Best cartridges for compact bolt actions? (SA or smaller)

WindstormSCR · Jul 17, 2024

Inspired by Aero's recent release of the Solus pistol line, but also because of the rise of more converted mag fed bolt actions and mag fed lever actions.

What Short Action or smaller cartridges do you think make the best candidates for an extremely compact bolt or lever action mag fed rifle?

My mind immediately went to 6.5 Grendel, which has historically shown excellent accuracy and performance in shorter barrels, along with things like .450 bushmaster that offer good large-bore performance and maximize subsonic capability without sacrificing much in the way of accuracy.

as a second question, what do you think are the best usages of these compact platforms?

mark5pt56 · Jul 17, 2024

You have to define use-what do YOU want it to do?
Short range target-.223 or .22, 16"
Mid range, .223, maybe 6Arc or the Grendel, 18-24"
Longer ranges-above would work, 6/6.5cm better or the latest and greatest wonder round
Hunting med game, why not--do a shorty and keep the range within your ability to make good shots under field conditions.
Any of the above-if you want to tinker and have fun.
Me personally, if you had nothing over a few hundred yards, just run a .223 unless you need a heavier caliber to hunt something a .223 won't take.

FuhQ · Jul 17, 2024

Honestly, having both a 6ARC and 6.5 Grendel, I’d pick the 6 ARC for suppressed supersonic work, since the 115gr bullets are significantly higher BC, compared to the 123gr 6.5mm bullets designed for use in the 6.5 Grendel. Also, increased velocity from the slightly lighter bullets.

Best suppressed subsonic mini bolt gun cartridge by far is the .300 BLK.

taliv · Jul 17, 2024

If you’re really bored take a 300blk and neck it down to 223.

Modoc · Jul 17, 2024

taliv said:
If you’re really bored take a 300blk and neck it down to 223.

Hell, I’ve got one of those in a Remington 700 Classic! It is a tack driver with 40g bullets (1:12 tw).

Easy_E · Jul 17, 2024

Remington .17 fireball or .221 fireball !

WindstormSCR · Jul 17, 2024

mark5pt56 said:
You have to define use-what do YOU want it to do?

The point here is really to identify which cartridges perform the best for different purposes at 15.9” and less.

Cartridges like 6.5 and .308 are going to have shitloads of unburnt powder, while cartridges like 7.62x39 will have minimal unburnt powder.

Another example might be the new .277 Fury since it’s designed with a 13” barrel in mind for .mil use

FuhQ · Jul 17, 2024

WindstormSCR said:
The point here is really to identify which cartridges perform the best for different purposes at 15.9” and less.

Cartridges like 6.5 and .308 are going to have shitloads of unburnt powder, while cartridges like 7.62x39 will have minimal unburnt powder.

Another example might be the new .277 Fury since it’s designed with a 13” barrel in mind for .mil use

Actually, the .308 Win has been proven to have a nearly complete burn in a 16" barrel...Just FYI. So, it won't have as much unburnt powder as a 6.5CM or 7mm-08 or .260 Rem, or 6mm CM, or anything like that. The case capacity to bore diameter ratio allows the .308 Win to burn more powder gasses per inch... This goes for anything the higher up in bore diameter you go, while maintaining the same case capacity. Sort of like how .300 BLK is so efficient in shorter barrels. .300 BLK was designed to be subsonic and used suppressed in 10.5" barrels, and it does great in both 8" and 10.5", as well as 16" barrels.

I know that my 16" Christensen Arms MPR (bolt action) 6mm ARC is an extremely efficient setup, and produces an average MV of 2,575 FPS with the Nosler 115 RDF's and LeverEvolution powder. I'd be willing to bet it would do great in a 12.5" to 14.5" barrel, as well.

WindstormSCR · Jul 17, 2024

FuhQ said:
Actually, the .308 Win has been proven to have a nearly complete burn in a 16" barrel...Just FYI. So, it won't have as much unburnt powder as a 6.5CM or 7mm-08 or .260 Rem, or 6mm CM, or anything like that. The case capacity to bore diameter ratio allows the .308 Win to burn more powder gasses per inch... This goes for anything the higher up in bore diameter you go, while maintaining the same case capacity. Sort of like how .300 BLK is so efficient in shorter barrels. .300 BLK was designed to be subsonic and used suppressed in 10.5" barrels, and it does great in both 8" and 10.5", as well as 16" barrels.

I know that my 16" Christensen Arms MPR (bolt action) 6mm ARC is an extremely efficient setup, and produces an average MV of 2,575 FPS with the Nosler 115 RDF's and LeverEvolution powder. I'd be willing to bet it would do great in a 12.5" to 14.5" barrel, as well.

Fair point, but my statement still stands where the thread goal is to find the best cartridges to take advantage of this (relatively) new shift in what's easily commercially available.

An example that comes to my mind might be a 13" .277 Fury built on something like the Solus chassis, where you can fold it up very compact as a ranch gun, but has better accuracy than a similar sized semi-auto by a non-insignificant margin.

noremorse92 · Jul 18, 2024

You won't go wrong with a fast twist 223. If you handload go 223AI. It's basically all I shoot now.

A 7 or 8 twist 223 or 223ai with heavy bullets hangs in there with the 6mms at distance and is a lot cheaper to shoot with even less recoil. Barrel life is also fantastic. With the AI version you can shoot normal 223 in it with zero issues as well. No downside to the ackley only upside.

FuhQ · Jul 18, 2024

noremorse92 said:
You won't go wrong with a fast twist 223. If you handload go 223AI. It's basically all I shoot now.

A 7 or 8 twist 223 or 223ai with heavy bullets hangs in there with the 6mms at distance and is a lot cheaper to shoot with even less recoil. Barrel life is also fantastic. With the AI version you can shoot normal 223 in it with zero issues as well. No downside to the ackley only upside.

Not if you’re running 108, 110, 115gr 6mm bullets in something like the 6 ARC or larger. Then the 6mm’s start really pulling away from the heavy .223’s, and still have virtually no recoil.

HerCoStarNTheBeaverPictur · Jul 18, 2024

FuhQ said:
Actually, the .308 Win has been proven to have a nearly complete burn in a 16" barrel...Just FYI. So, it won't have as much unburnt powder as a 6.5CM or 7mm-08 or .260 Rem, or 6mm CM, or anything like that. The case capacity to bore diameter ratio allows the .308 Win to burn more powder gasses per inch... This goes for anything the higher up in bore diameter you go, while maintaining the same case capacity. Sort of like how .300 BLK is so efficient in shorter barrels. .300 BLK was designed to be subsonic and used suppressed in 10.5" barrels, and it does great in both 8" and 10.5", as well as 16" barrels.

I know that my 16" Christensen Arms MPR (bolt action) 6mm ARC is an extremely efficient setup, and produces an average MV of 2,575 FPS with the Nosler 115 RDF's and LeverEvolution powder. I'd be willing to bet it would do great in a 12.5" to 14.5" barrel, as well.

This is interesting to me. Do you happen to know if there is a formula used for powder burn rate, bore size, barrel length that gives useful information?

FuhQ · Jul 18, 2024

HerCoStarNTheBeaverPictur said:
This is interesting to me. Do you happen to know if there is a formula used for powder burn rate, bore size, barrel length that gives useful information?

It’s just simple fluid dynamics…The smaller the tube at the same volume = greater pressure. It’s the same reason why you have to decrease your power charge, the smaller in bore diameter you go. Anyone who’s messed with wildcatting and enough different cartridges off the same basic parent case can tell you this. Just takes experience, and not necessarily an engineering degree.

Example…

The .308 Win can run upwards of 45-46gr of Varget with a 168gr bullet (top end load) before showing extreme pressure signs. And the .260 Rem will start showing those same pressure signs around 38-39gr of Varget with a 140gr bullet. Same case, different bore diameters and bullet weights.

steve123 · Jul 18, 2024

6mmBR is my vote in 7.5 twist. The over achiever. Heck I was able to hit our 20" plate at 1987Y with mine using 107's. I haven't tried again since then but if it were calm out I could hit it a fair amount of the time I bet.
Largely because it's not hard to get SD in the 4's and groups in the .2's at 100Y.

Another time I could keep most of the shots on a 4" head of a man silhouette at 785Y.

Not to mention the many benchrest wins and records it's set over the years.

Too good.....

HerCoStarNTheBeaverPictur · Jul 18, 2024

FuhQ said:
It’s just simple fluid dynamics…The smaller the tube at the same volume = greater pressure. It’s the same reason why you have to decrease your power charge, the smaller in bore diameter you go. Anyone who’s messed with wildcatting and enough different cartridges off the same basic parent case can tell you this. Just takes experience, and not necessarily an engineering degree.

Example…

The .308 Win can run upwards of 45-46gr of Varget with a 168gr bullet (top end load) before showing extreme pressure signs. And the .260 Rem will start showing those same pressure signs around 38-39gr of Varget with a 140gr bullet. Same case, different bore diameters and bullet weights.

Right. Maybe I’m just looking for an easy button but I’m curious if there’s a “sweet spot”. Like most things, there are probably only trade offs.

Guns&WhiteWater · Jul 18, 2024

A 30 GT would be an efficient cartridge in a short barrel.

hlee · Jul 18, 2024

I think the OP defined questions are backwards. Literally, “a solution in search of a problem.” Start with the use case, then define the equipment requirements.

WindstormSCR · Jul 19, 2024

hlee said:
I think the OP defined questions are backwards. Literally, “a solution in search of a problem.” Start with the use case, then define the equipment requirements.

Normally, yes. However this isn’t intended as a “solution in search of a problem” but to try and collate a resource for those looking to do builds with barrels significantly shorter than those seen in classic bolt and lever actions.

So far for candidates, we have:

Wildcats: 6mmBR, 30GT, .223 AI, .375 Raptor, .45 Raptor

Factory: 7.62x39, .300 Blk, 8.6Blk, .50 Beo, .450 Bushmaster, .350 Legend, .277 Fury

Upper end of length range (12-15.9”): .308win, .223rem, 6mm ARC, 6.5Grendel, 6.8 SPC II

steve123 · Jul 19, 2024

WindstormSCR said:
Normally, yes. However this isn’t intended as a “solution in search of a problem” but to try and collate a resource for those looking to do builds with barrels significantly shorter than those seen in classic bolt and lever actions.

So far for candidates, we have:

Wildcats: 6mmBR, 30GT, .223 AI, .375 Raptor, .45 Raptor

Factory: 7.62x39, .300 Blk, 8.6Blk, .50 Beo, .450 Bushmaster, .350 Legend, .277 Fury

Upper end of length range (12-15.9”): .308win, .223rem, 6mm ARC, 6.5Grendel, 6.8 SPC II

6mmBR is actually a factory loaded cartridge through Lapua. I think they sell 90's and 105's. However a bit expensive.

45-90 · Jul 19, 2024

The 308 Win, of course.
Example: Magnesium upper, titanium carrier, light fluted barrel, 6 lb AR 10 308, with 16" barrel 168 gr ELDM 2756 fps 1/2" 5 shot groups.
155 gr 2815 to 2900 fps, pictured chronograph on rifle.
208 gr ELDM 2442 fps pictured in mag.
Light and accurate
Lighter than most AR 15s but brings more energy and velocity then my 18" 6 mm ARC with 108 ELDM at 100 fps less, and similar BC values .536 for 6mm vs .523 for 308. And the 308 has 2" less barrel, and 100 fps more velocity.
I like my 6 ARCs but the 308 has better ballistics.
And incase one happens on a Grizzly bear the mag full of 208s at 2442 fps will handle that situation too.

WindstormSCR · Jul 19, 2024

45-90 said:
The 308 Win, of course.
Example: Magnesium upper, titanium carrier, light fluted barrel, 6 lb AR 10 308, with 16" barrel 168 gr ELDM 2756 fps 1/2" 5 shot groups.

you entirely missed the point of the thread, congratulations

45-90 · Jul 19, 2024

WindstormSCR said:
you entirely missed the point of the thread, congratulations

I know its about bolt guns, ...and other things that are much less defined on the OP.
Performance in short barrels with different cartridges, mentioned.

I don't have short barreled 16" bolt guns, but I do have ARs with short barrels to compare performance.

So an example of actual comparison was made with the two cartridges with similar bullets, with best effort loads, in short barrels.

That comparison might be of use, regardless of action, auto or bolt, to help make a decision on the ambiguity of the post.
The best option...in My opinion was 308 based on performance, accuracy, long barrel life, cheap components, LC brass, 147 gr fmj for plinking, variety of primers LR or SR cases, lots of match bullets.
Plus accurate 175 gr subs...work with 12 to 8 twists.
Plus I use hybrid 277 cases in my 308 bolts...you can too, for extra performance, if wanted.
A bolt gun can be made very light or very heavy.
The powder that gives you the highest velocity in a long barrel will likely give you the highest velocity on a short barrel, for the same bullet...but may have a large fireball at the muzzle, and larger S/D, not so good for LR.
QL will give the percentage of powder burned for each load, and barrel length, and bullet. Everything one needs to know...a scientific estimate...atleast.

The 450 bushmaster was mentioned, I got the fast 16 twist over the standard 22 twist, so I can shoot 502 gr bullets in sub sonic mode...again a 16" auto loader...but a bolt in this caliber can have more pressure and be more accurate. And one can resize any .458" bullet to .452". If one chooses the 450 Bushmaster route.
IMO best versitle caliber is the 308, I own 8, but also a bunch of others. Your choice.

One day, Consider a lapua magnum action, a more difficult caliber to load, the .510 whisper.
With 1002 grs subsonic load that has 2000 ft/ lbs at 1000 yds..or just some exploding APIT bullets to entertain you, or damage your AR 500 plate at 1250 to 1300 fps and almost penetrate at just 1450fps.
The more you know, the better choice, one can make for their personal shooting endeavors.

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