Precision Load Development - specifically for a 7mm IHMSA

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  • Wikun

    Well-Known Member
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    8   0   0
    Jun 28, 2020
    65
    8
    Metairie, La
    I come here seeking knowledge with what will hopefully be an interesting topic for some and may hopefully help others on similar journeys.

    Recently I purchased an older Silhouette rifle from an estate sale. The rifle is a Remington 700 SA ADL on a typical synthetic stock. It does have a Timney trigger and is bedded. It sported a 22" stainless heavy barrel that didn't appear to have any markings on it. Caliber to the seller was unknown. It also had a Leuopold VXiii3 scope on it. It also came with some forming dies and other reloading "things"
    Since I reload and collect; I figured, heck, take a chance on it, see what it is and then go from there. If I use for parts, ok, whatever.

    I got it home and disassembled it. On the barrel's underside was marked 7MM-INT. Also stamped on the barrel are "BDL" and "1-87".
    After doing some research I landed on this rifle being chambered in 7mmIHMSA. Now this IS NOT the cartridge based on the 30-30. This is based on the 300SAV case.

    After figuring all this out, I now find myself in a situation, where I want to work up and develop a load for it and shoot it, because I haven't run across something that someone obviously put a lot of time into personally building this gun to make it competitive and then unfortunately passed away and now I have it. It was for silhouette and the widower said he built it "for the rams". So researching that the gun should be good for .5 MOA. I have wanted to work on my precision shooting more and felt hey why not cut my teeth on this. I have figured out how to form cases and I am ready to begin loading. Now to my dilemma...

    I have reloaded thousands of pistol rounds and hundreds of rifle rounds. I have NEVER attempted to reload for precision accuracy or even know how to start load development for this project. With pistol and AR; I didn't put too much thought into it, worked up something that felt right and performed, and boom done. With this I know I need a crono, BUT, can anyone get me started? Does anyone have experience with this round (not the 30-30 version)? Anyone have some pointers? I have some recipe's from one of my manuals "Sierra Rifle and Handgun Reloading Data", but other than those (and they all use sierra bullets) I got nothing.

    So to boil it all down, Requesting Pointers on Precision Rifle Load workup AND Requesting tips and pointers for 7mmIHMSA (300SAV) load development.

    Thanks All
     

    Saintsfan1977

    Member
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    1   0   0
    Dec 2, 2015
    6
    1
    West Monroe
    Bullet and headspace comparators are a must for precise adjustments.

    Neck turning tool


    Maybe a runout gauge to check concentricity.

    Chronograph

    After that it's just shooting. The process is the same, your just more methodical for the precision.
     

    highstandard40

    Well-Known Member
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    4   0   0
    Apr 14, 2009
    1,365
    63
    Prairieville
    Back in the 80s I had an XP100 in 7 IHMSA that I used in IHMSA competition. The "7 International" as we called it can be a very accurate cartridge. The 30-30 based cartridge was called the "7 International R". There was also a variant called the 7 International X which had more of an "improved" case body with less taper. This came about so that you could rechamber a 7 BR barrel to use the 300 savage based cartridge. The most commonly used load for the 7 IHMSA at that time was either a 154 gr Hornady spire point or the 162 gr Hornady BT Match bullet along with H4895 powder. At that time IHMSA was supplying preformed brass with the proper head stamp which was being manufactured by Federal. As I was saying, accuracy could be quite impressive. Perfect scores on the silhouettes were the norm and tie breaker shoot-offs were common on some very small targets. At one time we were shooting snuff cans at 200 yards with iron sights. As I said, very accurate cartridge.
    You didn't mention what your intended use for this rifle will be so I can't make a suggestion for loads. You should determine the twist rate to arrive at an idea of what bullet weight to start with. If this rifle was built for silhouette it will likely be suited for heavier bullets.
    Good luck with your project.
     

    Barry J

    Well-Known Member
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    2   0   0
    Dec 5, 2011
    1,334
    48
    Thibodaux
    I would bring it to a gunsmith and have the chamber measured to make sure it is the caliber marked on the barrel. Don't want to go through forming brass to find out it has been re-bored.
     

    Wikun

    Well-Known Member
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    8   0   0
    Jun 28, 2020
    65
    8
    Metairie, La
    Awesome comments. I have had the bore cerrosafe(d) and determined it is the 7mm INT cartridge. I actually shot it this past weekend with using the 5 rounds that came with it.
    I have loaded some Hornady ELDx 162 bullets over 34gn of Varget just to get it out there as I have a good bit of Varget but rather than start the load ladder just yet, I wanted to load a few more to keep shooting.

    So the intended use is develop my skills as a long(ish) distance shooter. Work on trigger mechanics, breathing, fundamental stuff. Rifle is there and cap[able and since I load, no problem once I find a good recipe. I have a 270 that is my deer rifle, this one though will be for accuracy training.

    Any direction from that that you guys can think of?
     
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