deerslayer Posted January 12, 2020 Share Posted January 12, 2020 (edited) I am working on a Precision Delta 124 HP load for my Gen 5 17 MOS for CO. Started at 4.0 grains of Titegroup at 1.120, which was slow and was not a big surprise. Went to 4.1 and 4.2. Need 1009 to make minor and I want 1050-1060 (130-131 pf). 4.2 averaged 1022 (126,728). I had hoped the 4.2 charge would get me where I wanted to be. Have any of you thought your gen 5 was slower than previous Glocks? 4.1 went 1060 in my gen 3 34. Yes it has poly rifling and an additional 7/8" barrel, but others have said that 4.0 makes 130 pf or so all day out of a 17. I've seen no pressure signs, so should I shut up and add powder or shut up and get a 34 MOS? 4.3 or 4.4 seems high. Edited January 12, 2020 by deerslayer Link to comment Share on other sites More sharing options...
tdp88 Posted January 13, 2020 Share Posted January 13, 2020 I use 125gr Blue Bullets with 3.7 gr TG at 1.12 OAL. In my 34 this gets 133PF and the 17 is 128 PF. I don't think there is much difference in PF between the generations, but its possible to have a slow barrel. When I shot Tanfo my practice gun was almost 5 PF less than the match gun when they were both new. Link to comment Share on other sites More sharing options...
B_RAD Posted January 13, 2020 Share Posted January 13, 2020 16 hours ago, deerslayer said: I am working on a Precision Delta 124 HP load for my Gen 5 17 MOS for CO. Started at 4.0 grains of Titegroup at 1.120, which was slow and was not a big surprise. Went to 4.1 and 4.2. Need 1009 to make minor and I want 1050-1060 (130-131 pf). 4.2 averaged 1022 (126,728). I had hoped the 4.2 charge would get me where I wanted to be. Have any of you thought your gen 5 was slower than previous Glocks? 4.1 went 1060 in my gen 3 34. Yes it has poly rifling and an additional 7/8" barrel, but others have said that 4.0 makes 130 pf or so all day out of a 17. I've seen no pressure signs, so should I shut up and add powder or shut up and get a 34 MOS? 4.3 or 4.4 seems high. I think my gen 5’s were a little slower than previous gens. Link to comment Share on other sites More sharing options...
dg370 Posted January 14, 2020 Share Posted January 14, 2020 Confused. By definition the speed should be greater with polygonal rifling.http:// https://en.m.wikipedia.org/wiki/Polygonal_riflingSent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
Malarky112 Posted January 14, 2020 Share Posted January 14, 2020 4 minutes ago, dg370 said: Confused. By definition the speed should be greater with polygonal rifling. http:// https://en.m.wikipedia.org/wiki/Polygonal_rifling Sent from my iPad using Tapatalk You’re correct and that’s what the OP is saying I believe, that the gen 3 34 has it but the gen 5 doesn’t, well it kind of does but it’s supposed to be more accurate To the OP, the gen 5’s have different rifling so I could see it making a difference. obviously the barrel length in your 34 will make some difference as well. Are temps the same as when you chronod the 34? Link to comment Share on other sites More sharing options...
dg370 Posted January 14, 2020 Share Posted January 14, 2020 If you read the Wiki it states increased speed. I agree that measurements taken under the same controlled environment are in order to compare one Gen against another. Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
deerslayer Posted January 14, 2020 Author Share Posted January 14, 2020 9 hours ago, Malarky112 said: Are temps the same as when you chronod the 34? Yep, 36F. Taken about five minutes apart. I suspect the Marksman barrel with the new rifling may be to blame. I guess I'll load some 4.3s and go from there. Link to comment Share on other sites More sharing options...
12glocks Posted January 14, 2020 Share Posted January 14, 2020 (edited) We have 4 Glocks 34's in the stable. Two are Gen 3 guns and the other two are Gen 5 guns. I recorded a 25 FPS decrease in velocity with the Gen 5 gun, almost exactly shooting the same as a Gen 3 gun with .1 grains less propellant. The Gen 5 gun was new at the time and the Gen 3 gun had many thousand of rounds down the barrel. I have not checked it in a year or two. I just went up a .1 grains and shot the gun. I have said it a lot in other threads but I will add it hear as well. I can tell the Gen 5 guns are more accurate. Edited January 14, 2020 by 12glocks Link to comment Share on other sites More sharing options...
9X23Guy Posted May 12, 2020 Share Posted May 12, 2020 Gen 5s that I have tested are a bit slower. I believe the difference is in fact the rifling. The polygonal rifling used before was meant as a way to increase barrel life but it doesn't bite into the jacket as hard. The rifling in the new barrels are. The flip side is there is a slight increase in the the new design barrels though not appreciable for most. I tested this at 25 yards off of a rest. I took gen 4 and gen 5 17s, same load, triggers, sights and found that the groups averaged 0.15" - 0.25" ( ten round groups) better in the gen 5 barrels. I've seen the same results for a 34 as well. Both 147 grain loads I shot in the 17s performed noticeably better in the gen 5 barrels than they did in the gen 4 barrels, being 0.25" improvement, ten shot groups, extreme spread. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now