The Accurate Reloading Forums
Changed COL and lost 200 FPS?
20 June 2010, 21:14
Jager100Changed COL and lost 200 FPS?
Here is one for the experts. I am loading 300 Win Mag. Powder=R22, Primer GM215M, 180g Accubond. Remington 700. I am new at this and am going by the Nosler reloading book. I started by seating my bullets at the SAAMI spec. of 3.340. Worked up powder measuremnets in .5g increments to the Max. of 75.5.
Results of highest 2.
75g R22
Ave. Velocity 3036 FPS
75.5g R22
Ave. Velocity 3078 FPS
NOW
I bought a Hornady OAL gauge. Averaged 5 measurements. Made a dummy round and cycled it 10 times. Could see a ting ring on the bullet, so I backed it off .020 as recomended by the book.
Original OAL 3.340 New OAL is 3.542
Mew velocities
75g R22 2806 FPS
75.5g R22 2850
I lost 230 Feet per second? Same batch of powder, bullets, primers. Chrono at same distance. Temprature was 10-15 degrees cooler, but that does not explain it.
Acurracy of the longer OAL was increadable better. 3/4" groups. Any ideas? Any recomendations?
(Cartridges show no signs of over presure)
21 June 2010, 02:27
Mike_DettorreWell by moving the bullet out you increased case capacity and therefore reduced pressure.
I doubt that it would account for all 230 fps.
Was the barrel in the same conditon meaning cleanliness?
Aditionally, do you really care? I bet if you check the difference in drop between 2800 and 3000 fps @ 300 yards with a 200 yard zero it is less than 1.5 inches.
MikeLegistine actu quod scripsi?
Never under estimate the internet community's ability to reply to your post with their personal rant about their tangentially related, single occurrence issue.
What I have learned on AR, since 2001:
1. The proper answer to: Where is the best place in town to get a steak dinner? is…You should go to Mel's Diner and get the fried chicken.
2. Big game animals can tell the difference between .015 of an inch in diameter, 15 grains of bullet weight, and 150 fps.
3. There is a difference in the performance of two identical projectiles launched at the same velocity if they came from different cartridges.
4. While a double rifle is the perfect DGR, every 375HH bolt gun needs to be modified to carry at least 5 down.
5. While a floor plate and detachable box magazine both use a mechanical latch, only the floor plate latch is reliable. Disregard the fact that every modern military rifle uses a detachable box magazine.
6. The Remington 700 is unreliable regardless of the fact it is the basis of the USMC M40 sniper rifle for 40+ years with no changes to the receiver or extractor and is the choice of more military and law enforcement sniper units than any other rifle.
7. PF actions are not suitable for a DGR and it is irrelevant that the M1, M14, M16, & AK47 which were designed for hunting men that can shoot back are all PF actions.
8. 95 deg F in Africa is different than 95 deg F in TX or CA and that is why you must worry about ammunition temperature in Africa (even though most safaris take place in winter) but not in TX or in CA.
9. The size of a ding in a gun's finish doesn't matter, what matters is whether it’s a safe ding or not.
10. 1 in a row is a trend, 2 in a row is statistically significant, and 3 in a row is an irrefutable fact.
11. Never buy a WSM or RCM cartridge for a safari rifle or your go to rifle in the USA because if they lose your ammo you can't find replacement ammo but don't worry 280 Rem, 338-06, 35 Whelen, and all Weatherby cartridges abound in Africa and back country stores.
12. A well hit animal can run 75 yds. in the open and suddenly drop with no initial blood trail, but the one I shot from 200 yds. away that ran 10 yds. and disappeared into a thicket and was not found was lost because the bullet penciled thru. I am 100% certain of this even though I have no physical evidence.
13. A 300 Win Mag is a 500 yard elk cartridge but a 308 Win is not a 300 yard elk cartridge even though the same bullet is travelling at the same velocity at those respective distances.
21 June 2010, 03:12
Larry Gibson230 fps is a lot of difference for just a .020 change in seating depth. I suspect something else changed that you are not aware of. Suggest you load 10 shots of each OAL with the same components and test them back to back on the same day. Let the barrel cool at least 1 minute between shots and cool completely between test strings. If you start the first string with a clean barrel then clean it before beginning the second string. That will tell you the story. It is an interesting question and one we can only conjecture on. You are the only one who can truely answer your question. If you seek the answer let us know what the results are.
Larry Gibson
21 June 2010, 03:36
Jim C. <><Larry, the change was .2", not .02".
I wonder how you established both velocities. I mean, how many rounds did you clock? As Larry suggests, you really need to check at least 10 rounds to get a good idea of the actual average speed and statistacally it won't be absolutely correct even then.
Adding a typical Extreme Spread to random variations of a small sample and a modest loss of speed taken together could explain it.
21 June 2010, 04:02
wildboarAccording to Quickload, the longer OAL should cause a loss of about 23 m/s - 75fps.....
21 June 2010, 04:15
graybirdI shot some 300 Win Mag loads today with 69.9 grs of IMR7828 and experienced a loss in speed of about 50-70fps with a decrease in COAL. Initial COAL was 3.411 and final load I shot was COAL was 3.320, which was about 70 fps slower.
Graybird
"Make no mistake, it's not revenge he's after ... it's the reckoning."
21 June 2010, 05:51
greenjoy[QUOTE]Originally posted by Jager100:
Made a dummy round and cycled it 10 times.
Could see a ting ring on the bullet, so I backed it off .020 as recomended by the book.
[QUOTE]
"ting ring" ? Ya got me, I don't know what a ting ring is or were you are seeing this appear on your dummy cartridge.
21 June 2010, 07:17
ted thornBullet jump and more speed.....is this why Weatherby rifles have more free bore than most rifles? To get more speed?
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21 June 2010, 17:32
wildboarquote:
Originally posted by graybird:
...and experienced a loss in speed of about 50-70fps with a decrease in COAL....
You possibly were very close to the lands; seating the bullets deeper caused a drop of pressure and less velocity.
21 June 2010, 18:12
Hot Corequote:
Originally posted by Jager100:
...Any ideas? Any recomendations? ...
I had Erratic performance(Pressure wise) with RL-19, 22 and 25. Quit trying to make them work.
Recommendations:
1. Get some H1000.
2. Use
the never improved upon Creighton Audette Load Developmant Method.3. Shoot those at 300yds.
4. LEAVE THE CHRONOGRAPH IN THE BARN!!!
5. Pick the best Harmonic Node from the 300yd Target.
6. Load some more around the Harmonic Node and Fine Tune the Load by adjusting the Seating Depth and shoot again at 300yds.
7. Pick the Best Load shown on the Target and Load 100 or so like that.
8. Practice with the Load at various distances and Create a Drop Chart from actual shooting.
9. SELL the Chronograph, and don't give the Velocity more value than what it is really good for - pretty much worthless.
Best of luck to you.
21 June 2010, 18:57
Ghubert10. Buy the chrony back.
11. Chrony the resultant load to get an average speed to plug into your ballistics program and work out your drop and drift etc.
12. Re-sell chrony, hopefully at a small profit.
22 June 2010, 02:27
fredj338quote:
Originally posted by ted thorn:
Bullet jump and more speed.....is this why Weatherby rifles have more free bore than most rifles? To get more speed?
No, the freebore allows for slightly higher powder charges to urn at normal pressures. Freebore in itself will often cause a loss of vel.
LIFE IS NOT A SPECTATOR'S SPORT!
24 June 2010, 09:01
Larry Gibsonquote:
Originally posted by Jim C. <><:
Larry, the change was .2", not .02".
I wonder how you established both velocities. I mean, how many rounds did you clock? As Larry suggests, you really need to check at least 10 rounds to get a good idea of the actual average speed and statistacally it won't be absolutely correct even then.
Adding a typical Extreme Spread to random variations of a small sample and a modest loss of speed taken together could explain it.
Jim
Jager100 states; "so I backed it off .020 as recomended by the book." and then states; "Original OAL 3.340 New OAL is 3.542". That indicates the .2 as you mention and it is confusing(?). Granted .2 is quite a bit but I still think something else was changed. My advise to Jager100 is to conduct the test again as I mentioned. Only way to know.
Larry Gibson