RCBS 45-300-FN gascheck Accuracy?

[Forester]

Has anyone done much work with this boolit especially in the Marlin 1895 guns?

I tried it out today in my new 1895 with a scout scope and was fairly unimpressed with the accuracy. It seemed that as I pushed the boolit faster the accuracy deteriorated significantly. Is it a case of the boolit being too short and fat to stabilize well at faster speeds? It seemed the accuracy went to hell at about 15-1600fps and at 2000 it was more of a pattern than a group (11"!) and I was glad I had a big piece of cardboard to shoot at!

At 1450fps the group was about 4-5". Still not good, but at least it was an actual group.

I slugged the bore and found it tighter than expected so there should have been no problems with fit. Are .452" lands and .455" grooves normal in these rifles?

The boolits were sized to .458" and cast with WW alloy and 2% tin. Air-cooled and a BHN of about 13 according to my Lee tester. I had zero lead in the bore no matter the velocity. I used Hornady gaschecks, they were not an extremely tight fit when crimped on with the RCBS LAMII but seemed workable.

Powders used were IMR 4198 and IMR 3031.

As a side note...I love shooting this rifle and the scout scope is outstanding. After 40 J-word rounds yesterday and 40 Cast boolit rounds today, all out of sandbags my shoulder has had about enough!

Thanks for any info or input!

[Buckshot]

................With 0.0015" deep grooves it sounds like you have a Micro-Gruv bbl, yes? They'll shoot cast pretty well but ya gotta cast'em hard as a rule. Now after typing that, the author Paul Matthews had exceptional results with the Marlin and M-G barrels shooting pure lead. Not the 300gr RCBS, but a 400+ grain slug.

I have the mould and have shot it to 1850 fps from a MAS36 converted to 45-70 and it shoots as well as any. But the rifle has a conventionally rifled barrel. It also does well in 2 Trapdoors, and a 45-90 Sharps.

................Buckshot

[Dr. A]

I shoot that bullet sized .460 in my Marlin. I've used Lar's carnuba red and Lee alox. I use up to 50gr. of H4198 that gives me over 2300fps. The sizing issue may be a point you want to address. My best accuracy is down around 1900 to 2000fps, and I think this was around 45gr. or so. My barrel is firelapped.

I used both plain and water quenched wheel weights. It also does well with 1/2 wheel weights, 1/2 lead for hunting.

My gun never shot well with bullets that small. That also goes with my H&R Buffalo Classic and the Ruger #1 as well.

[BABore]

I'd be doing a muzzle only slug on that gun and compare it to your other bore slug. Kind of sounds like you may have some barrel constrictions. The 0.452 bore sounds right. The 0.455 groove is way smaller than a bunch I've seen or heard of. A few tight spots under the bbl threads, roll marks, or dovetails would size your bullet down and contribute to the dismal accuracy. Worth checking out.

[ACK450]

Forester: My Marlin Cowboy (ballard rifling) shoots those 300 gr. RCBS g.c. bullets very well.
I use the Rem. brass & Rem. # 9.5 std. primers with 48 to 51 gr. of 3031, and they stay in
darn decent groups if I am shooting well.
This is with straight WW alloy air cooled and Horn. gas checks, sized .359, as my bore is .458.

I agree with the other guys that you might have microgrove rifling with that tight bore.
Keep trying things! ACK450

[Forester]

This is a new gun and I was under the impression that they were now deep cut rifling. Is that not the case?

I will do the muzzle only slug and see whats I get there.

I would love to size them larger but the .458 die really only barely touches the boolit. It is a stretch to get the mold to even cast that big.

I hate to do it but I am going to go pick up some Honady J-word boolits and run a few of them to be sure its the cast boolit and not some other problem.

Are any commonly available brand molds known to cast to a larger diameter typically? Lyman? Hoch? Saeco? I would rather find something in the 350-450gr range with a gascheck.

Edited to add: If it is in fact microgroove then I think I can solve the problem. I had very good results up to 2100fps with a Marlin MG 30-30 by water dropping for the extra hardness.

[44man]

Welcome to the world of Marlin! What they call Ballard rifling is just as shallow as the micro groove. It actually gives less bite to the boolit then the micro groove. I have been trying to get everyone with a Marlin to write and complain but all I get are answers as to how good some guys get theirs to shoot. That is not the answer, we must all complain to make them take a look at the problem. The twist rates suck on some calibers too.

[Forester]

Well, more info. This is looking more like a boolit sizing issue all the time. I reslugged the bore and found no real tight spots all the way through (a small bit of good news!). The muzzle only slug came out the same size as the rest of the bore.

I also measured a good number of my boolits and found they are pretty much exactly bore diameter. In other words, too small. The bore appears to be .456 and the boolits are dropping .456"-.457". 1 thousandth out of round.

Just for good measure I loaded up several J-word bullets today and will see how they shoot in the morning. At least I will know for sure it is not a gun/scope/mount problem. I also loaded some very light loads with the cast boolits becasue what accuracy I could find seemed to be on the slower end of things.

Is there a gas check mold out there for sale that has a good track record of dropping boolits at least .458" and preferably .459"-.460"?

[jtaylor1960]

I have that mold and the RCBS-325-UTILITY mold.I have not shot either yet although my gun shoots a 420gr NEI bullet very well at about 1700fps.I will let you know as soon as I get to try one or the other of those bullets.

[leftiye]

Forester,
Try casting boolits from a higher antimony harder lead alloy, they should cast a little bigger. This should help with any possible gas cutting or leading. They'll hold those shallow grooves better too. Then I'd size them .457 or .458" to get all the boolits the same size, this should help with pressure variations, and therefore accuracy. Nextly, if they still won't shoot well, I'd go to a longer heavier boolit. They tend to be more accurate in many 45-70s.

[Forester]

Well, now I know it is a boolit problem of some sort (probably fit). I shot several different loads using Jacketed bullets from Nosler and Hornady today and they shot much better.

I did not make much effort at working out exact loads for the best possible accuracy; I just wanted to see if they would group better than I had done previously. The Nosler 300gr PP bullet shot into 2.867" @1947fps and 1.769" at 1744fps.

The Hornady 350gr. FP Interlock bullet shot at .867" at 1727fps. My other load with this bullet I had to stop in the middle for a few minutes and so it was really two separate groups, same point of aim. I had 2 groups measuring .622" and .611" with a total group size of 2.989". I can not explain the movement between the two groups except maybe barrel heat?

I also tried some very reduced loads 13-1500fps with the same cast boolit and got a little better groups, 5-8" instead of 10"+. That made sense to me because pushing the boolit faster would have to accentuate any problems.

Next up I will be trying to get the RCBS mold to cast a little bigger and I may give a heavier boolit a try as well.

[jack19512]

My gun never shot well with bullets that small. That also goes with my H&R Buffalo Classic and the Ruger #1 as well.

So far I am shooting a 405 gr. and a 340 gr. cast bullet out of my Buffalo Classic and so far the 340 gr. cast bullets seem to be more accurate. Mine are non gas check though.

[jhalcott]

I use these in a T/C contender with some success. I had to cut back on recoil,so stopped using the 420 grain NEI pointed bullets

[Lloyd Smale]

ive shot that bullet in the 4570 and back when heavy mold for the 45 colt werent so prevelent i used to size it to 454 and it shot well in the 45s too. Its basicaly the same nose design as the 500 and 405 rcbs bullets just shorter.

[44 WCF]

I shoot the same bullet in a Micro Groove Marlin, as cast except for gas check crimp, WW air cooled and it shoots very well but not near the velocitiy the other members hunt with. I use AA 5744 and SR4759, and using Remington Large Pistol primers that another member told me to try. I crimp very heavy too with the AA 5744 per Accurate Powder's advise. I had to use a Lyman M die to get get case to accept the as cast bullet. Much different application but sure works.

It's a very mild steel plate load and fun to shoot.

Good luck.

[Bullshop]

This is a 100 yard target fired from a brand new Marlin 45/70 XLR. This was in about the first 25 shots fired from a new barrel.
This is the load I used for my moose last year. Same shot as this year, angling through the base of the neck. There were a couple shattered vertibra and the boolit exited the off side. The boolits were ACWW at 2150 fps.
OOPS! The boolits pictured are the RCBS 405 but the target was fired with the 300.
BIC/BS

[Forester]

I sat down today determined to make this mold work for me, and I had some success. By playing with the alloy temp and casting speed I got them to cast up to almost .459". I ran them through a .459" size die and loaded them over several different charges of 4198.

I also got my hands on a Hoch Nose pour 420gr mold and tried that today...it sure cast a good looking boolit. It ran about .460" on the rear driving band and a little less on the forward ones. I ran them through the same .459" sizer and loaded them over several charges of 4198 as well.

I don't usually do this, but to give things the best possible chance I sorted the boolits by weight. I did not have much variation in the lot of them but all boolits in this batch of loads are within .9gr of each other.

Bullshop: If I get the velocity and groups you have there then I will be a pretty happy camper! If I can not make mine shoot I may have to order a few from you to prove to myself once and for all the gun will shoot cast.

Tomorrow I will further bruise my shoulder. I don't mind the hot loads at all off hand, but from sandbags they can be a little rough. I have 110rds through the gun now, both J-word and cast. If the cast boolits show improvement tomorrow, I will knuckle down and work out the best load I can in the next couple weeks. I figure I have about a month to get things ironed out before deer season.

[Bullshop]

Forester
I read back through all your posts and I think you have a problem with the barrel. The double grouping tells the story. I would look at the forend contact at the receiver and at the cap. I would also remove the cap and forend and check the mag tube and hangers. Something there is in a bind and causing a variable pressure on the barrel. Thats the problem with trying to hang a mag tube and forend on the barrel. It can work good but ya got ta work the buggs out.
Going on memory I was shooting 53.5 gn Scott 4197 on that target. Scott 4197 is very much like the 4198's but possibly a tad slower. Its no longer available as Scott powder, but I believe when Accurate Arms took over Scott they just renamed it AA 2015. I get the same results with like charges of both.
Sure wish you could just bring it over to our shop and we could work on it and get it figured out.
BIC/BS

[Forester]

Forester
I read back through all your posts and I think you have a problem with the barrel. The double grouping tells the story. I would look at the forend contact at the receiver and at the cap. I would also remove the cap and forend and check the mag tube and hangers. Something there is in a bind and causing a variable pressure on the barrel. Thats the problem with trying to hang a mag tube and forend on the barrel. It can work good but ya got ta work the buggs out.
Going on memory I was shooting 53.5 gn Scott 4197 on that target. Scott 4197 is very much like the 4198's but possibly a tad slower. Its no longer available as Scott powder, but I believe when Accurate Arms took over Scott they just renamed it AA 2015. I get the same results with like charges of both.
Sure wish you could just bring it over to our shop and we could work on it and get it figured out.BIC/BS

I need to clean it up good and get any copper out of the barrel this morning before I shoot the cast boolits in it again so I will take a good look at the forend contact and mag tube. I had all of that off once before and did not notice a problem, but I was not looking for one either. Would it hurt anything to shoot the gun without the mag tube and forend in place just to eliminate one posibility?

If it was a few less than 4000 miles between us I might take you up on that! If I am lucky I may be cutting the distance down by almost half in the next few years but it remains to be seen if that will happen.

[Bullshop]

I think trying without the forend is a good idea. It wont hurt anything, but will likely have a differant POI. Also check the hangers in thier dovetail cut for movement. They can be peened slightly to make a better fit. Check all contact points for burnishing mark that are uneven between sides. I go for light even contact of the forend butt to the receiver which seems to be one of the criticle points. Another is the forend cap on the barrel. If uneven it will show up as a shinney spot on a stainless barrel or as a whear spot on a blued barrel. You find that so many of the old Marlins shoot so good and I think one reason is that with time and wear these forend issues have corrected themselves with wear. If you take apart an older rifle you will see how the forend hangers have worn into the wood and how many will have very slight play fore and aft in the forend. Worn in to be sure with no binding. Thats how I like to set up a forend, with ever so slight almost imperceptable play.
BIC/BS