[Resjudicata]

I've seen on TGO's website an open gun he used in Bianchi shooting that has a frame mounted comp that is part of the Bianchi shroud. I've have heard that Keonig also used one and maybe others.

I'm wondering what the benefits are of a comp mounted to the frame versus a comp mounted to the barrel? Also, has anyone shot one using major PF ammo and how did the comp work with that ammo?

Thanks,
Chris

[Action Pistolero]

Doug is still using one. The advantage is that there isn't any weight on the end of the barrel. With a normal set up with the comp on the barrel you have to use lighter recoil springs and a lightened slide to get the gun to work reliably. Doug uses 6" barrel, 10+ pound recoil springs and a commander slide.

I use a 6" barrel in a 5" slide with an aluminum comp and jam nut on the end. Initially I have to use a 7 lb recoil spring but after things break in I can go to a 9. The disadvantage to my set up is that the aluminum comps will crack. I seem to have better luck than most, however.

The disadvantage to Doug's gun is that to clean it he has to remove the shroud. There is extra material welded to the sides of the frame so that each screw has more threads to use.

In order to run major ammo through these guns the recoil spring would have to be substantial, 18 to 20 pounds worth, so I would think that there wouldn't be anything to gain by doing it.

[Resjudicata]

Thanks for the info. I would think that to run major you would just run the recoil spring weight that would be needed without a comp. Is that not right? Does the comp end up unlocking the barrel/slide faster therefore needing a heavier spring?

How does the sight tracking and recoil impulse feel as compared to a barrel mounted comp? I've tried an Open major gun with a barrel mounted comp and it was good at the beginning of the recoil impulse but when the slide hit the frame it still jumped quite a bit. I'm wondering if the frame mounted comp would let the gun unlock and complete the slide movement faster and therefore allowing the gases in the comp to help with the sight raising due to the slide hitting the frame.

Maybe this doesn't work but I'm just trying to find out what has been tried.

Chris

[Action Pistolero]

It has been my experience that a non comped gun will take a heavier recoil spring than a comped gun. One would think that they wouldn't be so different because the comp is just re-directing the gas. In my case, there is some friction on the barrel from the bushing because of the extra weight out front but not much.

In the case of a frame mounted comp there is no friction to overcome up front so it would need a heavier spring. It sounds to me like you would be correct in saying that this set up would need a recoil spring the same weight as a non comped gun.

Slide speed would certainly increase but I don't know if it would decrease the sight jump that you mention when the slide hits the rear of the frame. If the comp is working well then it should keep the muzzle down so that you won't see much of a jump.

At this point, I'm getting a little over my head as I don't shoot major much. The Open gun that I shoot major in uses a full profile slide and a 10lb spring. I like a heavy gun. Most USPSA shooters like a lighter one.

Kevin

[Allgoodhits]

I'll jump in here since I have a shroud mounted comp gun and a barrel mounted comp gun.

Hopefully, I'll address your questions with my experiences with my guns as they are set up.

My shroud mounted comp gun is bullet proof. It will run hot loads, light loads or whatever you put through it. It has a 6.25" barrel and a slide shortend to about commander length of 4.25 inches thus "lightened". I can use a 7 through a 16 lb spring depending on the load. It'll run at 850 fps or 1300 fps with proper spring. I tune the spring to the load to get the slide feel that I prefer for the load. I find that a 12-14 lb spring will work quite a range and is what I use most often. The gun is heavy since my shroud is hand made from steel. The shroud also gets hot. If I had to do it again, it would have an aluminum or similar weight shroud. Having said that, off hand the gun is very flat shooting, cycles quickly, but it is HEAVY.

Having spent multiple thousands of dollars on my one of kind shroud comp guns, I would not do it again. Build a normal comp gun. It will cost less, be easier to clean, and easier to get work done on it if necessary. I love mine, but I like my barrel comp gun just as much, but for different reasons. Both, in my case are pretty equally accurate, with a slight edge to my shroud comp gun most likely because of the weight advantage. It is NOT for quick draws, because it is too heavy.

I do not shoot major our of either of these guns, but if I were to build an USPSA type gun it would be a barrel comp gun, since they will run with the hotter loads, in fact they seem to like the hotter loads, more so than the real light loads. I know some shooters who run a 5 lb spring in their Bianchi Comp guns just to get them to run. That light of a spring, may yield a malf with a little crud or a rough rimmed piece of brass, whereas a heavier spring sometimes will make a gun a tad more reliable when dirty or other issues arise. For this reason it appears that some run a heavier spring for stripping the rounds off the mags, then they have to run a hotter laod because they ran a heavier spring and so on. In Bianchi, reliability can not take a back seat to anything.

Hope this helps!

Martin

[Toolguy]

Another option is to have the comp on the barrel, but the barrel bushing solid in the shroud. The slide is shortened, making it lighter.
With this setup, it's easier to get a 9mm to run because the slide is free to run without the comp pushing down on it and binding it up.
The slide only touches the barrel at the chamber and lug area while the bushing is stationary in the shroud.

[gm iprod]

Warren,

That is essentially the system GrantJ and I run. Grant on his Tanglefoot and mine is STI based.

Grants gun is easier to disassemble than mine. Mine does take some effort but it unbelievably flat under recoil. It is also a little heavy. I have a 6" barrel and Titanium Comp, comp is currently 100K plus rounds old.

Chris,

From scratch, to get a simple to use gun especially if it is your first AP gun, then build as per Martins theory, thereafter find what works and build your version of the perfect gun. Look about for a used gun and get going on that for less money.

[Jaxshooter]

Would you please post a pic of each type of gun so we can see the difference?
Thanks

[gm iprod]

I would if my open gun would show up the difference well enough. I have a few pictures and they are all 1Mb+ so I will do a bunch of smaller ones later.

[GrantJ]

Check out this thread on this forum, 1911 Bianchi Shrouds, pictures are included.

GrantJ

[gm iprod]

http://www.brianenos...?...=69151&st=0

Try this

[Resjudicata]

Thanks for the responses guys.

Those that have shot/own both types of comps, is the timing of the recoil and slide to frame bounce effected differently by the two different comps or is the difference negligible?

Chris

[Allgoodhits]

Resjudicata, on Nov 14 2009, 07:01 AM, said:

Thanks for the responses guys.

Those that have shot/own both types of comps, is the timing of the recoil and slide to frame bounce effected differently by the two different comps or is the difference negligible?

Chris

For clarification: My comp/shroud gun is as follows. Slide shortened to about 4.25", barrel length about 6.25". The bushing which contacts the barrel is "fixed" in the shroud. The "other" bushing is reamed out and it does not touch the barrel, it merely contains the recoil spring. My comp is mounted on (threaded) into the shroud and does not touch the barrel at all. I can remove my comp and still shoot the gun with no effect except significant difference in muzzle action/recoil. In fact, I can and have removed the comp, removed the detachable barricade wings, removed the scope and mounted a sighted rib on the gun and used it for metallic. It works fine either way, and accuaracy with or without the comp is indistinguishable. In fact I have a steel comp and a titanium comp to amend muzzle weight. Remember, I told you this gun was very expenseive, and would never do it again.

Your comment about how it feels. My shroud/comp gun has a 14 lb spring and a lightened (shortened) slide. The comp is not sprung on the barrel, so there is no added weight, nor is there any down force on the barrel from the comp gas, so it unlocks and cycles very fast (snappy). The comp gases work, they just don't apply force to the barrel, but the apply downward force ahead of the muzzle, since the comp is in front of the barrel! I like it for offhand shooting, say the mover or the longer timed strings. It would be great on the shorter strings too, except remember it is very heavy.

Why did I do this? One, I like things different. I designed my own proprietary MJ Custom Reticle for the Gen One HOLOsight, and I like tinkering. The other reason, was that I started with a revo and the "normal" comp guns of that era had a pretty fat shroud, and I didn't like the way they felt on the barricade. My shroud design has a smaller diameter and feels good to my small hands. What I didn't account for was the heat build up of the tight fitting steel shroud and the fact that the muzzle of the barrel is contained in the shroud in that the bullet/gases have a jump similar to a revlover's cylinder barrel gap, and this heat/flash is contained and adds to heating up the shroud. In the summer, you definitely do not want to shoot an aggregate with the barricade event last!

There are hundreds, probably thousands of quality barrel comp guns out there. Some with shrouds for BC, some set up for USPSA. I have a comp/shroud gun with bushing mounted in the slide built by NVGW in a Springfield, VA. I think Dougs are similar to that design. There is at least one other one similar to these in PA, but I don't remember the guys name who has it, and I am sure who built them. It may have been a joint effort. Grant has a similar setup, but I think his differs from the basic design of mine and Dougs. There are no doubt a few others. Round wheels roll better than any other wheels. Unless you have lots of time, lots of money, lots of patience, and build two of them, DON"T DO IT.

I have to add that I shot the shroud comp gun for several years and have shot the only 1920 I ever shot with that gun. In fact, I think I followed my 1920 with a 1918 the next month. I had shot a 1918 with a revolver a year or so before that, so as always it is not a magic gun, it is whether the nut behind the trigger is all there, or somewhere else when the shots are being fired.

So, having said that, let me know how it works for you. If someone told me not to do something, or that I can't do it, then I'd start right away!

MJ

[Resjudicata]

That last bit is unfortunately a good description of me, too.

I didn't really explain myself very well in the beginning. I'm working on building a USPSA open topend for my USPSA Limited gun in .40. I had to ask the question about frame mounted comps in this section because nobody in USPSA uses a frame mounted comp. Of course this led you all to think that I was building an open cup gun. Sorry about that.

I had seen the photo and description of Leatham's open cup gun and it got me thinking through how the two different type of comps would work. USPSA open guns seem to all be barrel mounted comps. I'm sure at some point there were reasons why USPSA guns went that way. It may be weight savings helping with the larger number of transitions in USPSA shooting. It may be the fact that it is easier to disassemble for cleaning. Or, it may be that the barrel mounted comp just works better. I'm thinking that for USPSA the weight savings and easier disassembly is the more dominant reason for barrel mounted comps over frame mounted. Because it seems to me that the frame mounted comp would actually do the most in keeping the dot/sight under control through the complete recoil and slide movement period.

Therefore, it seems to me that even for a USPSA open gun, if you can keep the weight down as much as possible and the shooter isn't too weight sensitive in transitions then a frame mounted comp may actually be a good idea for a USPSA open gun. Any thoughts on that? I think you have probably convinced me already that a barrel mounted comp is the way to go but I would still like to hear what you think about a lighter gun with a frame mounted comp and no Bianchi shroud.

Thanks,
Chris

[Allgoodhits]

Chris,

Bottom line is I don't know enough about gases, cycling, weight and IPSC types of shooting to render an absolute answer. However, I have opinions whether they be right or not is subject to testing or absolute knowledge by others to refute.

Here goes.... Barrel comp guns I would think would be the lightest possible combo. Two, barrel comp guns require a lightened slide and/or a very light spring compared to a non comp gun of the same design and load in order to run. I would basically compare the "running" of a non comp or non barrel mounted comp gun to be quite similar as far as spring/slide/load configurations for purposes of gettin it to run.

Most would agree that a non comped gun will feel softer with a heavier bullet moving slower, vs a lighter bullet mover faster to reach a given mathematical PF, and most would likely agree the opposite for a comped gun of about any design. I don't know enough about powder selection variations that would reverse these positions, but my guess would be that no powder would reverse the feel, some podwers may close the gap.

The non barrel mounted comp gun with a major load would have a very fast slide, so one may have to beef up the recoil spring to slow the slide, I would think that this would lead to complicated process of getting the slide weight, the spring weight in balance and I would think that you would still have more felt recoil than you would with a normal comp gun in major loads.

IMO the benefit of the shroud comp gun is forward unsprung and noncycling weight. Since the comp has no effect on the barrel, then the barrel will unlock like a normal gun, and if properly sprung, you can run unbelieably light loads. Light loads, low slide weight, heavy forward end of a gun and a comp equals very little recoil and very little muzzle lift. Having thought this through ( I may be dead wrong ) I would think that a shroud or frame mounted comp gun may be better for Steel Challenge (similar to Bianchi load) than a major PF applications. Someone smarter or with more experience than I may chime in here.

I have some photos of my shroud/comp gun, but I don't know how to upload them here. PM me with an email ansd I'll send them to you if you want.

MJ

[Action Pistolero]

Craig Ginger from Australia has an odd bird similar to what you are talking about, Martin. He has an STI long dust cover frame and I'm assuming a 5" slide. It is a bull barrel setup but there is a collar right behind the comp that attaches to the frame thus making the front of the barrel fixed. It too is set up for light loads.

Kevin

[Service Desk]

Action Pistolero, on Nov 14 2009, 07:16 PM, said:

Craig Ginger from Australia has an odd bird similar to what you are talking about, Martin. He has an STI long dust cover frame and I'm assuming a 5" slide. It is a bull barrel setup but there is a collar right behind the comp that attaches to the frame thus making the front of the barrel fixed. It too is set up for light loads.

Kevin

The guns use a frame mounted bushing (the collar that Kevin refers to) with a 3 port alloy comp attached to the barrel.
The slide is heavily cut away at an angle from just infront of the last locking lug to about 12mm infront of the recoil plug shoulder.
The gun is built by Ray Pulver - most top Australian competitors use his guns, so they work ! The accuracy, reliability and longevity is really exceptional.
The latest craze is to put an integrated shroud / comp / mover-mount unit onto a CZ SP01 - for a low-cost AP gun.

Ray makes cut-rifled barrels to fit the SP01 in just about any twist and chambering. I shot one a couple of weeks ago it was chambered in 38 Supercomp. Good handling and very accurate.

This post has been edited by Service Desk: 16 November 2009 - 01:04 AM