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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 16:17
trigger29 View Drop Down
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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I have just started reloading, and gathering data for my .270 WSM. I looked up a load for some 150 gr. Speer Hot Cor's They suggested an OAL of 2.800, but my bullets are touching the lands at 2.710. Then I looked up a load for Sierra sbt. gamekings with an OAL of 2.860, but they hit the lands at 2.780. I am assuming my throat in my rifle is just that short? I haven't gotten any really good groups yet, with most averaging around 1.2 in. I have shot several that put two bullets in the same hole, and then thow one off to the left or right. I don't know what's causing it, but it's irritating. Should I use my own data for OAL, and try to set the bullet so many thousanths off the lands, or how can I figure up a killer load for this thing. Right now I have the Speer hor cor's sierra gamekings, and 130 gr. Hornady interlock softpoints. For powder I have IMR 4831, and 7828ssc, and RL-22. Thanks in advance for your insight.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 16:38
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Trigger, who made your rifle? I have seen a lot of reloaders load their round just a couple of thousanths off the lands to help with accuracy, but never touching the lands because it will cause a preassure spike that could be dangerous. Sounds to me like your throat is to short. You may want to contact the manufacturer of your rifle. JMO
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 16:56
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How are you determining your distance to the lands?  I've never loaded for a short magnum, but I've never had a suggested OAL that was longer than I was able to seat my bullets.  The suggested OAL doesn't have much meaning.  At least I don't think it has any meaning other than what the bullet was seated at when the company tested them.  It the bullet has a cannule the suggested OAL usually coincides with that.  I usually just seat about .02 off the lands and am happy with that.  I'm not concerned, usually with benchrest type accuracy.

Edited by ckk1106 - February/03/2009 at 17:06
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 16:59
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I'm looking at my speer book and the COAL tested with the 150 grain bullets are 2.700, 2.670, for the 3 different bullets that they have.  2.670" is for the hot core. 


Edited by ckk1106 - February/03/2009 at 17:02
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 17:14
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The overall all length is not important other than for fitting in the mag.  You may have a bullet with a very long point (like a ballistic tip) that sticks way out or another with a shorter point (like a soft point).  You need to get a bullet comparator and use that to measure the length of your bullets. 
Even using the exact same bullets you can get a big variation of OAL from loaded round to loaded round.  You need to get some kind of tool to measure the true distance to your lans in your chamber and then get a bullet comparator to get your correct length for your rounds.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 17:15
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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 17:43
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  Here's another. I've got both a Stoney Point and Sinclair,either will do.
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 22:09
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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Originally posted by ckk1106 ckk1106 wrote:

How are you determining your distance to the lands?  I've never loaded for a short magnum, but I've never had a suggested OAL that was longer than I was able to seat my bullets.  The suggested OAL doesn't have much meaning.  At least I don't think it has any meaning other than what the bullet was seated at when the company tested them.  It the bullet has a cannule the suggested OAL usually coincides with that.  I usually just seat about .02 off the lands and am happy with that.  I'm not concerned, usually with benchrest type accuracy.
 
For  my measurement, I seated a bullet at 2.725, and made a ring around it with a sharpie. I chambered the round, and could see 4 perfect rifling marks on the bullet. I kept seating it deeper until the marks went away. This might not be the most precise way, but it gave me an idea of where I am. I would like to find a load that shoots to about 1/2" consistantly. I know I'm asking a lot, but it already shoots it's best factory load to 3/4" or better every time.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 23:01
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What length OAL that is will the magazine allow? The only downside I can see with being concerned about OAL is if you are using longer bullets that are crowding powder space.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/03/2009 at 23:47
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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The magazine in this thing is huge. The longest round that I can fit in the magazine measures 2.890 I can't imagine having to load anything that long. Even a 150 gr. Berger VLD was recommended to me by walt berger to start at 2.860 OAL. I will load them to the lands if I can when I get some, but think I should have plenty of room in the mag. I'm wondering if the OAL I got before were just incorrect. I just checked Hornady's data for 140 gr. SST, and their OAL was at 2.785, and I can load them out to 2.880, and according to Coby's data I could load the Hot Cor's and be .030 off the lands, as they hit at about 2.710
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 01:28
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Just load them 2 thou off the lands and start at the lower end of your maximum powder as the case pressure will be higher with the deeper seated bullet. Slowly work your load up looking for signs of pressure building up. Also try 1 thou off the lands. Check for best grouping at the two seating depths and variuos powder charges.
Do normal factory rounds fit in the rifle?


Edited by 8shots - February/04/2009 at 01:28
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 01:56
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X = 180 Y = 90 (X+Pyro)+(Y-Pyro) = ?

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So far Winchester Power Points fit fine. I haven't tried too many loads, as the winchesters shoot great.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 03:59
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Then I would not think you have a problem with the throat length. I would in any case prefer a throat length where you can find the lands and seat your bullet just off the lands.
On my Remington for example the throat length is so far out that the bullet is not even one thou in the case neck and it is still far off the lands.
I am personally a believer in not having an excessive bullet jump.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 07:24
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The deeper you seat the bullet the less pressure you will develop and you will lose some velocity (up to a certain point).  If you seat too close to the lands then variations in bullet ogives will give you inconsistant results.  Best to seat .020" off the lands or further or seat into the lands with a reduced load.
 
You need to be careful with the WSM calibers and stay well below manual max until you have worked up slowly because the WSM's are all chambered in modern guns and the loading data is not conservative.
 
The pressure and velocity in a long throated gun will be less than the pressure developed in a short throated one.  One with a tight chamber will develop more pressure and you will reach max load with a lesser charge than one with a long throat.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 08:51
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there is nothing wrong against seating against the lands, have several friends which  jam seat .. down side---- on extraction of live round the bullet may pull out, and as suggested earlier the magazine length,  and if the gun is a gas gun there exists the possibily of non bolt closure. --- lee crimping dies are based on the premise of getting the uniform combustion a full seat offers. weatherby and I think Lazaronni freebore without effects on accuracy, --- going on 1400 rds, in a 300 wsm spr, with chrome lined barrel, with touch seating still under moa, and hasn't been cleaned once  -- 190 smk moly.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 09:29
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trigger, let your magazine length or distance to lands be your guide for reloading. In other words, I think that you are relying on what the reloading manual states to be your guide. They are probably listing SAAMI OAL specs or what ever their test barrel is throated for. I always let my rifle specs be my guide for cartridge measurements.

Edited by Roy Finn - February/04/2009 at 16:17
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 13:50
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This is my understanding concerning OAL.
The OAL listed in the manuals is a reference just like case mfg, primer, and bullet info.  It is a minimum for that test data.  If you seat the bullets deeper, you raise pressure due to decreasing case volume.  This becomes more of an issue as case capacity decreases - such as small rifle and pistol.  If you increase cartridge length to the point of touching or seating into the lands, you also raise pressure because it takes more pressure to start the bullet into the rifling as opposed to "jumping" the lands.  Most references suggest a starting range for seating depths.  It is something like 15 - 50 thousandths off the lands - this is from memory.  I usually start at 25 - 30.  Of course you must experiment to find which depth is optimum for your rifle.   
The easiest way to check OAL for your rifle is with one of the tools designed for that purpose.  You can also accomplish this by taking a piece of brass that was fired in your gun and put enough pressure on one side of the case mouth so that it will hold a bullet firmly.  Then mark a bullet with a permanent marker or equiv. on one side and start it in the case.  Chamber the round thus seating the bullet into the rifling.  As the bullet is pushed into the case, the case mouth will scrape the ink from the bullet.  Make sure the bullet is seated into the case up to this point and measure - this is the "touching the lands" measurement.
One of the reasons for seating the bullet into the lands is that it ensures that the bullet is straight when it starts into the rifling.  It removes runout as a variable.
One thing to remember is that if you have to measure from the ogive of the bullet to remain consistent.  Also, if you are serious enough about optimizing accuracy to go to all of the extra effort, then be sure to use a powder in the appropriate burn range.  Check your manuals to see which powders are recommended.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 13:52
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Trigger is trying to get better accuracy out of his reloads and I think having a short throat he is not gaining anything on seating depth . I think he needs to go in a different direction ie.powder charges/powder types/primers??.... although I personally never found much difference there. his gun seems to prefer the winchester factory loads can anyone help him duplicate those?

Edited by rifle looney - February/04/2009 at 13:53
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 14:03
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Sako says that the deeper you seat the bullet the more pressure you will have.  Geezer says that the deaper you seat the bullet the less pressure you'll have.  I've also heard that seating depth has nothing to do with pressures, unless the bullet is touching the lands, cause the amount of pressure needed to push the bullet from the case to the lands is negligible.  I wonder what the answer is.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 14:07
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I think Sako is saying to seat deep meaning into the case not the lands.this in return gives less volume for powder.ie less velocity.


Edited by rifle looney - February/04/2009 at 14:08
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 14:09
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[QUOTE=trigger29] I am assuming my throat is just that short? I don't know what's causing it, but it's irritating. QUOTE]
 
You and I couldn't go on a date then!!!!!
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 14:16
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Originally posted by rifle looney rifle looney wrote:

I think Sako is saying to seat deep meaning into the case not the lands.this in return gives less volume for powder.ie less velocity.

Yes I think he is saying that, but also that it produces less pressure.  Geezer says the opposite.  I'm just curious as to which is right or even if it matters.Big Smile
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Less powder less pressure?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 14:54
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Originally posted by rifle looney rifle looney wrote:

Less powder less pressure?

That's true.  I just didn't see where he was suggesting less powder.  Powder can be compressed.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/04/2009 at 15:04
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yes this is true...compressed loads can cause high pressure too I believe .we need to find out the truth its buggin me.
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