Comps on open guns?

[XRe]

So how do we define whether the comp is working effectively or not? Is it when the muzle has very little rise?

Effectiveness of the comp would be defined by:

- stability consistency of the dot during recoil (ie, it moves the same every time, and it doesn't have an inordinate about of lateral movement in it)

- how flat the gun stays during the early portion of recoil (perceived by the shooter as the gun shooting flatter, usually)

Realize that the muzzle will always lift (see the various slo-mo videos that have been posted on the forum), and the effectiveness of the comp is also determined by the load the shooter is using, so...

Several other factors are also affected by the comp, but they're also adjusted by things like recoil spring rates, FP stop geometry, etc, so it's hard to pin them exactly on the compensator... This is also why it's hard to hand a bunch of guns around and have everyone shoot them to determine what they think works best - you're shooting a whole system, and if there are multiple variables changing between each gun, you're not really evaluating one particular thing, in the end. That's very difficult to do correctly, unless you have a gunsmith at your disposal or a lot of free cash...

[Hi-Power Jack]

So how do we define whether the comp is working effectively or not? Is it when the muzle has very little rise?

Yup.

I remember reading many years ago that Rob Leatham was experimenting

with a 9 x 25 or 9 x 27, that produced muzzle DIP when fired:)

Not sure why that went away.

Jack

[XRe]

I remember reading many years ago that Rob Leatham was experimenting

with a 9 x 25 or 9 x 27, that produced muzzle DIP when fired:)

Not sure why that went away.

9x25 Dillon went away because:

- inconsistent dot movement (theoretically due to turbulence in the comp)

- while possible to load it to where it would dip a bit as the bullet exited the muzzle, the gun would still flip up (again, see slo-mo videos). This motion was extremely hard to time accurately.

- frequently poor accuracy - loading a bottlenecked pistol cartridge consistently is a bitch

- caused tendonitis in a number of shooters

- when they started playing with loads to try to fix the inconsistent dot movement, they discovered that the loads that worked best fit nicely in a .38 Super or Supercomp case...

- capacity figured in there somewhere...

In short, while an interesting idea on paper, it just didn't work well in practice...

[CocoBolo]

Hello Eric - Put that DP-2 on and shoot it you will lose all interest in the others. I've tried 3 of the 4, haven't tried the V-Port looking thing. The other two I have and sorry at my average slide weight of 10 oz they were a no go. If you go a full heavy slide YMMV. Gans basis his comp decisions on slide weight or at least partially. However, if you want to go a drllin as well then you got a chance with the others.

I have to say that Brazos with 4 poppel holes, and I'm talking AKAI built gun, its a honey of a flat soft shooter just the thing to give you that over confidence you need to launch those second shots right over the right shoulder of the target, shooting like the gun doubling (38S 9.6gr HS6 w/115gr Zero). An no doubt XRE can fill you in on the Brazos gun with the holes.

The Bedell takes a lot of gas and powder to get it shootable, 10.2gr of AA#7 makes 168 pf and you need a bowlers wrist brace shooting it, pump it up with another .3gr and is is still a bit bouncey, then get that drill out and poke a hole in it and its starts to feel nice. (38S 125gr)

If you decide to have a fire sale I'll take that DP2 off your hands, I don't need it but who know's might get the bug for Open Gun #5.

TrevorF take that Old Shool gun out and shoot it, if it ain't broke don't fix it.

[Hi-Power Jack]

I remember reading many years ago that Rob Leatham was experimenting

with a 9 x 25, that produced muzzle DIP when fired:)

Not sure why that went away.

9x25 Dillon went away because:

- inconsistent dot movement - while possible to load it to where it would dip a bit as the bullet exited the muzzle, the gun would still flip up (again, see slo-mo videos). This motion was extremely hard to time accurately.

- frequently poor accuracy - - caused tendonitis in a number of shooters

- when they started playing with loads to try to fix the inconsistent dot movement, they discovered that the loads that worked best fit nicely in a .38 Super or Supercomp case...

In short, while an interesting idea on paper, it just didn't work ...

Thanks, XRe, always wondered about that - the 9 x 25 sounded perfect to me at the time,

even though I was light years from shooting OPEN. Sounds like .38 Super is now "perfect"?

Jack

[TrevorF]

TrevorF take that Old Shool gun out and shoot it, if it ain't broke don't fix it.

Basically that's the plan in the beginning but I love to work on/modify/experiment with stuff. Every hobby I've ever had evolved trying to make things, better, faster, more efficient etc. That how it was with RC cars, RC planes, target archery and now guns. I started with a Glock 35 back in January that was set up for the standard division in IPSC and short of sending the frame away for custom work there's nothing left on that gun that I have worked on or replaced. That's what I love about open guns but it's also what scares me about open guns. The sky’s the limit.

I'm not even sure if I'm going to stay in open but if I do I know I am going to want to work on the gun. It seems to me that after a decent trigger job the next place to go is the barrel & comp. So although I will shoot it as is for a while I plan to learn as much as I can over the winter so that when the season starts up again if I do decide to stick with it I'll have an idea of what I want to do first to it.

Thanks,

Trevor

[surfmaster]

Agreed. I have a full-size Major 9mm pistol and it used to have a Bedell titanium comp. It was too light and did not allow me fast follow-up shots. I had to up the powder charge and switch to lighter 115 bullets at the expense of higher pressures. It still had too much muzzle flip.

So, I changed the titanium to a steel M2i comp (the one with the V-ports). What a world of difference. My double taps are fast and accurate like the way an open gun should be running. The gun now shoots flat and cycles fast; the lightened slide with the heavier comp sure helps. There's more weight but you don't even notice it.

Another factor is the gun also has a Gogun *thumb rest [generic]*. The combination of the *thumb rest [generic]* along with a heavier steel compensator has created a flat, double-tap positive open gun. Icing on the cake is winning a local match with this new setup--after firing it for the first time (with the new comp/*thumb rest [generic]* install) at the match and not firing a shot for four whole months.

Go with a heavier steel comp and *thumb rest [generic]* for Major 9mm for best results.

Hello Eric - Put that DP-2 on and shoot it you will lose all interest in the others. I've tried 3 of the 4, haven't tried the V-Port looking thing. The other two I have and sorry at my average slide weight of 10 oz they were a no go. If you go a full heavy slide YMMV. Gans basis his comp decisions on slide weight or at least partially. However, if you want to go a drllin as well then you got a chance with the others.

I have to say that Brazos with 4 poppel holes, and I'm talking AKAI built gun, its a honey of a flat soft shooter just the thing to give you that over confidence you need to launch those second shots right over the right shoulder of the target, shooting like the gun doubling (38S 9.6gr HS6 w/115gr Zero). An no doubt XRE can fill you in on the Brazos gun with the holes.

The Bedell takes a lot of gas and powder to get it shootable, 10.2gr of AA#7 makes 168 pf and you need a bowlers wrist brace shooting it, pump it up with another .3gr and is is still a bit bouncey, then get that drill out and poke a hole in it and its starts to feel nice. (38S 125gr)

If you decide to have a fire sale I'll take that DP2 off your hands, I don't need it but who know's might get the bug for Open Gun #5.

TrevorF take that Old Shool gun out and shoot it, if it ain't broke don't fix it.

[shred]

The main reason people I know (me included) quit shooting the 9x25 Dillon was it's 3-4 rounds down on a Super in a big stick, reloading for it was a nuisance.

That plus what Dave said-- and the 'Angus rule' of IPSC/USPSA limiting Major bullets to no lighter than 115 and there wasn't enough advantage to be worth it.

(there's a lesson here for those that insist their splits are too slow )

I've got the Briley catalog cover gun from somewhen in the mid 90's-- in 9x25. Most everybody, as did I, made a new top end in Super once the 9x25 comp wore out, which they did pretty rapidly when you're pushing 17 grains of H110 down the barrel. Still, that was the cleanest load I've ever shot. Cases came out looking like new inside and out.... if they didn't crack.

[SN13]

I thought open major minimum was 112gr?

[shred]

I thought open major minimum was 112gr?

Back then all you could get was 115, 100, 95, 90 & 88gr, so it was effectively 115 minimum whatever the actual rule (which I've forgotten anyway) was.

You could get the little 88gr JHPs up over 2000 fps, but the groups sucked.

[Powder Finger]

I remember reading many years ago that Rob Leatham was experimenting

with a 9 x 25 or 9 x 27, that produced muzzle DIP when fired:)

Not sure why that went away.

9x25 Dillon went away because:

- inconsistent dot movement (theoretically due to turbulence in the comp)

- while possible to load it to where it would dip a bit as the bullet exited the muzzle, the gun would still flip up (again, see slo-mo videos). This motion was extremely hard to time accurately.

- frequently poor accuracy - loading a bottlenecked pistol cartridge consistently is a bitch

- caused tendonitis in a number of shooters

- when they started playing with loads to try to fix the inconsistent dot movement, they discovered that the loads that worked best fit nicely in a .38 Super or Supercomp case...

- capacity figured in there somewhere...

In short, while an interesting idea on paper, it just didn't work well in practice...

Also exactly what Steve said earlier, the energy does not just go away, and it doesn't, it becomes very unpredictable.

[supreme135]

Gan's guns and Brozo's have alot of info on there web pages

[1911Prof]

Hello Eric - Put that DP-2 on and shoot it you will lose all interest in the others. I've tried 3 of the 4, haven't tried the V-Port looking thing. The other two I have and sorry at my average slide weight of 10 oz they were a no go. If you go a full heavy slide YMMV. Gans basis his comp decisions on slide weight or at least partially. However, if you want to go a drllin as well then you got a chance with the others.

I am curious about the two different Dawson comps, the original DP-2 only has the side bleeder holes in front chamber and the TJ version has an extra set in the first chamber (presumably to create more horizontal stabilization). Presently, I have an old EGW comp with 5 graduated chambers (the last one is inconsequentially small) and I experience a lot of flip even with a lot of powder. At this point it is either replace the comp or try adding popple holes to try to flatten it out a bit.

[Aircooled6racer]

Hello: You may want to try some other powerds that create more gas first. HS-6 is a good one and well as AA#7. If they don't do what you want then I would install some holes in the barrel. If that does not work for you then a more modern comp may do the trick. I have not run the Dawson comp I have yet as well as the others. I do know the Bedell comp likes lots of gas and the Tru Bor really likes the "Hill Hell Holes". Thanks, Eric

[Kriojas]

The tru bor runs great with 2 popple holes in the barrel.

[1911Prof]

The problem for adding holes in my barrel is that I have a cone comp and have been advised that it is not a great idea to drill through the cone and barrel so I thought changing comps might be a better option.

[XRe]

I am curious about the two different Dawson comps, the original DP-2 only has the side bleeder holes in front chamber and the TJ version has an extra set in the first chamber (presumably to create more horizontal stabilization).

Reportedly, Todd felt that the original DP2 had too much blast on the brim of his cap (ie, too much upward direction of the concussion wave). Dave cut two more side ports, and it alleviated the distraction for him. Whether or not that provided improved lateral stability, that apparently wasn't part of the design decision

[XRe]

The problem for adding holes in my barrel is that I have a cone comp and have been advised that it is not a great idea to drill through the cone and barrel so I thought changing comps might be a better option.

I've seen plenty of guns built with that arrangement (some intended to run at old Major), and never seen one that had a problem that was directly attributable to drilling through the cone and barrel...

[shred]

I am curious about the two different Dawson comps, the original DP-2 only has the side bleeder holes in front chamber and the TJ version has an extra set in the first chamber (presumably to create more horizontal stabilization).

Reportedly, Todd felt that the original DP2 had too much blast on the brim of his cap (ie, too much upward direction of the concussion wave). Dave cut two more side ports, and it alleviated the distraction for him. Whether or not that provided improved lateral stability, that apparently wasn't part of the design decision

This is the same story I've heard and I don't think I was the one to tell it to XRe In theory those ports will cause the comp to be a little softer and a little flippier, but you'd have a hard time telling.

As for drilling barrels. I asked Dawson about it once since I'd read somewhere that you should to put the holes in the grooves of the barrel to avoid problems. He said "I'm real lucky then. I've put holes in hundreds of guns [without measuring the rifling] and hit them perfect every time "

[XRe]

This is the same story I've heard and I don't think I was the one to tell it to XRe

I was thinking you were, but I didn't want to indict you for spreading incorrect rumors if it turned out to only be urban legend... Might've heard it from Chethro, though...

[Dawson Marketing]

Might've heard it from Chethro, though...

Yeah, it was me.

We were talking about comps in between doing commentary voice-overs for some DVD project.

-Chet

[lcs]

The problem for adding holes in my barrel is that I have a cone comp and have been advised that it is not a great idea to drill through the cone and barrel so I thought changing comps might be a better option.

My primary open is cone comp and has 4 popple holes. No problems. It is my second open in that configuration.

[1911Prof]

Can anyone explain the thoughts behind why progressive chambers in a comp are designed for fast moving bullets. I would think the speed of the bullet would be inconsequential compared to the percieved upward vector of the gas expansion out of the chambers

[XRe]

Can anyone explain the thoughts behind why progressive chambers in a comp are designed for fast moving bullets. I would think the speed of the bullet would be inconsequential compared to the percieved upward vector of the gas expansion out of the chambers

Generally speaking, faster moving bullet = more gas and/or pressure...

[1911Prof]

I get that, but why progressively smaller chambers? Is it it really believed that the shooter will expience a more level upward force because the higher pressure is going through a larger chamber and the lower pressure (further away from the chamber) is going through a smaller chamber?