How fast is too fast in a .30 cal

[mto7464]

using WW with some tin and water dropped? I was getting very poor accuracy at 50 yards using a new load (WC860) that chronographed at 2200 fps. Is this too fast for the hardness?

I realized after I posted this I left alot out.
K31, 200 grain Lee, 58 grains of wc860. Sized them to .308 I can't remeber off hand the barrel dimensions. Groups were 5" at 50 yards. With a reduced charge of 4895 I was getting sub 2" groups at 50 yards.

No leading. bore was dirty looking but one patch make it come out shiney.

PS I read about this load here and wondered why I was getting such poor results. I also have read about Lee's data on pressure and bullet hardness and that is what I am referring to even though I stated it in velocity VS pressure. I have also considered oven treating a batch of boolits to see if it would allow me to shoot higher pressure/velocities.

[scrapcan]

How does the bullet size compare to your barrel dimensions? Are you getting any leading? What kind of rifle? What condition? What caliber? What do you consider poor accuracy?

Sorry it is a lot of questions but others will want to know also.

[Junior1942]

What's the barrel twist?

[Maven]

"I was getting very poor accuracy at 50 yards using a new load (WC860) that chronographed at 2200 fps. Is this too fast for the hardness?"

mto7464, Ya think? It ain't the rifle or the 10.3 twist rate that's the problem, but the very heavy powder charge. I have two K-31's and a number of other ".30cal." rifles that I use WC860 in with repeatably good results (~1 moa). I use 48gr. WC 860 + a LR mag. primer in all of them and have only 1 complaint about it: Lots of unburned powder in the bore. In fact, I retested this load (48gr.) in my 8mm Mau. with the Lee 175gr. CB today and got good results, but the amount of unburned powder didn't please me*. Btw, when using 860, use CB's of at least 175gr. (heavier is better) to improve the burning efficiency.


*There are two ways of dealing with the problem: (1) Use ~5gr. of H/IMR 4198 next to the primer, reduce the main charge by ~3gr. - 5gr. and seat the CB deeply enough to compress the duplex load. (2) Use a filler such as Cream of Wheat or poly shotshell filler, 1.0cc for the 7.5 x 55mm case and compress the charge with the CB. I'm about to try #2 with my 8mm Mau. very soon.

[mroliver77]

Speed is not the enemy. Pressure is. You have to be making some serious pressure to push the 200gr .30 cal to 2200 fps. The water dropped alloy will not take this kind of pressure. Not having any data to actually know I am guessing but would bet $3 that is the problem. Try mavens load once. Do more reading on pressure/ alloy/ hardness. For kicks read up on oven heat treating and mebbe heat treat a batch and see where that will get you.
J

[Larry Gibson]

Ain't speed and it aint pressure; it is RPM. I know others will disagree but the ugly fack is that 2200 fps produces too much RPM in a 10" twist. Your post is just another example of it is all. Drop back to 1700-1900 fps using a medium burning powder or less veloity with a faster burning powder and accuracy is/will be there.

Larry Gibson

[Bass Ackward]

Ain't speed and it aint pressure; it is RPM. I know others will disagree but the ugly fack is that 2200 fps produces too much RPM in a 10" twist. Your post is just another example of it is all. Drop back to 1700-1900 fps using a medium burning powder or less veloity with a faster burning powder and accuracy is/will be there.

Larry Gibson


MTO,

HT so that your metal hardness is commensurate with your pressure. HT'd WW is good for 45,000 psi up to about 55,000psi in 30 caliber depending on bullet weight. So how ever fast you can go with that pressure using your bullet weight in your cartridge is about the max. Stay away from crappy bore ride designs that can get off center in your bore and you can shoot full power. Might even beat what you are getting now if your gun is mechanically sound.

[Marlin Junky]

I've taken RCBS 30-180FN at 14 BHN to over 2100 fps with my Ballard rifled 336A which has a 10" twist and consistently get 1.5 MOA for five rounds when I hold my rifle properly. In my case, I believe the .0045" deep grooves are the key to success. If you have shallow rifling, I believe you need to sacrifice speed for accuracy but I don't think over stabilization (too many RPMs) once the bullet has left the barrel is detrimental to accuracy.

I should also add that my bullets in this case are just about .0010" to .0015" over bore diameter.

MJ

[scrapcan]

mto,

glad you added those few items. It makes it much easier to address your questions.

[Junior1942]

A 10 twist @ 2200 fps = 158,400 rpms. That's about 50,000 too many IME.

[Marlin Junky]

Where does the effect of too many RPMs take its toll? In the barrel as a result of the bullet being stripped by the rifling?

MJ

[JIMinPHX]

I’ve gotten a 13BNH 150-grain GC RNFP Lee boolit going a little over 2400fps out of a 30-30 microgroove barrel with no problems using Reloader 7, Moly lube & boolit that was sized .002 over groove diameter. I recovered the fired boolits & everything looked normal.

[JIMinPHX]

Where does the effect of too many RPMs take its toll? In the barrel as a result of the bullet being stripped by the rifling?

MJ

The only time that I had problems with too many RPM was when I pushed soft thin-jacketed .223 varmint pills out of a 1:9 twist barrel at max velocity. I ended up with a cloud of gray dust at the muzzle & no hole in the paper. That slug was doing over a quarter million RPM. Backing off the speed by about 400fps gave me good accuracy.

[45 2.1]

All these RPM guys are running on polluted fuel. There are quite a few of us that run the 308 full bore with cast. Mine run fine at way more than what they spout..........with excellant accuracy.

[Marlin Junky]

All these RPM guys are running on polluted fuel.

Perhaps the motor oil of their minds can't take the friction?

MJ

[BABore]

Guys,

It looks like I'm going to need your help here. I've got lots of bullets to pull now that I've heard all these facts.:roll:

Lets see 30-30, 30'06, 338 WM, 375 H&H.................... They all got to go. Every stinking one of them is loaded to well over 2,200 fps. Some up to 2,500 fps. Plus they pretty much all have bullets that are only 18-22 Bhn. Worst yet they will all shoot sub-inch. The worst offender is my 338 WM with a 1 in 10 twist. It will only group them into 3/8 inch groups at 2,400 fps.

I've long suspected I was screwing up somewhere with these cast boolits. Now that I'm so thoroughly enlightened, I can start over. [smilie=w:

[Marlin Junky]

Guys,

The worst offender is my 338 WM with a 1 in 10 twist. It will only group them into 3/8 inch groups at 2,400 fps.



Who made the barrel? If it is an original Winchester barrel, is it button rifled? If you don't know the answer to that question, what are the bore and groove dimensions?

Thanks,
MJ

[BABore]

Who made the barrel? If it is an original Winchester barrel, is it button rifled? If you don't know the answer to that question, what are the bore and groove dimensions?

Thanks,
MJ


This should answer your questions.

[Marlin Junky]

BABore,

Ah yes, a Bullberry barrel... very popular with the Benchrest fans. With those shallow grooves though, I'm wondering how it shoots with ACWW metal (or something in the BHN 13 to 14 range). Any input in that regard?

Thanks,
MJ

[Larry Gibson]

Where does the effect of too many RPMs take its toll? In the barrel as a result of the bullet being stripped by the rifling?

MJ

Disagrree; In the barrel the bullet is damaged whether it holds the rifling or not. If it is stripping then it is not rotating as fast. On exiting the barrel the damaged bullet is then adversely effected by RPM. It occurs during flight.

Larry Gibon

[Larry Gibson]

Guys,

The worst offender is my 338 WM with a 1 in 10 twist. It will only group them into 3/8 inch groups at 2,400 fps.

I've long suspected I was screwing up somewhere with these cast boolits. Now that I'm so thoroughly enlightened, I can start over. [smilie=w:

Not that I doubt what you claim (actually I do) but being the nice guy I am I'll help you start over; I will give you $5,000 for your "worst offender", the .338 with a 10" twist, if we can sit down at a bench with it and shoot 5 consectutive 5 shot groups into 3/8" at 100 yards with your cast bullet loads that run 2,400 fps.

Are you game? If not then with that rifle I'd expect to see your name at the top of many cast bullet bench rest records. How many accuracy records have you set?

Larry Gibson

[BABore]

Not that I doubt what you claim (actually I do) but being the nice guy I am I'll help you start over; I will give you $5,000 for your "worst offender", the .338 with a 10" twist, if we can sit down at a bench with it and shoot 5 consectutive 5 shot groups into 3/8" at 100 yards with your cast bullet loads that run 2,400 fps.

Are you game? If not then with that rifle I'd expect to see your name at the top of many cast bullet bench rest records. How many accuracy records have you set?

Larry Gibson


Larry,

I never claimed it would shoot 5 consecutive 5-shot groups that averaged 3/8 inch. That's your criteria. I shoot 3-shot groups and use this as a hunting rifle, not so I can pat myself on the back in front of my benchrest buddy's. It's called personal satisfaction through individual achievement. In my shooting world, it's where the first few shots land that's important.

What I did claim, along with several others, is this "you can't do this cause I can't attitude" is pure bunk. There are enough knowledgeable people on this forum that can guide you on how to acheive accuracy at above 2,000 fps, if your willing to put in the work.

[Char-Gar]

As a simple answer to your simple question, let me say that ACWW rolls snake eyes for me at velocities (pressure/rpm/ad nausuem) of 1.8 K fps to 2K fps depending on all of the various factors. I will let the rest of the crew battle it out over the why and wherefore.

[Bass Ackward]

Not that I doubt what you claim (actually I do) but being the nice guy I am I'll help you start over; I will give you $5,000 for your "worst offender", the .338 with a 10" twist, if we can sit down at a bench with it and shoot 5 consectutive 5 shot groups into 3/8" at 100 yards with your cast bullet loads that run 2,400 fps.

Are you game? If not then with that rifle I'd expect to see your name at the top of many cast bullet bench rest records. How many accuracy records have you set?

Larry Gibson


I can see tomorrows lead story in the anti gun newspapers.

Today, there was a murder committed at the benchrest nationals when after a new world record was established, the victim, a REALLY NICE guy named Larry Gibson, was killed when he suggested that the winner and world record holder fire the exact same group three times in a row without cleaning before it became official.

:bigsmyl2:

[felix]

I tend to agree with BAB. Why, because I have done what he effectively claims. But..... Put me in a match situation, I would not even come close to hitting a barn, much less shooting a group worth talking about. Yes, I have done magic beer can dances with a stupid lever gun when even I thought impossible. Repeatable? Yes, when perfectly relaxed and not a worry in the world. In other words, not hardly repeatable. ... felix

[BABore]

I can see tomorrows lead story in the anti gun newspapers.

Today, there was a murder committed at the benchrest nationals when after a new world record was established, the victim, a REALLY NICE guy named Larry Gibson, was killed when he suggested that the winner and world record holder fire the exact same group three times in a row without cleaning before it became official.

:bigsmyl2:


You mean you get to stop and clean your gun for that stuff. :shock:

Now I bet your going to try telling me you get to cool the barrel down too. :-D

These are the typical groups (3-shot, 100 yards) from a bench I get with my 338. Velocities are from 2,200 to 2,400 fps. The gun, bullet, lube and load are capable of this all the time. The shooter, only on good days. The last group is 15 shots taken approximately 30 seconds apart. No cleaning, wind flags, or such. Well maybe a beer or two. It's a bit over an inch, so I guess it don't count in some crowds.

[CSH]

The best accuracy I have been able to achieve in a 10" twist 30 cal rifle at velocity exceeding 2K was a consistent 1.5 MOA at just a tick over 2300 fps using a caseful of WC860. Bullet was a 311041 sized to .310, oven heat treated WW (27 BHN) using LBT blue soft. The rifle was a Weatherby Vanguard in 30-06. I tried a few different things (including other bullets) to approach this accuracy using softer bullets (for hunting) at the same velocity, but always came up empty. It is definitely easier to get accuracy with cast if you stay around 1700 fps with a 10" twist, but I don't think RPM is the only issue. Increased RPM shows there is a problem with bullet balance. If the bullet is well balanced and doesn't get damaged in the firing process, accuracy will happen. Easier said than done with most factory rifles using high velocity cast.

[Marlin Junky]

Disagrree; In the barrel the bullet is damaged whether it holds the rifling or not. If it is stripping then it is not rotating as fast. On exiting the barrel the damaged bullet is then adversely effected by RPM. It occurs during flight.

Larry Gibon

The key here is "damaged bullet". Other than that, you'd have a hard time proving high RPM causes good bullets, that uniformly exit good barrels, to yaw and deviate from their intended course.

[Marlin Junky]

BABore,

What about a response to my last question about using ACWW in your .338? Have you ever tried pushing ACWW metal beyond 2000 fps from your 1-10" .338?

MJ

[BABore]

BABore,

What about a response to my last question about using ACWW in your .338? Have you ever tried pushing ACWW metal beyond 2000 fps from your 1-10" .338?

MJ

Sorry about that. No I haven't tried them, but wouldn't be surprised if they shot well too.

I started with OHTWW's at 28-30 Bhn figuring harder was better. Accuracy, 1" or smaller, dropped off at around 2,200 fps. Another 100 fps and the groups blew apart. Based on a suggestion, from 45 2.1, I switched to an alloy of 50% WW's and 50% Pb. This alloy HT's to around 22 Bhn for me. Now how the #!@% could a softer bullet shoot faster? It does cause it's a tougher alloy and has half the antimony. The grey wash I was getting in my bbl was mostly antimony. Now I can get a 230 gr bullet into the 2,600 to 2,700 fps range with acceptable hunting accuracy. 2,300 to 2,400 will do 1/2 to 3/4 inches consistently. Anything below 2,000 fps is pretty boring.

[Marlin Junky]

Sorry about that. No I haven't tried them, but wouldn't be surprised if they shot well too.

If you try ACWW someday I'd like to hear about your results. I am aware of the advantages of HT'd 50/50 (WW to Pb) and will also migrate to a lower Sb alloy as soon as I can acquire a larger quantity of soft lead. From what I understand, Pb has lubricating properties of its own whereas Sb is abrasive. At what temperature are you HT'ing your 50/50 alloy? That's 50% clip-on WW metal to 50% "pure" lead, right?

MJ

[BABore]

If you try ACWW someday I'd like to hear about your results. I am aware of the advantages of HT'd 50/50 (WW to Pb) and will also migrate to a lower Sb alloy as soon as I can acquire a larger quantity of soft lead. From what I understand, Pb has lubricating properties of its own whereas Sb is abrasive. At what temperature are you HT'ing your 50/50 alloy? That's 50% clip-on WW metal to 50% "pure" lead, right?

MJ

Yes, the WW's are sorted of all soft lead stick-ons. I smelt them seperate and usually use them as pure lead.

I oven heat treat at 435 F for one hour, then quench. My alloy is 9-10 Bhn air cooled, and will attain 21-22 bhn when hardened. It usually takes 3-4 days to set up right, but I typically wait 1-2 weeks before shooting them. Water dropping 30 cal bullets will typically make them hard throughout. Larger calibers can be water dropped to yield a hard shell and soft inner core. Great for hunting. You have to cast in a timed sequence to get this to work. The idea is to quench the bullet at a temp where it is just slightly above the temperature threshhold of where it will heat treat. The inner core passes below that threshhold before rapid cooling can harden it. I'm working on an oven temperature that will allow the same effect.

I've just designed up a new 338 bullet that I hope to start wringing out this weekend. It's the one in the pic of my chamber/throat dimensions. I'm going to start with 22 Bhn bullets, but will try some air cooled ones and let you know.

[PatMarlin]

Well maybe a beer or two. It's a bit over an inch, so I guess it don't count in some crowds.

No but we have to disqualify you for using a STANLEY tape measure.. :groner:

NIce shootin' there BA.

I'm to busy for the OHT. How close can a guy get with 50/50 ww and Pb with water drop, and does the temp of the water and timing between drops have an effect with much variation in hardness?

[BABore]

No but we have to disqualify you for using a STANLEY tape measure.. :groner:

NIce shootin' there BA.

I'm to busy for the OHT. How close can a guy get with 50/50 ww and Pb with water drop, and does the temp of the water and timing between drops have an effect with much variation in hardness?

Now don't tell me you run with the crowd that has to have the decimal/fraction embossed on the tape. Them different sized tick marks, between the whole numbers, can be confusing for some. :razz:

As long as your running things hot enough, you shouldn't have any problem getting full depth hardness water dropping. Maybe a slight soft core on big diameter bullets. What I'm talking about with a strict time/temp drop rate is to acheive a soft inner core on purpose for toughness and expansion. I usually use ambient temperature water. Running a set cadence with a particular mold will also reduce your wt. variation to near zero.

[Larry Gibson]

The key here is "damaged bullet". Other than that, you'd have a hard time proving high RPM causes good bullets, that uniformly exit good barrels, to yaw and deviate from their intended course.

Problem is the bullets may be good going in but how do you know they are "good" going out? You don't. As perfect as they may be going in it is the defects caused by accelleration and obturation that are effected by RPM during the bullets flight.

Larry Gibson

[Larry Gibson]

I can see tomorrows lead story in the anti gun newspapers.

Today, there was a murder committed at the benchrest nationals when after a new world record was established, the victim, a REALLY NICE guy named Larry Gibson, was killed when he suggested that the winner and world record holder fire the exact same group three times in a row without cleaning before it became official.

:bigsmyl2:

Cute Bass.......

BABore stated quite clearly his rifle shoots 3/8" at 2400 fps. Now he back pedals. I see from his target that the velocity is estimated at 2300 fps. An "estimation" of 2300 fps when he said 2400 fps, and you buy that? What is it a guess or fact? He's got 3 nice 3 shot groups there so if he can sit down with me at a bench and show me 5 groups just like those at a measured (I've got 3 chronographs so it won't be hard to measure) 2400 fps he $5,000 for the rifle still stands. Otherwise I still call BS regardless of his "I can and you can't" attitude. I'm obviously willing to pay a considerable amount for him to show me.

Larry Gibson

[Marlin Junky]

As perfect as they may be going in it is the defects caused by accelleration and obturation that are effected by RPM during the bullets flight.

Larry Gibson

That's your proof? :groner:

You need to isolate the (in-flight) RPM variable! Anyone can f-up a virtually perfect bullet at LOW RPM by subjecting it to more pressure than it can handle. How are you going to isolate the (in-flight) RPM variable? You need to determine that the bullets are not damaged at both low and high RPM (inside the barrel) and shoot for group at the same time. The only way I can think of accomplishing this feat is to use high speed photography a few feet from the muzzle... and then, those bullets would need to be virtually perfect inside (no voids) as well as on the photos.

MJ

[PatMarlin]

Hey I just got admonished by KenJuudo for making the disparaging comment against STANLEY.

He wiped the floor with me in his email. He knows Karate don'tchaknow... :mrgreen:

[Larry Gibson]

That's your proof? :groner:

You need to isolate the RPM variable! Anyone can f-up a virtually perfect bullet at LOW RPM by subjecting it to more pressure than it can handle. How are you going to isolate the RPM variable? You need to determine that the bullets are not damaged at both low and high RPM (inside the barrel) and shoot for group at the same time. The only way I can think of accomplishing this feat is to use high speed photography a few feet from the muzzle... and then, those bullets would need to be virtually perfect inside (no voids) as well as on the photos.

MJ

Apparently the concept that ALL bullets are "damaged" when fired, whether jacketed or cast and whether at low or high velocity. Cast bullets are damaged more than jacketed bullets because they are not supported by the jacket. As the bullet IS IN FLIGHT when the RPM effects it the RPM "variable" IS isolated. The more the bullet is damaged the lower the RPM required to cause inaccuracy. The less the bullet is damaged the higher the velocity before the RPM increases inaccuracy. You don't need high speed photography as the location of the bullet holes in the target give ample evidence of inaccuracy.

Larry Gibson

[Marlin Junky]

The damage I'm referring to is not the normal engraving by the rifling! I'm referring to stripping or uneven obturation at the base... the kind of stuff that happens when the rifling pitch and/or the pressure is too high for accurate shooting. That's why I'm suggesting the boolits are inspected visually as they leave the muzzles. For example, if the same (design & hardness) boolits (forget about copper patched) fired from two different twist barrels at the same velocity and pressure appear identical on quality enlargements AND the target shot by the slower twist gun has a smaller 10 shot group on it than the target shot with the fast twist gun, THEN and only then, would I place any credence on the too high RPM theory. Do you now understand what I'm saying?

MJ

P.S. OK, here's another example: Let's say, hypothetically, the boolit photographed as it leaves the fast twist barrel shows signs of stripping and it shoots a poor group compared to the slow twist barrel who's boolit photo indicates no stripping. Would you still claim it was in-flight RPM that was killing the accuracy?