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Old 05-15-2012, 14:15   #4
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Join Date: Jun 2010
Location: Texas
Posts: 2,952
Converting the Glock 30 to 10mm Caliber

A Glock 29 10mm factory barrel actually will function in a G30/G30SF slide and maintain good accuracy. This has been clearly proven in live-fire tests, the results of which are available in multiple cases, for example, Post #76 of the Glock Talk thread titled "Glock 21 conversion to Glock 20?" posted in the General Glocking Forum (Update: the thread has been retired). The O.D. of a G30 and G29 barrel are identical and the barrel lugs are compatible. The same holds true for an aftermarket G29 replacement barrel in the G30 slide (aftermarket G29 barrels from Bar-Sto, KKM Precision, StormLake, Lone Wolf, EFK Fire Dragon and others). While a G29 barrel is a good fit in the critical dimensions, the 10mm barrel chamber hood is narrower than the 45ACP barrel hood by slightly more than .050 inch. The dimensions of a 45-10mm conversion barrel are identical to a G29 10mm factory or aftermarket replacement barrel except that the barrel hood of the conversion barrel is made .050" wider to better fit the 45ACP pistol breechface.

Although a G29 10mm factory barrel will function in the G30 slide, the recommended conversion of the G30/30SF .45ACP pistol to 10mm caliber strongly favors a 45-10mm conversion barrel or aftermarket G29 10mm replacement barrel for best results. An aftermarket barrel typically has better chamber support than the Glock 29 10mm factory barrel, thus the brass casings are less likely to suffer damage which is critically important if you reload them. The aftermarket barrel has conventional rifling (land and groove) suitable for non-jacketed (hardcast lead) bullets of all weights for 10mm. In addition, the aftermarket barrels are available in extended lengths which provide greater velocity and energy. For all these reasons, most shooters want this capability to take full advantage of the potential of the 10mm caliber in their converted pistol.

A drop-in 10mm barrel (aftermarket 45-10mm conversion or G29 10mm replacement barrel recommended) and G29/G20 mag change are the two minimum requirements to shoot 10mm caliber ammo with the G30/G30SF pistol.

Some G30 owners find that the stock .45 extractor functions reliably to extract the 10mm case in their converted pistol. A G30 pistol that happens to have a looser fit in the distance between extractor claw and bore axis can experience erratic ejection and occasional failure-to-extract problems. Replacing the .45 extractor with a G29 10mm stock LCI extractor is an alternative (Part No. SP 01909 and 3442 Spring-Loaded Bearing for a slide with 15 ejection port). This option requires more time and effort to convert the pistol from 45ACP to 10mm and return it back to 45ACP service. Furthermore, while the 10mm extractor is different, it does not necessarily improve extraction reliability on the G30 slide since it doesn't reach any closer to the bore axis. There is another option suggested by KKM Precision, Inc.

Barrel manufacturer KKM Precision, Inc. recommends some minor gunsmith work on the stock .45 extractor that enables it to function more reliably for 10mm and continue to work for 45ACP. It involves removing no more than 0.020 inch from the 'fitting pad' on the inside of the .45 LCI extractor (see photo below) allowing it to travel closer to the axis of the bore and make solid contact with the 10mm case. As material is filed from the fitting pad, test for proper tension of the extractor against a cartridge. With the slide removed from the frame, insert an empty 10mm case or dummy round underneath the extractor claw from the bottom of the slide. There should be some measurable tension being applied by the extractor claw to the cartridge. A dummy round should remain suspended by the inward force of the extractor. Some who have studied this .45 extractor modification believe it functions better than the option of installing a stock 10mm extractor. I made the modification to a spare .45 extractor and have been completely satisfied with the function and reliability for the factory ammo I prefer to carry. Underwood 10mm ammo and 45ACP Speer Gold Dot 230gr JHP feeds and cycles normally in rapid fire. Such is our confidence in the pistol, my gal uses the G30SF with modified .45 extractor and 45ACP factory barrel for EDC. She converts it to 10mm for woods protection with an extended length KKM 45-10mm conversion barrel (no longer offered by KKM). Contact KKM for advice and instructions before attempting this modification (Phone: 775-246-5444). It is best to modify a spare extractor in case of a problem.

Test-Posts Here

All the Gen3 and Gen4 Glock .45 ACP and 10mm pistols use the same ejector (marked 8196-2) so that is never an issue for the conversion.

Referring to the thread at Glock Talk in The 10 Ring forum titled "Conversion report G30 to 10mm", some factual information from two different perspectives by GT members humphreys19 and ennis are good examples of conversion projects and approaches.

humphreys19 converted his G30 with just a KKM drop-in conversion barrel and G29 mags. The stock G30 .45 extractor and stock recoil spring in the G30 slide worked for him with zero malfunctions. He found the stock G30 .45 extractor worked better than a 10mm extractor from Lone Wolf. See his update in Post #35 of the thread where he expresses complete confidence in the reliability and states, "I would carry this gun."

ennis installed a KKM conversion barrel with a 23-lb recoil spring and modified the G30 .45 extractor per KKM's instructions. The combination worked perfectly for 10mm and 45ACP in his G30 pistol.

A 45-10mm conversion barrel in stock length (3.78") is offered by StormLake. The MSRP is ~$170 and discounted prices from distributors are common. Rather than purchase directly from StormLake, buy the barrel from a distributor that has a good money-back refund policy in case there are problems with fit and function (for example, MidwayUSA). IGB Austria reportedly offers 10mm conversion barrels for the G30 up to 6.02 inches long for import into the USA, but I have never read a review from anyone using an IGB barrel in a G30. IGB 10mm barrels are more expensive at $220 for stock length. As mentioned above, aftermarket suppliers offering G29 10mm replacement barrels include Lone Wolf, KKM Precision, Bar-Sto, StormLake, and EFK Fire Dragon.

Another conversion option is to purchase a complete G29 upper assembly (factory slide with 10mm factory barrel and internals) and install it on the G30 frame. The Generation of the upper and frame should match. The complete upper swap is the one option that will produce a converted G30 10mm pistol most closely resembling the factory G29 pistol. For reference, a complete G29 upper retails for $360 from Glockmeister and wait times are long. A complete upper from Glockmeister includes a Glock factory 10mm barrel. The cost to include the factory barrel is a waste of money if the shooter needs better chamber support for hot ammo and the ability to shoot non-jacketed (hardcast lead) bullets. Other sources of a complete, used G29 upper include The Want Ads at or A Glock complete upper assembly is not a firearm under federal law and can be shipped directly to the buyer.

IMPORTANT: A complete G29 upper is the only option to convert a Glock 30S pistol to 10mm caliber. The G29 factory barrel or commercially-available aftermarket 45-10mm conversion and G29 replacement barrels for the Gen3 G30/G30SF and Gen4 G30 will not fit in the G30S slide. IGB Austria reportedly makes a 10mm conversion barrel for the G36 that might fit in the G30S slide, but subtle differences in feed geometry between the single-stack G36 and double-stack G30S will almost certainly cause failure-to-feed malfunctions. It's just as well the G30/G30SF conversion barrels don't fit (probably intentional on Glock's part) since the lighter slide of the G30S isn't an optimal design to handle muzzle velocity and energy greater than the normal range for 45ACP +P ammo.

Glock warns owners not to fire non-jacketed (hardcast lead) bullets in the factory barrel with polygonal rifling. Doing so voids the Glock warranty. Many shooters believe the chamber support of the G29 factory barrel is insufficient to prevent damage to the brass casings of full-power 10mm loads rendering them unsuitable for reloading. The factory barrel with polygonal rifling is known to have problems stabilizing some full-power loads of 10mm non-jacketed, hardcast lead bullets heavier than 220gr. Greg Kinman (Hickok45) has shown that DoubleTap 10mm 230gr WFNGC hardcast lead bullets tumble and accuracy suffers drastically when fired from the factory 10mm barrel but perform well when fired from an aftermarket barrel with conventional rifling. The lighter DoubleTap 10mm 200gr WFNGC hardcast bullet performs well with the factory or aftermarket barrel. Reference Video: Glock 20 with Heavy Cast Bullets (Chapter 2)

If you plan to frequently shoot full-power 10mm loads, then you can consider something stronger than the factory standard 17-lb recoil spring in the G30, perhaps one in the 21-23 lb range. Springs are available from Wolff Gunsprings and ISMI. I prefer Wolff springs because I have greater confidence that the measured spring strength matches the rating of Wolff springs and they are available in matched sets of inner and outer springs for the G30 RSA. If the converted pistol with stock recoil spring exhibits signs of frame battering or brass is thrown a great distance, try a 21-lb spring first and increase the strength if brass is thrown further than 10 feet making brass recovery difficult. One can overdo recoil spring strength so don't assume that the stronger the spring the better. Perceived 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. Examples of full-power, factory 10mm loads are 135gr at 1600 fps, 155gr at 1500 fps, 165gr at 1400 fps, 180gr at 1300 fps, 200gr at 1250 fps, 220gr at 1200 fps and similar loads.

What you most want to prevent when firing full-power 10mm loads, and the thing most likely to cause serious damage, is an occurrence of out-of-battery detonation. You can minimize this risk by keeping the chamber clean and using a stronger recoil spring. A stronger recoil spring also yields more consistent muzzle velocity from shot to shot for a given ammo load.

The experienced 10mm shooters at Glock Talk in The 10 Ring forum can give you advice on the appropriate guide rod and recoil spring strength.

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Last edited by GRT45; 04-02-2015 at 15:40..
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