter, depending on barrel length, works well with 6.5 Grendel in my experience at 1000yds.

1/7.5” twist works well for the shorter barrels.

Longer bullets with long boat tails suffer more through the transonic region if they aren’t spun really fast, while they do better for maintaining speed down to Mach 1.2 (from the muzzle to Mach 1.2).

My experience shooting Grendel at 1000yds and farther has usually been anywhere from 4400-6600ft above sea level, so the air is a lot thinner and doesn’t resist bullet flight as much as the soup down near sea level.

Even with my lightweight Lilja 17.6” Grendel shooting 123gr A-MAX at 6600ft, 1000yd shots on 3/4 IPSC steel is almost boring if the wind is steady below 10mph full value.

This is a combination of me and someone with a 24” 6.5CM bolt gun shooting this piece of steel at 1000yds at North Springs:


For a Grendel bolt gun, I would either chamber it around the 130gr Nosler RDF, factory 123gr ELD-M or 123gr SMK, spin it tight at 1/7.5-1/8, load it long to get more of a BR case capacity, use a Bartlein pipe in a nice micro action, and set the barrel length for the anticipated altitude region I’d be shooting. Low altitude would get a longer barrel.

If you’re planning on shooting a lot of factory ammo, going with 6.5 Grendel makes a lot of sense if you want a micro action.

If you don’t have a problem forming cases, you could shoot a 6 BR variant or 6mm AR variant. What type of magazine you use will matter as well.

6mm Micro action bolt guns are a lot of fun too.

I’d do some type of aluminum chassis and fit the build to your anatomy so the rifle points and handles optimally for you.

You can get measured b a true craftsman gunsmith, or measure your own length of pull, cheek location, eye height with comfortable neck position, wrist angles, and build around all of that.

I just enjoy shooting gas guns more and hitting steel. If I were punching paper with a range that had pits, I might choose something different.

[Rteague77]

Thanks guys for info y’all provided. Still trying to figure it out.
I don’t want a 6.5C.
I want to test the limits of the Grendel.
Not trying to be a dick, but I just need your opinion or recommendations on:
Action, barrel, and parts to build the best Grendel I can for maximum long range capabilities.
Let me worry about what the bullets does or doesn’t do at 960yards and if it’s still supersonic or not. I’m a retired sniper from the Army & competitive shooter. I understand bullet dynamics and how to read wind, calculate the rotation if the earth and humidity to adjust a round onto target. Thanks.