Higher velocities out of Glock OEM or traditionally rifled barrel?

[SirLoin]

Folks,

Do you experience higher velocities / power factors when you shoot bullets out of a Glock OEM barrel or a traditionally rifled barrel?

Please vote as follows:

1. 
   
2. Higher velocities out of a Glock OEM barrel
   
3. Higher velocities out of a traditionally rifled barrel

It has been commonly stated that the polygonal rifling of Glock barrels leads to higher velocities. However, others have reported experiencing actually LOWER velocities when shooting out of a Glock OEM barrel. For example, “Mike Orrick (GlockTalk's "BrokenArrows") has pointed out that his chronographed results of identical loads in conventionally-rifled barrels versus same-length polygonal barrels yielded higher velocities in some of the conventionally-rifled barrels” (from http://www.glockfaq.com/content.aspx?ckey=glock_faq_reloading.

(Perhaps the unsupported nature of a Glock OEM barrel leads to there being a looser seal, resulting in lower gas pressures, and thus pushing the bullet out at a lower overall velocity despite the advantages of polygonal rifling?)

My experience has been 2. higher velocities out of a traditionally rifled barrel, i.e., like that of Mike Orrick’s: my bullets shoot faster out of non-Glock / non-polygonal barrels.

I’m hoping to get people’s opinions to see if my experience is typical.

Thanks!

Edited November 8, 2011 by SirLoin

[Sarge]

Glocks are faster.

[Sin-ster]

Good poll!

You already know my story/vote. Can I add 3-5 more, for other shooters I know?

[MarkCO]

Depends on the caliber, bullet type, bullet diameter, barrel brand and length. My Bar-Sto in my G35 definately has higher velocites with the same competition load than the stock barrel. In my G27 with 135 grain defense loads, as compared to a KKM, slightly higher with stock barrels. So, depends.

[LPatterson]

Glock barrels are Polygonal in the 9 & 40, 45 ACP's are hexagonal.

[MarkCO]

Glock barrels are Polygonal in the 9 & 40, 45 ACP's are hexagonal.

Polygonal means "many sided" and a hexagon IS a polygon.

[SirLoin]

I think polygonal is just the general heading, referring to multiple sides, and hexagons, octagons, etc. are specific types of polygons (hexagons = six sides; octagon = eight sides).

I believe Glock barrels have hexagonal rifling in general, vs the octagonal rifling in the 45 ACP (http://en.wikipedia.org/wiki/Polygonal_rifling; http://en.wikipedia.org/wiki/Glock)

Glock barrels are Polygonal in the 9 & 40, 45 ACP's are hexagonal.

[leas327]

I don't know between an aftermarket barrel and a stock barrel. But I have shot the same loads out of my 35 and my friends p16 back to back. There wasn't a velocity difference that didn't fall between the extreme spread.

[Biloxi23]

I am shooting the same load out of my G24 with a LWD stainless barrel that I shot for almost a year out of the stock barrel. the bullet is a 185 Precision Moly bullet over WSF and I am getting an average of 50 fps faster from teh Lone wold barrel. This is from four different chrono sessions, and at different temperatures. The difference is consistent. the Lone Wolf barrel seems to be very accurate and a whole lot easier to clean. The OEM barrel would "moly up" but not so bad that it had to be cleaned during a match. Based upon other comments here, I sent five dummy rounds loaded to COAL of 1.1385 to Lone Wolf and they reamed the chamber to fit my loads. I have laoded a new bunch of ammo to chrono that is .2, .3 and .4 less and will see what PF they chrono to.

[SirLoin]

Biloxi123, that's pretty close to what happens to me when I shoot my rounds through a Glock 35 Gen4 OEM and when I shoot them through a Para Ordnance S16-40 Limited with its OEM barrel: it's consistently faster across different loads on the Para OEM barrel than in the Glock OEM.

I chronoed 180, 165, and 155 gr plated Berrys using two different chronos (put them front-back so that each bullet would go through both chronos), and the results were consistently faster in the Para.

I am shooting the same load out of my G24 with a LWD stainless barrel that I shot for almost a year out of the stock barrel. the bullet is a 185 Precision Moly bullet over WSF and I am getting an average of 50 fps faster from teh Lone wold barrel. This is from four different chrono sessions, and at different temperatures. The difference is consistent. the Lone Wolf barrel seems to be very accurate and a whole lot easier to clean. The OEM barrel would "moly up" but not so bad that it had to be cleaned during a match. Based upon other comments here, I sent five dummy rounds loaded to COAL of 1.1385 to Lone Wolf and they reamed the chamber to fit my loads. I have laoded a new bunch of ammo to chrono that is .2, .3 and .4 less and will see what PF they chrono to.

[skeeter]

when i got my kkm barrel i was sure that i would loss some speed, but when i got to the range and chrono'd i was pleased to see that the kkm go 50 to 75 fps faster. i think that the extra comes form the tighter chamber.

[Poppa Bear]

My OEM is quicker. My OEM chamber is also .0005 tighter than my KKM. I think it all comes down to tolerances, whichever barrel has the tighter specs will have the greater speed.

Edited November 12, 2011 by Poppa Bear

[SirLoin]

Yeah, I think that a tighter chamber trumps the rifling advantage. Thing is, I thought that the Glock OEM had the looser tolerances, as they designed it to eat any ammo, so I'm surprised that your OEM is tighter.

My OEM is quicker. My OEM chamber is also .0005 tighter than my KKM. I think it all comes down to tolerances, whichever barrel has the tighter specs will have the greater speed.

[Sin-ster]

Yeah, I think that a tighter chamber trumps the rifling advantage. Thing is, I thought that the Glock OEM had the looser tolerances, as they designed it to eat any ammo, so I'm surprised that your OEM is tighter.

My OEM is quicker. My OEM chamber is also .0005 tighter than my KKM. I think it all comes down to tolerances, whichever barrel has the tighter specs will have the greater speed.

The ability to "eat" a wide range of ammo comes from a loose chamber, not barrel. The projectile itself has a fixed maximum diameter-- no need to account for anything "sloppier".

IIRC, a 124 MG JHP touches the rifling in my G17 at 1.189-- meaning I could load to 1.175 and still have a huge safety margin. (The mags begin to choke around 1.165 though.) It also leaves a lot of room for the case to expand.

In comparison, the M&P 9 Pro I just got maxed out at 1.145, and was definitely tighter on the case walls. Ironically, it's magazines would accomodate my "no go" Glock dummy rounds of ~1.170 without nose dive or snag.

Barrel-to-barrel tolerances definitely account for the greatest variations in velocity, but I still believe the polygonal rifling of the Glock plays some role as well.

[SirLoin]

Yep. Thanks for pointing that out.

I do agree with you that differences in rifling affect velocities. I do think that significantly tighter barrel tolerances probably trump rifling differences, all else being equal -- as you point out. Thus, given two barrels with the same tolerances, I believe that the polygonal would spit out faster bullets. However, given:

1) a barrel with tighter tolerances AND traditional rifling, and

2) a barrel with looser tolerances AND polygonal rifling,

I think 1) would spit out faster bullets.

Yeah, I think that a tighter chamber trumps the rifling advantage. Thing is, I thought that the Glock OEM had the looser tolerances, as they designed it to eat any ammo, so I'm surprised that your OEM is tighter.

My OEM is quicker. My OEM chamber is also .0005 tighter than my KKM. I think it all comes down to tolerances, whichever barrel has the tighter specs will have the greater speed.

The ability to "eat" a wide range of ammo comes from a loose chamber, not barrel. The projectile itself has a fixed maximum diameter-- no need to account for anything "sloppier".

IIRC, a 124 MG JHP touches the rifling in my G17 at 1.189-- meaning I could load to 1.175 and still have a huge safety margin. (The mags begin to choke around 1.165 though.) It also leaves a lot of room for the case to expand.

In comparison, the M&P 9 Pro I just got maxed out at 1.145, and was definitely tighter on the case walls. Ironically, it's magazines would accomodate my "no go" Glock dummy rounds of ~1.170 without nose dive or snag.

Barrel-to-barrel tolerances definitely account for the greatest variations in velocity, but I still believe the polygonal rifling of the Glock plays some role as well.

[Braxton1]

My G-17 OEM barrel is actually as fast as my KKM G-34 barrel, believe it or not (within 6 fps or less).

4.1 of N320 behind a MG 124 runs 1060 in either barrel.

I don't have an OEM 34 barrel to do an "apples versus apples" comparison.

[Chuckdee]

On my G35, I gain about 40-50 fps with my Bar-Sto barrel over the stock. I have always been told that the rifling and twist rate will play the biggest roll in terms of friction causing the bullet to slow down. I will say, that without a doubt, the chamber is also tighter on the Bar-Sto then the stock. I can tell because the case comes out much with a lot less residue on the outside of the case compared to the black burn mark from the stock barrel. This makes me believe that there is a slight loss of pressure pushing the bullet through the barrel. I have never been able to get a clear answer on this on whether that makes a significant loss of velocity. Sounds like it should to me.

I have a KKM For my G34. I will compare the two next time I hit the range. I will report back soon..

My reloads have a SD of 5-10fps, so I know for a fact it wasn't just inconsistent reloads.

[SirLoin]

Yeah, the charred-on-one-side-brass only happens with my Glock OEM, so I've thought that unsupported/larger chambers lead to more gas escaping to lower velocities. I haven't seen anything online that definitively says that though, but that intuitively makes sense to me.

I will say, that without a doubt, the chamber is also tighter on the Bar-Sto then the stock. I can tell because the case comes out much with a lot less residue on the outside of the case compared to the black burn mark from the stock barrel. This makes me believe that there is a slight loss of pressure pushing the bullet through the barrel. I have never been able to get a clear answer on this on whether that makes a significant loss of velocity. Sounds like it should to me.

My reloads have a SD of 5-10fps, so I know for a fact it wasn't just inconsistent reloads.

[Smokecloud]

without digging out my papers, My KKM was about 35fps faster on average with lead and plated bullets out of my G35, than my OEM barrel. But the KKM is very finicky about what it eats. I dont recall if I did a comparison with jacketed. Chrono tested of course.

[SirLoin]

Just did another round of chronos yesterday.

My KKM is definitely around 10 PF or more faster than my Glock G35 OEM.

The Para shoots out the same ammo 20 PF stronger than the G35 OEM, and 10 PF stronger than the KKM.

I'm starting to wonder if maybe my G35 G4 OEM barrel is even partially defective.

Attached are my chrono results using an F-1 chrono.

without digging out my papers, My KKM was about 35fps faster on average with lead and plated bullets out of my G35, than my OEM barrel. But the KKM is very finicky about what it eats. I dont recall if I did a comparison with jacketed. Chrono tested of course.

[LPatterson]

If you do call Glock don't tell them it was with reloads as that voids the warranty. Say it was some factory ammo in the two different guns and ask why yours was so much slower. You could mention the brass though.

[SirLoin]

I called Glock about it weeks ago, and they too were surprised. They would only talk about replacing it if I were a Glock armorer, which I'm not. I've actually tried to sign up for a Glock armorer course, but I can't find a class that fits my schedule.

If you do call Glock don't tell them it was with reloads as that voids the warranty. Say it was some factory ammo in the two different guns and ask why yours was so much slower. You could mention the brass though.

[LPatterson]

I called Glock about it weeks ago, and they too were surprised. They would only talk about replacing it if I were a Glock armorer, which I'm not. I've actually tried to sign up for a Glock armorer course, but I can't find a class that fits my schedule.

If you do call Glock don't tell them it was with reloads as that voids the warranty. Say it was some factory ammo in the two different guns and ask why yours was so much slower. You could mention the brass though.

Hopefully there is a forum member near you who is a Glock armorer who can handle that for you. I'm a bit far away from you or I would offer my services.

[SirLoin]

Thanks man. I appreciate the thought.

As much as possible, I wanted and want to stick to OEM parts, especially as I shoot IDPA, but I decided to go ahead and get a KKM while I sorted this thing out with Glock.

I called Glock about it weeks ago, and they too were surprised. They would only talk about replacing it if I were a Glock armorer, which I'm not. I've actually tried to sign up for a Glock armorer course, but I can't find a class that fits my schedule.

If you do call Glock don't tell them it was with reloads as that voids the warranty. Say it was some factory ammo in the two different guns and ask why yours was so much slower. You could mention the brass though.

Hopefully there is a forum member near you who is a Glock armorer who can handle that for you. I'm a bit far away from you or I would offer my services.

[rc51g]

all of this is very interesting. i have recently become interested in a bar-sto barrel and would love some extra velocity to boot. My g35 is nothing to complain about though. it is very accurate and runs great. lately i have been playing with some loads and someone said that 4.3 wsf/200gr bullet = 169pf out of their gun (2011). i only got 160 pf out of my stock g35 barrel. i also have an XDM 4.5 9mm and a g34 and i think the vel were about equal with the XDM running slightly higher with its shorter barrel. it runs very well and does not bulge the brass. i have noticed the soot on the brass though. For me a tighter chamber, increased accuracy with 100% reliability would be great and worth the money for me. ?????