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Forum Index > Precision long range hunting and shooting > Re: Thanks Nathan & True Flight

Re: Thanks Nathan & True Flight

09 Nov 2018
@ 10:45 am (GMT)

Nathan Foster

Thanks for your kind words Todd. That is a great. Hopefully it also has a sweet spot at full speeds.

While we are on this topic, I may as well share some of my own current research on the subject of the .30-06.

First and foremostly, it is important to understand that SAAMI min and max specs for the .30-06 vary widely. Min spec is fine for light bullets but badly cramps heavy numbers. Max spec can create long jumps with short bullets.

Body specs can differ by a few thou.

Throat specs can differ by well over 80 thou. Some exceptions exist where the throat may be under or over SAAMI spec by around .020" in both the 06 and Win Mag. As best as I can tell, these have been deliberate deviations.

CNC tolerance for reamers are within a half thou so a reamer can be made to within a half thou of the supplied drawing. In other words, the drawing dictates the specs, not the manufacturing tolerances.

A gun company may select a max spec reamer for maximum safety (Your Remington Todd), something in the middle or a tight chamber leaning towards optimum accuracy. But do note that the final chamber depth (therefore size) will be determined by the machinist working on the rifle.

A max chamber spec reamer combined with extra deep reaming can create extreme tolerances. If we combine both of these with a batch of minimum spec brass, we may also experience excessive head space issues, even if the gun just made it through inspection.

In many instances, the gun makers are not really aware of the choice of reamers, not fully educated on these principles due to the time it takes to learn about each and every cartridge. The reamer supplied to the smith is simply called SAAMI spec along with a picture of what that spec is. This is the reality of the situation and it differs vastly to what we assume. We all know about match reamers but we take other specs for granted.

I have now put countless hours into studying the .30-06 (and AI) chamber designs. Many of you will have read about the R&D I underwent with Grant as outlined in the Cartridges book. This research has been ongoing. The giant OAL's in current Remington 06 rifles are actually made to SAAMI maximum, not out of tolerance but are accentuated via machining pactices. I had to have chambers made especially (Studying how far can SAAMI be pushed) to study this after your initial email to me Todd. David Manson put a great deal of time into this for me, creating reamers and cross sections of absolute min and max allowable so that I could study the extremes of tolerances.

Although we think of the .30-06 as being tried and true, the 06 is now over 100 years old and the bullet designs have changed a great deal since it was first introduced. On the one hand, the case design is absolutely brilliant, on the other hand, the OAL's and geometry leave a lot to be desired when shooting modern bullets.

The work we (Manson, Lovelock Foster) are doing will continue for some time.

Please understand, in this one particular cartridge, it was not possible to find an ultimate compromise due the very nature of the neck design. I have therefore leaned towards optimizing the .30-06 with the newer heavy bullets, simply because these allow the .30-06 to achieve the same trajectories as the likes of the 6.5 and sevens but with a much heavier pay load. Wounding potential is increased exponentially over that which can be obtained with either a 150gr .30 cal bullet or any of the little 6.5 pills when hunting deer sized game (suitable resistance). Having said all of this, the new design will allow 165-168gr bullets to be used without any issues. There may be some jump with 150gr bullets but the geometry will allow for excellent accuracy as you would expect from a .308 Match rifle.

In a nutshell, the new reamers will contain both min and near max specs at various points in the case and throat along with match type specs but without going over or under SAAMI limits (factory ammo users). Expect 2700fps from a 208gr bullet (basically duplicating the WSM). The reamers will not be an either or type of affair. They contain a mixture of specs and some completely new specs.

If using short bullets, you may have to seat out into the neck of our universal .30-06 due to the neck design of the 06. For example the 150gr SST or 110gr V-Max cannot be seated to the neck shoulder junction of the case (ogive ends up in the case neck), as is the normal practice for shorter neck cartridges. This is simply how it is for the .30-06 with some bullets. So when using shorter bullets, set the seating depth at roughly one caliber Or use a cannelure as your guide or seat slightly deepr if you want added control. Following this, you will need to make sure that the bullet and brass stay together. Over time, a donut may form within the case neck where the base of the bullet was seated and as a result of continued fire forming processes. After several reloads, you may not be able to seat a 200 grain bullet in the case neck because the donut will now act as an internal crimp, raising pressures. So, if you want to run different loads, make sure you have different head stamped brass to avoid any donut type crimping. For example, you might want to use Hornady for a 208gr and some cheaper NNY for a 110gr load. Note also that as the case grows, the donut will be forced forwards to some degree. There is no way around this in the .30-06 if shooting short bullets.

We are still some time away from completion but the basic cartridge group will be: .280, .280 AI, 7mmRM, .30-06, .30-06 AI, .300 Win Mag. David Manson designed a .308 Winchester reamer of similar specs some years ago (Manson M-852 Match) which can also be lumped in with this group as it can be used universally (with factory ammo). Each are designed to make life easier on the barrel maker, smith and end user.

I focused on these cartridges simply because these are still the most commonly sourced cartridges that are expected to perform at long ranges, yet were not optimally designed for LR shooting. Yes, the .300 WM has been used in major comps and yes, its chambered in the Accuracy International rifle as a sniper cartridge. We can waffle on all day about how accurate the .300 already is. But this is like a driver talking about his car as if he was the person who built the engine. In this regard, these matters are too much for me to explain via a forum thread. But if I am to put it bluntly, some of the specs for these rifles are quite frankly a joke. In any case, I hope to have these enhanced designs (David currently calls them ‘Universal’ as in hunting / match / LR hunting) available sometime during 2019.

I am sorry we could not get such a design to you now Todd. However I still need to perform trials including pressure and accuracy tests to ensure end user safety. I have been trying to avoid saying anything about this subject as I do not want added noise around me. It is the one subject I have been able to plod away at while under the weather, a little bit each day, just quietly. Your Remington was exceptionally long, more than was needed for a 200-208gr bullet and far too long for the lighter bullets you wanted to use on lighter weight animals.

As an aside, I hope that this thread helps explain some of my frustration when answering certain questions. There are often many subtle variables to consider, more than such questions as whether the .300 Norma is a better sniper cartridge than the .300 Win or whether a non belted cartridge is better than a belted one.


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