Glocks have polygonal rifling, which doesn't work as well for most folks, when using lead bullets. The aftermarket barrels have conventional rifling and are recommended. Also, you will need a heavier recoil spring to shoot the hot, heavy loads.

Personally, I cannot see an advantage to having a 10mm that converts to .45 ACP. The 10mm is an excellent performer as a hunting round or self defense round, depending on how you set it up and what ammo you use. I love .45's, but can't imagine that I would downgrade from a 10mm to it, when the 10mm is such a fine chambering.

Originally Posted by Bisley

Glocks have polygonal rifling, which doesn't work as well for most folks, when using lead bullets. The aftermarket barrels have conventional rifling and are recommended. Also, you will need a heavier recoil spring to shoot the hot, heavy loads.

Personally, I cannot see an advantage to having a 10mm that converts to .45 ACP. The 10mm is an excellent performer as a hunting round or self defense round, depending on how you set it up and what ammo you use. I love .45's, but can't imagine that I would downgrade from a 10mm to it, when the 10mm is such a fine chambering.

My thought that having a .45 that converts to a 10mm would give more flexibility as I could shoot .45acp as well as 10mm. I am going to need a new barrel for the G20 to shoot the Heavy Loads so why not start with a G21 that can shoot 10mm with a new barrel. I need one anyway.

Am I missing something?

I get it, now. I wasn't even aware that the barrels and magazines would interchange, until you posted, and I own a G20.

If that is the case, it sounds like a cost-efficient plan.

Originally Posted by JohnCiccarelli

Please don't beat me up to bad. I am new to handguns and this seems to be my best option.

Thank for any thoughts, John

Your best option for what?

Originally Posted by VAMarine

Your best option for what?

It gives me the ability to shoot both .45acp and 10 mm ammo. I am new to handguns and thought the flexibility to use both instead of just using 10mm would be a plus. I will need an after market barrel to shoot the Heavy Double Tap ammo anyway.

Originally Posted by JohnCiccarelli

It gives me the ability to shoot both .45acp and 10 mm ammo. I am new to handguns and thought the flexibility to use both instead of just using 10mm would be a plus. I will need an after market barrel to shoot the Heavy Double Tap ammo anyway.

I understand the reasoning behind those options, but why in the world is someone new to handguns getting one of the largest polymer frame guns to convert to one of the hardest hitting, harder to handle cartridges? It does not sound like a recipe for success as far as honing shooting skill.

Originally Posted by VAMarine

I understand the reasoning behind those options, but why in the world is someone new to handguns getting one of the largest polymer frame guns to convert to one of the hardest hitting, harder to handle cartridges? It does not sound like a recipe for success as far as honing shooting skill.

I am in agreement with you on this one. If you want to get into handguns I recommend starting with a 9mm. The glock series (Generation 3) 9mm guns are excellent and if you think that a 9mm wont stop or kill your attacker that is just incorrect. I have personally seen people killed by a 9mm Berretta with ball rounds in Iraq and it worked mighty well. I can even show you pictures...

My point is you need to hit where you want to hit and that's what REALLY matters. A .45 might blow my hand to crap but I got another one, so if you don't hit me center mass I'm still in the fight at least til I bleed out. You hit me in the lungs, heart, head with a 9mm, 10mm, .45 I'm done for. That being said, caliber choice is a personal preference and no matter what you choose you need to understand pistol marksmanship. This is most easily and economically done with the 9mm round. After you become proficient you can then make a decision on your actual caliber choice.

For me 45's are just too darn big. I'm a bit of a skinny dude and in order to conceal a 45 I would be limited to about 5 rounds capacity - not enough for me. 10mm aren't as easy to find as 9mm. The 9mm is the best introduction to pistols and is the preferred choice of many experienced gun owners. If you can't hit what you aim at then caliber choice means nothing.

My recommendation is a 9mm. Get good with it, then go on to see if you like other calibers better. The thing about caliber choice is that there's a lot of "technical" differences and scientific analysis saying basically that "bigger rounds are better". I agree that if I had a choice I'd want to get hit with a 9mm rather than a 45, but if it's in a vital area it doesn't really matter - I'm dead either way so to me if you can aim and are proficient with your pistol it doesn't matter what size rounds you use. (not trying to offend anyone and their caliber choice, trying to do the opposite actually)

Okay, the actual question: Yes, the conversion barrels work very well, and you don't need heavier springs. I converted a G21SF to 10mm and it works fine. Lone Wolf doesn't make one, but KKM does.

Originally Posted by VAMarine

I understand the reasoning behind those options, but why in the world is someone new to handguns getting one of the largest polymer frame guns to convert to one of the hardest hitting, harder to handle cartridges? It does not sound like a recipe for success as far as honing shooting skill.

I don't mean to sound disrespectful, but I want a hard hitting gun in case I need the stopping power against a bear in the woods. I also thought that some flexibility might help me learn. I am not new to shooting, but I am new to handguns.

I bought a Glock 21 today and plan to spend some time shooting it with 45ACP. I also am getting a 22 Ruger from my dad and will be be shooting it a lot.

I will be getting a conversion barrel for the g21 for practice and when I will be in the woods. I really want the stopping power of the hot load 10mm when I may come across a bear. I will also be carrying a 12 Gauge and pepper spray. My wife thinks that I am over doing it, but I would rather be prepared.

Please do not misunderstand my intent. I will spend as much time as I need to be comfortable with anything that I will carry.

Originally Posted by HK Dan

Okay, the actual question: Yes, the conversion barrels work very well, and you don't need heavier springs. I converted a G21SF to 10mm and it works fine. Lone Wolf doesn't make one, but KKM does.

If he intends to use a steady diet of Doubletap 230 gr. Hardcasts, I think he will need the 22 lb. spring.

Originally Posted by Bisley

If he intends to use a steady diet of Doubletap 230 gr. Hardcasts, I think he will need the 22 lb. spring.

I will want to use what ever works the best. I do not plan to use a steady diet of anything. I just want to be ready for what I may find in the woods.

I carry my G20 when in the woods, mostly when squirrel hunting. While slipping around quietly in the river bottoms, with the wind in my face, I have accidentally sneaked up on large feral hogs, and not wishing to 'engage' them with a bolt-action .22 rifle, I usually just 'un-sneak' myself quietly back to where I came from. Also, I have had brief glimpses of large cats with long tails that I cannot identify, and that is very creepy when you are alone and weakly armed.

This hasn't happened since I started carrying the 10mm, so I haven't put it to the test to discover what ammo to use. So far, I'm still using the 180 gr. FMJ that I practice with, but if that doesn't get the job done, it's nice to know I can upgrade to considerably more power, for not a lot of cash.

Mainly, I just wanted a 10mm, and this was the best excuse I could come up with to justify the purchase.

I just got my KKM 10mm Conversion Barrel for my Glock 21. Using standard ammo it seems more accurate then shooting 45s through my Wilson Barrel. The recoil also does not seem much different. So far I am pleased. I did not change anything else. Kevin at KKM says to modify the extractor.

My question is how do I know what recoil spring I have and what would be different if I change to a heavier one?