Big Bore Cast AR Deer rifle conversion?

[vzerone]

After doing much research on this subject, especially on the .458 SOCOM that might shoot the various 45-70 cast lead projectiles I have molds for, this whole idea of converting an older Colt AR-15 to a lead shooting caliber seems to have many pitfalls. Besides being particularly expensive to do. I thought initially it would be a couple of hundred dollars and just swapping out the barrel for deer season. But I found it much more complex then that. And especially when most of the conversions might not even work in my Colt rifle. Or would require some modification of my "collectable" Colt rifle. It seems like the people that are successful with all of these conversions have many different AR-15 style rifles, so when one set of parts doesn't fit in one lower, they can just pick one or their other lowers that will work and be successful with the conversion. Where in my case I have just this one, old AR-15 rifle that I was hoping to convert on a temporary basis for deer hunting season. I appreciate all the help from everybody, especially the people that pointed out that my rifle may not be suitable for a conversion. So, I guess I will go deer hunting this year with my Browning 1885 in 45-70 and have to reload fast if I see two or three deer.

Don't give up entirely. If you search you may even find an old Colt upper if yours has the two different pin diameters. That bushing isn't as bad as I meant it to be. Other then those pins everything else is 100% interchangeable. Thing is with an old Colt upper, should you find one, is that it will have a handle on it and more difficult to mount a scope, whereas the new ones are flat tops. That's not to say you can't put a good scope mount on the handle. I think you'd get a kick out of an AR15 that KICKS!!! LOL I don't want to discourage you, lifes short, enjoy it.

[vzerone]

Here's a link to the bushing: http://www.jsesurplus.com/coltreceiv...etbushing.aspx

Pic of the bushing:

[HiVelocity]

Whats wrong with the 5.56 caliber for deer out to 200 yards? I handload some 75 grain BTHP's that work just fine. Why fix what isn't broken?

Just food for thought. BTW, here in SC, there are more deer/hog hunters using AR15's in 5.56 than any other caliber. Just saying.

HV

[Moleman-]

Do you have a lathe or access to one?

[Hamish]

Do you have a lathe or access to one?

(theme from Jaws heard playing in the background,,,,,,,)

It's about time.

[Moleman-]

Once you start making barrels for them they breed like rats.

[DonMountain]

Whats wrong with the 5.56 caliber for deer out to 200 yards? I handload some 75 grain BTHP's that work just fine. Why fix what isn't broken?

Just food for thought. BTW, here in SC, there are more deer/hog hunters using AR15's in 5.56 than any other caliber. Just saying.

HV

Years ago I tried using a 243 with jacketed bullets for deer. It was an accurate rifle and great for shooting coyotes. But just didn't have the bullet size and weight to kill deer with when I shot them in the chest. Even shooting them in the head wasn't always a sure thing and I ended up trying to track them for miles, but the non-existent blood trails were always a problem. And I sure wouldn't try using a much slower cast lead projectile in a 243 for deer. Of course my 45-70 with a 300 grain gas checked projectile was a whole different story and knocked all of the deer down where they were shot. So, my conclusion was with cast lead projectiles there is a law of diminishing returns as you go to smaller calibers for deer hunting. And 30 caliber is my cutoff line. All with a reasonably large flat meplat on their nose. And 6.5 mm is my minimum for jacketed bullets. So, when I saw all the 30 caliber conversion barrels and larger coming on the market I started looking for one. Thinking I could use my AR-15 for a woods gun with cast lead projectiles. Last year I killed 3 deer where they stood with a 170 grain gas checked projectile out of my Winchester Model 94 in 32-40, and it was almost automatic to operate it?

[DonMountain]

Do you have a lathe or access to one?

Yes, I have a lathe.

[vzerone]

Years ago I tried using a 243 with jacketed bullets for deer. It was an accurate rifle and great for shooting coyotes. But just didn't have the bullet size and weight to kill deer with when I shot them in the chest. Even shooting them in the head wasn't always a sure thing and I ended up trying to track them for miles, but the non-existent blood trails were always a problem. And I sure wouldn't try using a much slower cast lead projectile in a 243 for deer. Of course my 45-70 with a 300 grain gas checked projectile was a whole different story and knocked all of the deer down where they were shot. So, my conclusion was with cast lead projectiles there is a law of diminishing returns as you go to smaller calibers for deer hunting. And 30 caliber is my cutoff line. All with a reasonably large flat meplat on their nose. And 6.5 mm is my minimum for jacketed bullets. So, when I saw all the 30 caliber conversion barrels and larger coming on the market I started looking for one. Thinking I could use my AR-15 for a woods gun with cast lead projectiles. Last year I killed 3 deer where they stood with a 170 grain gas checked projectile out of my Winchester Model 94 in 32-40, and it was almost automatic to operate it?

When I was young I kept a tally of what hunters, who did harvest a deer, used to harvest it. Where I grew up those calibers were usually 30-30, 32 Special, 35 Remington, 300 Savage, 308 Winchester, 8x57 Mauser, 7.62x54R Russian, 30-06, 270 Win, and 7mm Mag Rem. I paid particular attention to the 243 harvests. The son of gun had dang near a 100% harvest ratio. That is, I mean, if someone shot one with the 243, it was one shot and they got the deer. Not always dropped where shot, but they got it. It's a deer killer in my opinion. The two calibers that stood out far and beyond the other ones mentiones were the 30-30 and the 35 Remington.

I agree with your not to use anything smaller then a 30 caliber cast bullet. Yes the 45-70 with cast is a deer whopper.

My opinion of the AR 15's chambers for some kind of 30 caliber is that if they don't match the bullet weight, velocity, and energy of a 30-30...then they are a no go for me. The 7.62x39 being an exception. The ones that shine for deer hunting are the AR 10's. Notice I said 30 caliber AR 15's. That doesn't include the 50 Beowulf, 450 Bushmaster, or the 458 SOCOM.

[Moleman-]

Yes, I have a lathe.

You can get a barrel extension for $20-$30 and a barrel blank anywhere from $45 to as much as you want to spend. The barrel extension wrench, barrel vise, chamber reamer and gauges can all be bought or made. A couple cheap wildcats that would be easy enough to make would be 357AR (like a rimless 357Max only run at 223 pressures) 44x1.6" (sarco has good $45 blanks and the cartridge can use 445SM data), 450Bushmaster (not really a wildcat anymore). I have made the 357AR and 44x1.6". You can use either a .357" or .358" blank for the 357AR but with heavier bullets you'll want a faster twist. We've shot deer from 60yds to 142yds and have been happy with the results. I have shot cast in it but not shot a deer with it yet. 180gr SSP QuickLoad guestimate at 2119 fps at 52,454 Kpsi for a 15.5" barrel. No way to verify the pressure, but the Magneto Speed average out of my sons 15.5" barrel was 2140 fps or within 21fps of the QL guess so I wouldn't think the pressure would be too far off. That puts it on par with a 35rem with a similar barrel length. Uses the same bolt you already have but requires a modified mag and carbine gas system. Cases are made from once fired 223/5.56 or 223basic brass and loaded with a 357die set along with a 357 lyman taper crimp die. There was just a group buy on 357AR barrels over on the modern sporting rifle site and they're talking of perhaps another at some point. 44x1.6" and 450BM will require a new bolt. Haven't made a 450bm yet but everyone I know that has one likes it. Haven't shot a deer with the 44x1.6" but it approximates my 50 hawkin with a 44 in a sabot which I've used since the early 90's. Since the bullets don't care what they were fired out of I know it will do great on deer. 240gr at 2000fps out of a 16" barrel. Shoots pretty flat out to 150yds. Cases are made from 308/30-06/270 or similar (have a few 8mm to try out at some point) and loaded with a 444marlin die. If you want to make a barrel and don't know how there are enough people here that have made them (myself included) that would help walk you though it. Same goes for chamber reamers and headspace gauges. Since these are straight walled cartridges it is pretty straightforward. I would suggest getting another upper as you're not going to want to keep changing the barrel on your's many times.

[vzerone]

You can get a barrel extension for $20-$30 and a barrel blank anywhere from $45 to as much as you want to spend. The barrel extension wrench, barrel vise, chamber reamer and gauges can all be bought or made. A couple cheap wildcats that would be easy enough to make would be 357AR (like a rimless 357Max only run at 223 pressures) 44x1.6" (sarco has good $45 blanks and the cartridge can use 445SM data), 450Bushmaster (not really a wildcat anymore). I have made the 357AR and 44x1.6". You can use either a .357" or .358" blank for the 357AR but with heavier bullets you'll want a faster twist. We've shot deer from 60yds to 142yds and have been happy with the results. I have shot cast in it but not shot a deer with it yet. 180gr SSP QuickLoad guestimate at 2119 fps at 52,454 Kpsi for a 15.5" barrel. No way to verify the pressure, but the Magneto Speed average out of my sons 15.5" barrel was 2140 fps or within 21fps of the QL guess so I wouldn't think the pressure would be too far off. That puts it on par with a 35rem with a similar barrel length. Uses the same bolt you already have but requires a modified mag and carbine gas system. Cases are made from once fired 223/5.56 or 223basic brass and loaded with a 357die set along with a 357 lyman taper crimp die. There was just a group buy on 357AR barrels over on the modern sporting rifle site and they're talking of perhaps another at some point. 44x1.6" and 450BM will require a new bolt. Haven't made a 450bm yet but everyone I know that has one likes it. Haven't shot a deer with the 44x1.6" but it approximates my 50 hawkin with a 44 in a sabot which I've used since the early 90's. Since the bullets don't care what they were fired out of I know it will do great on deer. 240gr at 2000fps out of a 16" barrel. Shoots pretty flat out to 150yds. Cases are made from 308/30-06/270 or similar (have a few 8mm to try out at some point) and loaded with a 444marlin die. If you want to make a barrel and don't know how there are enough people here that have made them (myself included) that would help walk you though it. Same goes for chamber reamers and headspace gauges. Since these are straight walled cartridges it is pretty straightforward. I would suggest getting another upper as you're not going to want to keep changing the barrel on your's many times.

You are correct about a lot of what you posted. Just let me add that drilling the gas port hole is not just a simple drilling job. Many barrel manufacturers like to drill the gas port hole so it ends up in the groove. Steve Satern of Satern Barrels has an index machine that does exactly that. Also not everyone knows what size the gas port hole should be. To complicate matters pistol length, mid-length, and rifle length gas ports hole dimensions are different. Then there's that burr on the inside where the drill breaks through into the bore. How about the torque range for the barrel extension? In a long run better off to just buy the barrel ready to go.

[ancientriflesmith]

Look no further than the 450 BM for a great big bore AR-15. Myself and three sons all use the 450 for deer, pig and bear hunting in Arkansas. If I knew how to post pics I could show several targets with ten shot 100 yd.groups from two or three of those guns that a nickle would almost cover. Actually after about the third shot I accused #3 son of just shooting beside the target to impress us with the group. When we all did about the same thing, we were all blown away at such accuracy. All groups were shot with Lee's 300 grain (cast 292 gr) .452 bullet powder coated without GC and sized to 452 @ chonographed velocity around 1825 or more, forgot exact number. Deer are easily hit at 150-200 yds and the wounds are massive with little meat bloodshot. I hesitate to post the load but 1680 was powder and over max listed in two manuals. Pressure signs are mild and function better than .223 it seems. Never a smidgen of leading, the bores always look as if just cleaned. Remember factory 250 gr. loads are about 2200 fps again old mind may be off a little. This comes from an old gunsmith with about 58 years making custom guns. I carried the M-16 for two tours in the "LOST WAR" (pure BS) and never gave another black gun a second thought till America appeared to be falling apart. Now they are shot almost daily here. Have .300 BK, 7.62 x 39, 5.56, 450 BM and AR-10 original.
Have shot all the others and none are bad, but none as accurate as a 20" 450 BM, by Bushmaster. Also make cases from Win 284 because many are on hand and the large primer seems to give more uniform ignition.

[Moleman-]

You are correct about a lot of what you posted. Just let me add that drilling the gas port hole is not just a simple drilling job. Many barrel manufacturers like to drill the gas port hole so it ends up in the groove. Steve Satern of Satern Barrels has an index machine that does exactly that. Also not everyone knows what size the gas port hole should be. To complicate matters pistol length, mid-length, and rifle length gas ports hole dimensions are different. Then there's that burr on the inside where the drill breaks through into the bore. How about the torque range for the barrel extension? In a long run better off to just buy the barrel ready to go.

You're overthinking this, it isn't a Camp Perry match gun. The vast majority of production semiauto barrels don't have the gas port timed to the grooves. For gas tube lengths you can compare a QuickLoad graph of your proposed cartridges pressure by the inch of barrel compared to a 223 graph will tell you which gas tube length will work the best. Barring that there are enough similar cartridges out there that you could just look and compare. Funny thing about the gas port burr. Years ago when the guys at Eagle arms were just starting up they went around to the gun shows selling barrels (new and test) as well as uppers, parts and complete guns. Looking at one of their extra heavy DCM match barrels (had a groove for the gas tube) I noticed they all had a huge flap where the gas ports were. I asked and the guy picked one up and looked. He said they all have that burr until they're shot the first time. Said it would disappear in 2-3 shots but to be sure to check your gas rings after that for any junk that found it's way in. The barrels were a very good price so I took a chance and got one. Ruined a couple brushes trying to remove it and finally just took his advise and shot it. 1st shot and the burr was gone. That barrel was one of the more accurate barrels I've owned. Bench rest with matchkings it would put them in the same ragged hole. When drilling the port start small as the bit will usually drill oversize. Then go up in size which will leave the burr much thinner. Out of the gas op barrels I've made only pistol cartridges like the 9mm and 45ACP took more than 1-2 rounds to remove any gas port burr. I consider it a non issue. Torque range for the barrel extension. I know guys that go as low as 80ftlbs, and as high as 150ftlbs. At 80 you're pretty close to the upper limit of the handguard torque range. I torque mine at 125ftlbs. You're basically just not wanting it to come loose. Buying a barrel is a good option and I still buy barrels, but enjoy making finished barrels from blanks. If it were me and I had a lathe, I'd figure out a good straight walled case and see if I could make it cheaper or buy it cheaper. If you're not set up to make a barrel there will be some effort making or buying the vise and wrench. Barrel vises are easy to make and the wrench can be had for $50 or made for a few dollars. I bought the ar15 wrench, but made my ar10 wrench. A simple version is basically a plus shaped profile and will work. A straight walled chamber reamer is easy enough to make. I make mine with 6 flutes as I find turning the blank to be more of a challenge than fluting it. For a one time use a D reamer will work fine. You aren't removing a great deal of metal with a straight walled cartridge. You can get the chamber dimensions for many cartridges off of the SAAMI website. Another option is buying one and selling it on ebay. They often sell for almost what a new one goes for. Many of my relatives and friends don't reload and want something they can buy ammo for. We've been looking at the 450BM as an option for them. Perhaps after deer season I'll make a reamer for it. $45 blank, $20 barrel extension, a little shop time and the end result is a $65 barrel. It's not for everyone though.

[vzerone]

You're overthinking this, it isn't a Camp Perry match gun. The vast majority of production semiauto barrels don't have the gas port timed to the grooves. For gas tube lengths you can compare a QuickLoad graph of your proposed cartridges pressure by the inch of barrel compared to a 223 graph will tell you which gas tube length will work the best. Barring that there are enough similar cartridges out there that you could just look and compare. Funny thing about the gas port burr. Years ago when the guys at Eagle arms were just starting up they went around to the gun shows selling barrels (new and test) as well as uppers, parts and complete guns. Looking at one of their extra heavy DCM match barrels (had a groove for the gas tube) I noticed they all had a huge flap where the gas ports were. I asked and the guy picked one up and looked. He said they all have that burr until they're shot the first time. Said it would disappear in 2-3 shots but to be sure to check your gas rings after that for any junk that found it's way in. The barrels were a very good price so I took a chance and got one. Ruined a couple brushes trying to remove it and finally just took his advise and shot it. 1st shot and the burr was gone. That barrel was one of the more accurate barrels I've owned. Bench rest with matchkings it would put them in the same ragged hole. When drilling the port start small as the bit will usually drill oversize. Then go up in size which will leave the burr much thinner. Out of the gas op barrels I've made only pistol cartridges like the 9mm and 45ACP took more than 1-2 rounds to remove any gas port burr. I consider it a non issue. Torque range for the barrel extension. I know guys that go as low as 80ftlbs, and as high as 150ftlbs. At 80 you're pretty close to the upper limit of the handguard torque range. I torque mine at 125ftlbs. You're basically just not wanting it to come loose. Buying a barrel is a good option and I still buy barrels, but enjoy making finished barrels from blanks. If it were me and I had a lathe, I'd figure out a good straight walled case and see if I could make it cheaper or buy it cheaper. If you're not set up to make a barrel there will be some effort making or buying the vise and wrench. Barrel vises are easy to make and the wrench can be had for $50 or made for a few dollars. I bought the ar15 wrench, but made my ar10 wrench. A simple version is basically a plus shaped profile and will work. A straight walled chamber reamer is easy enough to make. I make mine with 6 flutes as I find turning the blank to be more of a challenge than fluting it. For a one time use a D reamer will work fine. You aren't removing a great deal of metal with a straight walled cartridge. You can get the chamber dimensions for many cartridges off of the SAAMI website. Another option is buying one and selling it on ebay. They often sell for almost what a new one goes for. Many of my relatives and friends don't reload and want something they can buy ammo for. We've been looking at the 450BM as an option for them. Perhaps after deer season I'll make a reamer for it. $45 blank, $20 barrel extension, a little shop time and the end result is a $65 barrel. It's not for everyone though.

So you made some gas op 9mm and 45acp huh? Why didn't you just go blowback? Being that 9mm doesn't make that much volume of gas you had to have that port hole very close to the chamber end?

[Tripplebeards]

They have complete bushmaster uppers chambered in 450 bushmaster for $599 at midway USA right now in 16" and 20" barrels. Plug n play. If you check out some of my old posts I've been getting as tight as 1.1" groups with Lee 300g out of my ruger American 450 BM. All the big bore chamberings do about the same it just depends what you like. Finding brass is going to be the hardest part. 450 BM is probably going to be the easiest brass to find and cheaper compared to the other ar15 size big bore calibers.

[dragon813gt]

450 BM is probably going to be the easiest brass to find and cheaper compared to the other ar15 size big bore calibers.

They're all easy to find: https://www.starlinebrass.com

It's just that people don't like paying for new brass. Play w/ oddballs and be prepared to pay for brass.

[Moleman-]

So you made some gas op 9mm and 45acp huh? Why didn't you just go blowback? Being that 9mm doesn't make that much volume of gas you had to have that port hole very close to the chamber end?

They seem smoother to shoot sort of like how an MP5 is more manageable than most 9mm smg's. Used straight gas tube around an inch in front of the chamber. 9x19 is short enough that an empty case will start turning sideways between the chamber and front side of the barrel extension lugs. You can either ballance the ejector spring and gas to get reliable ejection or add a rail where the ejector lug would ride to keep the case from tipping until it is clear from the extension.

If going with 450BM: $20 barrel extension;$45 http://www.gmriflebarrel.com/45-blan...ion-raw-blank/ ; 450 uppers around $50 stripped and another $15 to complete; bolt carrier group $100; gas block $20; gas tube $10; handguard $50 to as much as you want to spend; muzzle break $15 to as much as you want to spend. Figure $325 at the low (would be nice to add in a $15 charging handle but you already have one) end and some of your time. If you went with a 357AR you could use your same BCG but would spend closer to $100 on a blank. So figure $290 low end. Scope and mounts can be as little or as much as you want to spend. Ebay has some decent cheap ar15 scope mounts. The one on my sons rifle was $15 shipped and has held up for a couple years of hunting without issue. He has a vortex scope that was around $100 and I have nikons that were about the same.

[vzerone]

They seem smoother to shoot sort of like how an MP5 is more manageable than most 9mm smg's. Used straight gas tube around an inch in front of the chamber. 9x19 is short enough that an empty case will start turning sideways between the chamber and front side of the barrel extension lugs. You can either ballance the ejector spring and gas to get reliable ejection or add a rail where the ejector lug would ride to keep the case from tipping until it is clear from the extension.

If going with 450BM: $20 barrel extension;$45 http://www.gmriflebarrel.com/45-blan...ion-raw-blank/ ; 450 uppers around $50 stripped and another $15 to complete; bolt carrier group $100; gas block $20; gas tube $10; handguard $50 to as much as you want to spend; muzzle break $15 to as much as you want to spend. Figure $325 at the low (would be nice to add in a $15 charging handle but you already have one) end and some of your time. If you went with a 357AR you could use your same BCG but would spend closer to $100 on a blank. So figure $290 low end. Scope and mounts can be as little or as much as you want to spend. Ebay has some decent cheap ar15 scope mounts. The one on my sons rifle was $15 shipped and has held up for a couple years of hunting without issue. He has a vortex scope that was around $100 and I have nikons that were about the same.

I like CMMG's AR45. They use what they call a delayed blow-back. The lugs on the bolt and the barrel extension are angles (to mate) and this delays the action. They claim the gun runs cleaner internally then straight blow-back and isn't a finicky as DI can be with pistol cartridges.

[rockrat]

I also use the Lee boolit in my 450 , but size it to .453". I haven't had problems with my uppers working with one lower , but not another.

[seetrout]

No need to overthink this. Couldn't a competent machinist be able to enlarge the pivot hole on a new complete upper to match the large pin lower he already owns.
Hey. I'll bet somebody here is a competent machinist who could go into business part time doing this.