Ransom rest and/or lead sled build?

[Blue68f100]

When testing pistol loads most use a Ransom rest if they have one. I'm thinking about building a test fixture and was thinking of making it like a rifle rest. If the pistol is allowed to rotate up and return, that is a source of error. Not returning to the same place every time. It only takes a min of a angle to be off. If one was to make the mount solid so it can not rotate up but can be pushed back I think is a better idea. We all try to handle the recoil in different ways. I've had surgery on both wrist so neither of mine are strong, so I let the gun jump to some degree.

Make the pistol mount to slide system means the gun will track the same every time without the error in tilting provide I can get a grip on the gun to hold it solidly. Can use a shock to absorb the recoil. I will anchor it to my shooting bench, have a scope mounted to the sled for aiming the gun. May use reference that's not related to the BE target. This will let me know if any thing has moved, fixture wise. I always think gripping the handgun grip is the weak link, and still may be. Should work for rifle too if I use long enough rails.

Do you think it will work?

 

[Demi-human]

Do you think it will work

Yes, but not affordably so.
There are many high precision linear bearing offerings. These are expensive, but not prohibitively so if you are more determined than I. An aluminum carriage would be easy to make if one had the skills for MIG welding, or is it TIG? Anyway I don’t, there’s more cost at the fabricator, but not much for such a durable good.
But to attach the pistol in a manner that allows multiple firings, while guaranteed not to move after sighting, firing and recoiling. And also accommodating other pistols. That is the tough part.
(And where I lost interest.)

There are a lot of rifle rail guns, but they are hard fastened down.
The trick is a clamp system that can have a hardened pin that can go through the trigger guard and resist upward movement completely, thus allowing it to transfer to the gas strut dampeners.

But then I thought I might bend a trigger guard.
A tinny rail under the barrel might work for such appointed pistols, but that leaves out most revolvers. Grooved side clamps could do revolver barrels, but not autoloaders. And anything I come up with for nice adjustments between firearms can’t handle recoil, and I wanted it for a Desert Eagle.

A conundrum for certain.

 

[Blue68f100]

Right now I'm only going to do 1911's. Which I can remove the grips and have the grip bushing slip into holes then clamp the receiver. Similar as to how you secure the frame when your doing mill work on the receiver.

I don't like anything contacting the barrel, for it impacts the harmonics to some degree.

For Al Tig is best, I use to do quite a bit of it when I worked. Mig can work but is not near as strong.

 

[LiveLife]

thinking about building a test fixture ... had surgery on both wrist ... pistol mount to slide system means the gun will track the same every time without the error in tilting ...

Do you think it will work?

As I approached retirement, I wanted to build a hybrid pistol/carbine machine rest that rolled on bearings and recoiled back from spring tension on to triangle mated base for repeatable zero -
https://www.thehighroad.org/index.p...-pcc-machine-rest-build.852174/#post-11147479

Pistol and carbine mounts were going to be fixed to sides of a triangle shaped tube with roller bearings on flat base riding on captured rail. Hard mounts would prevent movement of firearm frame yet allow slide movement. Scope mount on picatinny rail on top of the triangle tube would verify return of zero back on target POA before subsequent shots.

Trigger would be actuated with remote cable release to eliminate human factor.

Due to family issues/aging parents/deaths/surgeries and medical issues, this project got put on hold and since, I have focused on 22LR and 9mm carbine testing using Lead Sled rifle rest and bipods (I am currently buying another 20x-24x power scope for my testing purposes).

During this time, I had a chance to approach this machine rest from different perspectives some of which vastly different all to maximize repeated zero for subsequent shots.

I am still pursuing the project on low priority basis with initial prototype materials already purchased. I need to make an out of state travel next week to deliver our sectional couch PIF to wife's brother who is getting married and pick up a new sectional for us. I may deliver 200' length of cedar fencing to them as well so any testing will have to wait (I am pursuing T/CR22 ammo comparison test currently and would love to continue the machine rest test build).

 

[bullseye308]

If I’m not mistaken the ransom rest does allow the pistol to rise with the recoil, but then falls back to its start point to reset and be fired again. I have been thinking about building something similar, but I’m not a metal worker and it would have to be done in wood. Thinking 2” white oak probably.

 

[fxvr5]

If I’m not mistaken the ransom rest does allow the pistol to rise with the recoil, but then falls back to its start point to reset and be fired again.

The gun (held by the rocker arm) rotates when the gun is fired, but it is manually reset.

 

[earlthegoat2]

Pretty sure @jmorris has built something like this.

 

[LiveLife]

Pretty sure @jmorris has built something like this.

Yes he did and mounted his ransom rest to a corner of welded fencing.

I did thought about buying a ransom rest but considered the notion that ransom rest does not necessarily replicate how we shoot pistols and wanted to better duplicate the dynamics of recoil (lighter spring for pistol and heavier for carbine) for more applicable testing.

Yeah I know, now you know why I have been on pause contemplating the design for so long. In the end, the initial prototype could be a simple enhanced optical pistol/carbine rest that recoils and go from there. Good thing I am retired and have plenty of time (Yeah, right. ).

 

[Blue68f100]

Pretty sure @jmorris has built something like this.

Yes he did. He bought a ransom rest to test then decided it had to much slop so he built his own. His version had tighter tolerance and reduced the grouping by nearly 1/2. This indicates any slop any where will impact the group size. One of the reason I don't want to deal with rotating impulse.

LiveWire, I went back and re-read that thread. A lot of good info.

I'm leaning toward the linear bearing as the base, though drawer slides would be much cheaper. Will probably go with some kind of cylinder (oil) where I can control the impulse.

As far as impulse is concern. My shooing bench by the house weighs around 100 lbs. I use a lead sled when I'm testing loads or shooting my hi-power rifles. My bad back can not take the jarring due to nerve damage. I made a base to set the led sled in to keep it from slide back so I would not have to add the weights. I fired my 458 SOCOM in it one day and 3 shots slid the base about 1/2". That's with be sitting on it, 160 lbs. I ended up staking the back legs to keep it from moving. So its going to need some type of means to absorb/damper/control the impulse. My benches at 200 and 300 yrds are set into the ground so they don't move.

 

[jmorris]

If the pistol is allowed to rotate up and return, that is a source of error. Not returning to the same place every time. It only takes a min of a angle to be off….

Make the pistol mount to slide system means the gun will track the same every time without the error in tilting provide I can get a grip on the gun to hold it solidly. Can use a shock to absorb the recoil. I will anchor it to my shooting bench, have a scope mounted to the sled for aiming the gun. May use reference that's not related to the BE target. This will let me know if any thing has moved, fixture wise. I always think gripping the handgun grip is the weak link, and still may be. Should work for rifle too if I use long enough rails.

Changing position will mess things up pretty quickly. If one changed alignment by 0.001", the bullet displacement at 100yd will be much greater. Using 16” OAL (1.3ft) moving one end 0.001" would move the point of aim (300ft/1.3ft)*0.001"=0.231" (just under 1/4"). A longer OAL would change less, shorter, even more.

That said the steel to steel contact points are much more repeatable than other things. The Rotation of the Ransom rest is a bandaid for the rest of the system. Because the pistol wants to rotate when fired, the machines ability to rotate with it helps the main problem, that’s holding onto the firearm well enough it doesn’t move relative to the machine. In other words, if you didn’t allow the machine to rotate, you have greatly increased the difficulty of keeping the pistol from rotating in your grip inserts. Think about your 458 Socom moving your rest and you back 1/2” after 3 shots, if it were allowed free recoil in the rest, you could have likely returned it back to where it came from and the weight of the bench and you wouldn’t have been shoved back 1/2”.

So your not really holding on to the grips, rather the steel frame, with the grip inserts.


And you can put an optic on the firearm so you can see if it is moving around, relative to the fixture.


I do have a bunch of linear slides though and have played with them too, for rifle actions at least.

In simple form it’s enough metal that the base doesn’t move on what it’s sitting on, the action is free to slide back and forth on the rails only needing to over come the weight of itself and fixture on the rails to move.



And optics can be added at various points to see if anything is changing.



I suppose if one puts a pistol barrel in the V blocks that would work too, just not easy to do on many of them.

If you want to restrict movement by recoil, you are going to need a much more massive fixture to be the equal and opposite reaction, that doesn’t move at all.

Not mine but I liked this one enough to save photos of it.

You will also note that you don’t really need a linear guide. A precision “V” and rod can do the job as long as everything is heavy enough to maintain contact between the two.

 

[jmorris]

Might do a little looking into unlimited class benchrest rifles. They are essentially highly developed action fixtures created to shoot the smallest single hole groups. Might give you some ideas.

http://bulletin.accurateshooter.com/2016/01/unlimited-class-rail-guns-the-epitome-of-precision/

 

[AJC1]

If I’m not mistaken the ransom rest does allow the pistol to rise with the recoil, but then falls back to its start point to reset and be fired again. I have been thinking about building something similar, but I’m not a metal worker and it would have to be done in wood. Thinking 2” white oak probably.

If you have wood working tools I would recommend plastics. The riddout scrap bin is a treasure trove of goodies. Wood is wonderful for a lot of things but a synthetic would be far more stable in every way and just as easy to fabricate with the same tools
https://www.eplastics.com/?gclid=Cj...CeVqik6PZIk9A9XWfz_FabUENi7e1QOxoC_cYQAvD_BwE

 

[fxvr5]

I did thought about buying a ransom rest but considered the notion that ransom rest does not necessarily replicate how we shoot pistols and wanted to better duplicate the dynamics of recoil (lighter spring for pistol and heavier for carbine) for more applicable testing.

Why does this matter? It doesn't.

The purpose of any mechanical device for holding a gun to test accuracy is to reposition the gun in the same place for every shot. How it moves, or whether it moves, does not matter.

99% of the recoil's effect on the RR (or whatever device) occurs AFTER the bullet has left the barrel. Therefore, it does not matter if the device recoils more like a human or not.

 

[Blue68f100]

Changing position will mess things up pretty quickly. If one changed alignment by 0.001", the bullet displacement at 100yd will be much greater. Using 16” OAL (1.3ft) moving one end 0.001" would move the point of aim (300ft/1.3ft)*0.001"=0.231" (just under 1/4"). A longer OAL would change less, shorter, even more.

That said the steel to steel contact points are much more repeatable than other things. The Rotation of the Ransom rest is a bandaid for the rest of the system. Because the pistol wants to rotate when fired, the machines ability to rotate with it helps the main problem, that’s holding onto the firearm well enough it doesn’t move relative to the machine. In other words, if you didn’t allow the machine to rotate, you have greatly increased the difficulty of keeping the pistol from rotating in your grip inserts. Think about your 458 Socom moving your rest and you back 1/2” after 3 shots, if it were allowed free recoil in the rest, you could have likely returned it back to where it came from and the weight of the bench and you wouldn’t have been shoved back 1/2”.

So your not really holding on to the grips, rather the steel frame, with the grip inserts. View attachment 1018530
View attachment 1018531View attachment 1018533 View attachment 1018534

And you can put an optic on the firearm so you can see if it is moving around, relative to the fixture.
View attachment 1018538

I do have a bunch of linear slides though and have played with them too, for rifle actions at least.

In simple form it’s enough metal that the base doesn’t move on what it’s sitting on, the action is free to slide back and forth on the rails only needing to over come the weight of itself and fixture on the rails to move.

View attachment 1018541

And optics can be added at various points to see if anything is changing.

View attachment 1018539

I suppose if one puts a pistol barrel in the V blocks that would work too, just not easy to do on many of them.

If you want to restrict movement by recoil, you are going to need a much more massive fixture to be the equal and opposite reaction, that doesn’t move at all.

Not mine but I liked this one enough to save photos of it.View attachment 1018535View attachment 1018536 View attachment 1018537

You will also note that you don’t really need a linear guide. A precision “V” and rod can do the job as long as everything is heavy enough to maintain contact between the two.

I don't plan on trying to stop the recoil, will use something to absorb it and return to preset. Like the idea of the V blocks. Thanks for posting how the grips are done for hand guns, that makes more since.

One of the problems I have where I'm at is it's very dusty this time of year. I can walk out to my shop and you can see the dust storm behind me as I walk. With this know I need to use a sealed system to eliminate the dust jamming things up. Bellows may be needed. It looks like I should have 2 heads, 1 for pistol that can rotate up, and 1 for rifle. Don't know if a angled ramp would work for pistol. I'm still leaning toward a hydraulic (or air) cylinder to control the travel, with springs to push it back. This way I can control the rate of travel by adjusting a small metering valve, giving a broader working range.

Thanks for all the feed back. Gives me something to ponder on what will work. Now to start drawing things up.

 

[jmorris]

I'm still leaning toward a hydraulic (or air) cylinder to control the travel, with springs to push it back. This way I can control the rate of travel by adjusting a small metering valve, giving a broader working range.

Sounds like more parts/variables. Be sure to post a build thread though, sounds like a fun project.

 

[LiveLife]

Why does this matter? It doesn't.

Yes I agree and why I have been pondering as my intent for the machine rest wasn't just to produce the smallest groups rather perform "comparative" testing of different components (powder, bullets, brass, etc.).

What I realized conducting the "real life" 10/22 and T/CR22 22LR ammunition 10 shot group testing at 25/50 yards was that while my testing platform was crude and rough (many shooting variables), I was still able to conduct comparison between brands/types/weights of bullet type to determine which was more accurate.

So I am revising my machine rest design/prototype to be a simpler enhanced optical rest for now.