Could a .45 winchester magnum necked down to 5.7mm equal a 5.56 in range and velocity?

you said assault rifle and AR-15 in the same sentence, the AR-15 is not an assault rifle as it is semi-auto.

if you want a rifle that feeds from the grip why not just get something like a Cx4 or a Sub 2000

http://www.berettausa.com/products/cx4-storm/

http://www.keltecweapons.com/our-guns/sub-2000/rif...

Hi Jordan,

I read this question a few minutes after you posted it yesterday. Been thinking about all the pros and cons of all the different rounds I have used and wildcats I have heard about.

External ballistics is a no free lunch deal. What ever you 'get' you have to 'give up' something. The human hand can withstand just so much punishments and is only really steady for short range. I own the FN FiveSeveN pistol and have done extensive experiments with the caliber.....many ranchers perfer this pistol to carrying a 22 Hornet, 22 rimfire or 223/5.56mm for varmints from rats to coyotes out to 200 meters.

I've also done extensive shooting of the 223/5.56mm in competition at 200, 300 and 600 meters. I know the 16" carbine barrel AR-15's can do ok at 300yds but things fall apart at 400 meters.

I've built an AR-15 SBR with a 10.3" barrel - it is quite nice at close quarters to 100yds, it can do ok at 200 meters but is kinda lacking to 300 metets in accuracy.

300-400 meters in a .224 projectile seems to want at least a 14.5" barrel like the current M4 carbine. I would guess this would also be true no matter what case you had pushing it - the short and stumpy 45 Win Mag or a 22-250 cut to 14.5"........ a shorter than 14.5" barrel is not going to give great results and 14.5" is certainly a bit long for a pistol barrel!.

I do know some of the better 30 cal wildcats made by JDJ (J.D. Jones) especially the 309 (a 444 Marlin with a 308 neck) does do quite well for pistol deer hunting - it hits hard in that 300+ meter range. This tells me 30 cal is probably where you would want to be.

Instead of messing with the 22cal bullets and pistol cases - you might wanna think outside the box. The old 44 Automag pistol was a cut back 30-06 case necked to 44 cal. If you could find one of those old pistols - you could have a 30cal barrel custom made - and use cut back 308 or 30-06 re-necked to 30cal. That may work.

No, it would not work. You run into two problems:

ONE: Case capacity. The .45 winchester starts out without about 10% less case capacity than a .223. Any necking down would significantly reduce case capacity relative to a .223 in a brass that started out with less case capacity to begin with.

TWO: To neck down a brass that wide to 5.7mm on a brass that short would require one of two things: either the shoulder angle would be so steep that the round would never feed reliably in an automatic/semi-automatic action, OR if the shoulder angle was shallow enough to feed reliable, the shoulder would start down around the base and you reduce case capacity so low that the round wouldn't be good for anything.

As a general rule, you can't neck down a pistol cartridge to a rifle cartridge. Pistol cartridges are already designed for pistol velocities. You can't expect to reduce their case capacity by necking them down and hope to get rifle ballistics. It works the other around.

Kights Armament already solved that problem. Take a look at their PDW that shoots 6x35:

http://www.knightarmco.com/portfolio/pdw-8/?cate_c...

.45 to 5.7 (.224) is too much, .45 to .308 or .264 might be doable.

it would not be suitable for "assault rifles" or any kind of semiauto, but would make a good & interesting wildcat caliber.

A 7 MM mag will spank a 5.56 in about every way . good luck with building a gun to shoot this with>> pistol grip mag fed creation ..

Without actually running it through a ballistic computer, it looks like there isn't enough case capacity. Moreover, you can bet it would feed poorly.

This would be an interesting experiment, but I don't have the means to undertake it.

no

that's a really dum idea