PDA

View Full Version : 50 BMG SPADE GRIP BUILD TEST RUN


bubbapug1
05-06-2011, 9:24 PM
Those who followed this thread a few weeks back know the result didn't work.

The pics in post #1 are what did NOT work. Pics in post #2 are what I will test Sunday. Its a much beefier set up and I hope the springs take up some of the recoil and also slow it down a bit to make it more comfortable to shoot...

Range report late Sunday night or Monday morning.

As for getting service from Bohica...no working phone, not return emails...nada...buy a Ferret. Nothing is a good deal if you have to machine your own repair parts.

BOHICA 30" UPPER, KNS spade grip kit.

Cali legal 50 bmg

I will test this on 4 22 11 and post a report...and pics of the groupings if I can handle the recoil and don't break the mount!!

4 - 22 2011 TEST REPORT

4/22/2011 - I took the gun to Burro, and other than getting accused of stealing a rock....things went just like I feared!!

The mount to my adapter failed after two shots. It couldn't take the load of the 50. The M3 tripod really sucked up the recoil, but the STEEL rail/adapter ate it. The small mounting bolt broke, I can't see how it lasts even with normal shooting off a bipod. The forward dog ear extension on the tripod rail mount also bent like warm butter from two shots. Back to the drawing board.

http://i481.photobucket.com/albums/rr177/bubbapug1/DSC00888.jpg

http://i481.photobucket.com/albums/rr177/bubbapug1/DSC00889.jpg


As to the recoil it felt like catching a medium fast ball pitch on the palms. I am sure with out the M3 it would feel like catching a Nolan Ryan fastball!!

The gun worked well, no misfire, the chamber is a bit tighter than a M2HB thats for sure, no issues ejecting brass, and no issues with the lower afterward.

I will go to plan B and let you all know how it worked.

P.S. - Some LA PD right next to me...noted right away the gun was legal as it wasn't a rifle!! I guess they read cal guns too.


http://i481.photobucket.com/albums/rr177/bubbapug1/DSC00812.jpg

bubbapug1
05-06-2011, 9:25 PM
Reserved for PICS of new recoil device.

Here it is...2" of travel for straight recoil, than another spring in the back to deal with any muzzle flip around the axis of the hinge.

http://i481.photobucket.com/albums/rr177/bubbapug1/DSC00892.jpg

Machined rail adapter. This IS the weak link as the block is 7075 aluminum. I would hope the springs keep giving way before I would exceed the shear strength of the material holding the rail, but I can't be sure that will happen. The block will drive back against the springs and ride on two 1/2" bolts which are smooth and threaded into the back black. The back block can rotate about 30 degrees counter clockwise.

762.DEFENSE
05-06-2011, 9:30 PM
Sorry to hear about B.O.H.I.C.A.'s horrible customer service. Kudos on the professional machine work though.

Kerplow
05-06-2011, 9:34 PM
Who is ryan Nolan (http://en.wikipedia.org/wiki/Nolan_Ryan)? :p

j/k. :D

that thing looks sweet! It would be cool if you could get a rail mounted further to the rear for a scope.

bcrich
05-07-2011, 6:20 AM
You got some mad skillz, hope it works out. Keeping an eye on this one. I'd bring out my .50 and join you sunday but it's mothers day!

AJAX22
05-07-2011, 7:14 AM
I think part of it may have been how far forward the mount was.

You might consider welding one to the pistol grip stub.

You also might want to consider a mount with more give to it, I think a fiberglass pole would be a lot easier on the gun and mount.


very cool project

Z.1
05-07-2011, 7:39 AM
That is a mean-looking not rifle!
I'm guessing this qualifies as AOW?
Nice work on the mount, good luck this weekend

bubbapug1
05-07-2011, 9:58 AM
I thought about absorbing the recoil in the buffer tube assembly, but the bolt needs to ride backward in the buffer tube to eject the cartridge. Any deflection in that area would impair the action.

A fiberglass mount is probably an option, but its time consuming and also eventually I would need to machine hard points to hold a pintle or rail anyway. I wanted to work this gun with off the shelf items I already own, which I have done.

With 2" of horizonal movement and 30 degrees of vertical movement I would think this will stand up to the task, but we shall know tomorrow by noon I think.


I think part of it may have been how far forward the mount was.

You might consider welding one to the pistol grip stub.

You also might want to consider a mount with more give to it, I think a fiberglass pole would be a lot easier on the gun and mount.


very cool project

AJAX22
05-07-2011, 10:44 AM
for fiberglass I was actually envisioning a whip mount, like a cluster of tent poles attached to the pintle which were then fastened to a base...

if it was nice and long (3.5 feet or so) it should allow for a foot or more of give.

glocklover
05-07-2011, 11:11 AM
I personally think that your stick is sweet, screw anyone that thinks it's a waste of money or time. That is YOUR gun, no one elses. Your probably the only one, if not a VERY few in CA with this setup, how cutting edge is that.

I'm sure at one point folks thought that a "bullet buttoned" AR was a waste of time and money. Why not just get a mini 14, or bolt action???

The thread was opened by the OP for "info", just to show what he was doing and progress made, which was requested by others. He didn't ask anyone what they thought of his stick. Ever heard of "if you don't have anything nice to say, don't say anything at all".

Yes everyone is entitled to an opinion, that's why this country is great. However, in this instance, it wasn't requested.

This post is MY "opinion". I would also like to see updates.

Keep doing what your doing Bubba.:cool2:

CSACANNONEER
05-07-2011, 6:59 PM
Interesting mounting system. It sort of reminds me of a rail gun.

bubbapug1
05-07-2011, 7:25 PM
Why don't you sketch it up with some dimensions and post in on this thread.

for fiberglass I was actually envisioning a whip mount, like a cluster of tent poles attached to the pintle which were then fastened to a base...

if it was nice and long (3.5 feet or so) it should allow for a foot or more of give.

frigginchi
05-07-2011, 8:26 PM
I wonder if you can mount a mountain bike shock to soak up some of the recoil?

http://p.lefux.com/61/20100803/A25220000V/bike-shock-rear-shock-air-1-small.jpg

bubbapug1
05-07-2011, 9:12 PM
I wonder if you can mount a mountain bike shock to soak up some of the recoil?

http://p.lefux.com/61/20100803/A25220000V/bike-shock-rear-shock-air-1-small.jpg

If I could find one 3" long that would be perfect.

Test in 12 hours 48 mimutos

frigginchi
05-07-2011, 9:35 PM
Closest i could find

http://cgi.ebay.com/Mountain-Bike-155mm-Suspension-Rear-Spring-Shock-750lbs-/270742707205?pt=Cycling_Parts_Accessories&hash=item3f0985dc05

If I could find one 3" long that would be perfect.

Test in 12 hours 48 mimutos

Lostsheep
05-07-2011, 10:03 PM
First of all I want to say that I love it!

Now to be a little bit of a critic (sorry in advance).

I am assuming that the plan is for the mount to slide on the pins while compressing the spring. I am concerned that the recoil will create a torque on the pins that will cause them to bind and not be able to slide. How much slop did you design in, specifically on the slip fit?

If this is a non-issue than nevermind but if you find that it binds, remember that torque is force x radius. The closer you can get the slide to the barrel the less the binding torque. I look forward to your report.

MrPlink
05-07-2011, 11:40 PM
this rifle errrr... crew serviced weapon is the epitome of Ca gun laws!
Its such a backwards project I love it!

duc748bip
05-08-2011, 1:47 AM
So howm many people do you have in your crew? :D

thrillhouse700
05-08-2011, 9:17 AM
this rifle errrr... crew serviced weapon is the epitome of Ca gun laws!
Its such a backwards project I love it!

Me too, it should be named "The Pelosi" as a slap in the face. I love it Bubba keep us posted.

wash
05-08-2011, 10:47 AM
I'm not sure about this one.

I think you need a barrel block.

I hope it doesn't break but I think the picatinny rail is going to become the weak spot.

If your spring mount breaks, you are going to have a real handful.

If you still want a spring system, I suggest a larger single rod supported on both ends and the floating mount in the middle with something like heavy duty valve springs in front and behind the floating mount.

Good luck.

ke6guj
05-08-2011, 2:53 PM
I'm not sure about this one.

I think you need a barrel block.

I hope it doesn't break but I think the picatinny rail is going to become the weak spot.
I'm going off memory, but I think the pic rail is just bolted onto some additional framework inside the handguards. It may be better to completely remove the Pic rail and design the spring mount to mount directly to the framework.

wash
05-08-2011, 4:42 PM
Yep, that's what I was thinking.

A coaxial mount would be ideal but you would need a yoke long enough to pivot on the centerline to really get the benefit.

What I suggest might be overkill but I like that when dealing with a .50.

wash
05-08-2011, 4:45 PM
The problem with a spring mount is that a traditional T&E won't work.

1911su16b870
05-08-2011, 6:23 PM
Thanks for the pictures and excellent machine work! Can you post or pm me photos on how the linkage accesses the trigger? I've wondered how that spade trigger activator bolts up into the AR lower and runs the trigger. Thanks!

bubbapug1
05-08-2011, 10:59 PM
Took the unit to Burro today and put around 30 rounds through it.

It works!! There are some things that need to be improved, but the unit is beefy enought to deal with the recoil, and the picitanny rail mount showed absolutly no sign of wear!!

I also shot the gun twice without the recoil device...and it is horrible! You get a beating of the palms and the gun slid backward around 6". Not a fun thing.

So now I have a working concept which with I will keep improving, but for the purpose of shooting and sighting in a scope in California this unit is more than adequate.

Now I need to develop of T&E system to make the whole set up more accurate and easier to aim, tune in the springs a bit more, and remove some of the play in the guide rod holes due to poor workmanship and a very poor clamping set up when I match drilled them

Sorry, I do not have any videos, but I think some of the other Calgunners on site might have taken a few.

NorCalAthlete
05-09-2011, 7:35 AM
Awesome!!! :D

quick draw mcgraw
05-09-2011, 9:29 AM
Nice work Bubba!!!

I hope this one works like a champ.

supersonic
05-09-2011, 9:43 AM
OP: have you thought about trying out some polyurethane bushings in between your springs & retainer blocks? That, coupled with an AR-50 muzzlebrake would solve all your problems, guaranteed.:cool:

EDIT: the ArmaLite brake is threaded the same as the Bohica muzzle. I had the MK III brake (like yours) on mine & after 10-15 rounds of full power 50, my shoulder would tell me to call it a day. After upgrading to the AR, almost ALL the recoil is gone, & I can shoot all day long.:D

glocklover
05-09-2011, 9:54 AM
thanks for the update.

wash
05-09-2011, 10:36 AM
That sounds good, just keep an eye on it...

I initially suggested a T&E mounted to a mag well block so that you could remove the gun from the tripod easily but with that sliding mount, that probably won't work.

If you get rid of the springs, you could do a T&E that way but I fear the picatinny mount would take a beating and you are back to needing a barrel block.

I hope you can come up with a good solution.

dirtydeedsdoneinthedesert
05-24-2011, 10:08 PM
Wow, great machine work. Classic, one of a kind piece. I would have loved to have seen the looks and the LAPD's face when you whipped this baby out at the range. lol.

Quinc
07-26-2011, 2:31 PM
Bump! :D

762.DEFENSE
07-26-2011, 2:43 PM
Bump! :D

:confused:

hcbr
07-26-2011, 3:06 PM
:thumbsup:

luckystrike
07-26-2011, 4:30 PM
only in ca....

Madpyro
07-26-2011, 6:31 PM
SWEET!!!!!

bubbapug1
07-28-2011, 1:40 PM
I have a new and improved design about ready to go. Its a lot more simple to make and its also tighter on tolerances and stronger.

Pics to follow in about a month

stag6.8
07-28-2011, 3:08 PM
I wonder if your setup would work on a barrett .416 cal legal version. model 82A1? and make it featureless....hhhhhmmm

goodlookin1
07-28-2011, 7:02 PM
If I were you, I would stick some elastomer rubber stops in the spring recoil area just in case the recoil assembly bottoms out. If/when it bottoms out, you have nothing to further compress, so all that additional stress is going straight to the mounting block. The other thing is you have nothing to adjust for the forward motion recoil.....that could get quite jarring on the mount/(not)rifle because those springs look pretty stiff. If you purchased one of those mountain bike shocks with an adjustable dampener built in, you could really dial down the amount of stiffness you need when it recoils back and how slow it decompresses.

I know it's extra money, but it really looks like it's gonna get jarred around in the current setup.

Nice work though! Looks awesome!

bubbapug1
07-28-2011, 10:03 PM
If I were you, I would stick some elastomer rubber stops in the spring recoil area just in case the recoil assembly bottoms out. If/when it bottoms out, you have nothing to further compress, so all that additional stress is going straight to the mounting block. The other thing is you have nothing to adjust for the forward motion recoil.....that could get quite jarring on the mount/(not)rifle because those springs look pretty stiff. If you purchased one of those mountain bike shocks with an adjustable dampener built in, you could really dial down the amount of stiffness you need when it recoils back and how slow it decompresses.

I know it's extra money, but it really looks like it's gonna get jarred around in the current setup.

Nice work though! Looks awesome!

The srings don't bottom out. It would be nice to have a dampner, and I have found one and will try it to save the scope some shcok, but a mountain bike shock is way too long for the set up.

WDE91
07-28-2011, 10:55 PM
How is the trigger control the on the spade grips?
Heavy?
Creep?
Light?
Crisp?

goodlookin1
07-29-2011, 6:50 AM
The srings don't bottom out. It would be nice to have a dampner, and I have found one and will try it to save the scope some shcok, but a mountain bike shock is way too long for the set up.

As long as the dampener works.....if it doesnt, it could weaken the "weakest link" to the point of breaking. Not to mention that jarring forward motion of the recoil will surely jack up any rifle scope as they are really only meant to handle backwards recoil. They can even get jacked up on a spring loaded pellet gun (forward recoil), let alone a .50 BMG ;)

You seem like a decent machinist....i'll let you figure it out :D Cant wait to see the final results!

50BMGBOB
07-29-2011, 3:58 PM
Not to mention that jarring forward motion of the recoil will surely jack up any rifle scope as they are really only meant to handle backwards recoil. They can even get jacked up on a spring loaded pellet gun (forward recoil), let alone a .50 BMG ;)


Actually, the brake on a 50BMG already causes that same forward motion, like a spring loaded pellet gun and is one of the reasons 50BMG's are so hard on scopes.

bubbapug1
07-29-2011, 10:28 PM
Actually, the brake on a 50BMG already causes that same forward motion, like a spring loaded pellet gun and is one of the reasons 50BMG's are so hard on scopes.

That is the truth. The recoil isn't too bad on the spade grips. It feels like a bolt action 308 recoil. Supersonic says an armalite muzzle brake will work even better, and I might try one.

I just wanted not to break my wrists, and the recoil set up does that job well.

glocklover
10-03-2011, 3:34 PM
Any new info?

bubbapug1
10-03-2011, 8:03 PM
No new info or tests recently. I am going to make a few improvments to the set up.

1. First, I am going to try to add some, if not all, of the improvements in post #40 by goodlookin1 (thanks by the way). I am having issues trying to find a small dampener which fits my needs.

2. I am going to add a pistol scope as your face is about 1 foot back from the scope. While I can use the rifle scope, its a bit challenging but it works.

3. I need to machine an adapter to allow me to attach my Ma Duece T&E to the magazine well. The gun is hard to keep super steady and I want this gun to shoot at least 1" - 5 shot groups at 100 yards using my Lehigh match bullets. I know the Bohica upper can do it. Its chambered very tight, and the Ma Duece can do it with its very loose chambering.

After I get these items done I will take it back out to the range. If its dialed in I will go punish the 600 yard steel at Angeles!!

little_twin
10-03-2011, 11:14 PM
1. First, I am going to try to add some, if not all, of the improvements in post #40 by goodlookin1 (thanks by the way). I am having issues trying to find a small dampener which fits my needs.


Have you looked at any motorcycle steering dampers? Some have independent adjustments for zero to lock and return to zero. Most would be easy to adapt with minor machining.