Hey guys. I decided to pull out a old ruger m77 in 243 with a 22 inch barrel. The load i had worked up for it was a 100gr sgk with 41gr of IMR4350 at 2.655" accuracy is .5-.6" on 3 shots. Life is good, but ive never chronographed it. So i fired 10 rounds over a chrono and magneto speed and it was 2820 average. Sounded good for a 22 inch barrel. I have been tinkering with new loads with h1000 and h4831 and i cannot for the life of me break 2800 without high pressure signs. Do i not have enough barrel for a full burn? Should i try RL26? I am happy with the accuracy of my Imr 4350 load but would like to tighten it up as well. Ive messed with seating depth and powder and bullets and everything shoots .5-.75" no matter what i do. But the low velocity is driving me nuts. I shot some factory hornady 95gr superformace rated at 3100fps and am getting 2800fps. Any thoughts?
Mv has me stumped?
- Thread starter Mtstalker
- Start date
Short barrels DO NOT benefit from fast powders, this 'fact' bandied about on the interweb is actually a myth.
If a 24" barrel gets the fastest velocity with 'x' powder, then that same 'x' powder will produce the highest velocities in a 20" barrel.
Performance is an entirely different matter, some rifles produce better groups with fast powders due to barrel harmonics, they prefer the slower velocity.
I have a fast 25-06 and a slow 25-06, one is 250fps slower than the other at the SAME pressure. I don't care what others say about pressure and velocity being in direct correlation with each other, my pressure trace shows this not to be true in this instance. Even when pressure is the same, the slow barrel is always slower.
Just my 2 cents.
Cheers.
If a 24" barrel gets the fastest velocity with 'x' powder, then that same 'x' powder will produce the highest velocities in a 20" barrel.
Performance is an entirely different matter, some rifles produce better groups with fast powders due to barrel harmonics, they prefer the slower velocity.
I have a fast 25-06 and a slow 25-06, one is 250fps slower than the other at the SAME pressure. I don't care what others say about pressure and velocity being in direct correlation with each other, my pressure trace shows this not to be true in this instance. Even when pressure is the same, the slow barrel is always slower.
Just my 2 cents.
Cheers.
I started long range BR with a 243 WIN. It shot great but chewed up barrels at an alarming rate!
I ended up using H1000 with a full case barely compressed and 105gr SMK's.I read that H1000 was easier on barrels. I got ~ 3000 fps with the 105's.
You may try H1000 or maybe RL-17 as it is similar to H4350 but typically gets a bit more Mv with less pressure. Or, maybe the new RL-16. I have no experience with 20 inch barrels but I know often folks are surprised just how little the Mv reduces with short barrels.
I ended up using H1000 with a full case barely compressed and 105gr SMK's.I read that H1000 was easier on barrels. I got ~ 3000 fps with the 105's.
You may try H1000 or maybe RL-17 as it is similar to H4350 but typically gets a bit more Mv with less pressure. Or, maybe the new RL-16. I have no experience with 20 inch barrels but I know often folks are surprised just how little the Mv reduces with short barrels.
My guess is 20 to 40 FPS per inch would be a normal . Larry
.6" groups isn't bad for a factory gun & barrel. 5 shots would be bigger. There no reason to think you can get the groups much smaller with a factory gun. Looks like your 41 gr of 4350 is already close to max load. You have signs of pressure that should tell you are already maxed out for fps with your gun and powders considered very suitable for a 243 Win. Doubt there is any powder that will magically give you another 100 fps. You might have a tight barrel. Don't worry about speed go for accuracy with safe charges. Varmints and targets don't know the speed of the bullet.
My Sierra manual with a 22" barrel 100 gr bullet shows the following:
Max load 44.9 gr H4831SC 3000 fps
Max load 43.8 gr RE-22 2900 fps
Max load 41.7 IMR 4350 2900 fps
The Berger manual gives much lower max fps
No 100 gr bullet data
Fastest load in the chart
105 gr bullet H4831SC 2893 98% fill
I have found that powders have more soot as you call it if their not shot at near max pressure . So if your not burning 95% of the powder in the barrel they are sooty Larry
Winchester published load data to duplicate their factory ammo. Back in 1976 they suggested "exactly" 48.8 grains of WW785 for the 80 PP bullet. They noted that the load should be used as listed with no reductions in powder. Seems it was a critical load. That powder is no longer made as far as I know. They do list 43.5 grain load of WW760 (H414) with the same bullet with about 100 fps drop in velocity.
NOTE: this is very old data and bullet construction may have changed. The Hodgdon web site lists loads for the current winchester powders so please check the listed loads here with current load data.
NOTE: this is very old data and bullet construction may have changed. The Hodgdon web site lists loads for the current winchester powders so please check the listed loads here with current load data.
785, is the same as 780, Supreme 780 etc etc, Winchester just keeps changing it's designation.
I have used Supreme 780 powder with 780/785 data and it is within 1gr of each other according to the pressure trace. I still have a steel tin (2lbs) of 785 here and it is the same as Supreme 780 in every respect.
Cheers.
Im going to do a bit more charge testing this weekend and see what i can come up with. I might try some different primers and powders just to see how it does. Im happy with the original load for the rifle but i always have to see if i can make it better, at some point i will just have to leave it alone.
Short barrels DO NOT benefit from fast powders, this 'fact' bandied about on the interweb is actually a myth.
If a 24" barrel gets the fastest velocity with 'x' powder, then that same 'x' powder will produce the highest velocities in a 20" barrel.
Performance is an entirely different matter, some rifles produce better groups with fast powders due to barrel harmonics, they prefer the slower velocity.
I have a fast 25-06 and a slow 25-06, one is 250fps slower than the other at the SAME pressure. I don't care what others say about pressure and velocity being in direct correlation with each other, my pressure trace shows this not to be true in this instance. Even when pressure is the same, the slow barrel is always slower.
Just my 2 cents.
Cheers.
I always thought the same load would produce different pressure in different rifles. Different chambers, barrel diameter even wear in the throat would cause the pressure to be different. Most reloaders have no way or method to know what their actual pressures are. Case expansion has always been used. But this confuses things because brass made by different manufacturers is not the same. I've always used the SWAG method.
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