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Thread: 7mm WSM: just checking...

  1. #1

    7mm WSM: just checking...

    Guys I've been measuring Cartridge Overall lengths for my recently acquired Howa 1500 7mm WSM. The seller, dropmdead, had advised me that the maximum length of round which fits into the magazine is significantly shorter than rounds seated for the lands.

    Anyway, with supplies of 140gn Gameking Spitzers, 140gn Nosler Ballistic Tips, 162gn AMax and 175gn Matchkings and Stoney Point OAL Guage I've been measuring seating depth with each round to touching lands and also using a Sinclair Hex Style Bullet Comparator.

    The SAAMI spec for 7mm WSM has an overall length of 2.860"

    Each of the above bullets creates the following COL with in brackets the measured length to the point at which the bullet touches the lands:

    140gn Gameking Spitzers: 2.971" at which length the bullet does not seat by 1 whole calibre (2.288")

    140gn Nosler Ballistic Tips: 3.114" (2.441")

    162gn AMax: 3.153" (2.405")

    175gn Matchkings: 3.132" (2.425")


    Initial thoughts are these:

    1. My habit for the past 20 years has been to measure chambering to Max COL and then work back by 10thou. This has been a good starting point and I don't know of a reason why this wouldn't be an equally good starting point in this calibre.

    2. I'm not worried by rounds being too long to fit the magazine: I can manage with single feed.

    3. This rifle is going to do some duty as a deer rifle and some duty as an informal plinker and having a similar BC, weight and length of bullet for both roles will keep it simple. (I've tried using AMax on beasts and won't do it again. Okay they create a blood trail but I'd rather see more ballistic shock.)

    4. I'm going shopping for a different bullet for deer duty, longer and heavier than 140 gn

    Those of you using 7mm WSM: what bullets have you settled to using please?

    Do you load to 10thou off the lands or some other distance?

  2. #2
    Have you had a read of http://www.ballisticstudies.com/Know...rt+Magnum.html or Nathan's latest book? Both might give you some pointers on what to do next?

    Regards

    JCS

  3. #3
    Quote Originally Posted by jcampbellsmith View Post
    Have you had a read of http://www.ballisticstudies.com/Know...rt+Magnum.html or Nathan's latest book? Both might give you some pointers on what to do next?

    Regards

    JCS
    No I hadn't. (I had googled 7mm WSM but not found this) But I will now, thank you.

  4. #4
    Ive used a 7mm wsm for 10 years now and Iam on my 2nd barrel,just load to mag length with what ever bullet you choose.as to bullets use a non plastic tiped ones as they can be over long which will lead to far too much bullet in the case,I found Nosler Partion to be very good or Barns TSX,go for 150gr they will do everything you need
    forget the lands as a factory rifle will be chambered to use every weight of bullet so you will have a long throat,seat to mag length and play with the powder also I found match primers better than magnum.
    if using Winchester brass a light neck turn just to even the neck thickness out works wonders
    Last edited by see it shoot it; 24-11-2013 at 22:53.

  5. #5
    Quote Originally Posted by see it shoot it View Post
    Ive used a 7mm wsm for 10 years now and Iam on my 2nd barrel,
    Ah, real life experience - just what I was hoping for. Thank you.

    Quote Originally Posted by see it shoot it View Post
    just load to mag length with what ever bullet you choose.as to bullets use a non plastic tiped ones as they can be over long which will lead to far too much bullet in the case,I found Nosler Partion to be very good or Barns TSX,go for 150gr they will do everything you need
    Can I ask please, have you adopted this approach following experimentation or was this good advice which you've followed for ten years?

    I can see how 150s will be a good compromise on mag length and how 175s will just have too much in the case if they're seated to suit magazine length rather than to get close to lands.


    Quote Originally Posted by see it shoot it View Post
    forget the lands as a factory rifle will be chambered to use every weight of bullet so you will have a long throat,seat to mag length and play with the powder also I found match primers better than magnum.
    Really? So you're not troubled by a great distance for the bullet to jump to the lands? This has had no effect on load consistency and accuracy? You can see that I'm still working to overcome engrained instincts.


    Quote Originally Posted by see it shoot it View Post
    if using Winchester brass a light neck turn just to even the neck thickness out works wonders
    Yes I'm currently on Winchester brass so I'm reaching for my Sinclair catalogue now!

  6. #6
    Quote Originally Posted by tikkathreebarrels View Post
    Ah, real life experience - just what I was hoping for. Thank you.



    Can I ask please, have you adopted this approach following experimentation or was this good advice which you've followed for ten years?

    I can see how 150s will be a good compromise on mag length and how 175s will just have too much in the case if they're seated to suit magazine length rather than to get close to lands.




    Really? So you're not troubled by a great distance for the bullet to jump to the lands? This has had no effect on load consistency and accuracy? You can see that I'm still working to overcome engrained instincts.




    Yes I'm currently on Winchester brass so I'm reaching for my Sinclair catalogue now!
    yes real life experience and not shop counter hear say
    I have tried all manner of seating depths and mag length works,at the end of the day its a hunting rifle so a quick second shot maybe needed so don't single feed.
    buy a K&M tool there better reloading solutions stock them,well worth having as the brass becomes so much more consistent

  7. #7
    Initially, stick with standard Large rifle primers, Magnum primers gave some inconsistent chrono readings in my rifle.
    (The Unspeakable In Pursuit Of The Uneatable.) " If I can help, I will help!." Former S.A.C.S. member!

  8. #8
    Really? So you're not troubled by a great distance for the bullet to jump to the lands? This has had no effect on load consistency and accuracy? You can see that I'm still working to overcome engrained instincts.
    Whilst I don't have a WSM this comment just jumped out at me.

    IMHO the "need" to be close to the lands in pure bunkum. In fact in my rifles I found quite the opposite. The time it really came home was back in 2003 when preparing for a trip to the US with my BSA CF2 in 7x57. I was using Hornady 139 grain Spire Points and needed to load up some more for the trip only to find none available. They had Hornady 139's but Hornady made three different 139's in 7mm at least back then.

    So I picked up a couple of boxes of the 139BTSP to go and work up a comparable load as I already had some of the Flat pOint and whilst they shot small groups would not feed from one side the the BSA's magazine. The tip catching the edge of the chamber and jamming..

    Trying the BTSP and it being the same weight I chose to try the same powder charge as the Spire Points and at the time believing the hype seated them close to the lands. Grouping was terrible. So the seating depth was played with a bit with no improvement and panic began to set in as time was running short and the BSA was the only rifle on my Temp Form 6.

    Every possibly moment was spent at the range trying. Powder charge was played with as was eating depth to no avail. Then I made the decision to start from basics and forget all the BR hype. So I seated the bullet to it's cannelure over the powder charge that was good with the spire point and the group size shrank. We were now at least in acceptable hunting use size with the group being just over 1 1/2" at 100 yards.

    So I played with the eating depth and this resulted in the bullet seated with the cannelure being about 0.040" (1mm) out of the case mouth and was producing groups of around 3/4" for Five shots. Once the tip was over I began to think more on this seating depth and it started to become clear than not only did this rifle prefer quite a jump to the leade but most of my rifles did.

    Several were using bullets that it was simply impossible to have the bullet need the leade and it remain in the case mouth. Like the 6.5x55 with the 100 Grn Nosler Ballistic Tip of the Norma 77 grain bullet. The Rem PSP 100 grain bullet in the 270 Win of the Hornady 130 grn Spire Point in the 30-30 yet all short well.

    If you read through other posts here at TSD you will notice others have found the same and bullet jumps of 1/6" or more is not uncommon especially with lighter bullets for the calibre (LFC + Light For Calibre) as often used in vermin control.

    I now start with the bullets base seated to the neck shoulder juncture and work from there. Some bullets especially boat tails might have to go deeper but as i try to use flat based bullets where I can it often the case of working out from that starting point by 0.010" at a time.

    Let me also say that I am no BR shooter just like I am no F1 driver and just like a F1 car would be useless on our roads a lot of BR techniques can stay at the bench as far as I am concerned.

  9. #9
    Quote Originally Posted by Brithunter View Post
    Whilst I don't have a WSM this comment just jumped out at me.

    IMHO the "need" to be close to the lands in pure bunkum. In fact in my rifles I found quite the opposite. The time it really came home was back in 2003 when preparing for a trip to the US with my BSA CF2 in 7x57. I was using Hornady 139 grain Spire Points and needed to load up some more for the trip only to find none available. They had Hornady 139's but Hornady made three different 139's in 7mm at least back then.

    So I picked up a couple of boxes of the 139BTSP to go and work up a comparable load as I already had some of the Flat pOint and whilst they shot small groups would not feed from one side the the BSA's magazine. The tip catching the edge of the chamber and jamming..

    Trying the BTSP and it being the same weight I chose to try the same powder charge as the Spire Points and at the time believing the hype seated them close to the lands. Grouping was terrible. So the seating depth was played with a bit with no improvement and panic began to set in as time was running short and the BSA was the only rifle on my Temp Form 6.

    Every possibly moment was spent at the range trying. Powder charge was played with as was eating depth to no avail. Then I made the decision to start from basics and forget all the BR hype. So I seated the bullet to it's cannelure over the powder charge that was good with the spire point and the group size shrank. We were now at least in acceptable hunting use size with the group being just over 1 1/2" at 100 yards.

    So I played with the eating depth and this resulted in the bullet seated with the cannelure being about 0.040" (1mm) out of the case mouth and was producing groups of around 3/4" for Five shots. Once the tip was over I began to think more on this seating depth and it started to become clear than not only did this rifle prefer quite a jump to the leade but most of my rifles did.

    Several were using bullets that it was simply impossible to have the bullet need the leade and it remain in the case mouth. Like the 6.5x55 with the 100 Grn Nosler Ballistic Tip of the Norma 77 grain bullet. The Rem PSP 100 grain bullet in the 270 Win of the Hornady 130 grn Spire Point in the 30-30 yet all short well.

    If you read through other posts here at TSD you will notice others have found the same and bullet jumps of 1/6" or more is not uncommon especially with lighter bullets for the calibre (LFC + Light For Calibre) as often used in vermin control.

    I now start with the bullets base seated to the neck shoulder juncture and work from there. Some bullets especially boat tails might have to go deeper but as i try to use flat based bullets where I can it often the case of working out from that starting point by 0.010" at a time.

    Let me also say that I am no BR shooter just like I am no F1 driver and just like a F1 car would be useless on our roads a lot of BR techniques can stay at the bench as far as I am concerned.
    True that. It won't hurt, but there isn't much need; especially for hunting loads. The best factory match ammo produced is not loaded with any particular distance to the lands in mind. I made up some generic 30-06 this past week for my daughter: Small base FL resized and loaded to SAMMI dimensional specs. Shot 3/4" from her rifle from a loose rest. The same configuration of ammo from a different rifle, shot by someone who is not a very practiced markaman, gave 3/4 to 1MOA. In both cases never measured the distances to the lands and in one instance, never even handled the weapon before loading the ammunition. A month ago I did the same for some 308. The shooter -who is getting reloading lessons from me- said that ammo was the most accurate he'd ever used yet we never had the rifle in hand during the process. All just carefully made to SAAMI spec.~Muir

  10. #10
    Quote Originally Posted by Muir View Post
    True that. It won't hurt, but there isn't much need; especially for hunting loads. The best factory match ammo produced is not loaded with any particular distance to the lands in mind. I made up some generic 30-06 this past week for my daughter: Small base FL resized and loaded to SAMMI dimensional specs. Shot 3/4" from her rifle from a loose rest. The same configuration of ammo from a different rifle, shot by someone who is not a very practiced markaman, gave 3/4 to 1MOA. In both cases never measured the distances to the lands and in one instance, never even handled the weapon before loading the ammunition. A month ago I did the same for some 308. The shooter -who is getting reloading lessons from me- said that ammo was the most accurate he'd ever used yet we never had the rifle in hand during the process. All just carefully made to SAAMI spec.~Muir
    Muir
    as you know factory rifles will all have a long throat so they can use different weight bullets,so loading to the lands with the lighter bullet can cause problems IE not enough bullet in the case.
    I always like to find out the OAL with the bullet Iam loading even if Iam not shooting off the lands.
    if people are happy with 1 MOA accuracy ay 100 yards that's fine but what happens at further distance ???

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