M81 in .300 Savage Accuracy Test Today

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DWalt
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M81 in .300 Savage Accuracy Test Today

Post by DWalt »

After spending the better part of a month on restoration (not solid, however), I finally got it shooting today. This M81, by its date stamp is from December 1949, and the bore is excellent, except that I counter-bored the barrel about 1/4" deep to remove some rust pitting.

I formed 20 cases from 7.62 NATO brass (Lake City) by simply FL sizing and trimming. I made up 4 loads, all with 150 grain bullets, firing four 5-shot groups at 50 yards with factory open sights from a sturdy bench rest over sand bags. For me, under the circumstances, this is better than shooting at 100 yards, as my eyesight is poor. Groups at 100 yards will be roughly double the 50 yard size. Group measurement is done by measuring the center-to-center distance between the two furthest apart bullet holes in each 5-shot group.

All cartridges have an OAL of 2.60" All propellant charges were weighed.

1. 150 Grain GI M2 Spitzer, 40.0 grains of IMR 4895
Average MV = 2597 ft/sec
Group size = 4.0" (4 in 2.0") (@50 yards, all groups)
Comments: 2 failures to eject (jam in action); GI bullets are not noted for fine accuracy.

2. Same as #1, but 150 grain Sierra flat base spitzer bullet
Average MV = 2570 ft/sec
Group size = 2.35"
Comment: 1 failure to eject

3. 150 grain Sierra flat base spitzer, 37.0 grains of Hercules Hi Vel #2 (an obsolete propellant similar in performance to IMR 3031)
Average MV = 2440 ft/sec
Group size = 2.30"
Comment: No failures to eject

4. 150 grain Sierra flat base spitzer, 42.0 grains of IMR 4320
Average MV = 2696 ft/sec
Group size = 3.2" (4 in 1.8")
Comment: 2 failures to eject

Summary: from this test, I conclude that typical 5-shot group sizes will be from 4.5" to 6" at 100 yards. Not that much different from the best performance of my other M81 in .30 Remington. Of course, different bullets could improve groups. In my .30 Remington M81, 110 grain .30 Carbine FMJ bullets surprisingly grouped the tightest of any others I tested.

Some people prefer 3-shot groups to 5-shot groups. Those will be, on average, about 78% of the 5-shot group spread fired under exactly the same conditions, i.e., the average of a number of 3-shot group sizes vs. the average of the same number of 5-shot group sizes.

Conclusion: I wouldn't use any M81 with open sights for hunting deer at ranges much over 100 yards.

Help!: The only load that did not demonstrate failures to eject fully was the lighter one using Hi Vel #2. Factory MV of a 150 grain bullet in the .300 is given as 2630 ft/sec. All my loads are reasonably close to that, so I don't think there is a recoil impulse problem causing failure to eject. Any suggestions for improving this situation? No problem with using Hi Vel #2 for me as I have a fairly large stockpile of it, and besides, it's historically contemporary with the M8 and M81. I think my next step will be to jump to 38.0 grains of Hi Vel #2 with the same bullet and see what happens.

d-2
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Re: M81 in .300 Savage Accuracy Test Today

Post by d-2 »

I got to shoot mine today and I shot it at 100 yards with the Williams peep site. I shot 180 grain federal soft point loads. I hit what I was aiming at which was a target about the size of the kill zone on a deer, that part right behind it's shoulder. I didnt have any bullets touching but I would have killed the deer or hog with out any trouble. Tomorrow I will try 150 grain bullets and see how they do and I think 50 yards is where I will start and keep trying out my 81. My deer stand doesnt offer much more than 100 yard shots anyway...d2

DWalt
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Re: M81 in .300 Savage Accuracy Test Today

Post by DWalt »

Many of the local deer hunters have a belief that if you can hit a basketball at whatever range you hunt at, that's good enough accuracy. Around here, I'd say most deer are killed within 100 yards, and often much less, so they are probably right. I've seen no small number of hunters sight in their scoped rifles using paper plates as targets, and when they can put one shot in it, they stop. I doubt that most of them even understand the concept of group size, as most are hunters, not shooters.

I believe a tighter group capability of the rifle is always better, as that helps compensate for excitement of the hunter, blowing wind, range mis-estimation, a moving target, poor lighting conditions, and a less-than-steady shooting rest (or maybe no rest). No matter the circumstances, I'd always choose a rifle that can shoot 2" groups (or less) at 100 yards over one that won't deliver anything under 4". That gives one a bit more confidence.

Actually, zeroing your rifle at 50 yards is pretty much the optimum distance for close-range hunting, as you will hit a little high at 100 yards, and just a little low at 150, so no hold-over or hold-under is needed until you get out to beyond 150 yards

d-2
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Re: M81 in .300 Savage Accuracy Test Today

Post by d-2 »

I agree, if hunt out of a stand with more than a 100 yard shot I will use a rifle with a scope on it. I will use this the first couple of days of the new doe season and get my feet wet and my confidence up. 150 grainers for tomorrows shoot, they may shot a little tighter...d2

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imfuncity
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Re: M81 in .300 Savage Accuracy Test Today

Post by imfuncity »

Great job D-2. Exactly what was intended - minute of deer! Mr. Browning would be proud.

Personally, I've never been hunting but I know I have the ability to blow it - regardless of what my rifle can do. Wonder how many 1"-group-paper-punchers get buck fever and blow it! Sure hope I get the privilege of trying a hunt with a vintage shooting iron - be the highlight of my (so far) short firearm accumulating.

Will be watching for the photos of the freezer filler.
Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine

texassako
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Re: M81 in .300 Savage Accuracy Test Today

Post by texassako »

I got to try mine as well yesterday, and first time using open sights since I was a kid with a .22. Managed to get a 6" group with most of a box of buffalo arms ammo between messing with misfires. I definitely need to get a new eye prescription! My .321 Hornady FTX bullets came in; so now I just need some dies and the misfire sorted out (started a seperate thread for that) to try some reloads.

On your sticking cases, could the heavier/thicker military brass be the issue? Maybe try making some out of commercial .308 or .30-06(or derivitive)? I don't load it, but have seen that military brass is different than the commercial .308 brass in weight and powder capacity.

On further review, I find it interesting that the slowest load was the only one without a stuck case. I wonder if you will see a stuck case with that powder at 38 grains?

DWalt
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Re: M81 in .300 Savage Accuracy Test Today

Post by DWalt »

I wouldn't say the cases were sticking. They were apparently extracting but just weren't ejecting - creating what was more or less a stovepipe jam. Cases didn't clear the ejection port before the bolt closed. I'd need a high-speed video camera to see what is happening, and one of those I do not have (by the way - if anyone has a HS video camera, the M8/81 action functioning would be a neat thing to capture).

I wouldn't discount that the problem could be case-related but I doubt it. There should be little, if any, residual pressure in the chamber by the time the barrel starts moving forward. I'll probably form some .300 Savage cases from commercial .308 brass to see if it makes any difference. By the way, I have not seen any significant difference in case weights between .308 and 7.62 cases, at least the LC-headstamped cases I have, so the brass is not thicker. In fact, some commercial .308 cases are slightly heavier. But sometimes military cases may be a little softer. I have no way to test for that.

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81police
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Re: M81 in .300 Savage Accuracy Test Today

Post by 81police »

(by the way - if anyone has a HS video camera, the M8/81 action functioning would be a neat thing to capture).
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texassako
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Re: M81 in .300 Savage Accuracy Test Today

Post by texassako »

I mistook your original post to mean stuck. I checked Ken Howell's book on dimensions. Drawings show .308 has a .0540" thick base and .300 Savage has .0490". Pretty finicky if that was the issue, and only other ammo related thing I could think of. Maybe try a box of factory ammo to determine ammo versus gun?

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imfuncity
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Re: M81 in .300 Savage Accuracy Test Today

Post by imfuncity »

"Likey" - HS camera M8/81 action, way cool idea.
Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine

DWalt
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Re: M81 in .300 Savage Accuracy Test Today

Post by DWalt »

Back in a former life (about 5 years ago) I bought a Red Lake high-speed video camera, and used it for exactly this type of work (motion studies on automatic weapons). That camera was about $15K, and unfortunately, I no longer have any access to it. But an extremely fun toy to play with.

Regarding rim thickness, the SAAMI case drawings specify 0.044-0.054" (0.054"-0.01") for the .308, and 0.039-0.049" (0.049"-0.01") for the .300 Savage, so there is a lot of overlap. Shouldn't be a problem. Plus, there seems to be no problem in the extractor snapping over the 7.62mm rim properly, as I checked that first thing before I formed the first .300 case.

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imfuncity
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Re: M81 in .300 Savage Accuracy Test Today

Post by imfuncity »

DWalt, whatever did you do that justified that? (If you can tell me without having to shoot me afterwards.) Indeed that would be a fun toy.
Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine

DWalt
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Re: M81 in .300 Savage Accuracy Test Today

Post by DWalt »

I was the chief engineer of the USAF gunsmith shop (sort of the USAF's much smaller scale equivalent to the Army's Picatinny Arsenal or the Navy's NSWC-Crane), and we did all sorts of work on about any military small arms in the USAF's inventory. Everything from M9 pistols to .50 M2 ground machine guns, even development of guns, ammunition, and special purpose weapons modifications. Not aircraft weapons, however. That was done elsewhere.

I retired in late 2007. See http://www.youtube.com/watch?v=GkuQFyf8ZeM

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imfuncity
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Re: M81 in .300 Savage Accuracy Test Today

Post by imfuncity »

Looks like it could be a fun job. Thanks for sharing, way-cool for sure.
Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine

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jack1653
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Re: M81 in .300 Savage Accuracy Test Today

Post by jack1653 »

Hey Dwalt,

Thanks for sharing the information. I just knew that you weren't just another guy who liked guns. I can only imagine what you have done and learned while in that program. I have marveled at your knowledge level and appreciate so very much your service to the country and the contributions you make to this forum. Keep up the good work and may God Bless.

Respectfully,

jack1653

ctgodog
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Re: M81 in .300 Savage Accuracy Test Today

Post by ctgodog »

Dwalt,


thanks for sharing the info....really neat!!!

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81police
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Re: M81 in .300 Savage Accuracy Test Today

Post by 81police »

dito on that, cool video Dwalt :)
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Sarge756
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Re: M81 in .300 Savage Accuracy Test Today

Post by Sarge756 »

Dwalt....Thanks for the Utube link.Enjoyed it and have been busy last hour looking at the other suggested videos.Good way to spend a rainy morning.
Ok.This just begs the question. When are you going to get busy and whip up some of these detachable magazines we`ve been talking about? The orders would be enough from just our group to start a cottage industry.
Joe
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With seven hundred dollars and a thirty ought six."

texassako
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Re: M81 in .300 Savage Accuracy Test Today

Post by texassako »

Cool video Dwalt, sure explains the in depth knowledge of firearms in your posts. I try to learn as much as possible about each and every firearm I own, and it looks like you could teach us all a thing or three.

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