Am I better off jammed into the lands or seated too deep? (30-06)

Discussion in 'The Ammo & Reloading Forum' started by Distinct_Editz, Feb 25, 2018.

Seated Deep or Jammed Into the Lands?

  1. Seat it Deep

  2. Jam it into the Lands

  3. WTF are you doing?

  4. Other

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  1. Distinct_Editz

    Distinct_Editz Member

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    I am new to reloading and have a what seems to be, unusual question. I'm reloading 30-06 with 168gr A-Max and IMR 4064 (46.7gn to start with). The load manual calls for a Min. OAL for never exceed charges @3.330" however, Using the Hornady OAL gauge my gun likes these A-Max's seated no longer than 3.180"????? Or 2.570 O-Give OAL. I'm aware that seating these bullets so deep will increase pressures and also aware bullets being jammed into the lands increases pressures. Which of the two will result in higher pressures? Also, I am looking for accuracy so what would be more accurate... A (possibly) reduced load to compensate for the shorter OAL and seat the bullet just off the lands or leave it be and jam it into the lands and load it like normal. I have some testing to do but do not want to blow anything up in the process.
     
    Last edited: Feb 25, 2018
  2. dbcooper

    dbcooper Well-Known Member

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    When you load the longer OAL loaded round into the gun, does the bolt close smoothly?
     
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  3. Old Guns

    Old Guns Well-Known Member Supporting Member

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    What kind of gun. Picture of bullet. Have you done a chamber cast to see if the rifling starts to soon? A 168 grain bullet should not hit the rifling when properly seated. Neither situation is a good one.
     
  4. sharps4590

    sharps4590 Well-Known Member Supporting Member

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    Seat the bullet with the ogive .010 off the lands to start. each rifle is an entity unto itself and your chamber might not correspond to COAL's. I can't imagine the start load of nearly any powder would present a difficulty.
     
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  5. Nor Cal Mikie

    Nor Cal Mikie Well-Known Member Supporting Member

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    Larger calibers "prefer" a JUMP to the lands!!
    That means, just about anything over 22 caliber likes a jump. If it was me, I would start off with about a .020 jump to the lands. Maybe even more. Each chamber/barrel is different.
     
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  6. Distinct_Editz

    Distinct_Editz Member

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    Replying to a few people, Yes the bolt does close smoothly I am not forcing either of the two. I have found the shorter does close without resistance but the longer one still closes with minor resistance... something I would not be able to notice with the firing pin in the bolt (No it's not the case shoulder causing this.). The gun is an old Springfield Model 1903. If you lookup Hornady's 168gr A-Max .308 diameter... pictures will show up but if you want to know how the long one looks for me... well it's definitely got very minor scuffs around the O-Give of the bullet where it meets the lands. Also, Yeah I beleive the rifling starts too soon without doing a chamber cast because with normal 168gr "jacketed bullets" my load manual says 3.230" min OAL and my gun's rifling starts even sooner than that lmao.
     
    Last edited: Feb 25, 2018
  7. Kosh75287

    Kosh75287 Well-Known Member

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    Is "none of the above" an acceptable answer?
    Loading the round to a length that gives 0.10" - 0.20" space from the rifling lands is likely the best strategy, if it doesn't result in a terribly short O.A.L. I haven't blown up enough rifles to be sure of THIS, but I think I'd FAR rather have as little as 0.05" of "jump" between lands and projectile than to load the round that length too short. My previous experience with high-powered rifle cartridges suggests to me (and, again, I say this without having done any rigourous measurements) that chamber pressures almost seem to follow inverse-square law, with respect to decreasing case capacity. I'm reasonably certain that it's not quite THAT radical a progression, but it sure seems that a small decrease in case capacity jacks pressures up very quickly.


    The load you mention appears to be about in the middle in Hodgdon's data for .30-06, using IMR-4064 and 165 gr. GMXs (I know, their profiles aren't likely to be identical). If you must load the round too short, or load it touching the lands (PLEASE not "JAMMED INTO THEM!"), drop your starting load to the minimum listed (if that's what 46.7/IMR-4064/168 A-Max is, then forgive the unnecessary admonition), and work up in 0.2gr increments.

    I'm also puzzled as to why your M1903 might have what appears to be such a short chamber. Is there any chance or sign that it might have been re-barreled? With firearms that have been around for a lifetime or longer, so many things are possible.
    By the way, judging from your very thoughtful (and somewhat humorous) survey set-up, it's evident that you have an understanding of the risks involved, which is NEVER a bad thing.
     
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  8. sharps4590

    sharps4590 Well-Known Member Supporting Member

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    To my knowledge and experience the ONLY time you load a bullet into the lands is cast bullets over black powder or breech seating. Neither of which are part of your mentioned criteria.
     
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  9. jim brady

    jim brady Well-Known Member

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    The .30-06 is an amazing caliber to reload. It doesn't ask much in order to give you superb accuracy. I own many .30-06 rifles (collectors-shooters-hunters) and have loaded for them since 1972.

    I think I can make your life simpler and much easier: Find yourself a good reloading manual that lists the Cartridge Over All Loaded Length with a bullet of the weight you are using - and seat your bullets to that length. Don't try to over-think the .30-06. It has been around longer than you or me. Just load it to the length listed in your manual and don't get weird or fancy to 'just kiss the rifling' with the bullet or any of that stuff.

    Unless you are a Bench Rest Competition Shooter with a 20 pound rifle firing ammunition stored in special padded ammunition boxes - firing on a 70 degree day at Sea Level on a Dead Calm wind in National Competition - this hocus-pocus on seating depth is hooey.

    What I've found about the .30-06 vs. accuracy? Powder, bullet weight and jacket material. My most accurate 'Match' loads are with old, no longer made 173 grain military FMJ bullets. The most accurate hunting loads I've ever produced were 180 grain SPBT Speer bullets (in the old red boxes) with Remington LR primers, IMR-4350 powder (near max charge) in LC Match cases. I've used Remington and Nosler bullets of the same weight and design - but none equal the accuracy from the old Speer bullets (I suspect the copper jacket hardness was different in the Speer bullets).

    Your 168 grain bullets are a compromise between the 150 grain FMJ bullets and the old M72 Match 173 grain bullets. The 168s were quite popular with the 7.62mm NATO as fired from Match M-14 rifles in the 1960s and 1970s. More precise 7.62 sniper grade ammunition has since reverted to the old heavier 173s for long range shooting (as used in Match M1 Garand rifles).

    I'm gonna catch some flak over this - so I'm hunkering down and getting ready.....
     
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  10. Distinct_Editz

    Distinct_Editz Member

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    There is no chance at all it was re-barreled, It still has the SN on it and all factory markings. And yes, I have the load data for the A-Max's specifically but only for Accur 4064 which is very similar to IMR 4064... so doing some quick math comparing the 168gr A-Max's to the "Jacketed 168gr Bullets" in my book which has load data for IMR 4064, my start charge should be about 46.7gr of IMR 4064 for the A-Max's and 47gr for normal "jacketed bullets". Also, Excuse me if my history is wrong but from what I understand when the U.S adopted the spitzer bullet around 1905, they had to re rifle a few thousand barrels to bring the rifling back from the 30-03 for the new 30-06. The rifling was brought back specifically for 150gr bullets. I went and looked at min OAL for these 150gr's and sure enough some powders want the OAL to be at >3.180" which just happens to match mine.
     
    Last edited: Feb 25, 2018
  11. Distinct_Editz

    Distinct_Editz Member

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    Also, I must add before I got into reloading and had not a clue about any of this... all my factory ammo was always jammed into the lands.
     
  12. jim brady

    jim brady Well-Known Member

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    The barrels were not serial numbered - only the receiver. Just how old is your 1903? please indicate the serial number range. You are (of course!) aware that *early* 1903s (like the ones that were barreled with the 1906 conversions) are not considered safe for firing?

    Just for grins-and-giggles, please post photos (or at least a description) of the receiver, and if possible - the end of the barrel just behind the front sight. This will tell us a lot. Many of these rifles were rebarreled in the 1930s, and these barrels will have the Ordinance Stamp with the production year. Even more were rebarreled (and restocked) in 1942 when they were withdrawn from War Reserve for re-issue.
     
  13. Kosh75287

    Kosh75287 Well-Known Member

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    Okay, I thought I read "IMR-4064" in your original post, but I agree that ACCURATE 4064 could have markedly different loading data.

    Sadly, I haven't had much exposure to '03s, so I have no feel for what is normal for them. If you're getting that behaviour with factory rounds and nothing's blown up, it may be less worrisome than I'd first imagined.

    Y'won't get any flak from ME, over it... I LIKE the 168s, but there are certain things they don't do well at very long ranges. I've been told, by enough sufficiently knowledgeable people that I believe it, that they go trans-sonic past 600 yards in .308, which does bad things to accuracy. The 173s & 175s do NOT, somehow, which makes them the bullet of choice for longer shots. I GET that, and I see NOTHING wrong with what I read in your post.

    Since it's all I can do to SEE a Greyhound Bus at 600 yards, much less HIT it (not that I ever WOULD, of course), the need for the heavier projectiles is less of an issue TO ME. But that doesn't mean it is less of an issue, GENERALLY. Strangely, it appears that the 155gr. Palma bullets ALSO stay super sonic out to 1000 yards, so I dunno WHAT to think.
     
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  14. Distinct_Editz

    Distinct_Editz Member

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    Ah, well yes the receiver of course. Well it's stamped with U.S Remington Model 1903 3020051. The barrel on the underside of the front sight is marked with a P, and the upside has a different iron sight on it than military issue, but underneath this sight appears to be possibly a 4 on the left and a 2 to the right. I believe the rest of the stamp is underneath this sight. It's a sporterized version. I was aware of certain SN's being unsafe to shoot but, I do not think this is one of those. I could be wrong though.

    Possibly re-barreled? I'm learning a lot haha.
     
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  15. Old Guns

    Old Guns Well-Known Member Supporting Member

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    The Remington Model 1903s were WWII era guns. Springfield made guns below 800.000 are considered unsafe. As to the barrel there is no way to tell if it was re-barreled. It may well have the original barrel as these were late guns and may not have seen much use as the Garand was the main battle rifle. Couldn't you just run a reamer into the chamber and lengthen the throat a little.