flyandscuba
Master
I like to engage in handgun projects from time to time. In the past, I have converted a Sig Arms Mauser M2 from 40 S&W to 10mm Auto -- as well as converted a new production (High Standard) AMT Back-up pistol from 40 S&W to 10mm Auto (talk about a hand cannon!).
Currently, my project is to convert a S&W SW99 chambered in 45 ACP to fire 460 Rowland. S&W only made the SW99 for a short time as a joint project with Walther -- and the 45 ACP version only a brief portion of that time. So, the SW99s in 45 ACP aren't too common - but they can be found at a decent price ($300-$500 depending upon condition). However, S&W still supports the line with spare parts. My extra barrel arrived in the mail from S&W today -- and I have replacement small and large backstraps on the way.
Reaming the chamber of the barrel to accept the slightly longer 460 Rowland cartridge isn't all that difficult. The main concern in the conversion is to find a way to slow down the slide velocity during recoil to prevent accelerated wear or damage to the slide or frame of the pistol. The stock guide rod is polymer and the weight of the recoil spring is 14 pounds. I am having a new stainless steel guide rod made by BT Guide Rods ( http://btguiderods.com/ ), and I obtained a 24 pound extra power recoil spring for a S&W M&P 45 from Wolff Gun Springs to use in the SW99. I'm hoping that that will do the trick. However, most 460 Rowland conversions involve either porting the barrel or adding a compensator.
I despise ported barrels -- especially on a handgun that may be used for self defense (in this case -- as a woods gun against 4-legged predators with big teeth and claws). I have no idea if S&W would make an extended length barrel for me that could be threaded for a compensator -- but I plan to ask, even though I've already bought a spare stock length barrel from them.
For those who are not familiar with the 460 Rowland cartridge. It was considered a wildcat cartridge for hand loaders until ammo makers like Buffalo Bore, Double Tap, and now Underwood began to offer factory loaded cartridges. Essentially, it is a slightly lengthened 45 ACP case (so it can't be chambered in unmodified pistols) with a stronger area in the base/webbing of the case. The bullet is seated further into the case in order to retain the same OAL as 45 ACP -- so that the conventional 45 ACP magazines can be used and no modifications to the pistol frame or magazine well are required.
Of course, the 460 Rowland cartridge is loaded to a higher pressure. The hierarchy of 45 case lengths are as follows 45 GAP, 45 ACP/45Super, 460 Rowland, and finally 45 Winchester Magnum. 45 GAP and 45 ACP offer essentially identical ballistic performance in "standard" pressure loads. The 45 Super has the same external dimensions as the 45 ACP, but the casing is strengthened at the base/webbing to handle higher pressure. Think of the 45 Super as being a 45 ACP +P+ loading. I have successfully used 45 Super in unmodified firearms chambered in 45 ACP such as my Springfield XDS and HK USP Tactical.
460 Rowland is loaded to a much higher pressure than the 45 Super -- and it produces ballistics equal to mid-range 44 Magnum loads. Therefore, with a pistol converted to 460 Rowland -- you can get true 44 Magnum performance from a combat-sized semi-auto pistol, holding more magazine capacity. In the case of the SW99, I will have a 9+1 capacity in a relatively lightweight and slim pistol for woods carry. The semi-auto mechanism makes shooting much more comfortable (think shooting 357 Magnum from a snubbie compared to firing 357 Sig from a G33) than a 44 Magnum revolver.
As for the 45 Win Mag -- it is a monster that requires a monster of a handgun!
For other pistol conversion options to 460 Rowland, visit http://460rowland.com/
Here are some example pressures and ballistics for the various 45 caliber pistol cartridges (Underwood Ammunition)
Cartridge Bullet Weight Chamber Pressure Muzzle Velocity Muzzle Energy
45 GAP 230gr 23,000 900fps 414ft/lbs
45 ACP 230gr 21,000 900fps 414ft/lbs
45 ACP+P 230gr 23,000 1000fps 511ft/lbs
45 Super 230gr 28,500 1100fps 618ft/lbs
460 Rowland 230gr 40,000 1350fps 931ft/lbs
45 Win Mag 230gr 46,500 1600fps 1,307ft/lbs
In comparison, here are Underwood's comperable 44 Magnum loads to 460 Rowland:
44 Magnum 240gr 1400fps 1,045ft/lbs
44 Magnum 300gr 1200fps 959ft/lbs.
Although I plan to ream one barrel to accept the 460 Rowland cartridge -- and keep one barrel chambered in 45 ACP, I have seen other 460 Rowland shooters successfully shoot 45 ACP through their pistol without changing the barrel because the extractor is strong enough to hold the cartridge at the proper position without headspacing on the case head. I do not advocate doing this -- but in a pinch (say to save your life or provide food in a survival situation), it could be done.
My next step while waiting for the guide rod to show up -- is to order some 460 Rowland ammunition from Underwood and take the barrel to Phil at Jay's guns to have the chamber reamed to 460 Rowland specifications (unless someone here has a 45 ACP chamber reamer that they would allow me to rent/borrow). I plan to update this thread with the progress of the project -- as well as range reports (good, bad, or disasterous) along the way.
Let me know what you think!
For now, here is the project's base pistol that I picked up on gunbroker for $340:
Currently, my project is to convert a S&W SW99 chambered in 45 ACP to fire 460 Rowland. S&W only made the SW99 for a short time as a joint project with Walther -- and the 45 ACP version only a brief portion of that time. So, the SW99s in 45 ACP aren't too common - but they can be found at a decent price ($300-$500 depending upon condition). However, S&W still supports the line with spare parts. My extra barrel arrived in the mail from S&W today -- and I have replacement small and large backstraps on the way.
Reaming the chamber of the barrel to accept the slightly longer 460 Rowland cartridge isn't all that difficult. The main concern in the conversion is to find a way to slow down the slide velocity during recoil to prevent accelerated wear or damage to the slide or frame of the pistol. The stock guide rod is polymer and the weight of the recoil spring is 14 pounds. I am having a new stainless steel guide rod made by BT Guide Rods ( http://btguiderods.com/ ), and I obtained a 24 pound extra power recoil spring for a S&W M&P 45 from Wolff Gun Springs to use in the SW99. I'm hoping that that will do the trick. However, most 460 Rowland conversions involve either porting the barrel or adding a compensator.
I despise ported barrels -- especially on a handgun that may be used for self defense (in this case -- as a woods gun against 4-legged predators with big teeth and claws). I have no idea if S&W would make an extended length barrel for me that could be threaded for a compensator -- but I plan to ask, even though I've already bought a spare stock length barrel from them.
For those who are not familiar with the 460 Rowland cartridge. It was considered a wildcat cartridge for hand loaders until ammo makers like Buffalo Bore, Double Tap, and now Underwood began to offer factory loaded cartridges. Essentially, it is a slightly lengthened 45 ACP case (so it can't be chambered in unmodified pistols) with a stronger area in the base/webbing of the case. The bullet is seated further into the case in order to retain the same OAL as 45 ACP -- so that the conventional 45 ACP magazines can be used and no modifications to the pistol frame or magazine well are required.
Of course, the 460 Rowland cartridge is loaded to a higher pressure. The hierarchy of 45 case lengths are as follows 45 GAP, 45 ACP/45Super, 460 Rowland, and finally 45 Winchester Magnum. 45 GAP and 45 ACP offer essentially identical ballistic performance in "standard" pressure loads. The 45 Super has the same external dimensions as the 45 ACP, but the casing is strengthened at the base/webbing to handle higher pressure. Think of the 45 Super as being a 45 ACP +P+ loading. I have successfully used 45 Super in unmodified firearms chambered in 45 ACP such as my Springfield XDS and HK USP Tactical.
460 Rowland is loaded to a much higher pressure than the 45 Super -- and it produces ballistics equal to mid-range 44 Magnum loads. Therefore, with a pistol converted to 460 Rowland -- you can get true 44 Magnum performance from a combat-sized semi-auto pistol, holding more magazine capacity. In the case of the SW99, I will have a 9+1 capacity in a relatively lightweight and slim pistol for woods carry. The semi-auto mechanism makes shooting much more comfortable (think shooting 357 Magnum from a snubbie compared to firing 357 Sig from a G33) than a 44 Magnum revolver.
As for the 45 Win Mag -- it is a monster that requires a monster of a handgun!
For other pistol conversion options to 460 Rowland, visit http://460rowland.com/
Here are some example pressures and ballistics for the various 45 caliber pistol cartridges (Underwood Ammunition)
Cartridge Bullet Weight Chamber Pressure Muzzle Velocity Muzzle Energy
45 GAP 230gr 23,000 900fps 414ft/lbs
45 ACP 230gr 21,000 900fps 414ft/lbs
45 ACP+P 230gr 23,000 1000fps 511ft/lbs
45 Super 230gr 28,500 1100fps 618ft/lbs
460 Rowland 230gr 40,000 1350fps 931ft/lbs
45 Win Mag 230gr 46,500 1600fps 1,307ft/lbs
In comparison, here are Underwood's comperable 44 Magnum loads to 460 Rowland:
44 Magnum 240gr 1400fps 1,045ft/lbs
44 Magnum 300gr 1200fps 959ft/lbs.
Although I plan to ream one barrel to accept the 460 Rowland cartridge -- and keep one barrel chambered in 45 ACP, I have seen other 460 Rowland shooters successfully shoot 45 ACP through their pistol without changing the barrel because the extractor is strong enough to hold the cartridge at the proper position without headspacing on the case head. I do not advocate doing this -- but in a pinch (say to save your life or provide food in a survival situation), it could be done.
My next step while waiting for the guide rod to show up -- is to order some 460 Rowland ammunition from Underwood and take the barrel to Phil at Jay's guns to have the chamber reamed to 460 Rowland specifications (unless someone here has a 45 ACP chamber reamer that they would allow me to rent/borrow). I plan to update this thread with the progress of the project -- as well as range reports (good, bad, or disasterous) along the way.
Let me know what you think!
For now, here is the project's base pistol that I picked up on gunbroker for $340:
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