Accurate at 100 yards, wildly inaccurate at 200 yards

[joeb33050]

ACCURATE AT 100 YARDS, WILDLY INACCURATE AT 200 YARDS

Savage Striker pistol, 308 Win., 314299 sized .312”, Lyman Super Moly lube, 197.6-198.1 grains, IMR4227, Rem. 2 ½ LP primers, 2.790” OAL Simmons 2-6 scope.
With 16 grains of IMR4227 at 100 yards it shoots averages of 5 5-shot groups of less than 2”.
I wanted a 200 yard zero, there’s no 200 yard range near home in FL, so I brought the pistol and some reloading stuff up to MA. At Old Colony, at 200 yards, I didn’t hit a ~2’ X2’ target once in 20 shots at 200 yards. I had a pal watch as I shot at a rock, and the bullets were hitting all over the place.
John Bischoff kindly used Quickload to give me the following information:
16/IMR4227 MV 1101 fps, 100 yd 1048 fps, 200 yd 1004 fps
18/IMR4227 MV 1220 fps, 100 yd 1140 fps, 200 yd 1080 fps
20/IMR4227 MV 1340 fps, 100 yd 1236 fps, 200 yd 1150 fps
(John recommended IMR3031, but I don’t have any.)
Yesterday, 8/11/09, the 18 and 20 grain loads were shot. Both shot reasonably good 200 yard groups, and will also shoot under 2” at 100 yards. I had 20 of each to shoot, zeroing at 100 yards and then moving to 200 yards.
18/IMR4227 shoots ~ 18.5” low at 200 yards when zeroed at 100 yards.
20/IMR4227 shoots ~ 14.75” low at 200 yards when zeroed at 100 yards.

I’ve read and thought that the bullet RPMs diminish only slightly over the bullet’s travel. If this is true, then the wild 200 yard shooting must be because velocity falls to below some critical velocity, or because the bullets go below the speed of sound between 100 and 200 yards.
Any thoughts?
joe b.

[klcarroll]

I think you're on the right track with your last remark.

In the past, I did a lot of experimenting with sound suppressed weapons; .....And I observed several times that certain combinations of bullet length, configuration, and twist seemed to have trouble with the "trans-sonic transition".

Kent

[44man]

Boolit design can drive a guy nuts. I have seen the same problem with my BPCR with 1" groups at 200 but the entire berm is safe at 500. When the boolit gets about 300 a spotter can see it go wild.
Another thing to consider is 4227. In certain cartridges it becomes very heat sensitive as the barrel gets hot. I would isolate that first.

[Bret4207]

Just out of curiosity Joe, how did you manage to legally bring a Florida pistol into Mass? I wouldn't carry in Mass even when I was on the job.

[243winxb]

Do you mean bullet #311299 ? IMR 4895 about 33.0 Gr. looks good to me on paper. How does it look to Quickload? Getting away from the sound barrier is a good idea. The sound barrier FPS changes depending on where your at by sea level / altitude/temperature.

[runfiverun]

33 grs is a bit much in a 10 twist 308.
28 and a filler is good and about 30 without.
i'd take 28 with everytime though.

[Tom Myers]

Joe,

I entered the velocities and ranges into the Precision Ballistics BC calculator (http://www.uslink.net/~tom1/calcvel.htm) and it returned the following Ballistic Coefficients for those values

1101 fps = 100yd BC of 0.5238 ~ 200yd BC of 0.5172
1220 fps = 100yd BC of 0.4924 ~ 200yd BC of 0.5294
1340 fps = 100yd BC of 0.4692 ~ 200yd BC of 0.4730

These Coefficients seem to be quite high for a cast bullet of this configuration.

I saw the image you had posted on the CBA forum and scaled out the bullet dimensions then entered the values into the Precision Cast Bullet Ballistic Coefficient Estimator (http://www.uslink.net/~tom1/cast_bc.htm) with the displayed results.

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/311299~BC.gif

Using the BCs calculated from the Quickload values, if your 100yd and 200yd ranges are, in fact, actually at 100 and 200 yards. the bullet drop from a 100 yard zero to 200 yards would calculate out to:

1101 fps drop from 100 to 200yds = 30.1 inches
1220 fps drop from 100 to 200yds = 25.2 inches
1340 fps drop from 100 to 200yds = 21.2 inches

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1101fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1220fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1340fps.gif

Using the calculated BC of 0.3198, the drop values would look like this:

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1101-fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1220-fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1340-fps.gif

In order to match your 200yard drop values, the BC would need to be extremely high to even calculate out close to those values

I am not saying that your values are wrong, only that "sumpthin ain't addin' up here" and my curiosity is aroused;

As to why your bullets are becoming unstable past 100 yards. If your twist rate is the 308 standard of 1 in 12 inches, that 1.2" bullet would need a calculated muzzle velocity of over 1700 fps to fall into the stability range.

Using Charlie Dell's Algorithm (http://www.uslink.net/~tom1/twistrate.htm) to calculate minimum muzzle velocity:

((Length x twist) / (Diameter x Diameter x 3.5)) squared

((1.2 x 12) / (0.312 x 0.312 x 3.5)) squared = 1786 fps

If your Striker has a 1 in 10 twist, the minimum muzzle velocity would be around 1241 fps so you should be close there.

No criticisms or judgments, just some things to think about that might help solve your problem.

Hope this helps.

Respectfully,
Tom Myers
Precision Ballistics and Records (http://www.uslink.net/~tom1/)

[Willbird]

I think you want the bullet to be supersonic to the target. That is a general rule in long range accuracy. There are exceptions to that rule but I think the amount of rifling twist has to be set up to deal with them.

Bill

[joeb33050]

Just out of curiosity Joe, how did you manage to legally bring a Florida pistol into Mass? I wouldn't carry in Mass even when I was on the job.
Bret;
I looked into this years ago, and my understanding is this. A pistol in a case, away from the ammunition, carried by a legal person, can be carried through any state and to any state for any legal purpose. Match, target shooting, hunting, etc.
joe b.

[joeb33050]

Tom;
Here's the dope. This pistol was ~sighted in 100 yards to be ~ dead center for height at 100 yards with 16/IMR4227.
With 18/IMR4227 the 1 100 yard 1 3/4" 5 shot group is ~1/2" high at 100 yards. The 200 yard 12 shot group is ~17 1/2" low at 200 yards. Then 1/2" X 2 = 1", and that 1" plus 17 1/2" =18 1/2". 12 shots in 6 1/8", 11 of them in 4 1/2", 10 of them in 3 1/2"
The 20 grains IMR4227 load shot 2 1/4" high at 100 yards, 10 1/4" low at 200 yards. 10 shots 200 yds in 6 1/8", 9 of them in 4 1/2". Then 2 1/4" X 2 = 4 1/2" + 10 1/4" = 14 3/4" low at 200 yards.
The ranges are right at 100 and 200- yards, years of traveling to other ranges and seeing Lyman STS settings work to center the groups tells me that they're very close.
I certainly don't know why your numbers don't seem to work out, but shooting tells the story.
I have no chronograph or measuring scale here. Note that the 200 yard groups were shot aiming at a 81/2X11 target ABOVE a ~2' square target, so the 18 grain holes are in the 10 ring and the 20 grain holes are in the white between bulls.
I think I remember that the Lyman CB book has a BC for 311/314299 at ~.3.
Remember, this is a pistol. I liked 16/IMR4227 because the recoil is low. AT 20 grains, the gun is quite snappy. Maybe snappy enough to shoot higher??
joe b.



quote=Tom Myers;635279]Joe,

I entered the velocities and ranges into the Precision Ballistics BC calculator (http://www.uslink.net/~tom1/calcvel.htm) and it returned the following Ballistic Coefficients for those values

1101 fps = 100yd BC of 0.5238 ~ 200yd BC of 0.5172
1220 fps = 100yd BC of 0.4924 ~ 200yd BC of 0.5294
1340 fps = 100yd BC of 0.4692 ~ 200yd BC of 0.4730

These Coefficients seem to be quite high for a cast bullet of this configuration.

I saw the image you had posted on the CBA forum and scaled out the bullet dimensions then entered the values into the Precision Cast Bullet Ballistic Coefficient Estimator (http://www.uslink.net/~tom1/cast_bc.htm) with the displayed results.

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/311299~BC.gif

Using the BCs calculated from the Quickload values, if your 100yd and 200yd ranges are, in fact, actually at 100 and 200 yards. the bullet drop from a 100 yard zero to 200 yards would calculate out to:

1101 fps drop from 100 to 200yds = 30.1 inches
1220 fps drop from 100 to 200yds = 25.2 inches
1340 fps drop from 100 to 200yds = 21.2 inches

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1101fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1220fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/1340fps.gif

Using the calculated BC of 0.3198, the drop values would look like this:

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1101-fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1220-fps.gif

http://www.tmtpages.com/LinkSkyImages/forum_images/Joe%20Brennam/BC~032~1340-fps.gif

In order to match your 200yard drop values, the BC would need to be extremely high to even calculate out close to those values

I am not saying that your values are wrong, only that "sumpthin ain't addin' up here" and my curiosity is aroused;

As to why your bullets are becoming unstable past 100 yards. If your twist rate is the 308 standard of 1 in 12 inches, that 1.2" bullet would need a calculated muzzle velocity of over 1700 fps to fall into the stability range.

Using Charlie Dell's Algorithm (http://www.uslink.net/~tom1/twistrate.htm) to calculate minimum muzzle velocity:

((Length x twist) / (Diameter x Diameter x 3.5)) squared

((1.2 x 12) / (0.312 x 0.312 x 3.5)) squared = 1786 fps

If your Striker has a 1 in 10 twist, the minimum muzzle velocity would be around 1241 fps so you should be close there.

No criticisms or judgments, just some things to think about that might help solve your problem.

Hope this helps.

Respectfully,
Tom Myers
Precision Ballistics and Records (http://www.uslink.net/~tom1/)[/quote]

[Bret4207]

Uh, no Joe. I think you misunderstand the law. What I believe you are thinking of is the wording of the Firearms Owners Protection Act of 1986. It says, basically, that a handgun legally possessed in one state may be transported ( unloaded, etc) to another State where it can legally be possessed. To the best of my knowledge, and anyone who knows for sure can correct me, unless you have a valid permit for Mass you're 100% in the wrong. It was my understanding at one time that even carrying a long gun into Mass was illegal unless you had a Mass FOID card.. If you're back home fine, but if you're still in Mass I'd hide that thing real deep in my trunk and keep it out of sight.

There are certain exceptions to that law for sanctioned matches, at least in NYS. I can say for sure that if your destination had been NY and you didn't have a valid NYS permit you'd be in clear violation of the law unless you were attending an NRA or other recognized organizations match. Target shooting by itself is not a sanctioned event. It is my understanding Mass law is about the same.

[joeb33050]

I never finished Law School and am sure that you are correct. I'll probably be arrested in MA, NH, RI, CT, NY, NJ, DE, MD, DC, VA, NC, SC and GA. All the years carrying pistols into NY and shooting there, with LEOs, was just a lucky fluke.
joe b.



Uh, no Joe. I think you misunderstand the law. What I believe you are thinking of is the wording of the Firearms Owners Protection Act of 1986. It says, basically, that a handgun legally possessed in one state may be transported ( unloaded, etc) to another State where it can legally be possessed. To the best of my knowledge, and anyone who knows for sure can correct me, unless you have a valid permit for Mass you're 100% in the wrong. It was my understanding at one time that even carrying a long gun into Mass was illegal unless you had a Mass FOID card.. If you're back home fine, but if you're still in Mass I'd hide that thing real deep in my trunk and keep it out of sight.

There are certain exceptions to that law for sanctioned matches, at least in NYS. I can say for sure that if your destination had been NY and you didn't have a valid NYS permit you'd be in clear violation of the law unless you were attending an NRA or other recognized organizations match. Target shooting by itself is not a sanctioned event. It is my understanding Mass law is about the same.

[Bret4207]

Well, take your smart mouth answer and stuff it Joe. I did complete 22 years as a NYS Trooper and can tell you definitively under the circumstances you laid out you are illegal.

Good luck bone head. Sorry for trying to keep you out of trouble.

[Dale53]

Bret4207;
When I was a wee lad, my father told me that there were some people you JUST COULDN'T HELP. It took a couple of years, but I realized he was (as always) correct.

Dale53

[dominicfortune00]

Or as the warden said in 'Cool Hand Luke' : "You just cain't help some people."

[hyoder]

Back to the accuracy problem - Your load is transonic at 200 yds. You need to adjust the load up or down to make it supersonic or subsonic all the way out. With your barrel twist I believe that I would opt for subsonic.

[SierraWhiskeyMC]

Considering that it's a 5lb pistol, I'd also opt for subsonic with that particular boolit.

If you want to get your FPS up, you're probably going to have to switch to a much lighter boolit - unless you're a real glutton for punishment. I don't have any data for 4227 in a barrel that short for that heavy a boolit. You're possibly getting close to pressing your luck with peak chamber pressures already.

[joeb33050]

The 18 and 20 grain loads of IMR4227 seem to be accurate at both 100 and 200 yards with 314299. I'll try a lower-than-16gr charge to see if the bullet shoots all-subsonic, that would be great for recoil reduction. But, if I understand Tom Myers's analysis, the bullet won't stabilize at lower velocities.
Thanks;
joe b.




Considering that it's a 5lb pistol, I'd also opt for subsonic with that particular boolit.

If you want to get your FPS up, you're probably going to have to switch to a much lighter boolit - unless you're a real glutton for punishment. I don't have any data for 4227 in a barrel that short for that heavy a boolit. You're possibly getting close to pressing your luck with peak chamber pressures already.

[joeb33050]

Back to the accuracy problem - Your load is transonic at 200 yds. You need to adjust the load up or down to make it supersonic or subsonic all the way out. With your barrel twist I believe that I would opt for subsonic.

If I was smart I'd use a ~150 grain bullet at higher V, as most of the LRH guys do. I'm prejudiced in favor of long heavy slow bullets to minimize wind drift, since I've never been able to read wind flags and compensate. I'm thinking it would be interesting to see how slow a bullet, ex. 314299, can go and still be stable.
Thanks;
joe b.

[joeb33050]

Bret;
Let me suggest a plan.
Step 1 is where you never respond to one of my posts for the rest of your life. This will save you much time and keep you happier.
Step 2 is where I never read another of your posts. I'm implementing Step 2 today.
Thanks for the constant bad-tempered error-ridden assistance in the past;
joe b.



Well, take your smart mouth answer and stuff it Joe. I did complete 22 years as a NYS Trooper and can tell you definitively under the circumstances you laid out you are illegal.

Good luck bone head. Sorry for trying to keep you out of trouble.

[Bret4207]

You would know about errors betters than anyone else I'm aware of Joe.

You other guys are right, you can't help some people.

[cabezaverde]

Brett is right Joe, and you have been very lucky.

NY will put the screws to you if caught. They will not care about your age, or who you know. They hate guns, especially hand guns.

[44man]

I see all kinds of charts and predictions, paper foolishness! :mrgreen::mrgreen:
This is a short barrel pistol and rifle rules go out with the kitty litter.
The bottom line is to still see what a boolit does when shot under actual conditions.
One powder type for a test is not enough either.
Stop personal stuff too, I agree with both of you a lot but I also disagree with both of you too, many times.
If a boolit will not shoot after all tests, discard it for that gun and buy another gun it will work in or sell the mold.
My drawer is full of molds I will never use again. :Fire:

[cabezaverde]

Stop personal stuff too, I agree with both of you a lot but I also disagree with both of you too, many times.


Joe, this board is full of posts where one or more member helps to save another a lot of grief, such as when someone talks about a dangerous loading practice and many jump in. It is what we are supposed to do.

Brett and I are doing the same - if Joe is in NY with a pistol under the circumstances he described - he is running an equivalent risk to loading a 30-06 case full of Bullseye.

I am a mere mortal carry permit holder in NY - we are not even supposed to fire a pistol that is not specifically listed by make and serial number on our permit.

Brett is a retired trooper, and I am sure knows the laws (many, many laws) far better than I.

They will screw Joe if he is caught. I go back to the case full of Bullseye analogy - we all would warn any fellow board member about it.

[SierraWhiskeyMC]

The 18 and 20 grain loads of IMR4227 seem to be accurate at both 100 and 200 yards with 314299. I'll try a lower-than-16gr charge to see if the bullet shoots all-subsonic, that would be great for recoil reduction. But, if I understand Tom Myers's analysis, the bullet won't stabilize at lower velocities.

Are you seeing any evidence of keyholing at this point?

The speed of sound in dry air is approximately:
30°C,86°F 349.15m/s = 1,145.5 f/s
0°C,32°F 331.45m/s = 1,087.4 f/s
Humidity has a slight affect on the speed, but not nearly as much as temperature.
In aircraft, buffeting occurs when you approach supersonic speeds. There's a LOT of buffeting during transition, which is why projectiles get knocked around so much.

Just to throw some numbers out there, let's take the extremes and make some assumptions. Let's make the assumption that you should either keep the projectile at least 10% below the lower FPS or at least 10% above the higher FPS for it's entire flight. Since it's risky to try to push that boolit much faster, we'll look at the subsonic side.
1,087.4 f/s - 10% = 978.66 f/s.

If you were trying to keep it supersonic for the entire flight, you'd need to have it going around 1260 f/s at 200 yards, which means your muzzle velocity would have to be a good bit higher than that.

On the stability issue:
I'm unfamiliar with Charlie Dell's formula that Tom Myers used, but it is pretty simplistic.
I'd looked at Greenhill's formula, but it's also too simplistic. After some more searching, I found the Don Miller stability formula (Google will show a number of hits on that) which seems to me to be a reasonable approximation. Miller's formula indicates that you should be OK even with muzzle velocities under 800 f/s with that boolit with your 1:10 twist.

However, the proof's in the puddin'. Try some lighter loads, and see if you get any indications of keyholing at 100 and 200 yards.

[HORNET]

According to Joe's first post on this thread, he's not in N.Y., he's in Massachusetts. which used to be even worse on handguns. IIRC, they used to have a mandatory 1 year in the slammer if you didn't have the proper (IE: expensive & hard to get) paperwork within state boundaries....

[cabezaverde]

Hornet,

Look at post #12.

I cannot address MA laws, though I am sure you are probably correct.

I am sure about what Brett and I said about NY.

[Char-Gar]

Some of the others guys said it. Either start sub-sonic, or start super-sonic and end super-sonic at the target. At least that is what I have always been told by the big boys.

[Char-Gar]

Well, I did graduate from Law School, but stil don't have a clue about all of the twists and turns of firearms laws in Yankeeland. But from what little bit I have overheard, I am awaful glad I live in Texas, and the surrounding states are filled with gun friendly folks..ie. New Mexico and Oklahoma.

[Recluse]

I am awaful glad I live in Texas, and the surrounding states are filled with gun friendly folks..ie. New Mexico and Oklahoma.

AMEN!

:coffee:

[felix]

There are at least 10 different "estimation" coefficients in calculating trajectories. Calculating these coefficients is a heuristic process as determined by chrono results at various ranges using different leading and trailing projectile configurations. Picking the correct coefficient for a projectile in hand is mandatory for the math to compute a correct trajectory. All this really means is that there has not been a natural (describing the dynamic nature of) formula derived to date. ... felix

[BD]

Joe,

I am currently nearing the end of a 15 month stay in NY on a construction project. I did research the handgun issue here before I arrived and the bottom line is that a non-resident may not possess a handgun while residing in the state of NY. The 1986 act only protects those on a continuous and peaceful journey through the state. I was refused a NICS check here for a group buy AR lower receiver on the basis that it "could become a handgun". Arriving at the range in a car with South Carolina Plates has resulted in my being "checked out" by off duty LEs three times since I've been here. One guy actually went through my range bag, (with my permission) and found a couple of 9mm and .45 acp round in the bottom. I managed to calm him down with a couple of state CCW permits and my IDPA card with the SO sticker. I'm sure the odd rounds were "show clear" rounds out of my pocket that I'd picked up as SO at the last IDPA match I attended in GA. A handgun in the bag would have been big trouble for me.

During the 1980s I made biannual trips through the state of Massachusetts bringing a handgun. The drill prior to 1986 required that I call the MA state police and give then my name, serial number of the handgun, and my dates of travel. After 1986 when I called they told me to quit calling, keep it in a locked case, out of reach, and "don't spend the night". I have always been very wary of MA due to a friend of mine having been arrested on his way to a Bullseye match in the 1970s for failing to make the call. Only the fact that he was registered in advance for the NRA sanctioned match, and the interest of of Maine's Senate delegation, got him out of a year in the MA crow bar hotel.

You may be in some totally different situation. But, I'f I were you, I'd be careful before I pushed my luck.
BD '

[Fadi]

Um, can we just talk about making and shooting cast boolits please?

[1Shirt]

To me Charger pretty well nails it!
1Shirt!:coffee:

[Hurricane]

No good deed will ever go unpunished.

[outdoorfan]

Joe,

I am currently nearing the end of a 15 month stay in NY on a construction project. I did research the handgun issue here before I arrived and the bottom line is that a non-resident may not possess a handgun while residing in the state of NY. The 1986 act only protects those on a continuous and peaceful journey through the state. I was refused a NICS check here for a group buy AR lower receiver on the basis that it "could become a handgun". Arriving at the range in a car with South Carolina Plates has resulted in my being "checked out" by off duty LEs three times since I've been here. One guy actually went through my range bag, (with my permission) and found a couple of 9mm and .45 acp round in the bottom. I managed to calm him down with a couple of state CCW permits and my IDPA card with the SO sticker. I'm sure the odd rounds were "show clear" rounds out of my pocket that I'd picked up as SO at the last IDPA match I attended in GA. A handgun in the bag would have been big trouble for me.

During the 1980s I made biannual trips through the state of Massachusetts bringing a handgun. The drill prior to 1986 required that I call the MA state police and give then my name, serial number of the handgun, and my dates of travel. After 1986 when I called they told me to quit calling, keep it in a locked case, out of reach, and "don't spend the night". I have always been very wary of MA due to a friend of mine having been arrested on his way to a Bullseye match in the 1970s for failing to make the call. Only the fact that he was registered in advance for the NRA sanctioned match, and the interest of of Maine's Senate delegation, got him out of a year in the MA crow bar hotel.

You may be in some totally different situation. But, I'f I were you, I'd be careful before I pushed my luck.
BD '



You know, sometimes it's just plain hard for me to comprehend what's actually becoming of this country. What can happen in one state (or a few) can happen in any state.

DISGUSTING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!

[jsizemore]

Back to the 308. I just filled the case to the base of the neck with 4227 and then weighed it. Got 43 grains. Part of your wild shots could be powder position in case shot to shot. Time for some filler.

[joeb33050]

Thanks for the reloading info and suggestions. There is no keyholing on the targets. We're on the road, and I just found an email saying that the Miami Range will be closed until November. Maybe I can get into the Key Largo club/range.
I intend to try to see how slow the 314299 will go before getting wild at 100 yards.
If anyone wants to try it I'm very interested in the results.
joe b.

[SierraWhiskeyMC]

Well, your barrel has such a fast twist (1:10) that it'll stabilize your 200gr 1.2" boolit even down to sqib loads at sea level during a cold snap, according to Don Miller's formula.

Charlie Dell's formula is simply:
((Length x twist) / (Diameter x Diameter x 3.5)) squared

Quite a few variables have been lumped into the constant value of 3.5.

Don Miller's formula is:
Sg = (30*BulletGr)/((BarrelTwistInchesPerTurn/CaliberInInches)^2 *CaliberInInches^3* BulletLenInches/CaliberInInches* (1+(BulletLenInches/CaliberInInches)^2))* (MuzzleVelFPS/2800)^(1/3)* ((TempF+460)/(59+460)*29.92/PressureInHg)

For caliber, I entered .304, since the lands would be .300" and grooves .308".
Weight 200gr, length 1.2", twist 10, temp 0°F, pressure 29.92 with a muzzle velocity of 400 gives an Sg of 1.4. Under some criteria, 1.4 and higher is considered fully stabilized, where Miller's own criteria is 1.5 and higher. Anything less than 1 is unstabilized. If Sg is > 2, you might benefit from reducing the rate of twist.

There is an Excel spreadsheet containing Miller's formula available for free about halfway down on this page:
http://accurateshooter.wordpress.com/2008/06/03/

[w30wcf]

Several years ago I worked with some subsonic loads with heavy bullets in my Rem 788 .30-30 (10" twist). I found decent accuracy with the 314299 at 200 yards. (2"to 3" groups) Load was 7.0 / 231 for just under 1,100 f.p.s.

In fact, it still was shooting pretty well at 500 meters on the NRA high power steel ram silhouette. Had to use plenty of holdover though.

w30wcf

[gwilliams2]

AMEN!

:coffee:

I second that one... I just got back home (to Texas) after traveling through 4 states and never had to unload, pack up of worry about it... Many surrounding states except our permits...

[MtGun44]

IIRC, if you violate any Massachusetts firearms law you get a 1 year prison sentence, mandatory,
and it cannot be suspended or reduced under any circumstances by the judge.

A New Hampshire native had a single shotshell in the rear footwell of his car. It was
spotted by a Mass. trooper at a traffic stop in Mass. He spent a year in the slammer. NO gun, just
one round of shotgun ammo without a proper permit. Mass. is run by gun hating people, do not
cross them.

Bill

[Bret4207]

IIRC, if you violate any Massachusetts firearms law you get a 1 year prison sentence, mandatory,
and it cannot be suspended or reduced under any circumstances by the judge.

A New Hampshire native had a single shotshell in the rear footwell of his car. It was
spotted by a Mass. trooper at a traffic stop in Mass. He spent a year in the slammer. NO gun, just
one round of shotgun ammo without a proper permit. Mass. is run by gun hating people, do not
cross them.

Bill

You're talking to the wind Bill. Let him think what he wants, he can let us know how it worked out from jail.

[qajaq59]

When we lived in MA, before my wife even began to shoot, she had all the necessary paperwork to carry. Otherwise, if I had accidently left one round in the car and they found it when she was driving, she'd have gone to jail. Don't mess with MA unless you like being cuddled by some 6' 4" inmate!!!!

[MtGun44]

OK, Bret.

That report was from the American Rifleman, by the way.

Bill

[Jaybird62]

I'm shooting subsonic to keep the RCBS 200gr silhouette stable out to 200 yards. Load is 9.6 gr. of Trail Boss. This is out of a 16-inch Encore w/ 1-n-10 twist, and it's suppressed. The suggestion for a filler might help, but I doubt it.

[JSH]

This is quite the interesting thread to say the least....................
I will throw in my .02
I fooled with the sub sonic a bit a few years back with FLGC stuff. Not a lot of real promising looking groups. This was in a 30x221 and a 30-20, both pistols. Mine were 1-10 twist and heavy bullets180+. The 180's shot the best, but not as good as I wanted. Gave up the sub sonic.
Then I started casting and got back to sub sonic with cast. Pretty much the same results. I think anything over BR or PPC case capacity is to large for sub sonic heavy bullet shooting. A fast twist barrel is needed to almost over stabilize the bullet ( if that is possible?) in order for it not to go into a yaw past 100Y/M. Most of the folks I know that shoot sub sonic any disatnce have a fast twist barrel. Some get lucky with a 10 twist, with the right powder and bullet combo.
I have had less problems shooting super sonic, than trying to keep everything under control shooting slow. Even if my super load drops below the speed of sound before the target.

Now as to what I consider off subject on this thread. I recall an issue when IHMSA had a range back east. Folks traveling could not legally get from point A to point B. I think that range was only up for a year or so?
The comments of the above only reinforce my ideas of straying to far east of the Mississppi river.
jeff

[James C. Snodgrass]

[smilie=1:I can't recall the exact amount of powder I was shooting but it was a heavy charge of IMR-7383 in my Striker with a 200gr Lee it was definitely super sonic and produced good groups I would guess a velocity of 2K or so . As far as the recoil if you use the muzzle brake it is timid W/O it ain't bad . As far as I can tell in my striker or any pistol firing bottle neck cases I like to use a case full of the slowest powder that will give a constant push on the boolit instead of the fast powder light charge theory . I know a lot of folks have great luck with Unique,2400,4227...and such in /06 size cases with out filler I ain't though . As far as the law in Ma goes I ain't got a clue but if they want any of my business they better get right with their bogus laws . James

[joeb33050]

I tried to get the bullets to fly wild at 100 yards. 30BR, Savage Striker, 314299, .3095
Shot shoots <2" 5 shot 100 yard groups with 16/IMR4227, out of control, 6' groups at 200 yards
Loaded 5 each, shot at 100 yards today
15/IMR4227 2.5"
14/IMR4227 1.6"
13/IMR4227 2.175"
12/IMR4227 1.55"
Sighters/foulers 16/IMR4227, 8 shots in 2.4"

I can't figure out what's happening between 100 and 200 yards with 16/IMR4227.
joe b.