Sako 6.5 Grendel

[LRRPF52]

Yes, you're maxed out at 33.3gr for sure I would say. 31.9gr is 50,000psi in a SAAMI chamber with a 123gr Hornady.

With 33.2gr, I got 2640fps from my 16" AR15 Grendel, but loaded to 2.275" COL and that was on a ladder, nothing I would ever mass produce for the AR15.

That is 56,848psi in my records. 33.5gr would be at least 58,439psi.

To get real numbers, you would need to pressure trace with the gauge over the center of the cartridge in the chamber, but you are at the upper end, depending on how that thing is throated.

[Hunter307]

Any new pics of this rifle? Such a cool build

[Sauer 150]

Yes, you're maxed out at 33.3gr for sure I would say. Snap snap

With 33.2gr, I got 2640fps from my 16" AR15 Grendel, but loaded to 2.275" COL and that was on a ladder, nothing I would ever mass produce for the AR15.

That is 56,848psi in my records. 33.5gr would be at least 58,439psi.
.

I believe our results match pretty well. I used to have a Oehler 43P until I attempted to have a Windows upgrade :-(
Peak Strain I have a somewhat ambivalent preception of.

I would be perfectly happy to run 55-58'k in a bolt as long as brass doesn't suffer. None of the loads I have tried so far has shown any sign off casehead expansion. Micro meter controll of all cases before and after firing.

I would have wished for a wee bit more barrel. I know I saw a barrel lenght vs velocitiy chart in here somewhere but I was unable to locate it when looking. I believe it would have been possible to get near 2600f/s with 129/130grs bullets in a +20" barrel in a bolt gun without excessive pressure

Pictures?

On my way to Denmark to visit my silencer company this morning. I 'll see what I can do within a couple of days.
If you look in the beginning of the post you will find a few youtube links showing the rifle in action. This is one of them.

https://youtu.be/oZVshUg7QGs

[JASmith]

Yes, that velocity chart does tend to drift way down in the unread threads.

In any event, it was created using this software: 6.5 Grendel Velocity Estimator

[A1Vixen]

Hi Roe and all other fans of a bolt action Sako.
Love your Videos and you inspired me to order a new 6.5 Grendel barrel for my old 6PPC Sako A1 Vixen.

I will order a custom reamer, so I can change everything which can help me getting the best chamber possible for a bolt action.
There a lot of threads where they argument what is the best reamer for a bolt action you could buy.
But I'm pretty sure all the reamers made for a AR aren't perfect for a bolt action rifle.

What would be the best Neck for a match chamber?
295, 292 or smaller, like 288, even if it will be a lot of work to turn all the necks down, would this make sense?
Or do you think this would not bring any advantage in accuracy, better going by the smallest neck, you don't need to turn down the case necks?

How much deeper did you cutthe throat? What are your COL's with 123 Lapua, SMK,...
Roe's COL's will probably be shorter then those of the shooters who do single loading without using the mag.

I have another 2 weeks before I'll do the final order, so if someone has drawnings of good bolt action reamers or can help me with other informations, this would help a lot.

[jason miller]

If I'm remembering correctly, I believe my favorite gun writer has said that a reasonable "rule of thumb" in ballistics is that and increase in case capacity and the correlating velocity have a 4:1 ratio. The Creedmoor is listed as having 52.5 grains of case capacity, which is exactly 150% of the Grendel's listed 35 grains capacity. Divide that extra 50% by 4, and the Creedmoor theoretically produce 12.5% more velocity than the Grendel at like pressures.

Hodgdon's data only has the Creedmoor doing approximately 3150 fps with a 100 grain ballistic tip, which would correlate to approximately 2800 fps of potential velocity in the Grendel with the same bullet, barrel length, and pressure. Theoretically...

[A1Vixen]

I have a Creedmoor and I'm happy with this great rifle. Got good results in my first LR competition.
Now I want something different for my small 6PPC Sako action.

I think I will go with the Grendel II reamer, but custom made with smaller neck.
Will get my Lapua brass next week, than I will measure the neck dimension with a bullet seated and know what neck size I will take.
I want to turn down the brass neck just enough that there is no more difference in the wall thickness.

[LRRPF52]

Hi Roe and all other fans of a bolt action Sako.
Love your Videos and you inspired me to order a new 6.5 Grendel barrel for my old 6PPC Sako A1 Vixen.

I will order a custom reamer, so I can change everything which can help me getting the best chamber possible for a bolt action.
There a lot of threads where they argument what is the best reamer for a bolt action you could buy.
But I'm pretty sure all the reamers made for a AR aren't perfect for a bolt action rifle.

What would be the best Neck for a match chamber?
295, 292 or smaller, like 288, even if it will be a lot of work to turn all the necks down, would this make sense?
Or do you think this would not bring any advantage in accuracy, better going by the smallest neck, you don't need to turn down the case necks?

How much deeper did you cutthe throat? What are your COL's with 123 Lapua, SMK,...
Roe's COL's will probably be shorter then those of the shooters who do single loading without using the mag.

I have another 2 weeks before I'll do the final order, so if someone has drawnings of good bolt action reamers or can help me with other informations, this would help a lot.

The first thing I would look at for a bolt gun are the application and the magazine length allowable, which is the raw internal max length minus enough wiggle room for reliable feeding.

That COL limitation is going to drive bullet selection.

If the magazine doesn't allow much over 2.280", then the SAAMI chamber isn't a bad option at all, and will allow you to shoot a wide range of projectiles well.

If there are no plans to shoot steel case, I would consider a chamber with a .295" neck for a hunting bolt gun that will also double as a fun lightweight target rifle.

For a dedicated target rifle that will only ride a bench on a clean range with overhead cover, maybe consider a .292" neck diameter. For Scandinavian thermal shifts, I personally wouldn't go lower than .295" neck, but I like to get away from clean ranges and I do shoot a lot in the winter.

If you decide to go custom chamber and are happy with just a few bullets with similar ogive lengths and origins relative to the shank, pick that line-up of bullets and set the throat length accordingly.

[A1Vixen]

Thanks for your concerns, I know that in the Sako the COL is not very long IF you use the mag.
I normally doesn't use it and if I want to do this later for plinking it would certainly be possible to find a load which isn't that bad, even with longer distance to the lands.
As brass I will use only hand loaded Lapua case. They will arrive next week.
At the moment I use match chambers in my rifles with neck turned brass and for the larger chambers I form the brass from a larger caliber and just turn enough neck down that the neck is just .002 thinner loaded with bullet than the chamber. ( we don't have hard winters like your Scandinavian thermal shifts. Rare colder than -6C)

After testing with old 6PPC brass, I think for the 136g Scenar the throat length could be some mm longer than those from a standard Grendel II reamer.
I'll try to get other bullets to test this, then I will send the results to the gun smith.

The objective is a varmint rifle with match chamber to practice lots more with cheaper ammunition (powder is expensive in Europe), to have fun and maybe shoot some competitions with it to get more experience in competitions. (I know that this will not be a winning rifle, but if you can annoy some people by beeing with a Grendel in the top 10...)

[A1Vixen]

I placed my order.
Now I need to wait e few month, but here are the details.

I ordered my custom reamer based on a Grendel II but with .290 neck.
The barrel will be a 26" .264 1:9 twist Lilja in the Sako Varmint contour and a M18x1 barrel thread for a silencer.
All together in my nutwood sportster stock. The stock will get a pillar bedding.

And the rifle will be under 6,5kg with riflescope and bipod for the BDS 300m competition in Germany.


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[VASCAR2]

[A1Vixen]

[VASCAR2]

Sorry to bring the twist issue up as I didn’t know if you had researched this aspect. I have two 6.5 Grendels, a 20” and a 16” both in AR-15’s. I never planned on running bullets heavier than 125 grains and the majority will be 123 grains or less. Had a 1:8 twist been available when I bought my first two 6.5 Grendels I would have bought 1:8 twist. From my reading and limited experience as the bullet inters the transonic zone the faster twist produces better accuracy. With the 6.5 Grendel the point where the bullets start getting close to the speed of sound is roughly 1000 yards depending on the barrel length and altitude above sea level.

Like many other cartridges there has been a movement to longer higher ballistic coefficient bullets. This has happened with the 223/5.56 and the 7.62X51 as well as the 243/6 MM cartridges. From my reading going from 1:9 to 1:8 twist will not over stabalize a 6.5 Grendel bullet in the 85 to 140 grain weights/length. The length of the bullets is what generally requires the faster twist to maintain stability.

It all depends on how your going to use your 6.5 Grendel. If you will never shoot past 800 yards/meters and never want to move to a longer bullet 1:9 twist will be adequate. Brian Litz from Applied Ballistics is one of the engineers working with the extended long range shooting. I suggest you check out Brian’s research.

To me the 1:9 twist versus 1:8 twist reminds me of when I was a teenager. I had a little Dodge car with a 225 cubic inch slant six 2 barrel carburetor. I bought the car thinking the six cylinder engine would be better in the small car. A Friend had basically the same car but with a 318 cubic inch V-8 with 2 barrel carb. My car was a little under powdered, his car got better fuel mileage, was safer if you had to pass and just a better car. Both cars got you where you wanted to go but the V-8 was really more suited to living in a rural area driving at highway speeds. In town with speeds less than 40 MPH the slant six was adequate. All depends on your parameters on use.

Maybe a couple other more experienced long rang shooters like Bwaites who has a 28” barrel 6.5 Grendel will chime in. I don’t have any research I have done myself comparing the 1:9 versus 1:8 twist. Here is a link to Brian Litz at applied ballistics.

http://appliedballisticsllc.com/products/books/

A web site I visit which might be helpful.

http://www.6mmbr.com/index.html

[A1Vixen]

The Berger Twist Rate Stability Calculator is a great tool.

After trying lot of bullets in the calculator, it seems that 1:8.75 would be the perfect twist for me.

Now I will try to get a 1:8.75 or 1:8.5 twist barrel, then I can use every bullets until 130g.

Thanks for your concerns about the twist rate

Edit: Thought long time about the avantages and disadvantages of a other twist.
I will stay with the 26" 1:9 twist and 123g bullets.
For LR and fast wind I have the 6.5 Creedmoor and will probably buy a second Creedmoor in semi auto

[VASCAR2]

Sounds like you have rationally figured out what your going to do. I think since you have other rifles like the Creedmoor you’ll likely stick to 123 grain match bullets in your 6.5 Grendel. I bet you’ll be satisfied with the Lilja barrel in 6.5 Grendel and with the length you should get excellent accuracy. You’ve got the Creedmoor to shoot heavier bullets. Report back when you get your rifle built.