I got results at the range that were somewhat unexpected.  This was shooting my 30-06, M1 Garand.  
I was shooting at 100 yards.


The Objective of the Test
I wanted to compare my accuracy using 147 FMJ bullets (inexpensive) to that of the 168 Sierra MatchKing (SMK).  
The question was, how much accuracy do I lose using the inexpensive bullet?  
Put another way, how much do I gain using the more expensive bullet?


The 30-06 Reloads
147 bullet; LC brass; IMR-4895 powder (45.0 gr, hand weighed); CCI#34 primer
168 HPBT Widener's bullet (PRVI?); LC69 brass;  IMR-4895 powder (45.0 gr, hand weighed); CCI#34 primer
168 SMK bullet, LC 60 MATCH case; IMR-4895 powder (45.0 gr, hand weighed); CCI#34 primer

Expectations for 30-06
I was expecting the FMJ, HPBT and SMK to be inside a ~6 MOA circle (barely inside the black).  
I believe this is the accuracy limit of my M1 Garand and cannot be affected by changing bullets.  

Results for 30-06
HPBT and SMK shot into 6 MOA groups
FMJ bullet gave me my best groups ever from this M1 (~3 MOA).

30-06 Chronograph Results
The loads seemed slow - 2415 fps at the muzzle (measured at 25 yards).
Standard deviation of velocity was fairly high, despite hand weighed charges - 50-67 fps.  The FMJ gave the lowest SD.
Extreme spread was 130-188 fps. The FMJ gave the lowest ES.



Discussion and Questions
Were the speeds low given that powder charge?  
Sierra said 2600 fps for commercial brass and a 26" barrel.  They also say military brass is heavy and to reduce the charge by 1-1.5 grains.  My loads should have been 2700 fps in my LC brass.

If I match my chrono data to the Sierra data, I am off by 3 to 5 grains!

The M1 has a 24" barrel.  Would the 2" difference cause a 200-300 fps reduction?

Are the ES and SD values ridiculously high, or typical for 30-06 in an M1, or...?

Any thoughts or insights would be welcome.

The load you are showing is a little low and slow.
Don't forget that there is sometimes some detail missing when folks say muzzle velocity but use some distance out in front of the muzzle, as in the example of some Mil Specs.
Nowadays, when folks say muzzle they mean muzzle, not way out in front of the muzzle.

Here is a capture of the old Master Po's loads that someone had the foresight to capture before that site went down.


Recommended .30 caliber M1 loadings from the NRA


147 - 155 grain FMJ or HPBT bullets

IMR 3031 - 48.0 grains
IMR 4895 - 49.0 grains
IMR 4064 - 50.0 grains
W748 - 48.0 grains
AA2460 - 49.0 grains
AA2520 - 51.0 grains
AA2495 - 50.5 grains
H4895 - 49.0 grains
BLC-2 - 49.0 grains
H335 - 49.0 grains
RL-12 - 48.0 grains

165/168 grain FMJ, HP or SP bullets

IMR 4895 - 47.0 grains
IMR 4094 - 48.0 grains
AA2520 - 47.5 grains
AA2495 - 47.0 grains
H4895 - 47.5 grains
BLC-2 - 49.0 grains
H335 - 47.0 grains
RL-12 - 44.5 grains

173/175 grain FMJ or HPBT bullets

IMR 4895 - 46.0 grains
IMR 4064 - 47.0 grains
AA2460 - 46.0 grains
AA2495 - 46.0 grains
H4895 - 47.0 grains
BLC-2 - 48.0 grains

180 grain FMJ, SP or HPBT bullets

IMR 4895 - 43.0 grains
AA2460 - 46.5 grains
AA2495 - 45.5 grains
H4895 - 44.0 grains
BLC-2 - 47.5 grains
RL-12 - 41.5 grains



Master Po's comments

These loads only duplicate military spec. velocities for the given bullet weight, using commercial cases and powders. If you are using military cases, drop all charges by 2 grains.

If you are looking for accuracy, drop all charges by 1 grain and work up .2 grains at a time.

Master Po's Ancient M1 load secret.

This is my personal M1 load I use in my CMP M1. It will shoot better than Master Po can. I worked this load up, as you should for your own rifle.

Remington .30/06 cases, flash holes deburred and weighed within 1 grain.
Federal GM210M Primers (Master Po has heard the horror stories of Federal match primers in the M1/M1A rifles. If you're squeamish or new to reloading, use Winchester Large Rifle)
47.0 grains IMR 4064
Sierra 175 grain MatchKing
Overall length 3.340 inches

This load, in my M1, duplicates almost perfectly the M72 match load specification with a very low standard deviation. Groups off the bench run 1 - 1.5 inches with the original 1945 barrel on the rifle. Of course, Grasshopper YMMV.



And here is a copy of the old John Clarke article on Reloading for the M1 Rifle
https://www.m14forum.com/attachments/nra-pdf.437318/

And more Garand Loads

All of which say your loading is a little light and slow. You can leave it there if you like the group, cycling, and ejection.
In my experience, the H4895 version does better when light loaded than the IMR version.

Generally speaking, your SD/ES should tighten a little once your pressure goes up a little higher, but as long as she groups where you need her to, it doesn't really matter of those are tight or not.
https://hodgdonpowderco.com/wp-content/uploads/2023/04/m1-final-data-1.pdf

My sierra reloading ap shows that charge weight at 2500 fps so I don’t see your velocity as out of line …..

Sounds like your book is different this is why I’ve come to look at them as a report / place to start

Looks liike the accuracy node is at 2800 in my app so id say its possible that could improve with some speed.

I’m mot a 30-06 loader but my bil is and your load sounded light from what I remembered him saying that’s why i looked.

Thanks for the info.

As stated above, speeds were measured at 25 yards and corrected back to the muzzle.  JBM Ballistics gave 45 fps as the loss over that distance, so that was added to the measured data to get a value at the muzzle.  

Earlier tests using 47.0 gr of IMR 4064 yielded
Mean = 2652 fps
ES = 178 fps
SD = 53 fps

Just to add to it, that's a rather mild load, so it's not surprising the velocity is so low.  Also, their test barrels not only are longer, but tend to have tight dimensions.  Where a ~100 year old combat spec Garand barrel is going to be loose and leak gas pretty much everywhere, starting at the throat before the bullet even gets into the barrel to try and seal.  And that seal is going to be over fairly loose and worn bore.

There also tends to be lot-to-lot variability, especially with IMR (IMHO) - so it sounds like you got a weak lot; of what might be fairly old powder?   Also, that's a high-void load, which I've found I don't care for, as the primer flame can at times not even light so good. I had a batch of S&B primers that would hang-fire high-void 30-06 loads on me like that.  Magnum Research (the importer) actually replaced them, and I gave my "bad" ones to a .308 shooter, who says they run great never a problem.  I see you are running CCI31's ,which I woudl think are about as good as you can do though.

The 47 gr load also has a large void in the case and SD was similarly poor.  2 gr additional just isn't that much additional powder volume, given the size of the void.

I am trying to get this rifle to shoot as well as it can before committing ~$500 for a new barrel (which may not fix the problem).  Plus, it is fun to shoot it.  :-)

what is your barrel like?  does the muzzle eat a ball round?  any nicks in it?  6 moa is pretty poor but 3 isn't bad.  I shot HXP in 200 yd cmp matches and I would shoot 180's prone. going to quality sierra or hornady bullets would get me into the low 190's on a good day(even better if you let me drop that 7 or 8)

This............. I'd look at your rifle first.  A standard M1 isn't a match rifle but it isn't (normally) a 6 MOA rifle either.
After you've straightened the rifle out.............. then do the test over.

I know all of that is true.  

I am deciding whether to spend the money on the rifle or just give up on it and live with it as is.  If I had a bolt action in 30-06 that could prove the ammo was good enough, this might be easier.  

I got the rifle from the DCM and have had it for over 30 years in this condition.  

It was the last rifle I bought that was not accurate.  After messing with it (and giving up), I bought my first truly accurate rifle.  

Still, it can be great fun when shooting amongst others with similarly inaccurate rifles.

My muzzle will eat a complete CARTRIDGE.  :-)  jk

Let me go do that test.  I know there is rifling visible but ... let me go and check.

I don't have a throat/muzzle erosion gauge, so I used a 190 SMK.

The muzzle would not take the base of the bullet at all (where the bullet is 0.308" in diameter).  The boat tail goes in, but the "driving band" does not, not at all.

Once I inserted the pointy end, I spun the bullet to mark where it was contacting the lands.  

The bore diameter at the point of contact is 0.301" versus a SAAMI spec of 0.300 - 0.302".

That contact occurs about 0.1" behind the crown of the barrel.  That 0.1" dimension includes the radiused end of the barrel (the crown).

ie, he got the best accuracy out of the lighter bullets because they were moving at a higher velocity.

147 FMJ were 2397 fps.  168 SMK were 2415 fps.  

I did say the results were "unexpected".   :-)

This might be due to the small sample sizes (n=8) and large SD (SD>50 fps).  Still, I was expecting the lighter bullet to be noticeably faster, even if it was just a little bit.


I surely did have fun shooting.  It was a gorgeous day.

Sir:
Is this the same rifle you've posted about before with the accuracy issues?
Was that you ?

Either way, and I humbly suggest this..............

Don't use an inaccurate rifle for accuracy tests.
It's self defeating.

IIRC about this rifle (your history/posts about it) either:
get it to a good M1 'smith
rebarrel it with say, a new Criterion  
or sell it.  

But be done with this.

PS.......... if you want to use, and show us, the muzzle erosion........ use one the loaded 147 rounds.
Just drop it bullet down (so pointy end) in the muzzle, then view it from the side.
Don't over think it................. it's that simple.
..........and post a picture if you want.

I'd add 2 grains.

Check bedding and trigger group lockup.

Then if still unsatisfactory, replace the barrel. I don't know if CMP still has a 'smith available at the regional Games.

Otherwise, save money and further throat burn with pistol powder reduced loads and the FMJs.

My m1 likes heavy slow cast bullets. my Lee 170 fp cast powder coated gas checked loads over h4895 will do better than 6 moa. Like 3-4” 10 shot groups at 100 yds. If I do my part sorting and loading the best of the best cast bullets. All shot Off a lead sled.  My cast loads just barely cycle the action so I don’t have to chase the brass. My regular 150 -165 gr jacketed loads will shoot better. Don’t have my load data where I’m at, so can’t post my load or speeds etc..

I would scrub that barrel with sweets or Barnes copper solvent and then bore scope looking for throat erosion or heat damage. If it looks ok then check gas cylinder alignment and any binding on op rod etc.  if your barrel is worn out, get a criterion or better installed by someone who knows m1s. Have them check it out.  These old war horses are so much fun! Always have someone who wants to shoot it at the range. Especially the younger guys who have played the ww2 video games… I always have a clip or 2 of my cast loads to let them shoot all 8 and experience the ping! The smiles are worth it!! Ringing steel with some of the best iron sights ever put on a military rifle is a joy.  

Shot my best 600 meter group with a match conditioned M1 prone. Rifle belonged to a serious match shooter and he was spotting and coaching us at the time  nearly a 5” five shot group. Had a steady full value wind and took me 3 shots to dial the wind and  get on the target then shot for group.  I was hooked on owning a M1 after that… I don’t think I could repeat that again now. 20 year old eyes and was trying my best to do exactly what he was coaching me on. Glad that old guy took the time to teach us something.

Don’t use this data cause it is higher than you should go but I shoot lapua 155 senar-l with 49.5gr of varget.  That’s 1.5gr over Hodgons max but I do have a gas plug.  I get 2875fps if memory serves and it shoots 1.5” groups at 100yards which is about what my eyes can do.

So, you went from a 6" group @ 100yd with match bullets to a 3" group in a rifle with a poor muzzle simply by swapping to a plain FJM?

I would be ecstatic!  

Here is an observation from my loading history.  Simply put, some firearms have individual personalities (no better explanation).  They like what they like even if it should not be so.  Usually, it will be a lighter than standard bullet.

Here's 1 example: very nice 270 Parker Hale, rifle is designed and set up to use 130gr bullets.  Simply won't shoot them, tried every bullet/powder combo imaginable ... no luck.  One day tried a what the hell & loaded up 110gr Sp.  Instantly started shooting 3/4" groups on the first test load.

If you can get consistent 3" groups from a worn Garand, I would consider swapping out the sights for NM sights to see if things improve a little.  Then just be happy with it.

MLG

If the rifle isn't in good shooting shape then it's only going to shoot "good" groups.


Yes, your loads are all on the low side.  The 168s want to move faster.  Mine are 2700+ish MV and my 150s are 2800+.

Okay, a little progress has been made!

Once again, Gordon's Reloading Tool came to the rescue!  <-- I am REALLY liking this tool!

I plugged in all the reload data (the recipe) and out pops a muzzle velocity of 2473 fps for the 168 Sierra out of a 24" barrel.  This compares favorably with my measured value of 2415 fps.  

It's not as close as I'd like, or as close as other GRT predicts have been, but it is much closer than the Sierra data.  Maybe the gas blowby from a worn barrel accounts for that short fall.

I also compared the GRT results to some older chrono data I have at 47 gr and the agreement is good there, too, a better match than the Sierra data.

I am going to trust the GRT results and ignore the Sierra data altogether.  

Because I used the Sierra data to set my expectations, my results were "unexpected" (not as expected).


Gordon's Reloading Tool Is Great!



Consensus has it that a 6 MOA rifle not the proper tool to evaluate relative bullet accuracy.  Relative to the original accuracy objective, the bullet makes no difference for this rifle, so I may as well go cheap (147 FMJ).

I have deferred the rebarreling for over 30 years.  It is an old war horse - December, 1941 receiver and a Korean War barrel.  I am hesitant to have it messed with.


Thanks for all the help, guys.

Don't be afraid to put a new criterion on it and maybe a new stock to tighten things up.

That should get you down to ~ 2 MOA.


Life's too short to shoot an inaccurate rifle.

Truly!  But I will make exceptions for an M1 Garand.

The last 2 M1s I put criterion barrels on were 1 MOA rifles after I was done with them. Criterion makes a good barrel.

A lot of times a rifle will prefer a particular bullet and load. But, depending on how your barrel gauges, it might well benefit from a barrel change.

If it's a shooter then just put a new barrel on it. You're not preserving history or anything by leaving it as is.