ULT reactivity

[Joni]

I have a theory I would like some opinions on.

A lot of people complain about the lost reactivity with ULT, and it's only logical that the reactivity lessens. With ult you have a trigger pull of about 15 oz, and I'm guessing that it might give about 25 oz of return force due to reactivity. 10 oz is a lot less difference than between the 3lb trigger pull/5-6lb return force with the original on/off. I'm not sure about the exact numbers, but they prove my point.

Now to the interesting stuff. I have read the thread about shortening the trigger pull by drilling a hole further up in the sear for the trigger rod. This also makes the trigger pull heavier. Let's say that we shorten the trigger pull enough to make it as heavy with the ult, as with the original on/off. Assuming the number I wrote earlier, this would give a trigger pull that is about 1/3 in length to the original, but with the same reactivity. For people that like RT triggers that would probably a pretty sweet trigger.

What are you're thoughts on this? Have I missed something in the reasoning that would make this a moot point?

[QUINCYMASSGUY]

Very cool Joni, it was actually myself and Jack & Coke who seperately came out with this idea and one of the theories I expanded on was how the ULT would really make the idea of cutting 20-25% of the pull off and still result in a trigger pull that was reasonably light. Kind of finding a perfectly happy medium as the ult is as light as it could have gotten since no smaller orings are available, and the benefits of a short pull. 25% was always my favorite number with this, and would be possible. And as far as I know (theory as opposed to actual testing) doing what you suggested would bring the reactivity up to the normal levels, but alot of questions would arise about easy runaway and such with that short of a pull. Now 50% would be nice and I know just how to do that.... but I'm being a little secretive on that one, it would be a whole new sear that would allow for this and who knows, I might produce it :)

Oh yeah, shorter pull+more reactivity=quicker, easier return=little to no chuffs

[Joni]

Yes, creds to both of you for coming up with this. I think I'm gonna be experimenting a little, but I would have to get someone to drill a sear a. I have no extra sear, and as I understand drilling it is not a simple task. I also know that with the current geometry of the sear there is a limit to how much you can shorten the pull. It would be very interesting to see how a new sear would perform.

[QUINCYMASSGUY]

MOD

Effectively doing this mod takes top of the line equipment, someone who knows what they're doing, and alot of trial and error. It's the fabrication that stopped me from doing it.

[Big'n slo]

I just finished modifying my sear for this last night. The MAX distance above the original sear rod hole was 0.30" (center to center) anything more and I could not re-seat the sear and pin in the rail. I have not finished tweaking yet (still have some bolt stick) my setup is:
ULT w/7 shims
LVL w/3 shims
Sear rod extended to account for pivot point

The pull *feels* shorter with a definite added weight when compared to a standard ULT setup. I believe trigger stops will improve the way the feel of the shortened pull.

[QUINCYMASSGUY]

trigger stops are definitely useful, something like a cam adjuster, a trigger stop like the kind an angel uses, or an idea I have somewhere in the workshop called "the stopblock idea" which is a drop-in trigger stop apparatus for mags would all allow you to remove the extra slop so you don't pull beyond the point of firing and waste the intent of this mod.

There is a way to make it MUCH shorter, and a smoother pull on top of that..... ...... but it would involve a redesign of the sear in a ways. Also, now that the shims allow the point where the on/off opens, I feel there is benefit to a shorter, thicker sear. Same pressure would be exerted as a whole but spacing it out over more of an area horizontally instead of vertically would allow a shorter pull without risk of chipping.

[Big'n slo]

Originally posted by QUINCYMASSGUY
trigger stops are definitely useful, something like a cam adjuster, a trigger stop like the kind an angel uses, or an idea I have somewhere in the workshop called "the stopblock idea" which is a drop-in trigger stop apparatus for mags would all allow you to remove the extra slop so you don't pull beyond the point of firing and waste the intent of this mod.

I read through your stopblock thread, very interesting. It's slightly more complicated than the setscrew trigger stops I'm planning.

Originally posted by QUINCYMASSGUY

There is a way to make it MUCH shorter, and a smoother pull on top of that..... ...... but it would involve a redesign of the sear in a ways. Also, now that the shims allow the point where the on/off opens, I feel there is benefit to a shorter, thicker sear. Same pressure would be exerted as a whole but spacing it out over more of an area horizontally instead of vertically would allow a shorter pull without risk of chipping.

Do you have a sketch of your idea? I'm not quite following your description.

[QUINCYMASSGUY]

More complicated but totally removable, no permanent drilling and fully adjustable so easy for anyone to install. Fits right in the groove on the top of intelliframes.

I'll work on the pic, but it's something I've actually considered producing, part of it would involve a new trigger as the slope would be greatly exaggerated, the next step in the process would be to find a way to make the ULT even lighter or to balance out the pull weight distribution so a pre-loaded spring can be used in front of the trigger to apply pressure before the pull, making it superlight. With the retro being 3X the pull force, there would still be plenty to reset with.

[Joni]

I have considered the the spring idea myself. I've read on pbr about a guy who had good results with a spring on a non-ult. An original ult probably has problems with resetting, but a modded sear would give it enough return force. The question is if using a spring would result in lessened recharge time and/or worse consistency.

[QUINCYMASSGUY]

spring

It would have something of a reg effect, DEFINITELY not work on a non-retro valve, but let's go with this scenario:

Trigger pull: 15 oz pull/45 oz return (ULT standard)

Mod to sear, cutting 50% of the pull, balancing out the pull weight based on the radius between the pivot point of the sear and where force is being applied to it, basically making it a smooth, evenly weighted pull from start to end

Trigger pull: 30oz pull/90 oz return (modded ULT)

Spring installed in front of trigger, pushing up near the top of it applying, let's say, 20oz pressure. The sear should be modded that the pull resistance decreases slightly as it goes so the decreased spring pressure as it unwinds balances out with it.

Trigger pull: 10oz pull/70 oz return (spring loaded mod)

Now, the retro effect still exists but less return than before, I am confident that as long as the weight is balanced throughout the pull, it will work, but in the current mag you'll hit light spots at the start and the end, so the sear won't reset to start and if you help it move it will reset a little but not all the way.

I am not sure what is more important, the net volume of return force or the ratio, the ratio of pull weight to return force, or the ratio of spring resistance to return force. I unfortunately don't have the engineering knowledge or the funds to trial-and-error this. Alot of prototyping needed.

[RRfireblade]

Originally posted by QUINCYMASSGUY
Very cool Joni, it was actually myself and Jack & Coke who seperately came out with this idea

Not that it matters any but 'some' people have been doing that 'mod' for quite some time before the ULT.


: please continue:

[QUINCYMASSGUY]

ok, then let me rephrase: Jack & Coke and I came up with it without any prior knowledge of it being done and were, as far as we know, the first to publicize it here on AO. If you did it before us, congrats, and please by all means share your input on how it worked for you.

[RRfireblade]

Nah, no biggie.

I've just been noticing your threads on the subject for the last little while and thought it was kinda humorous,that's all.

I won't take credit for being the first either,it goes back quite a way is all I know.I had mentioned it to J&C way back when he was talking about shortening the Mag pull,he probably doesn't even remember.I have maybe half a dozen sears drilled in various locations as well as altered pivot points and re-timed sear geometry,ultimately though,there still is no free lunch.That's when I built my first Pneu-Mag,which some evolution of will likely be the future of Mech Mags IMO.

There were a few different sear mods that have been done,this is just one.AGD pretty much frowns upon any of them so they never get much airplay.(don't even get me started on trigger rod adjustment)

So,
Don't mind me,you keep tinkering.You never know what may come of it,the ULT does add a few new variations.I have it in a X valved Micro w/ a modded/re-timed sear and a trigger w/ a relocated rod pocket that works pretty well but I'm still undecided between that and the good 'ol R/T effect.

No worries.

Jay.

[trains are bad]

Is there any way to anneal the sear to be drillable? I tried heating it to bright cherry red and letting it cool slowly but it didn't work (I had the important parts clamped in a machine vise so they wouldn't get hot.)

[RRfireblade]

Drilling it's no biggie.There's a little trick to it.PM me for details.

Jay.