30 378 weatherby

[Doublezranch]

They all sport an assassin brake and weigh around 14-15 pounds. The kids carry them up the mountains and across the prairies.

 

[WYO300RUM]

They all sport an assassin brake and weigh around 14-15 pounds. The kids carry them up the mountains and across the prairies.

That's awesome !

 

[memtb]

My rifle weighs 12,4 pounds and recoil was 49.2 ft/lbs with this load and no brake.

After testing it with my brake, recoil dropped to 17.3 and after tuning the brake for that load it measured 12.8 ft/lbs of measured recoil. The recoil reduction was 74.1 % and near the highest reduction achieved to date. The powder to bullet weight ratio is very high with this cartridge (3 : 1
and this helps.

The biggest powder charge tested was 122 grains but as stated there was very little increase in velocity. (It looks like it can only burn so much powder inside the barrel and the rest is wasted)

So this is definitely a good place for a muzzle brake.

J E CUSTOM

Were these numbers for the 30-378? If so, I guess my "guesstimate" wasn't very accurate, as I was lower than your 49 ft/pounds, with a lighter rifle. I used the Weatherby weight specs (8.4#), a 32 oz. scope, a 118 powder charge with 200 grain bullet @ 3200 fps.....to acquire my number (46.2#) Where did I mess-up? memtb

 

[J E Custom]

Were these numbers for the 30-378? If so, I guess my "guesstimate" wasn't very accurate, as I was lower than your 49 ft/pounds, with a lighter rifle. I used the Weatherby weight specs (8.4#), a 32 oz. scope, a 118 powder charge with 200 grain bullet @ 3200 fps.....to acquire my number (46.2#) Where did I mess-up? memtb

Yes, The numbers were measured On out recoil test machine (The accuracy is within less than 1 ft/lb) and not calculated, On my website, we have a Video of a test of a 338/378 that Is heavier than my 30/378 and it will give you a comparison of sorts, the efficiency is not as good because of the heavier bullet and less powder. also the brake was tuned for a different cartridge (A 338 Lapua) and not for the 338/378. The rifle owner would not let me take it off and tune it to his rifle after he shot it even though I told him I could get 3 or 4 more ft/lbs of reduction by tuning it to his rifle. but you can see the test machine used. I did not video the test with the 30/378 but It was less than 1 ft/lb difference than the calculated recoil.

The highest percentage of recoil reduction we ever got with a tuned brake was using a Weatherby Accumark in 30/378 and 180 grain bullets and 119 grains of 50 BMG.

Here is the Video of the 338/378.



J E CUSTOM

 

[memtb]

J E Custom, Is it safe to assume that calculated numbers from various formulas, are "not" very accurate? If you have faith in any one particular computer based formula, could you post it for me. Thanks! memtb

 

[J E Custom]

J E Custom, Is it safe to assume that calculated numbers from various formulas, are "not" very accurate? If you have faith in any one particular computer based formula, could you post it for me. Thanks! memtb

When calculating recoil there are so many variables that the calculations are just not accurate enough. They are close, but with to many variances. This is the reason we built the machine for testing the rifle and load in real world firing situations as hunted with or shot.

The recoil machine had to be very accurate and repeatable in order to do R&D on different brake designs in order to measure actual recoil changes from one brake design to another. Also we can/could test the actual rifle as used scope and all.

J E CUSTOM

 

[memtb]

JE Custom, WOW! I assumed that there would be some differences between programs, or other methods of measurement.....but "never" anticipated the difference I'm seeing using my program .....ShootersCalculator.com. Comparing your measured numbers with my computed numbers (for your rifle).....your numbers are approximately 11 ft/lbs lower than my calculated values. Now I wonder what the actual numbers are for my rifle! Calculated, my rifle comes in at just under 60 ft/lbs. If the error value is similar on my rifle......no wonder it is a bit uncomfortable off of the bench. Plus, I'll have to start treating my wife with "much" more respect. Her rifle comes in at 39 ft/lbs. memtb

 

[J E Custom]

JE Custom, WOW! I assumed that there would be some differences between programs, or other methods of measurement.....but "never" anticipated the difference I'm seeing using my program .....ShootersCalculator.com. Comparing your measured numbers with my computed numbers (for your rifle).....your numbers are approximately 11 ft/lbs lower than my calculated values. Now I wonder what the actual numbers are for my rifle! Calculated, my rifle comes in at just under 60 ft/lbs. If the error value is similar on my rifle......no wonder it is a bit uncomfortable off of the bench. Plus, I'll have to start treating my wife with "much" more respect. Her rifle comes in at 39 ft/lbs. memtb

As I said earlier, we tried as many programs as we could find to get a base line for our test bed and couldn't find any that agreed with each other. so we ended up using spring rates at distance traveled and weighed each spring and the load it took to move it at any distance. we also had to add the effect of momentum and inertia to the set up. The electronic load cell was one of the tools we compared out recoil tester against, and found that even the load cell had a 4% average error (Different reading shot to shot). the downside to the load cell was it,s ability to respond to the speed of load presented to it consistently.

Our search for more information also led us to Hatcher's note book for the testing he did for over many decades. He had recoil values based on millions of our tax payer dollars for equipment and had all the recoil values for the military weapons so we use his information on the 30/06 Springfield as a base line In the same model of rifle he used to test with. Once armed with this information we compared his calculations and test numbers. with our actual numbers and found them to be less than One ft/lb more that his and with a one pound preload on the machine to return it to battery, It was almost identical to his test numbers.

So now with all the data we have generated, we can use the data to predict the actual recoil and when we test the rifle, It agrees with the numbers we can generate off our data. We still run actual test to verify actual recoil and regularly test the machine to re verify it's accuracy. The real advantage to testing this way has been the ability to measure subtle changes in the design differences proving that some changes are counter productive, while other changes have improved performance.

We also ran many test to try and alter the sound signature of the muzzle brake (The part that most people object to) Without effecting efficiency and did find ways to reduce the sound somewhat, but could never reduce it enough to make it safe to un-protected ears.

Sorry for the long winded explanation, but it was necessary to explain the difference in calculated numbers and actual/real recoil numbers. And I agree with your fear of your wife If she can handle 35 to 40 ft/lbs of recoil. . Most people can handle the recoil of a 30/06 but beyond that, the numbers go down.

J E CUSTOM

 

[Big Jake Duke]

"...
But anyway after trying every powder I narrowed it down to 120 grains of US 869 like for the above 220 hornady. They would chrono right at 3200 fps with a low ES. I loaded up a bunch of 210's for elk hunting one year and I just used 122 grains of us 869
[/QUOTE]

 

[Big Jake Duke]

"...
But anyway after trying every powder I narrowed it down to 120 grains of US 869 like for the above 220 hornady. They would chrono right at 3200 fps with a low ES. I loaded up a bunch of 210's for elk hunting one year and I just used 122 grains of us 869

[/QUOTE]
He Budlight,

You've always had good ideas.

I have been running my 30-378 with 869 and 190s and have had high pressure at 116grs.

Somebody told me that maybe I didnt have enough powder in the case because it is spherical and doesnt stack well u less it is almost compressed.

Did you have anything done to your chamber ?

Is there any truth in the story about 869 needing to be packed?

116grs is alot

 

[Brandon.in.parts]

Shooting 180gr accubonds at 3360fps and 115.5gr of US869.

 

[budlight]

Hey Budlight,

You've always had good ideas.

I have been running my 30-378 with 869 and 190s and have had high pressure at 116grs.

Somebody told me that maybe I didnt have enough powder in the case because it is spherical and doesnt stack well u less it is almost compressed.

Did you have anything done to your chamber ?

Is there any truth in the story about 869 needing to be packed?

116grs is alot
[/QUOTE]

First of all thanks for the kind words!

Type of bullet has a lot to do with pressure. Maybe softer copper or less bearing surface. Look up loads on the Hodgdon site. Those are lawyer friendly loads. They list 118 for a 200 grain at only 52,500 cup. If you make a slicker bullet or even take the time with a bore snake and liquid chrome polish and run it through your barrel 150 times before you ever fire the first shot. This was also back during the time when coating the bullets in a tumbler was the rage. You actually had to increase the powder charge to get the FPS back to previously chrono testing with uncoated bullets. The Moly coat with carnuba wax. The bullets are black and dirty. I haven't tried the new product.

Yes, when I had the gunsmith rebarrel the rifle I asked to have it throated an extra .250 inches . I was trying to see if I could make the cases and barrel last longer with a big jump out to the lands. Accuracy didn't really change. But pressure goes way down.

I had also met someone that had made a 30-378 AI with a 30 inch barrel. He had the big throat idea before me. He was looking for more case life with even more powder LOL

I've had some other rifles that I pulled bullets on extremely compressed loads using 7828. using a tall drop tube and you can hear crunching powder when you seat the bullet. well I pulled some bullets and you couldn't even dump the powder out. It was compressed into a solid chunk. I.m not a ballistics tech, but I always wondered how that might effect the original burn rate.

 

[budlight]

Those are lawyer friendly loads. They list 118 for a 200 grain at only 52,500 cup. That is a brain fart I was looking at CUP correlation to PSI. and that 52,500 is equal to 65,000 PSI.

I was buying Weatherby 30-378 brass back in the day when the local sporting goods store was selling them for $54 bucks for a bag of 50 and I went through a lot of them. It's hard to quantify the cost from 20 to 30 years ago with today's cost. What was your annual income then on tax records compared to today. Like when I was kid in the early 70's and reloading my 22-250 . I remember when min wage went from $1.25 per hour to $1.50. Someone gave me a box full of really old Speer bullets of all kinds of calibers from an estate sale. One from Longs drug store has a price tag of $2.21 for 100 50 gr. So back when I first started reloading I probably had to work an hour and a half @ to buy 100 bullets. Comparing minimum wage things cost more now!

 

[Big Jake Duke]

Ok. Here is the load I settled with. NORMA 217
104GRS. Cutting edge Lazers 220 gr.

3320fps. 7/8" 3 shot group at 250 yards.

I do have a 32" barrel on the beast.

I'm calling load development DONE!