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Old 08-21-2013, 20:36   #26
GRT45
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Originally Posted by Roger G23 View Post
Man. If I want to modify my G21SF to shoot .45 Super and .40 Super I hope the G21 slide can handle those pressures. You may know, .40 Super surpasses 10mm velocities and muzzle energy.
There is no need to worry about the structural integrity of the G21 slide with .45 Super or .40 Super affecting the safe operation. The added mass of the G20 slide was left there to slow the recoil reaction (unlocking) for the higher energy 10mm round and to attenuate felt recoil, but not as a structural requirement for safe operation. You must contend with a higher slide velocity with the G21 slide, of course, and mass is king, but that can be partially compensated for with a stronger recoil spring in the G21 slide to absorb some of the additional kinetic energy. Nevertheless, the felt recoil with the converted G21 will always be a bit more than a G20 with the same recoil spring and choice of ammo.

I've made the conversions with a G30 pistol with no ill effects. However, in the case of .40 Super and .460 Rowland it was necessary to include threaded barrels and a compensator in order to add mass and delay unlocking with the lighter slide. That will not be necessary for the G21 converted to shoot .45 Super or .40 Super.

You might enjoy watching the two excellent videos below produced by Ammo Test on YouTube if you haven't seen them already. Ammo Test is registered at Glock Talk with the user name icelandicstud.

Glock 21 45 Super Ammo Test - Accuracy, Velocity, Recoil

Glock 21 40 Super Ammo Test - Accuracy, Velocity, Recoil
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Last edited by GRT45; 08-21-2013 at 21:58..
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Old 08-21-2013, 22:36   #27
Roger G23
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Originally Posted by GRT45 View Post
There is no need to worry about the structural integrity of the G21 slide with .45 Super or .40 Super affecting the safe operation. The added mass of the G20 slide was left there to slow the recoil reaction (unlocking) for the higher energy 10mm round and to attenuate felt recoil, but not as a structural requirement for safe operation. You must contend with a higher slide velocity with the G21 slide, of course, and mass is king, but that can be partially compensated for with a stronger recoil spring in the G21 slide to absorb some of the additional kinetic energy. Nevertheless, the felt recoil with the converted G21 will always be a bit more than a G20 with the same recoil spring and choice of ammo.

I've made the conversions with a G30 pistol with no ill effects. However, in the case of .40 Super and .460 Rowland it was necessary to include threaded barrels and a compensator in order to add mass and delay unlocking with the lighter slide. That will not be necessary for the G21 converted to shoot .45 Super or .40 Super.

You might enjoy watching the two excellent videos below produced by Ammo Test on YouTube if you haven't seen them already. Ammo Test is registered at Glock Talk with the user name icelandicstud.

Glock 21 45 Super Ammo Test - Accuracy, Velocity, Recoil

Glock 21 40 Super Ammo Test - Accuracy, Velocity, Recoil
Really appreciate the info. and reassurance. I have just recently (two days ago) seen his videos. It's actually what sparked my interest in this. I subscribed to his channel and asked him some questions. He has been extremely generous and helpful in sharing his knowledge about the subject. A real stand up guy.
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Old 08-22-2013, 11:39   #28
Arnold Kuhl
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GRT: Am interested in trying out the .45 Super, preferably 230gr., in my G21SF. I have a KKM 4.6" bbl, and have ordered a combo kit from Wolff. It's a 22 lb. recoil spring and stainless steel guide rod.

Is this suitable in YHO, or do you think I should go with an increased power spring (24 lb.) or a reduced power spring (20 lb.)? Also, do I need a shock buffer?

Thanks for your input. Never shot .45 Super before.

AK
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Old 08-22-2013, 12:19   #29
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Originally Posted by Arnold Kuhl View Post
GRT: Am interested in trying out the .45 Super, preferably 230gr., in my G21SF. I have a KKM 4.6" bbl, and have ordered a combo kit from Wolff. It's a 22 lb. recoil spring and stainless steel guide rod.

Is this suitable in YHO, or do you think I should go with an increased power spring (24 lb.) or a reduced power spring (20 lb.)? Also, do I need a shock buffer?

Thanks for your input. Never shot .45 Super before.

AK
The Wolff guide rod and 22 lb. recoil spring will be good with the G21SF and .45 Super. Wolff spring ratings are accurate and something in the 21-23 lb. range from Wolff works best for me with the Underwood 45 Super 230gr Speer Bonded JHP ammo. In comparison to Wolff, the strength of ISMI springs tend to measure less than their stated ratings in my experience. I'm running a Wolff 21 lb. dual recoil spring set in my Gen4 G30 for 45 Super now.

One can overdo recoil spring strength, so it shouldn't be assumed that the stronger the spring the better. Felt recoil will increase with a stronger recoil spring and one that is too strong will induce failure-to-feed malfunctions with weak loads in practice ammo. A Wolff 22 lb spring is a good compromise for the Gen3 G21.

I don't recommend a shock buffer for this application in a Glock. The G21 polymer frame can handle 45 Super no problem. I don't favor tinkering with the interior clearances by introducing a part that isn't durable or required.
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Last edited by GRT45; 09-10-2013 at 17:40..
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Old 08-22-2013, 12:48   #30
Arnold Kuhl
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The Wolff spring and rod should get here anytime now. Only problem is Underwood .45Super ammo is still out of stock, and I don't want to break the bank by paying more than a dollar per round someplace else.

Thanks for the feedback.
AK
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Old 08-22-2013, 16:16   #31
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Originally Posted by Arnold Kuhl View Post
The Wolff spring and rod should get here anytime now. Only problem is Underwood .45Super ammo is still out of stock, and I don't want to break the bank by paying more than a dollar per round someplace else.

Thanks for the feedback.
AK
I've got good news for you. Look what just came in.

http://www.midwayusa.com/product/974...cket-box-of-50
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Old 08-22-2013, 16:20   #32
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Originally Posted by GRT45 View Post
The Wolff guide rod and 22 lb. recoil spring will be good with the G21SF and .45 Super. Wolff spring ratings are accurate and something in the 21-23 lb. range from Wolff works best for me with the Underwood 45 Super 230gr Speer Bonded JHP ammo. In comparison to Wolff, the strength of ISMI springs tend to measure less than their stated ratings in my experience. I'm running a Wolff 21 lb. dual recoil spring set in my Gen4 G30 for 45 Super now.

One can overdo recoil spring strength, so it shouldn't be assumed that the stronger the spring the better. Felt recoil will increase with a stronger recoil spring and one that is too strong will induce failure-to-feed malfunctions with weak loads in practice ammo. A Wolff 22 lb spring is a good compromise for the G21.

I don't recommend a shock buffer for this application in a Glock. The G21 polymer frame can handle 45 Super no problem. I don't favor tinkering with the interior clearances by introducing a part that isn't durable or required.
Really value your points here. Two days ago I ordered a 24 lb. Wolff spring. I'll just exchange it for a 22 lb. once it arrives.
Question: Do the striker springs that come with the "combo pack" correlate to the specific weight also? Is using an extra power striker spring also very important?
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Old 08-22-2013, 16:28   #33
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Originally Posted by GRT45 View Post
The Wolff guide rod and 22 lb. recoil spring will be good with the G21SF and .45 Super. Wolff spring ratings are accurate and something in the 21-23 lb. range from Wolff works best for me with the Underwood 45 Super 230gr Speer Bonded JHP ammo. In comparison to Wolff, the strength of ISMI springs tend to measure less than their stated ratings in my experience. I'm running a Wolff 21 lb. dual recoil spring set in my Gen4 G30 for 45 Super now.

One can overdo recoil spring strength, so it shouldn't be assumed that the stronger the spring the better. Felt recoil will increase with a stronger recoil spring and one that is too strong will induce failure-to-feed malfunctions with weak loads in practice ammo. A Wolff 22 lb spring is a good compromise for the G21.

I don't recommend a shock buffer for this application in a Glock. The G21 polymer frame can handle 45 Super no problem. I don't favor tinkering with the interior clearances by introducing a part that isn't durable or required.
Although, I am going to modify (bought LWD 45-40S barrel) the G21SF to shoot .40 Super too.
Do you think the 22lb. spring will be OK for this "hotter" caliber? Or hold on to the 24lb. spring for .40 Super?
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Old 08-22-2013, 16:33   #34
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Originally Posted by Arnold Kuhl View Post
Only problem is Underwood .45Super ammo is still out of stock, and I don't want to break the bank by paying more than a dollar per round someplace else.
This Underwood XTP JHP offering, currently in stock, will do the job if the 230gr Speer Bonded JHP is out of stock. It's rated at 1100 fps and the price is 84/rnd. I may pick up a box or two myself.

45 Super 230 Grain XTP Jacketed Hollow Point Box of 50
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Last edited by GRT45; 08-22-2013 at 16:34..
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Old 08-22-2013, 16:55   #35
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Originally Posted by Roger G23 View Post
Although, I am going to modify (bought LWD 45-40S barrel) the G21SF to shoot .40 Super too.
Do you think the 22lb. spring will be OK for this "hotter" caliber? Or hold on to the 24lb. spring for .40 Super?
Hold on to your Wolff 24 lb. recoil spring when it comes in for the .40 Super conversion. I think you will appreciate having the 24 lb spring with the 40 Super barrel without a compensator. The 24 lb. RSA will work with .45 Super ammo although it may kick a bit harder, assuming you will be shooting full-power 45 Super ammo. You will probably find it necessary/desirable to reinstall the factory RSA when shooting low-power 45ACP practice ammo for plinking.
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Old 08-22-2013, 17:06   #36
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Question: Do the striker springs that come with the "combo pack" correlate to the specific weight also? Is using an extra power striker spring also very important?
Wolff includes a stock 5-lb. firing pin spring with their recoil springs. Just keep them for spare parts. Here is the statement from the Gunsprings.com website:
"Wolff recoil springs for use in Glock pistols are available with load-rated specifications to tailor the recoil function to individual needs. Due to the design of the Glock pistol, all Glock recoil springs now include a factory strength replacement striker spring."
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Old 08-22-2013, 17:07   #37
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Originally Posted by GRT45 View Post
Hold on to your Wolff 24 lb. recoil spring when it comes in for the .40 Super conversion. I think you will appreciate having the 24 lb spring with the 40 Super barrel without a compensator. The 24 lb. RSA will work with .45 Super ammo although it may kick a bit harder, assuming you will be shooting full-power 45 Super ammo. You will probably find it necessary/desirable to reinstall the factory RSA when shooting low-power 45ACP practice ammo for plinking.
I'll be shooting Underwood and Buffalo Bore in both calibers.
I got a LWD threaded barrel and LWD compensator for the .45 Super and a LWD 6'' 45-40S barrel.
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Old 08-22-2013, 17:09   #38
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Originally Posted by GRT45 View Post
Wolff includes a stock 5-lb. firing pin spring with their recoil springs. Just keep them for spare parts. Here is the statement from the Gunsprings.com website:
"Wolff recoil springs for use in Glock pistols are available with load-rated specifications to tailor the recoil function to individual needs. Due to the design of the Glock pistol, all Glock recoil springs now include a factory strength replacement striker spring."
Wow, OK. Just keep the stock striker spring in place.
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Old 08-22-2013, 17:17   #39
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Wow, OK. That being said...do they even make "extra power" striker springs? Do I need to find and order them shooting these calibers?
Glock does make a 28 Newton (6.29 lbf - red) and 31 Newton (7 lbf - blue) firing pin spring for special purpose ammo with extremely hard primers. These extra-power springs are not necessary (or desirable) for the caliber conversions you have planned.
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Old 08-22-2013, 17:20   #40
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Originally Posted by GRT45 View Post
Glock does make a 28 Newton (6.29 lbf - red) and 31 Newton (7 lbf - blue) firing pin spring for special purpose ammo with extremely hard primers. These extra-power springs are not necessary (or desirable) for the caliber conversions you have planned.
I see you shoot the G30. I heard factory mag springs feed .45 Super fine. Do you know if that's the case with the G21 also or do I need Wolff extra power mag springs?
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Old 08-22-2013, 18:06   #41
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Thanks, GRT. I just ordered some, along with some .45ACP+P and 9mm+P SD loads. Of course, my life will be instantly and unceremoniously terminated, not if, but when my wife discovers I bought more GUN STUFF!

AK

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Old 08-22-2013, 18:16   #42
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Originally Posted by Roger G23 View Post
I see you shoot the G30. I heard factory mag springs feed .45 Super fine. Do you know if that's the case with the G21 also or do I need Wolff extra power mag springs?
The factory mag spring (in good condition) is sufficient for .45 Super and the G21 with 22-lb. RSA. I've tested that config extensively in preparing a friend's G21 pistol with good results and have read of similar success by others. I use Wolff extra-power mag springs for .460 Rowland, but don't find it necessary for .45 Super.

However, be forewarned about a possible problem feeding .40 Super from the G21 13-rnd mags. If you're not already aware of the possible nose dive issue causing failure-to-feed malfunctions, be sure to watch this video recently published in July by Ammo Test on YouTube: Glock 21 40 Super 13rd Mag Fix

Prior to this fix discussed by Ammo Test, the typical solution to avoid nose dive problems was to use 10-rnd, single stack G21 mags for 40 Super. I haven't encountered this problem with my Gen4 G30 10-rnd mags and 40 Super, but be aware it may crop up with G21 13-rnd mags.
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Last edited by GRT45; 08-22-2013 at 18:38..
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Old 08-22-2013, 18:38   #43
Roger G23
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Originally Posted by GRT45 View Post
The factory mag spring (in good condition) is sufficient for .45 Super and the G21 with 22-lb. RSA. I've tested that config extensively in preparing a friend's G21 pistol with good results and have read of similar success by others. I use Wolff extra-power mag springs for .460 Rowland, but don't find it necessary for .45 Super.

However, be forewarned about a possible problem feeding .40 Super from the G21 13-rnd mags. If you're not already aware of the possible nose dive issue causing failure-to-feed malfunctions, be sure to watch this video recently published in July by Ammo Test on YouTube: Glock 21 40 Super 13rd Mag Fix

Prior to this fix discussed by Ammo Test, the typical solution to avoid nose dive problems was to use 10-rnd, single stack G21 mags for 40 Super. I haven't encountered this problem with my Gen4 G30 10-rnd mags and 40 Super, but be aware it may crop up with your G21 13-rnd mags.
Really thank you for all the info. Found your link here regarding your G30 very interesting. You clearly are one we all learn from and appreciate your generosity.
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Old 08-22-2013, 18:59   #44
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You're welcome and I'm glad that some of the information provided was useful to you.
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