So You Want To Build An Open Glock

[Mad Scientist]

So you have decided to build an open Glock and want to do it your self. I may have some insight that will open your eyes.

the first topic i would touch on is optics. some prefer a slide mounted sight and that is cool i can see the alure of a low sight picture and the ability to go from limited to open with out much trouble.these guns are easy to build and are reliable in must regards except the optic themself. I have not found one yet that would hold ip to the rigors of open major work. Ipersonaly like the c-more or comparable sight. I am not married to any one but the c-more is the easiest to get and has the longest track record.

once you decide on optics ther are things to consider. eithe way will require a mount ar machine work to atach your desired sight. this is decision time. do you frame mount as I do or slip mount on the rail or machine the slide slide. either option requires some machine work.the frame mounted or slip on mounts will require the ejection port to be lowered and the ejector tuned . some cases require exstractor work and I will get into that in another article.

the next question is how acurate do you want the gun. I have seen sub1" groups at 25 yards and beyond. this requires all dementions in the slide and barrel lock up to be tightened up to as little movement as posible with the parts that are now available.

so how do you get there . work in small incraments and fit every thing as close to 0 as posible.I like a gun to just snap into batery as it locksup when new. You must realize that a gun this tight will need to be shot in.I recomend at least 500 rounds to break a new gun in.

Alot of people ask me how much weight can I take out of the glock slide.

I donot take any weight out of a major gun and the reson being the glock has a linkless design that relies on spring tension and overal assy weight and then slide weight to control barrel timming. keeping things as close to factory weights in the asssy is optimal.

That being said a comp that is as light as posible is optimal. that is the main reson I use alluminum comps. People always think that I use them to keep the front of the gun light but this is only a benifit not the root cause. what happens as a glock unlocks is that pressure aplies force to the case and breach face keeping the gun locked up untill the bullet clears the barrel and comp. some of the pressure is aplied to the baffels make ing the comp work the phisics aplied of equal and opisite then stillpushing on the breach moves the assy to the rear . the locking block pulls the barel free allowing the slide to move freely to the rear.this si where the right combo be comes critical.with a light comp and heavy slide the barrel has less mass and slows and slops on the stop without bouncing.

this alows for consistant placement of the case as it is released from the barre.

that being said ejection paterns are much more prodictable.

As far as the slide goes as the slide comes back the added weight alows for a little slower dwell time alowing for the cartrages to come up from the magazine.

My theory alows for a heavier recoil spring in major loads up to 14 pounds thus keeping the gun in battery longer allowing dwell time as the case is exstracted.

this is important as dwell time alows the presure to relive and the case to shrink down to a level that is easily pulled from the barrel.also the longer the dwell the easier on the gun in the long run.

light slides and heavy comps can work because the overallassy weight is similar.

what you will find is a gun that comes out of battery at the same rate and as pressure drops the slide accelerats faster than the barrel resulting in a slow rounding of the locking surfaces.at first thsi wont hurt things but over time the lock up shears off and eventualy the slide will peal up at the locking surface. I found this out when working with 34's .I would cut them down to 9 oz with a heavy bussing comp assy . these where supper guns but would not hold up.

also heavier than normal barrels will show the same type of problem. especialy when porting is involved. porting works well but there is nothiung for free the trade off is added pressure and blast .I have shot bith ways abd have one of each types a couple of times over. the reality is that at todays power factgor they are not need ed as much or in the size of the old days of 175. I feel equaly comfortable with either set up and have leaned to non ported guns to help in slowing the timmieng down.

This is the theory of the open glock as I see them

i am but a humble tinkerer at heart with many years in the trade.

I hope you can use this info to help you in your indever.

John Nagel

mad scientist at heart.

Edited October 31, 2006 by Mad Scientist

[Flexmoney]

Good post John.

[Micah]

Excellent post! Do you feel that there is a significant difference in having a tight barrel over sticking with a stock/drop in barrel?

And...what advice do you have on improving the trigger on an Open Glock?

[Mad Scientist]

Excellent post! Do you feel that there is a significant difference in having a tight barrel over sticking with a stock/drop in barrel?

And...what advice do you have on improving the trigger on an Open Glock?

there in lies the challenge of it all tight enough but still functions . I would build my first one so that it ran right away by making sure that it wasent to hard to pull out of battery.

trigers in an open glock always have to run a light striker spring other wise any thing else goes.

Edited November 1, 2006 by Mad Scientist

[A-shot]

Thanks for the post and great info! I'm glad you're gonna build mine!!

[DrKyle1]

Not to be ... pushy but (and I know as soon as you say 'but' it negates anything said prior) when is the next article/post!!!! I am itching to build an open glock on my own. Thanks for the great info.

[uscbigdawg]

I'm just going to send mine and the fiance's to Mad Scientist.

Rich

[nphd2000]

John,

I purchased parts from you and built an early version of your "Stealth" package for a G35. Now I'm thinking of switching to 9mm with a G17. What spring and loads would you suggest for a minor steel load and a major USPSA load? I have your "Major" (longer) 9mm comp and would like to use that for both minor and major, then I would, in theory, just have to change a recoil spring to switch between PF's.

Any info will be appreciated.

Thanks,

Nick

[Mad Scientist]

John,

I purchased parts from you and built an early version of your "Stealth" package for a G35. Now I'm thinking of switching to 9mm with a G17. What spring and loads would you suggest for a minor steel load and a major USPSA load? I have your "Major" (longer) 9mm comp and would like to use that for both minor and major, then I would, in theory, just have to change a recoil spring to switch between PF's.

Any info will be appreciated.

Thanks,

Nick

nick,

i use a 10 pound govt model spring with a wolf 4 pound striker spring works well with 135 power loads if the gun is not to tight 14 pond wolf for major loads.

i like wsf powder for both minor and major. work them up over a crono as all barrels differ and loading practices differ. for major 9 make sure to use a KKM gun smithfit barrel as they have the most support.

john

[Suburban Commando]

John,

I purchased parts from you and built an early version of your "Stealth" package for a G35. Now I'm thinking of switching to 9mm with a G17. What spring and loads would you suggest for a minor steel load and a major USPSA load? I have your "Major" (longer) 9mm comp and would like to use that for both minor and major, then I would, in theory, just have to change a recoil spring to switch between PF's.

Any info will be appreciated.

Thanks,

Nick

nick,

i use a 10 pound govt model spring with a wolf 4 pound striker spring works well with 135 power loads if the gun is not to tight 14 pond wolf for major loads.

i like wsf powder for both minor and major. work them up over a crono as all barrels differ and loading practices differ. for major 9 make sure to use a KKM gun smithfit barrel as they have the most support.

john

Excellent! I was just about to ask how to get my Glock to run with a Major Comp and factory-type ammo.

I had been running a Wolff 14 pound spring. Tried the KKM barrel and comp, and it kept choking. Removed the comp, and gun works fine with the KKM. I'll order a 10 pound 1911 spring next time I order from Midway, do the vertical test a few times, and try the comp again.

[nphd2000]

Thanks for the info John. I may be asking more questions in the near future.

Thanks again,

Nick

[DrKyle1]

Flex - can you make this a sticky? Great info and especially if there is more to follow!

John,

Thanks for the info and the suggestions on my open G17! I was able to run it at the GSSF in San Antonio on 12/3 (57.67 - respectable given maiden run was the competition other than 10 rounds sighting in the dot!)

[Suburban Commando]

Any reccommendations for loading for these open pistols? The Glocks in Competition book says not to use plated bullets with compensators. Lead or jacketed?

Edited December 30, 2006 by Suburban Commando

[Pigdawg]

BIG no on the lead bullets. I know alot of people they use them and swear its ok but all the stories about blowing up glocks from using cast bullets still makes me a little nervous. If you just want to go cheap Masterblasters shot fine out of mine. I have had good results with plated bullets out of my G22 and G24 but I do not shoot much past 15yards and they are accurate enough for that. Just watch the crimp go as light as you can to hold the bullet and keep it from setting back.

[Mad Scientist]

Any reccommendations for loading for these open pistols? The Glocks in Competition book says not to use plated bullets with compensators. Lead or jacketed?

Ilike wsf with jaceted hollow point bullets.lead and lead based bullets will lead up your comp quickly. work up slow and watch for presure. use a barel with a supported chamber

as the stock profile is not up to major loads.

john

[Joe D]

John, did you get my PM?

[Mad Scientist]

John, did you get my PM?

yse

[Joe D]

Just trying to help.

[Suburban Commando]

I think I've found a combination that works.

G17

SJC 9mm Major comp

ISMI 10 lb. 1911 recoil spring

Spring set from Vanek production trigger kit

.40 S&W ejector

Most factory loads or 115 gr. bullet over 4.5gr. of TiteGroup and a WSP primer

If you run a J-Point, you can probably skip the .40 ejector. Ejector was required to keep the brass from hitting my frame mounted scope and bouncing back into the ejection port. A 9 pound spring had the same effect on ejection, but wouldn't fully close the slide reliably.

[ctgun]

I have found a very interesting combination that works well for me so far. I had a G17 with a KKM barrel and comp and a JPoint on it. I was having a b*tch of a time with it. I didn't know that you needed a 3rd generation frame to make it work till I had read it here and I had a 2nd gen frame. So I gave up the idea for a while. It is very hard to find a 3rd gen here in Mass. I did have a 3rd gen G31 though and just for the hell of it put the 17 slide on it and now I have an open gun that has run flawless for 400 rounds. Right now I am happy as a pig in sh*t. I just change top ends to have a limited or an open set up. Has anyone else ever tried this or have any warnings on long term use of such a set up. Mad Scientist I would appreciate any words of wisdom that you could share on this.