Speed of a CB

[Mike in MD]

I wasn't sure where to put this. Hope I'm good.

Wondering how fast one could push a CB. My guess is that it may depend on the alloy, but also possibly bore diameter.

Thanks Mike

[Txcowboy52]

Can’t speak to rifle rounds , but pistol rounds I try to stay under 1100 FPS. If powder coated or gas checks are used I would say maybe 1500 FPS .

[MT Chambers]

Most consider 2500 fps tops but Lyman has some loads to 3000fps.

[Conditor22]

Using monotype with 1% copper/PC/GC I've gone 3,300 fps with 223

but usually I'm a slowest accurate load type of guy

[JM7.7x58]

Bullet type, alloy composition(and resulting hardness), powder selection, bullet sizing, and the type of lubrication used are all major factors when you start going faster. I’ve been developing a load for my 30-06 with the Lee 312-155-2R. These are gas checked and powder coated, air cooled Lyman #2, over 36 grains of Reloder 7. Per Quickloads this load should be up around 2300fps. Accuracy is ok, but nothing to brag about, 2 1/4” five shot group at 60 yards.

Can I go faster? Yes. Will accuracy suffer as I go faster? What is my lowest acceptable accuracy limit? Is it 1, 2, 3, or 4 MOA? My goal is to continue to adjust this load until I can get it under 2 MOA.

JM

[Nobade]

Somebody here was using a 300RUM to shoot paper patched cast boolits WAY over 3000 fps with good results.

[Harter66]

Naked 225-55 NOE 62 gr gas checked in a Savage 222 2,640 fps sub MOA .
Naked 279-124 NOE @130 gr GC 6.8 SPC 2250 fps 1.5 MOA .
Naked 35-250 RCBS @253 gr 358 Win 2100 fps sub MOA .
Naked 458-201 Rapine @255 gr plain base 45-70 2,000 fps 2" @50 yd .
30-30 and 32 Rem use plain base 150 and 170 to MOA at max jacketed velocities at or just under start loads . Both are pointy bullet safe and loaded off book for bullets .
All but the 6.8 were well into jacketed speeds and it really isn't very far off and exceeds the NV big game required 1000# @100yd .

Paper patch makes for a whole new level .
I took a 308 , 175 to 2500 fps at 1.5 moa
7.62-39 200 gr to 1800
7×6.8 to 140 to 2400 (bad idea data used was for a jacketed 130 after the primer pocket failed I discovered the 27-130 weighed 141 gr naked not the anticipated 132 )
Also in a 1-8.5 twist . While this will work with 7mm I just can't make it work with 30 cal ...... 1-12 is the only solution .

[charlie b]

All depends on caliber, barrel rate of twist and how good your bullets are.

It is all about the RPM of your bullets and the effect that has on any defects in the bullet and the structure.

[osteodoc08]

Larry Gibson has posted several posts about RPM threshold. When the 30 XCB came to be it seemed to work well with slower twist. Have a search for RPM threshold and old articles about the 30 XCB wildcat