Prototype Portable Combination Pistol and Carbine (PCC) Machine Rest Build

Status
Not open for further replies.
fxvr5 said:
If you liked that article, you'll probably like this one too.
Click to expand...
Nice.

Fact is, recoil force, even for pistol loads, must be factored and managed on the machine rest for more consistent return to zero and certainly for blowback

fxvr5 said:
The important feature for using 9 Major is having enough case support to prevent the case from rupturing. The chamber wall thickness on some 9mm pistols is sufficient. People are building 9 Major guns on 9mm Glocks and S&W M&Ps.
Click to expand...
One of many reasons for me switching to 40S&W was option of shooting 9mm Major with 40-9 conversion barrel with thicker chamber/barrel walls to better contain chamber pressures. And KKM barrel with longer leade/freebore allowed loading bullets to longer than SAAMI max length to stuff more powder charge in the case.

When I get the prototype machine rest going, I may do 9mm Major load development for match shooters considering 9mm Major.
 
bds said:
One of many reasons for me switching to 40S&W was option of shooting 9mm Major with 40-9 conversion barrel with thicker chamber/barrel walls to better contain chamber pressures. And KKM barrel with longer leade/freebore allowed loading bullets to longer than SAAMI max length to stuff more powder charge in the case.

When I get the prototype machine rest going, I may do 9mm Major load development for match shooters considering 9mm Major.
Click to expand...

What gun is your 40 S&W?

A concern for loading to longer than SAAMI length is that the round might not fit in the magazine even though it fits in the chamber. My Glock 19 magazine won't handle anything longer than SAAMI length in round nose, and they have to be even shorter if using flat point (i.e. JHP) bullets.

I'm not sure THR will allow posting of 9 Major data since most of it will exceed SAAMI specs.

Below are links for 9 Major data, and there is a lot of information and load data for 9 Major at the Brian Enos forum, shown below.

9 Major: https://www.ssusa.org/articles/2018/1/9/how-to-use-9-major-in-a-short-barrel/
https://www.ssusa.org/articles/2017/7/27/reloading-tips-for-9-major/

Brian Enos: https://forums.brianenos.com/
https://forums.brianenos.com/forum/72-9mm38-caliber/
 
Glock 22.

I was thinking of posting 9mm Major test results for evaluating accuracy of different powders. I could check with Walkalong to see if posting 9mm Major loads with disclaimer will satisfy THR rules. If not, I could omit the load data and just post target group pictures and powder used.

Yes, spent a lot of time on Brian Enos forum for USPSA matches. Good times.
 
bds said:
Glock 22.

I was thinking of posting 9mm Major test results for evaluating accuracy of different powders. I could check with Walkalong to see if posting 9mm Major loads with disclaimer will satisfy THR rules. If not, I could omit the load data and just post target group pictures and powder used.

Yes, spent a lot of time on Brian Enos forum for USPSA matches. Good times.
Click to expand...

With respect to accuracy, every gun is different so you can't claim too much about how a good/bad load in your gun will shoot in someone else's gun that will have a different barrel, with different twist rate, leade, and other dimensions.
 
bds said:
Yes, I did look at them but decided on fidget spinner bearings because I plan to use adjustable/tensioned brackets.


ATV strut would be overkill. I would only need hatch strut/strong arms but even those would be too much.

My guess is I need to tame only a few pounds of recoil force for pistol/PCC loads. I may look at more beefy recoil management when we approach rifle loads.
Click to expand...
What about a screen door closer? It's adjustable tension and retracts.
 
bds said:
Glock 22.
Click to expand...

Yeah, you're not likely to get any 9mm over SAAMI specs to fit in that magazine since it's built on the same frame as a 9mm. You need a longer front-to-back magazine, like one made for a 45/10mm/38 Super.
 
OK, went to an estate sale and found a castered stainless steel cart with wooden top. I will see which will work out better as testing platform base and may test both. Dimensions are 35"L x 21"W x 26" H (not including the casters). Cart is very rigid due to the middle slanted shelf that forms an "L" shaped support and just as heavy as my stainless steel table. I think the cart has less torsional twist/flex than the table.

Thinking about welding a long base the cart will be mounted to provide more stable resting with dirt ground I have to use on BLM land. Remember, this is a "portable" machine rest as I have no access to concrete slabs and solid bend to mount my "platform" the pistols/carbines will be hard mounted to.

index.php


And here's my table with dimensions of 48"L x 26"W x 19"H showing base of triangle testing platform on top.

index.php
 

Attachments

  • MR new.jpeg
    MR new.jpeg
    98.9 KB · Views: 45
Last edited:
The first consideration in designing and building a "machine rest" is a means of holding the firearm securely without damaging it. Chuck Ransom ( Ransomrest system) finally solved this problem brilliantly after experimenting with other holding fixtures. The rotating feature of the Ransomrest solves another problem inherent in accuracy testing handguns and handgun ammo with in-line rests. I have worked with machine rests designed for use with a specific firearm, such as formally us by arsenals for testing military small arms, but they have little application to other types of small arms, especially sporting rifles. Some amateur attempts at building machine rests have generally resulted in unwieldy contraptions such as shown in series of photos early in this thread. Attached are pics of a machine rest built and sold by Bo Clerke several years ago. I don't know how many he built, but I ordered this one after seeing one like it being used at a military instillation. The clever holding fixtures have allowed me to do extended accuracy with a wide range sporting rifles. Currently a "slave" rifle is installed for long term accuracy testing plus simultaneous velocity and pressure. The carrage would be easy copy as it simply glides on a pair of 29" one inch rods on fiction-less bearings. McnRest1.JPG McnRest2.JPG McnRest3.JPG McnRest4.JPG ..
 
Thanks for posting.

Offfhand said:
The first consideration in designing and building a "machine rest" is a means of holding the firearm securely without damaging it.
Click to expand...
Yes, I have studied many machine rest designs and learned to appreciate the objective of solid/hard mounting and why it has taken so long to even arrive at the prototyping stage as I have discarded many earlier designs and considerations after I deemed them unable to reliably repeat "return to zero".

And I need to build a hybrid machine rest that will accommodate both pistols and carbines, one of my requirements from OP - https://www.thehighroad.org/index.p...-pcc-machine-rest-build.852174/#post-11147472

Another requirement is sub $100 budget so it would be affordable for most THR members to build (and for me to PIF more copies :D). Right now, I am looking at most "stability" bang for the buck options hence why I decided on a triangle tunnel design to hard mount pistols on one side and carbines on the other side.

Keep in mind, I only have access to BLM land to conduct my testing. So no solid slab of concrete or heavy bench. This is a "portable" machine rest build for me and why I am thinking of using my 250 lb body weight along with lead filled bags for around 500 lb base. But subsequent copies will be made to "C clamp" onto heavy benches at the range.

Offfhand said:
The carrage would be easy copy as it simply glides on a pair of 29" one inch rods on fiction-less bearings.
Click to expand...
Yes, I started with two rod glides and bearings but since my ultimate goal is to produce cheaper copies (out of plywood/metal hardware) for PIF to THR members, I am examining other low friction recoil rail management options with focus on "return to zero".
 
Last edited:
I think it would help to keep these in mind:
  • I am not trying to build a laboratory grade machine rest that demands utmost precision and absolute repeatability of zero
  • I am trying to build an affordable, low cost, easy to build DIY machine rest that will be "good enough" for 25 yard pistol load testing
  • IF proof of concept works out for pistol load testing, I will expand the testing for 50 yard carbine load testing (Pistol Caliber Carbines)
  • IF DIY machine rest produces "good enough" consistency for PCC at 50 yards, carbine loads will be tested at 100 yards and perhaps rifle (.223) load testing also
While many of us may dream about $2000 higher end 1911, sub $1000 Colt, Sig, S&W, SA, Ruger may be "good enough" for most of us (Heck, I like my Sig 1911 enough that I no longer need to buy a Dan Wesson PM7). For some, even RIA may be "good enough". I am trying to build a RIA version machine rest.
 
Last edited:
After comparing the stainless steel table to the stainless steel cart I recently picked up at an estate sale, I am thinking the table may provide greater stability as base for the testing platform. But I am thinking of welding a long base (with sharpened rebar/plate feet) for the cart to be anchored to (and perhaps be attached to 2" receiver mount of truck for easy stow) so it may work out.

I will probably test both to see which provides greater stability for the triangle testing platform pistols/carbines will be hard mounted to.

BTW, dimensions are 35"L x 21"W x 26" H (not including the casters). Cart is very rigid due to the middle slanted shelf that forms an "L" shaped support and just as heavy as my stainless steel table. I think the cart has less torsional twist/flex than the table.

index.php


And here's my table with dimensions of 48"L x 26"W x 19"H showing base of triangle testing platform on top.

index.php
 
I am taking an out of town trip for father's day with my parents and visit my sister/BIL next week but when I return, I am planning to resume work on building the triangle testing platform and mock up a low friction recoil management rail.
 
Thinking about welding a long base the cart will be mounted to provide more stable resting with dirt ground I have to use on BLM land. Remember, this is a "portable" machine rest as I have no access to concrete slabs and solid bend to mount my "platform" the pistols/carbines will be hard mounted to.
Click to expand...

I think I would go with 3 legs and spikes that could be driven into the ground. Large disks rig above that so there is a “stop”. Not unlike the bottom of a ski pole, just larger.
 
Status
Not open for further replies.

Similar threads

LiveLife
  • Locked
Reloading projects for retirement - Happy 4th of July (Independence from work?)
2 3 4 5
Replies
104
Views
9K
LiveLife
LiveLife
LiveLife
THR Group Project - PISTOL - Advanced Reloading Concepts and Discussions
2 3 4 5 6 7 8 9 10 11
Replies
273
Views
74K
jmorris
jmorris
LiveLife
  • Locked
THR Group Project - RIFLE - Advanced Reloading Concepts and Discussions
2
Replies
49
Views
6K
wombat13
W
LiveLife
  • Locked
Neck tension affects bullet setback. How about accuracy?
Replies
9
Views
1K
moxie
M
F
  • Locked
.308 load Chrono Data
Replies
6
Views
699
USSR
U
Back
Top