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Chrono Data: .40 S&W 165gr. GDHP and 180gr. SXT – GLOCK 23 and GLOCK 27

1602 Views 14 Replies 5 Participants Last post by  SCmasterblaster
165gr. SPEER GDHP/53970 (Mrs. awoodpd13’s current duty ammo)

G-23 (Gen. 4 – Mrs. awoodpd13’s current issued duty firearm)
  1. 1097
  2. 1081
  3. 1069
  4. 1087
  5. 1065

AVG: 1079/426


G-27 (Gen. 3 – Mrs. awoodpd13’s personal)
  1. 1034
  2. 1056
  3. 1044
  4. 1062
  5. 1050

AVG: 1049/403


G-23 (Gen. 2 - Mrs. awoodpd13’s former issued duty firearm; now personal)
  1. 1089
  2. 1124
  3. 1115
  4. 1088
  5. 1112

AVG: 1105/447




180gr. Winchester SXT/RA40T (Mrs. awoodpd13’s former duty ammo)


G-23 (Gen. 3 – Mine)
1. 931
2. 926
3. 968
4. 949
5. 921


AVG: 939/352


G-27 (Gen. 3 – Mine)

1. 921
2. 898
3. 951
4. 953
5. 932


AVG: 931/346




Sunday, August 16, 2015/~85degrees F.
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Anyone else curious as to the higher velocity obtained with the Gen2 Glock as opposed to the Gen4? Could it be the higher round count leading to a "polishing" of the bore? Could it simply be the random variation in two individual barrels? Were the loads fired at the approximate same time and temperature?
 
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Anyone else curious as to the higher velocity obtained with the Gen2 Glock as opposed to the Gen4? Could it be the higher round count leading to a "polishing" of the bore? Could it simply be the random variation in two individual barrels? Were the loads fired at the approximate same time and temperature?
I have often wondered about this phenomenon.
 

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Discussion Starter · #9 ·
Anyone else curious as to the higher velocity obtained with the Gen2 Glock as opposed to the Gen4? Could it be the higher round count leading to a "polishing" of the bore? Could it simply be the random variation in two individual barrels? Were the loads fired at the approximate same time and temperature?

They were fired MAYBE 30min. apart, with no noticeable change in temp. (no thermometer, though).
 

· woo woo
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Its
Anyone else curious as to the higher velocity obtained with the Gen2 Glock as opposed to the Gen4? Could it be the higher round count leading to a "polishing" of the bore? Could it simply be the random variation in two individual barrels? Were the loads fired at the approximate same time and temperature?
It's weird, I have three 4" bbl .38sp K frames (mod 10, 15 and 64) and have chrono'd them side by side and seen 5 shot avg vary as much as 50-60fps between the three. Then on another day the 64 will be the 'hot' gun instead of the mod 10 or 15. Some guns just like certain ammo better than others.
 

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A newer/stiff recoil spring compared to a used/looser one could account to velocity differences. Remember, part of the rounds energy is used to move the slide rearwards. Bolt action rifles get slightly higher velocities than a semi-auto with the same ammo.

It would be interesting to see this same test done, but after the first set of results, swap recoil springs and retest, then swap barrels and retest. Granted, you wouldn't be able to do the barrel swap with a gen2 and gen4, but you could try the gen2 RSA in the gen4 with one of those washer adapters
 

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A newer/stiff recoil spring compared to a used/looser one could account to velocity differences. Remember, part of the rounds energy is used to move the slide rearwards. Bolt action rifles get slightly higher velocities than a semi-auto with the same ammo.

It would be interesting to see this same test done, but after the first set of results, swap recoil springs and retest, then swap barrels and retest. Granted, you wouldn't be able to do the barrel swap with a gen2 and gen4, but you could try the gen2 RSA in the gen4 with one of those washer adapters
This sounds complicated.
 

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This would mean that the pistols with more rounds through them will always produce higher velocities. How much can the recoil spring assembly play a role before the bullet leaves the barrel, anyway?


Very curious.
 
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