How fast is practical

[Lead pot]

Dan mine don't shoot as well as my Ballard rifling rifles do.

[dave roelle]

Thanks for the pics Leadpot !!!!!!!!! interesting stuff------------i remember seeing some snow recoveries that lookied like "pulled taffy"-----i can't get my mind around the mechanisms that "stretch" bullets ?

I'll start the higher velocity tests as soon as i can, first step is to cast boolits in a range of hardnesses--probably aquire some "tougher" paper around 0.003 thick.

Results to follow

Thanks again for all the input folks !!!!!!!!!

Dave

[Dan Cash]

Dan mine don't shoot as well as my Ballard rifling rifles do.

Want me to take them off your hands?

[Lead pot]

Want me to take them off your hands?

Hmmmm, well if you have a 1881 Marlin we could talk about it.

[Harter66]

I have a 7x6.8 Rem. 1 of the 1st things that I did was us known load data to get a starting point. The 6.8 Rem data gave an overlapping load for 120 and 130 grain j-bullets . This worked for me as I had 120 gr SP Serria bullets on hand and a 27-130FP in hand as well. I shot a 5 shot group of 3 inches or so from a brand new test fired only rifle build over the chrony with the 120s for an average speed of 2230fps. The same load of 22 gr of RL10X behind the papered 27-130 (actual weight 135 gr )dry wrapped sized 286 with basically Darrs lube gave 2250 over 20 rounds and yielded 10 inside 3" and a final 5 under a quarter. The load was stepped up to 24.5 where there was a catastrophic pressure jump that caused primer pocket erosion and all things considered a firm bolt lift. The 23.5 load gave 2360 fps while the 24gr load showed 2410. I established that 23 should be a maximum load for the rifle and the 135 gr 27-130. All of those were water dropped 50/50 WW/1-20 with a BH of 14 or so. The slower powder on hand were dismal failures with that bullet but may work with some heavies I have planned for it . I don't know what the pressures are but there has never been any leading even from the case failure load (80 kpsi?).

I have sent more than a few of a personally hacked out 200gr spire point 30 cal patched has gone quite fast but with poor groups above ,presumably, alloy strength. Hardening the bullets from the above to WQWW allowed me to reach 1800 fps in 2 rifles and 1900 in a 3rd . Twist I believe plays a substantial role in this case in the bullet failure . The two 8.5 twists were far more touchy about topping out than the 1-10 and another 1-12 just wouldn't shoot it at all. I didn't see any stripping or cutting in the recovered boolits but nose slump or possibly stretching of the body was present . Those were mostly just over 30,000 psi based on IMR 4350 burn cleaning up at 30k based on other research.

While the above is probably not helpful it may show that bullet shape has as much to do with bullet survival as twist and pressure on a particular alloy.

[dave roelle]

Hi Harter66------------interesting information-------certainly bullet design has everything to do with the length of the section of the bullet accepting the rifling, with flat nosed hunting types having the most area to grip rifling---spitzers have the advantage of better flight characteristics but less "grip"and susceptibility to nose slump that isn't necessarily symmetric, causing unpredictable results.

Ill be working with flat nosed bullets of 270 grains in two styles that both seem to fit the throat of this rifle well--------------i'm going to see how fast i can get these moving, trying to deliver all the energy i can to the target ------accurately-----it will be fun for sure

Keep well and stay safe

Dave

[Old Coot]

If you want rifles with Micro Groove rifling to shoot cast or patched bullets better; use a larger diameter bullet. Bullets will always get longer if they are swagged down even when they are done in a press. That metal has to go somewhere.

I can not honestly say that the bullets in you photo look like they have been stripped or have skidded in any manner.
If they had the rifling would not me so apparent. Especially micro groove rifling. Brodie

[Dan Cash]

Dog gone it Old Coot, don't clue him in; he'll just raise the price if he knows his microgroove will do as well as Ballard rifling.

[wmitty]

Old Coot

Are you saying that paper patching for a microgroove barrel requires sizing larger than .0015" over bore diameter?

[Lead pot]

Dog gone it Old Coot, don't clue him in; he'll just raise the price if he knows his microgroove will do as well as Ballard rifling.

Nope Dan my offer stands
My rifle is a 1967 rifle and I have drug it through a lot of Michigan UP ravines and brush and over dead falls hunting Deer with it and it has served me well for a dark woods rifle.
Using my jacketed swaged truncated or the 1E round nosed flat point that rifle will shoot just as well as my Sharps do. But the cast I can just keep them inside a 4 or 5" circle at 100 yards with everything I have shot through it looking for a smokeless of black powder load using 230 to 300 grain cast bullets. 4-5" is not satisfactory for me with a scope mounted on a rifle at 100 yards.

[Dan Cash]

Hmmmm, well if you have a 1881 Marlin we could talk about it.

Lead Pot, if I had an 1881 Marlin, I am not sure that I would want to trade. Seriously, I believe you can achieve real accuracy with your microgroove tubes. As has been suggested, try increasing the bullet core diameter by a bit (.001), change the paper used for patching, use a slower propellant. If you are sizing your bullet after patching, stop doing that as it can result in an out of round projectile.

[Old Coot]

Old Coot

Are you saying that paper patching for a microgroove barrel requires sizing larger than .0015" over bore diameter?

Wmitty;
Perhaps I am. I have to patch to at least .015 or .003 over bore diameter in my 7.62x39. These things are not written in stone, but are simply guidlines.
When I started casting I just sized the bullets (for rifle or pistol) to what ever the published groove diameter was (.308 for 30 cal, .457 for my 458 Win., .452 for the 45 acp etc.) By and large I got abominable accuracy and lots of leading. It wasn't until I started experimenting and got some data from others (we did not have the internet then--1970, 71) that I started getting some accuracy. My mantra is: 'Do what works!". When the Ruger Ranch 30 came out it had a .308 dia or so groove barrel and shot 7.62x39 ammo in it. Jacketed bullets measuring approximately .311 to .312. The bullets squeeze down and shoot just fine, without dangerous pressure spikes. Cast lead alloy bullets squeeze down even easier.

My Zastava Mini Mauser in 7.62x39 has a very large and deep throat. Marilyn Chambers would envy it. As a result I have to patch to at least .315 and seat the bullets out as far as possible to attain some accuracy. I am still working with the rifle and will let you know when I find a combination that works best. At least as well as I can shoot it with iron sights. But, the combo may not fit any established idea or creed. If you read through some of the old posts you'll find that many of the things that have worked are a little different it not just plain strange. Brodie

[.22-10-45]

When I was doing paper-patch loading in .22 Hornet & .222 Rem. (there are more enjoyable ways to drive yourself nuts!) I was mostly using slicks right at bore dia. (land-land) or .001 over. I found that loads were way up into jacketed bullet charges (H4227) before I obtained accuracy. Slicks were cast from a soft 20-1 up to Lyman #2. Accuracy fully equalled best match J words at 100yds.

[Old Coot]

22-10-45
You probably had to get up enough pressure to obdurate the bullet. Brodie

[303Guy]

When I was doing paper-patch loading in .22 Hornet & .222 Rem. (there are more enjoyable ways to drive yourself nuts!)

I once patched some .222 boolits!

Actually, it can be done but is quite tricky.

So I'm still trying to figure out why Marlin rifling should be so challenging. Is there something about the throat?

[Dan Cash]

So I'm still trying to figure out why Marlin rifling should be so challenging. Is there something about the throat?

A microgroove .30-30 was the second rifle I learned to paper patch for. It was not any different than the older Ballard rifled Marlin that I was patching for. I did have to seat the bullet deeper for the microgroove to chamber the cartridge. A friend has yet another microgroove .30-30 which requires yet deeper seating but all three guns shoot about the same.

[nanuk]

My 45/70 rifles with microgroove barrels all have large bores, so boolit sizing is far more fat than one would think.

all three of my rifles measured (as best I can) around 0.4555/0.4595, so only had 0.002 deep rifling.

I want to PP for them but am concerned about paper thickness. It won't take much paper to make 0.005/0.006 thick patch

[303Guy]

The BP 45-70 guys patch to fit the bore - that is to say, the patched boolit fits the bore. The boolit upsets to fill the grooves on firing. Apparently the 45-70 doesn't have a throat and looking at the SAAMI drawings that would seem to be so. I have found my fairly soft alloy 303 Brit patched boolits obturate pretty well so it doesn't only work for BP but BP may upset the boolits earlier.

[Old Coot]

303 Guy;
I don't know if micro groove barrels are hard to patch for or get to shoot lead bullets well or it is just something that was started by some gun writer back when Marlin came out with those barrels. There has been so much BS written by people who know very little about their subject that it is hard to tell just what is truth and what is over spray.

The idea is that the micro groove rifling with its many small grooves would grip the bullet less firmly than the Ballard rifling. As I type this I cannot recall any instance when someone published a proper test or study on the matter. I think that some writer got the idea looking down a barrel and it just took off from there. I have a Marlin in 44 mag and it shoots cast quite well. Also, the 22's made by Marlin have micro groove barrels and nobody has complained about their accuracy.
To get an idea of what the micro groove rifling looks like go back to the pictures on page one and look at the recovered bullets and the slugs driven through the barrels.
Brodie

[303Guy]

Those sample boolits show no sign of 'skid'. I'd have guessed that micro-groove bores would be better, having more driving surface - providing the boolits were large enough. It can't be the rifling style itself. With shallower grooves I would expect less base distortion. I would expect thinner paper to be called for with the shallower rifling. Interesting because Marlin barrels turn up from time to time at reasonable prices.