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Old 03-11-2007, 05:36 PM   #1
 
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Default Does seating depth and crimping affect velocity?

I have a few questions for you guys to answer,
1) Does seating the bullet .005 off the lands change velocity as opposed to seating .020 off the lands?
2)Does a light crimp make velocity slower as oppossed to no crimp?
3)I shot some reloads with my 7mm rem the other day, it was -15c or a 5f (cold) my loads were
RL22 66.5gr with 140 accubonds out of a 26" barrel,Sauer 202, my average speed with these loads was 2975fps.The Nosler book list that laod at 3240fps with a 24' tube, WHY THE BIG DIFFERENCE does the cold affect the velocity that much or is my barrel a bit slow? It is a new gun this was the 2nd time at the range with it.
Sorry for all the questions guys
Thanks
Elmer
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Old 03-13-2007, 08:56 AM   #2
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Default RE: Does seating depth and crimping affect velocity?

Don't expect to get anywhere close to Noslers velocities w/ the charges they list. Noslers max load of 67.5grs of R-22 gave me an avg. of 3060fps in my 26"M700 and 3020ish in the 24" guns w/ the 140's. I was able to safely shoot 70grs of R-22 behind a 140 Accubond in my gun for 3310fps in 45 degree weather. This may not be safe in your gun so work up slowly. Your velocity sounds just about right. As far as crimping is concerned, I've actually seen slightly higher velocities in crimped 30-06 loads. I think this is because the pressure builds more before the bullet leaves the brass. Hope this helps. Brett
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Old 03-13-2007, 10:24 AM   #3
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Default RE: Does seating depth and crimping affect velocity?

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ORIGINAL: elmer deer

I have a few questions for you guys to answer,
1) Does seating the bullet .005 off the lands change velocity as opposed to seating .020 off the lands?
2)Does a light crimp make velocity slower as oppossed to no crimp?
3)I shot some reloads with my 7mm rem the other day, it was -15c or a 5f (cold) my loads were
RL22 66.5gr with 140 accubonds out of a 26" barrel,Sauer 202, my average speed with these loads was 2975fps.The Nosler book list that laod at 3240fps with a 24' tube, WHY THE BIG DIFFERENCE does the cold affect the velocity that much or is my barrel a bit slow? It is a new gun this was the 2nd time at the range with it.
Sorry for all the questions guys
Thanks
Elmer
Yes seating depth has a direct relationship to pressure and velocity. Its a give and take. Closer to the lands you seat, the more pressure spike you can have, but now you opened the area in the case for explosion, but further from the landsyou give the bullet more of a running go but less space in the case. I have made loads that hit the lands, and I hit pressure signs early. I moved them back some and was able to go up a grain or even two.

A light crimp probably will make pressures go up some.

I think Nosler was way off on that load. I got a good friend I shoot with that posts on here, that also uses that load, and his shoots 3050fps consistently. I dont believe much has to do with the cold, but mroe that nosler is far off with this load.
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Old 03-13-2007, 11:04 AM   #4
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Default RE: Does seating depth and crimping affect velocity?

+3 on Nosler being very optimistic with published velocities. (FYI, Lymans, Alliant& Barnes show 70gr RL22 to get 32-3300fps with 140gr bullet - as mentioned work up slowly).

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Old 03-13-2007, 11:52 AM   #5
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Default RE: Does seating depth and crimping affect velocity?

alot of time I get Nosler's velocities. Or within 50fps. But this load in particular, I hear alot of people complain.
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Old 03-13-2007, 05:17 PM   #6
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Default RE: Does seating depth and crimping affect velocity?

Quote:
ORIGINAL: bigcountry

alot of time I get Nosler's velocities. Or within 50fps. But this load in particular, I hear alot of people complain.
What about 150gr -63gr IMR4350 for 3248fps?(as an example)


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Old 03-15-2007, 02:26 PM   #7
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Default RE: Does seating depth and crimping affect velocity?

I agree with hunter5325. I too have found those Nosler velocities to be "optimistic" quite optimistic, in fact, in a number of rifles of different calibers.

Your velocity problem is not caused by the way you are seating the bullets or crimping/not crimping! More likely, by a too-light powder charge.

In my 7mm Rem. Mag., a Ruger No. 1 with 26" barrel, it takes 71.5 grains of H4831 to get 3350 FPS with 140-grain bullets, and 70 grains of IMR 7828 to get 3050 with 175-grain bullets. I get 3000 FPS with 140 grain bullets from a 7X57mm caliber No. 1A Ruger with 22" barrel using 53.5 grains of WW 760 or H414.

I believe it would take between 69 and 70 grains of RE22 to get the 3240 FPS you are looking for with those bullets in your rifle. But your 7 Mag. should be capable of that velocity level with 140-grain bullets without straining the brass or the rifle.

If you try it, work up in 0.5-grain increments, chronographing each batch of rounds loaded with half a grain more powder. Obviously, you must be watchful for indications of too-high pressure as you work up...... But to me there isn't much point in dragging a 7 Mag. up the mountain if it is producing 7mm Mauser ballistics!

Here's a 3-shot, 100-yard group from my little Ruger 1A 7X57mm withNosler 140-grain Partition bullets at 3000 FPS using 53.5 grains of WW 760, WW cases, Fed. 210 primers.


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