July 15, 2007
I made a fancy looking recoil slide for testing recoil of rifles with different weights of bullets and with different brakes installed. I put a chronograph just past the slide. On July 15, 2007 I tested a few rifles. Large chamber brake means the inside was turned out resulting in a baffle at the end of the brake. Small channel means a small hole, .015"over bullet diameter, all the way from the muzzle to the exit of the brake.
Here are enough to get an idea how different weights of bullets affect free recoil travel. Which translates into usable information.
No brake
.223 26" heavy barrel 55 grain moly 3,306 feet per second 1 13/16"
.223 22" light barrel same ammo 3,260 2 3/8"
.223 22" light barrel 60 grain 3,118 3 1/8"
7 Rem Mag 120 grain 3,380 12 7/8"
7 Rem Mag 140 3,027 15 5/16" 7 Rem Mag 170 2,852 19 15/16"
7STW 130 3,763 15 1/8"
.375.-416 Rem Mag 270 2,968 29 ¾"
.375-.416 Rem Mag 300 2,858 35 11/16"
Factory brake with large chamber
7 Rem Mag 120 grain 3,419 7 ½"
Homemade small channel brake
7 Rem Mag 120 grain 3,417 3 3/8"
7Rem Mag 140 grain 3,056 4 ¼"
7STW 130 3,761 4 7/16"
Large chamber brake
.375-.416 Rem Mag 270 2,885 17 3/8"
.375-.416 Rem Mag 300 2,915 21 1/16"
Small channel brake
.375-.416 Rem Mag 270 2,952 12 3/8"
.375-.416 Rem Mag 300 2,882 17 ½"
Shooting Recoil slide 11/29/14 60 degrees
All holes are perpendicular to bore.
Started with a Savage using a Midway 24" barrel chambered to .257 Weatherby weighing 8lb 5.5 oz. The load was Nosler 100 grain Ballistic Tip about 3,500 feet per second. The powder charge of IMR7828 weighed 71.0 grains. A Federal 215 Magnum primer sparked the powder.
Conclusion first: Lots of smaller holes seem to be better than a couple large holes.
With no brake the free recoil rifle travel measured 15 3/16".
With the Shark gill brake made by Tom Hart of MOA Precision the travel was 3".
With the small "rectangle" brake made by yours truly the rifle traveled 3 ¾".
With the larger "square" brake again made by me the rifle traveled 4 ¼".
Switched to the Weatherby .257 SLR with a 26" Pac-Nor barrel. I t weighs 6 lb 13 oz. The bullet was a Nosler 85 grain Ballistic Tip about 3,800 feet per second. H4831from WW2 weighing 65.0 grains powered the cartridge. The same brand and number of primer was used in this rifle as the previous one.
No brake produced a free recoil travel of 16 5/16".
The six hole round brake made by me reduced the travel to 4 7/8".
12/6/14 60* brake with four angled slots at about 15 1/2degree threaded on both ends
Today I used the Weatherby Mark V ultralight six lug action without the scope. It has a Pac-Nor 26" barrel. The rifle weighs 5 lb 10oz. The load consisted of .270 Winchester cases necked down and blown out leaving about 3/16" neck. H4831 from WW2 @ 65.0 grains was ignited by a Federal 215 Magnum primer. The average velocity for the eighty-five grain G.S.Custom bullets was slightly over 3,800 feet per second. I fired three shots with each setup to verify the free recoil travel information generated.
Without a brake:
14 7/8"
14 5/16"
14 5/16"
Average - 14 ½"
With the brake installed so the ports angled toward the front:
4 5/8"
4 7/8"
4 7/8"
Average - 4 13/16"
reduction – 66.8%
With the brake installed so the ports angled toward the rear:
3"
3 ¼"
3 5/16"
Average - 3 3/16"
Reduction – 78%
I have no idea how these numbers would compare to a free hanging rifle with a way to record its travel. But at least we can see a pattern developing.
Today, 12/13/14, I took the Savage with a Midway fluted 24" barrel chambered in .257 Weatherby. With no scope it weighs 6 lbs 5.5 oz. The load was Barnes TTSX 80 grain bullets pushed by 73.0 grains of IMR7828. The primer was a Federal 215 Magnum. The temperature was about 45 degrees. I fired three shots of each test. Instead of resetting the rifle back to the start after each shot I decided to fire each subsequent shot where it stopped to get a total distance for the three shots fired.
I used the new brake which has four .800" slots .100" apart that were cut with a 5/16" endmill angled 20 degrees to see if it was noticeably better than the one with four .750" slots .125" apart cut with a 1/4" endmill and angled 15 degrees.
With no brake the total travel in the free recoil slide was 39 5/16"
With the slots facing forward the total for the three shots was 11 1/2".
The shark gill brake allowed the rifle to move a total of 5 7/16".
With the slots facing rearward the rifle moved a total of 4 9/16".
Conclusion: Rearward facing slots are way better than forward facing slots.
December 24, 2014
Took the slide to the range. The temp was about 45 degrees and it was raining. The slide was wet. With no brake on the unscoped Savage .257 Wea ( about five pounds thirteen ounces) the three shots slid the rifle 72 inches. The aluminum brake with four slots .800" long and .312" wide reduced the travel on the wet slide to 12 9/16". I cut off the brake right in front of the third slot and fired the rifle three more times. The travel was 14 13/16".
Just for fun I stuck the Mauley .22 with the Tasco 6-24X40 on there. With Federal red boxes ammo it moved 5/32".