We put the 10mm Glock models 29 and 20 against each other head to head to compare velocity from the two barrels in this video and we also fired 10mm Underwood 220 grain hard cast and 10mm Lehigh 140 grain Extreme Penetrator into a long row of ballistic gel blocks to find out which is the king of penetration.

After comparing five different loads, it is clear that the velocity difference between the 4.61″ G20SF barrel and the 3.78″ G29SF barrel is unremarkable for most loads. The G20SF did produce a higher velocity in every case, but the largest difference was about 67 fps. That is a small enough difference that you could see that when going from cold weather to hot. Of course, slower propellants might make for even greater disparities, but velocity should not be the primary factor in deciding between these two guns, at least for the loads tested here.

After velocity testing, we fired Underwood 220gr hard cast and Lehigh 140gr Extreme Penetrator through both pistols into ballistic gel and found another surprising result. Both of these loads have a reputation for deep penetration. We measured completely insane penetration from the Underwood 220 grain hard cast. It’s no surprise that a high sectional density solid in 10mm Auto at respectable speed can penetrate deeply. But the degree of penetration was absolutely nuts at over 5 1/4″ feet. Likewise, the relatively modest penetration of the Lehigh Extreme Penetrator was also unexpected. Not that 25″-27″ is anything to scoff at, but in comparison to the heavier hard cast bullet, the Extreme Penetrator did not penetrate extremely deep.

Best millimeter goes deep.

In more subjective terms, both guns are controllable and fun to shoot. But the G20SF allows a more complete grip and has a longer sight radius, making it easier to shoot well. That extra real estate matters when you want to get fast, accurate hits with a cartridge like 10mm. Conversely, the G29SF is obviously a lot easier to conceal. Either gun would be a good choice for carry and the primary consideration should not be terminal effect. If you have to choose, you should make your choice based on whether you consider ease of carry or ease of shooting to be more important. Of course, the correct answer is not to choose at all and to simply get both.

Data:

Underwood 220 gr hard cast from both G20 and G29 exceeded 62.5″
Lehigh 140gr Extreme pentrator from G29: 27.2″
Lehigh 140gr Extreme pentrator from G20: 25.3″

Hornady 175 grain critical duty G29
1,045
1,049
1,028
1,057
1,044
Average: 1,044.60
StdDev: 10.60
Min: 1,028
Max: 1,057
Spread: 29

Hornady 175 grain critical duty G20
1,085
1,075
1,034
1,089
1,074
Average: 1,071.40
StdDev: 21.87
Min: 1,034
Max: 1,089
Spread: 55

Ventura Heritage 180gr JHP G29
1,241
1,250
1,250
1,231
1,264
Average: 1,247.20
StdDev: 12.24
Min: 1,231
Max: 1,264
Spread: 33

Ventura Heritage 180gr JHP – G20
1,319
1,315
1,304
1,325
1,309
Average: 1,314.40
StdDev: 8.23
Min: 1,304
Max: 1,325
Spread: 21

Underwood 220gr hard cast – G29
1,084
1,096
1,090
1,084
1,097
Average: 1,090.20
StdDev: 6.26
Min: 1,084
Max: 1,097
Spread: 13

Underwood 220gr hard cast – G20
1,117
1,127
1,102
1,158
1,140
Average: 1,128.80
StdDev: 21.44
Min: 1,102
Max: 1,158
Spread: 56

Lehigh 140gr Xtreme Penetrator – G29
1,320
1,311
1,304
1,273
1,323
Average: 1,306.20
StdDev: 20.02
Min: 1,273
Max: 1,323
Spread: 50

Lehigh 140gr Xtreme Penetrator – G20
1,372
1,372
1,376
1,366
1,371
Average: 1,371.4
StdDev: 3.58
Min: 1,366
Max: 1,376
Spread: 10

HSM 180gr UHP – G29
1,056
1,048
1,056
1,054
1,056
Average: 1,054.00
StdDev: 3.46
Min: 1,048
Max: 1,056
Spread: 8

HSM 180gr UHP – G20
1,077
1,080
1,085
1,081
1,089
Average: 1,082.40
StdDev: 4.67
Min: 1,077
Max: 1,089
Spread: 12

LAX 180gr FMJ – G29
1,045
1,020
1,018
1,046
1,008
Average: 1,027.40
StdDev: 17.14
Min: 1,008
Max: 1,046
Spread: 38

LAX 180gr FMJ – G20
1,071
1,092
1,081
1,098
1,071
Average: 1,082.60
StdDev: 12.22
Min: 1,071
Max: 1,098
Spread: 27
True MV: 1,082.60

G20 averages:
Hornady 175 grain critical duty 1071.40
Ventura Heritage 180 grain jhp 1314.40
Underwood 220 grain 1128.80
Lehigh 140 grain Xtreme penetrator 1371.40
HSM 180 grain uhp 1082.40
LAX 180 grain FMJ 1082.60

G29 averages:
175 grain critical duty 1044.60
Ventura Heritage 180 grain jhp 1247.20
Underwood 220 grain 1090.20
Lehigh 140 grain Xtreme penetrator 1306.20
HSM 180 grain uhp 1054.00
LAX 180 grain FMJ 1027.40

Differences:
175 grain critical duty 26.8
Ventura Heritage 180 grain jhp 67.2
Underwood 220 grain 38.6
Lehigh 140 grain Xtreme penetrator 65.2
HSM 180 grain uhp 28.4
LAX 180 grain FMJ 55.2