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> Long throated 30-06 ?
Long throated 30-06 ?
@ 10:46 am (GMT) |
Rafal PisulskiHi,I'm starting new realods for my R700 LR in 30-06 with sierra 195gr TMK bullets. Knowing ttaht it is long bullet and 30-06 is not so generus in free bore departmnt I have measured max COAL using lightly sized case. Result is 89,68mm when optimum OAL with boat tail at neck edge is 87,72mm. So 2mm jump with looong bullet. That is normal or it is realy long throated rifle? All best, Rafał |
Replies
@ 07:28 am (GMT) |
Nathan FosterRe: Long throated 30-06 ?Hi Rafal, within a min SAAMI spec chamber, the OAL for the 195gr TMK is 86mm touching the lands.In a max spec chamber, the OAL is 89mm to about 89.1mm. Your chamber obviously beyond max. I have been seeing such specs within the Remington's for some years now. Not to worry. To avoid confusion, make sure that you have put a lot of time into prep. Make sure the rifle passes the 1 oclock test as described in the book set, the mag box not pinched, make sure the trigger is fit for purpose. Check over the scope mounts. Break the barrel in using basic ammo and monitor the rate of copper fouling (see video learning tab - trouble shooting the M700). Attend to the bore as required. Once you are have the basic variables under control, then finally you can look at reloading cause and effect, without being confused by other issues. At this point, try your basic load work up at your 87.2mm depth. Consider using a double base powder for maximum power. If using a single base extruded powder, look for sweet spots around 2500 to 2650fps. If using a slow burn double base, look for sweet spots anywhere from 2600 to 2750fps. If the loads are not accurate, try 88mm. It won't form a donut in the case neck with a single round of load development. A donut will only form in the neck following repeated loadings with the bullet sitting out in the case neck. And yes you can try seating even deeper (e.g. 86.5mm) if need be, but lets see how this initial work up goes. The barrel of your rifle is quite heavy and the bullet will not be going extremely fast so hopefully it produces consistent vibrations and is not overly sensitive to exit timing / 'when' the bullet leaves the bore. The Sierra bullets do vary a bit from one to another. Pick one, mark the tip with a marker pen and use it to set your depth, then put it aside. Do not try and make all the loaded bullets the exact same length as they will vary. Just use the dummy (the bullet you are currently using for quoted measurements) and then leave the die at that setting. Remember, if this were a .308, a 2.5mm jump would be the norm, also producing roughly the same speeds. All the best. |
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@ 07:52 am (GMT) |
Nathan FosterRe: Long throated 30-06 ?P.S, please note that there are major differences between the neck diameter of U.S brass versus Lapua, should you intend to use this. The Lapua brass only gives around .001" (.025mm) to .002" (.0508mm) chamber clearance and can jack up pressures (spikes) in some rifles / depending on chamber dimensions. This can be useful in max spec chambers (if the max spec involves diameters) but is otherwise problematic in modern sporting rifles.If possible, try to obtain an accurate measurement of fired case neck diameters versus loaded ammo (see also test at the end of my youtube video - is it me or is it my rifle). If your fired cases are only a couple of thou over loaded ammo neck diameter specs, then act with caution as the rifle will be liable to produce high pressure as you work up loads. Remedies include either neck turning or changing to another brand of brass. One should also be aware of the effects of using a suppressor in conjunction with heavy walled brass - not a good idea. This is otherwise a complex subject sorry. A .30-06 chamber neck needs to be relatively loose for the sake of heavy wall mil surp ammo (still in circulation). Heavy wall sporting ammo brass duplicates original specs and can help take up any chamber slack. But heavy wall brass can also limit breathing space in modern rifles reamed with modern reamers. Provided loads are mild, such things normally go unnoticed. But when searching for high speeds, heavy cases can ruin your day. There is no complete fix (reamer design level) for this. One must instead select components accordingly. |
@ 08:58 am (GMT) |
John StewartRe: Long throated 30-06 ?I have a Remington 700 in 30-06, it also has the long throat and it makes it easy to set the bullet way out and make room for powder. |
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@ 03:09 am (GMT) |
Rafal PisulskiRe: Long throated 30-06 ?Thank you very much for replays. It’s been a while, but I finally got to play with the loads. And yes it is nice to seat long when mag length allows.To sum things up: Rifle passed the 1 o'clock test over a year ago. After that Triggertech trigger was installed and the rifle glued and screwed. Brake in was done using 100pcs 175 scenars L in GECO brass using 56 grains of RS62 powder, coal 86,00mm. This load also has over 3mm jump, and was able to produce ~0,6 MOA groups. At around 40 rounds the barrel was lightly polished as per your book. Still fouling heavily (far better than before) but accuracy does not drop after another 30 -40 rounds, so it is fine by me. I'm using Hornady brass for reloads with Sierra TMK. Loaded ammo is 8,45mm in neck and fired case 8,63mm on average. After another careful look, optimum COAL is more like 86,10mm - 86,20mm, then the boat tail really pass the neck start. Load development was short and pleasant. I loaded RS62 powder from 53 to 55 grains in half grain step. Best groups were found with 54,0 grains. It is mild load clocking 792m/s with 3.1 ES. Group are consistently under 0,5MOA. Now the new problem: I’m using Lee collet die, and even with really heavy hand on it some of the cases have almost zero resistance when seating bullets. Is 8.63mm for fired case excessive , or brass needs annealing? Nothing like that occurred with GECO brass in 6 reloads |
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@ 03:14 am (GMT) |
Rafal PisulskiRe: Long throated 30-06 ?
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@ 07:26 am (GMT) |
Nathan FosterRe: Long throated 30-06 ?Hi Rafal, no problems regarding images. To correct your above image, I made sure it had an image bracket before - plus an image bracket after. As per:
This is a good and relevant question that all can learn from. It is important to understand that .30-06 chambers are made with a wide neck area. The same generally applies to all rifles / chambers which can fire military brass or military ammunition which is often thicker than civilian brass and civilian cartridge designs. One might assume that after decades of discontinued military service, that there might no longer be any military ammo floating about and that chambers could now be made narrow, more suitable for modern brass. But even if this were true, civilian brass varies a great deal, specifically the differences between European and U.S brass .30-06. European brass is quite often very thick and close to original specs. Modern U.S .30-06 brass is thin as per other civilian cartridge designs. The minimum neck diameter for the .30-06 chamber is .340 at the case mouth". Max diameter is +.002" Loaded U.S ammo (e.g. Hornady) usually measures about .333" Your Hornady loads fall within this. .007" is quite normal even if sub-optimal. It indicates that your chamber is quite normal. In practice, I find that .007" is somewhat loose, but as your photo shows, one can achieve desirable results provided one takes care with ammo concentricity etc. .004 is about ideal (.002" per side). Less than .004" may seem optimal, but it can instead produce finicky performance including changes / increases in pressure if a suppressor is employed, ruining accuracy and long range performance as a result of inconsistent speeds. There are no simple fixes for this regarding custom chamber designs. My .30-06 FMR for example has a .339" neck diameter and was designed for my majority U.S readers. I was unable to go any smaller than this. If one is using U.S brass, the gap averages about .006". If using European brass, the gap is just .001" to .002" which is undesirable. In this instance, one should consider neck turning to achieve .004" clearance. As for your dies. You will need to sand down your mandrel as per my reloading book if you wish to use Hornady brass. Having said this, check with your importer as they may have undersized mandrels in stock. Either way, it would be good to have two mandrels, one for Geco / Lapua etc, the other for Hornady. I hope that makes sense. Wishing you all the best. |
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