Pet Load for .308 Sierra 155gr HPBT Palma Match?

nononsense

October 12, 2005 06:31

I-girl,

First off, are you chambered for .308 Win. or are you chambered for the 7.62 x 51? There is a major difference between the two cartridges. The information below is for .308 Win. NOT 7.62 x 51 (Nato). Please be careful.

It is safest to duplicate military ball level loads.

The thing to avoid is pushing heavy bullets to maximum velocities and pressures in the M1A action. That will strain the gas mechanism and all the recoiling parts. It is "balanced" for medium-weight (147-73 g) bullets at moderate velocities. Therefore, firing commercial loads using 180 or 220 g bullets are not advised.

After some searching, I've found some .308 Win. loading data with pressure measurements. As `military' cases vary in weight, hence internal volume or capacity, these loads are with case weights of about 165 to 170 grains.

Pressure test barrels were used and the pressure listed is the average of several rounds. Barrel length is 24 inches.

Be aware that shooters are using more IMR-4064 due to the powder fouling encountered when shooting IMR-4895. DO NOT use powders slower than IMR-4320 since this will produce effects counter to the mechanics of your M1A.

Newer powders such as below, are proving to be as good and in some situations, better than the IMR powders of yesteryear.

AA-2520

V V N-150

Ramshot Big Game

Re-15

With the 155 gr. Palma bullets, you should probably start in the neighborhood of 40 to 41 grains and work up slowly and carfully watching for signs of pressure. Do not exceed 50,000 CUP as this is the range in which the rifle is meant to operate.

Bullet Charge Powder Average Average
Weight Weight Type Pressure Velocity

150 45.0 4895 51,600 2740
***48.5 4064 51,500 2905
***48.5 4320 52,000 2830

180 42.5 4895 52,000 2530
***44.5 4064 52,200 2630
***44.5 4320 52,200 2565

For comparison, here's the Lake City M118 and M852 7.62mm NATO Match ammo
specifications. Note that these cases weigh about 175 grains.

173 (M118) 42.0 4895 50,000 2580
168 (M852) 42.2 4895 51,000 2580

And finally, the 1992 Palma Match Ammo using 166-grain cases:

155 44.8 4895 52,800 2950 (THIS IS A BOLT RIFLE! 30-in.bbl)

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l-girl

October 12, 2005 06:39

7.62 NATO, 1 in 11 twist barrel.

Thanks,

Rich

Best regards,Rich

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nononsense

October 12, 2005 07:47

Rich,

You may or may not have read this material but I'll post it anyway since it involves the differences between the .308 Win and the 7.62 x 51 Nato. This is merely an attempt to promote safe reloading. No offense intended.

308 Winchester vs. 7.62 NATO...yes, there is a difference

The .308 Winchester & the 7.62NATO both evolved from the T65 experimental cartridge. The .308 was standardized in 1952 & the 7.62 in 1954
The two cartridges may be close, but they're not identical.
For example the M14 rifle 7.62NATO minimum chamber headspace specification is 1.6355" which is .0015" greater than the .308 Winchester commercial no go specification of 1.6340". even more important is the fact that 7.62NATO cartridge headspace length averages about .002"+ longer than the .308 Winchester minimum headspace chamber spec of 1.630".
In other words, .308 Winchester chamber headspace gauge sizes are 1.630" ( minimum), 1.634" ( no go ) & 1.638" ( field reject ) while 7.62NATO chamber headspace gauge sizes are 1.6355" ( minimum ) & 1.6455" ( field reject) ( national match chambers not included).
In summary, due to the nature of the intended use of the firearms, military & commercial cartridges are of necessity slightly different in design, even if the cartridge designation &/or bullet diameter is the same in the commercial equivalent. Military cartridges were designed to be used in semi & full auto weapons where constant use was a given, thus slightly different radial dimensions, primer seating depths, etc. were specified for the military stuff to minimize slam fires & cooks off the bolt of an M1 or M14 slams the cartridge into the chamber much harder than the bolt of a Remington 700 ever will, & while it might be up to it, the Remington 700 wasn't designed to fire between 20 to 40 rounds per minute where as the M1 & M14 rifle systems were.
So there is even a difference in military 30-06 cartridges as opposed to commercial 30-06 cartridges, but the difference is minute enough not to be a big deal in this case as long as you don't use military brass for a full power load (due to thicker brass, which means smaller case capacity & thus higher pressures.)
So basically if you have an m14 or an m1 chambered in 7.62 or .308, please pay attention to your headspace, especially if you decide to play around with hand loading military brass or interchanging cartridges of different calibers.
Used as a reference for this post were excerpts from " The U.S. .30 Caliber Gas Operated Service Rifles, A Shop Manual, Volumes I & II"
Please take notes, there may be a quiz toward the weekend. Please be sure to tune in for tomorrows topic, " Hand loading the .22 Long for hand gunning Africa's big 5".

I hope you mean you've been using military & commercial .308 rounds, as opposed to military 7.62NATO & .308 Winchester interchangeably.
Headspace is not something you want to play with. Brass will only stretch so much before it ruptures, & when/if it does that can be a bad thing.
You can get away with it if you have your chamber measured for headspace & reload to that dimension, or fire form your brass with a mild load if you don't want to size brass.
But if you put the 7.62 in a minimum headspace .308 chamber, then there is the potential for premature detonation of the cartridge. If the .308 chamber is between a no go & a field reject on the gauges, then 7.62 rounds shouldn't be a problem.
Likewise if you have a 7.62 chamber that's over minimum & load .308 rounds into it, then you may have excessive headspace, which is not good for you or the rifle.
Either situation may not cause an immediate problem, but it's just a matter of time before it'll catch up with you. Be safe & measure your chamber dimensions & headspace so you'll know what's going on.
Well, first off iceberg, I see that they have listed on that site a gauge for the .30-06 Remington. Maybe I just missed out on a new proprietary cartridge, but the `06 is my fav so I'm pretty sure I would have noticed a revamping of the old Springfield round.
The manual I used as a reference isn't a military manual, though the author takes a lot from old military manuals. It's more of a shop manual for gunsmithing on the M1 Garand & M14/M1A rifles. I picked it up after asking a smith some seemingly strange questions about what he could do to a Garand, but the thing has been pretty nifty to have around. I'd recommend getting it if you're interested in old military semi's.
Now according to my source it points out that while some industry drawings list the same cartridge dimensions for the .308 & 7.62, the chamber dimensions are in fact different, with the .308 chamber being slightly smaller than the 7.62 cartridge.
The author goes on to state that a gunsmith working on an M14 should ream 7.62 NATO chambers to 1.636" headspace length (7.62 minimum headspace specification of 1.6355" + .0005") & stamp barrels 7.62 NATO only & ream .308 Winchester chambers to 1.632" headspace length (industry min. headspace and go gauge dimension of 1.630" + .002" ) & stamp barrels .308 Winchester only.
Now to reiterate, you can get away with a lot, but it's best to know exactly what's going on. if you have a 7.62 chamber & use .308 ammo then maybe all you'll ever see is decreased brass life. might get a case head separation or two. Maybe get real unlucky & have the case rupture. but maybe not.
The big problem is when you have a .308 chamber that's close to minimum dimensions & you use a 7.62 round that is in spec for it's cartridge headspace. The 7.62 round is a little longer than the .308 chamber, so you have the potential for out of battery fires, slam fires, & excessive pressure if the cartridge is pushed too far into the chamber.
As to why some companies have the same specs for .308 & 7.62, I have no idea, unless the thinking is that if you use the same gauge for both chambers, then you would have the 7.62 chamber "corrected" to .308 dimensions & assumes you only intend to use .308 Winchester ammo, but that's just speculation.
Maybe some one at G&A has an answer. I am not a smith & I don't even own a .308 or 7.62. Truth is I'm a 30-06 kind of guy & would rather have a decently tuned Garand any day. But in the quest for Garand knowledge the above is what i have discovered about the .308 & the 7.62.
If you know what you're doing then i won't be the one to tell you that you can't do it, all I'm saying is know the dimensions you're working with in the chamber & cartridge, & be careful

A bolt action is much more forgiving than a semi. Once you fire form the brass, you should be o.k. I don't reload myself but I've always heard with a semi it's best to full-length resize very time you roll up a round. Mainly cause the tolerances have to be a bit closer to spec so you'll get safe, reliable feeding.
You can cam a bolt down till an oversized cartridge feeds, but with a semi you mainly rely on the force of the bolt return spring to drive a round home.
& the bolt on a semi travels with more speed than a manually operated rifle. More momentum is required to cam the lugs into place, where as with a bolt you do it by brute force. So with semi's you get an increased potential for slam fires & out of battery discharges. On a bolt you can usually skate by where you couldn't with a semi.
Mainly, the data I'm talking about pertains to semi's in general & M-14's & M-1 Garands in particular.
& John W.
A 30-06 Springfield has entirely different dimensions than a .308 Winchester. The '06 requires a long action, where as the .308 can do it in a short action. They've both inspired their own family of cartridges.
With the '06 you get the .270 Winchester, the .35 Whelen etc.
With the .308 you get the .243 Winchester, the 7mm-08, etc.
they both have the same diameter bullet, but the '06 measures around 64mm in length where as the .308 measures around 51mm. the case head size is slightly different, as is the shoulder angle & body circumference.
I like the '06 so I'm biased, but the '06 will give you around 100+ fps more in a given bullet weight than the .308. Both are suitable for damn near anything on this continent, & either makes a much better choice for a battle rifle than say a varmint round like the .223 Remington. But I'm sure our infallible government saw the need to be able to repel fascist groundhogs.
Next week: subversive groundhogs that kill & rifles that'll stop 'em!

Clint, What's the difference between .308 Winchester & 7.62x51mm NATO?
Jerry Kuhnhausen, in his classic Shop Manual (available from Fulton Armory; see the M1 Rifle Parts & Accessories or M14 Rifle Parts and Accessories Pages under Books) has published a somewhat controversial recommendation concerning .308 Winchester and 7.62x51mm NATO ammo, headspace & chambers. I broached the subject with him some months ago. He had his plate full, so we decided to chat on this in the future. When we do I'll report the results of our conversation.
I completely agree with Jerry that if you have a chamber with headspace much in excess of 1.636 (say, 1.638, SAAMI field reject), you must use only U.S. or NATO Mil Spec Ammo (always marked 7.62mm & with a cross enclosed by a circle) since the NATO mil spec calls for a far more "robust" brass case than often found in commercial (read .308 Winchester) cartridges. It is precisely why Lake City brass is so highly sought. Lake City brass is Nato spec and reloadable (most NATO is not reloadable, rather it is Berdan primed). Indeed, cheaper commercial ammo can fail at the 1.638 headspace (e.g., UMC) in an M14/M1 Garand. Many military gas guns (e.g., M14 Rifles & M60 Machine guns) run wildly long headspace by commercial (SAAMI) standards (U.S. Military field reject limit for the M60 & M14 is 1.6455, nearly 16 thousandths beyond commercial (SAAMI) GO, & nearly 8 thousandths beyond commercial (SAAMI) field reject limit!).
I also agree that 1.631-1.632 is a near perfect headspace for an M14/M1A or M1 Garand chambered in .308 Winchester. But I think that it also near perfect for 7.62mm NATO!
I have measured many, many types/manufacturers of commercial and NATO ammo via cartridge "headspace" gauges as well as "in rifle" checks. If anything, I have found various Nato ammos to be in much tighter headspace/chamber compliance than commercial ammo. Indeed, sometimes commercial ammo cannot be chambered "by hand" in an M14/M1A with, say, 1.631 headspace (bolt will not close completely by gentle hand manipulation on a stripped bolt, although it will close & function when chambered by the force of the rifle's loading inertia), though I have never seen this with NATO spec ammo. I.e., if anything, NATO ammo seems to hold at the minimum SAAMI cartridge headspace of 1.629-1.630, better than some commercial ammo!
So, why set a very long 1.636 headspace in an M14/M1A or M1 Garand? It probably is the conflict mentioned above. Military headspace gauges say one thing, SAAMI headspace gauges say something else, as do the spec's/compliance covering ammo. In a court of law, who will prevail? I think Kuhnhausen gave all those who do this work a safe way out. However, I believe it is not in your, or your rifle's, best interest. Whether you have a NATO chambered barrel (M14/M1 Garand G.I. ".308 Win."/7.62mm NATO barrels all have NATO chambers), or a .308 Winchester chamber, keep the headspace within SAAMI limits (1.630 GO, 1.634 NO GO, 1.638 FIELD REJECT). This subject is a bit confusing, and for me difficult to explain in a one-way conversation!

Clint McKee

They are not the same.
They are the same.
They are not the same, 'cause the .308 Win was released by Winchester several years before the Army standardized the T64E3 as the 7.62MM. You'll get an endless discussion of pressure specs, endless because SAAMI and the Ordnance Dep't measured pressure in different, unrelateable ways. However, the chamber drawings are different.
They are the same, 'cause nobody (and Clint's been looking for many years!) makes 7.62MM ammo that isn't to the .308 "headspace" dimension spec. So 7.62MM ammo fits nicely into .308 chambers, as a rule.
But in some 7.62MM rifles the chambers are long (to the 7.62MM military spec), notably the Navy Garands with 7.62MM barrels. Thus, using commercial ammo in such a rifle is not a good idea; you need stronger brass. Use military ammo or the best commercial only, e.g., Federal Gold Medal Match.
Most of the time it's a distinction without a difference. But if you intend to shoot .308 commercial in a military arm chambered for 7.62MM, first check the headspace with .308 commercial gauges first. You may get a surprise.
Best regards,
Walt Kuleck
Fulton Armory webmaster

7.62x51mm NATO or 308 Winchester?
An Armorer Explains the Differences
Do you have a military surplus rifle chambered in 7.62 x 51mm? If so, I'll bet part of the reason you bought it was to get a "308 Winchester" at a really low price. Well, you screwed up. It's like looking at a Northern Pike and a Muskie. They're close yes, but each is distinctive, and you have to understand what you're looking at.

Early in my military career, I worked on the FNC1 rifle (7.62 NATO). For someone that had previously handled and fired only shotguns and hunting rifles, this was a real treat! Maybe being an armorer wasn't going to be that bad! It was only natural then, that curiosity would generate questions and comparisons about what I thought was the same cartridge - 308 Winchester and the 7.62x51mm NATO.

FNC1
As part of my personal battery, I had a Midland 2100 chambered for 308 Winchester. This rifle was made in England by a small company - Midland Rifle Co I believe - but owned by Parker Hale. Having lots of military 7.62x51mm rounds available, I shot them from my 2100 from time to time. There was never a problem chambering or firing the military stuff. It was a pleasant diversion over the long (read boring) periods spent at the range for base small arms qualifications.
(I traded it off some years ago for a Smith & Wesson Model 686. It's the only rifle I ever regret losing! - Steve)
Around this period I discovered that shooting reloaded cases fired from an FN was virtually impossible. They didn't want to chamber. My frustration led me to ask an older armorer what was wrong. In a nutshell, he told me that they probably didn't fit because they stretched. I was using a Lee Loader in 308 Winchester and didn't know that they only resized the neck, leaving the rest of the case untouched. The shoulders were blown forward on initial firing, so the case was simply too long to fit my rifle's chamber! Hmmm...
I tried the gauges from work in my own rifle. What a shock! None of them would fit! The corporal brought a set in from home and explained the difference. Here's what I discovered.
308 Winchester (SAAMI) Gauges Shop (Military) Gauges
GO - 1.6300" GO - 1.6350"
NOGO - 1.6340" NOGO - 1.6405"
FIELD - 1.6380" FIELD - 1.6455"
The gauge sets were different too! What gives? He told me that the dimensions of the two new and unfired cartridges were basically the same. The difference lay in two areas - chamber size and cartridge makeup.
Chamber Size
Look at the picture below. The top chamber represents a military rifle, the bottom one, a commercial sporter. With many military rifles, their chambers can be significantly longer than, say, a Remington 700. Note that the military chamber would fail a NO GO check, but pass a FIELD check using the proper shop (military) gauges.
There is a .013" difference in chamber length however, between these two "Safe & Serviceable" rifles!

308-7.62Natochambers.jpg

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temblor

October 12, 2005 11:11

Usually between 45 to 46 grains of IMR 4064 shoots well in most guns with commercial brass. If loading military brass you may need to reduce charge to compensate for thicker brass........... good luck........be carefull...............[8D]

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Pet Load for .308 Sierra 155gr HPBT Palma Match?

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