Accurate 6.5 Swedish Mauser load

[38splpete]

I have tried loading the Lyman 266673 with light loads of 4759 (16-17g) without success. This bullet mikes about .002 over a jacketed Sierra 140g bullet which shoots accurately. The cast bullet loads are all over the place(6-8"). Any ideas? Maybe they need to be pushed faster in the fast twist of the Mauser?

[17nut]

How fast are you going?
As a general rule funny things start to happen above 1600fps in a Swede.
It can be driven much faster but the learning curve is like a hockey stick.

[sundog]

Ideas? Yes. Spend some time searching and reviewing the archives. There's only about a tome's worth of information on exactly this subject. If not careful, it will be like chasing Alice down the rabbit hole.

[JonB_in_Glencoe]

I have tried loading the Lyman 266673 with light loads of 4759 (16-17g) without success. This bullet mikes about .002 over a jacketed Sierra 140g bullet which shoots accurately. The cast bullet loads are all over the place(6-8"). Any ideas? Maybe they need to be pushed faster in the fast twist of the Mauser?

38splpete,
Welcome to the forum

It's tough to offer much advice, when so little details are provided...and since this is your first post, we have no clue about your background/experience in loading cast boolits in Rifle calibers?
Assuming you are new to that, you should be aware that there are some different things to be aware of, that are more important to loading cast boolits in Rifle calibers, as compared to loading jacketed bullets.
First, as a refresher, I'd suggest re-reading the chapter on loading cast boolits in your reloading manual.

As sundog mentions there are many many many threads on these details. Here are a couple that might help you out.

Since you are loading for a military rifle, this one is good, even if they don't mention the swede specifically.
http://castboolits.gunloads.com/show...Rifles-Article

Since you are choosing to use a bore riding boolit, this one is good. Be sure to read through all the comments on this one.
http://castboolits.gunloads.com/show...its-101-needed

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So with all that said, I'd like to mention a few things that are common stumbling blocks, many I, myself, have stumbled over.

Let's start with the Boolit. Are they "perfect"? It's much more important that Rifle boolits be perfect, as compared to pistol boolits, due to the distance they are required to travel, any imperfection can cause instability and inaccuracy. Is the GC seated squarely? A perfect Base is even more important that a perfect boolit. Could your boolits have gotten "bent" or damaged while sizing? What Lube? Did you experience any lead fouling from shooting them?

Most reloading dies are designed for jacketed bullets. Sometimes you can get by with them, sometimes you can't...many of us have used some alternative methods and/or modified dies or die parts...or custom dies? Have you checked the runout of you ammo after you seated the boolit? Runout problems can arise during seating cast boolits (Lee seating dies have been troublesome for me, due to the sloppy nose guide). Do you crimp or no crimp? Check runout after that?

You are using a bore riding boolits, does the nose engage rifling?

That should be a good start.

[yeahbub]

38splpete, welcome to the forum. The comments so far are spot-on, including winding up down a stumper of a rabbit hole. It would be helpful to know what your alloy and hardness is, the lube you're using, whether the bore-riding nose engraves on chambering (it should, slightly) and how you're getting square bases, with or without gas checks. That the boolit is .002 over the Sierras is no liability. The question is; does it seat in the throat with slight but noticeable resistance when you close the bolt? The nose should be supported by the lands, the front driving band should be firmly seated/centered in the throat on the front end and the base supported by the case neck in the rear. If this is not the case and/or the bore-riding nose is loose in the bore, things will go crooked and accuracy will be out the window. The hardest cast boolit is softer than the softest jacketed, so fit and alignment are critical. The load you quote is a good starting point. Have you gotten leading so far?

Given a good interference fit of the nose in the barrel's throat, you might try breach-seating and firing a few to see if your accuracy improves. Obviously, this isn't practical long-term, but it will tell you where some problems might be. Starting with fired cases which are reprimed and left unsized, generously lube a few boolits and drop one nose-first into the chamber, carefully pushing it into the throat until it stops with no more than firm hand pressure with a short rod. Then, charge a case, and with the muzzle up, chamber it, lay the rifle on your bench, aim carefully and touch her off. This practice eliminates alignment issues associated with seating boolits in the case, neck tension, seating depth, etc. and working them through the action. I'd hazard a guess that your groups will be much more like what you're looking for. If so, then we start analyzing what happens to your boolits during the loading process that could be introducing error, like, do you use an M-die to uniform the ID of your case necks and expand them a bit for consistent boolit seating? Do you neck-size cases or full-length size? Let us know how you do.

[dogmower]

i use the lyman 266469 sized to .269 over 18 grains of imr 4227. i was having accuracy problems with this, and the 7x57 mauser as well. both were cured with switching to imr 4227. next, I'm going to try it in the .243, another small caliber I've have trouble with.