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I'm a bit stumped...

I'm loading 350Hdy's over IMR3031 in a Marlin Guide Gun. I started at 54grs and noticed heavy swelling at the casehead. I just thought I was a bit heavy on the charge. Backed down to 50 & 48grs with same results. There is no way 48grs is too heavy....so what now? oversized/sloppy chamber?

350Hdy FP crimped on groove
WW Brass
Fed210

Thanks for any input

Beats me. Never had anything of the like happen to me. Is your brass a little too short for specs?

I think Keith is referring to "swelling" due to a compressed load, before it's fired. It appears though that you're talking about the case appearance AFTER the load is fired... correct? If true, then there's a definite problem with the chamber. It needs to go to a smith for a look-see.

Bob

www.bigbores.ca

Yeah, these aren't even close to being compressed. I'm talkin after the big bang.

What happens when you fire factory loads? If the same thing happens I would think sloppy chamber. Is the gun new to you (have you fired any other handloads, etc.)?

Is the gun still under warranty? Do you have a reliable smith nearby?

I've had a bunch of Marlin's in 45-70 (including a Guide Gun)and nothing has ever showed up of that nature... and I load 'em pretty hot! The barrel on the Marlin is pretty heavy, with lots of metal, so it's got to be, as you say, a "sloppy chamber". If you bought it new from a dealer, he should replace the gun once it's verified there's a problem with the chamber.

My current Marlin is the "classic" with a 22" pipe and it had a fault from the factory in a bent magazine follower which would not elevate the cartridges to the chamber. It went to my smith and he straightened it, saying it was a fairly common fault with Marlins. It's worked great ever since.

A faulty chamber is another matter entirely. Sorry to say it, but the gun will need to go back to Marlin, or at least to your dealer and hopefully he'll do the right thing.

Bob

www.bigbores.ca

Or, on the other hand, if you bought it from somone else (used)then they may have overloaded it and swelled the chamber, then "dumped it" in selling it to you. If so, I would seek recompense from that person... if that is the situation.

Bob

www.bigbores.ca

What I was referring to is, IF the brass is a little too short, and the case headspaces on the rim, there is an area on the case that may be 'back from the case mouth where the case is tapered prematurely by the case being too short. Then when the bang happens, the case swells to meet the size of the chamber, and because the case is not the same size as the chamber because it is too short, you get more expansion because of the small size difference due to the slight taper in the case as it is designed, but guys, I am NO expert on reloading and chambers and sizing. Just thinking out loud.

A picture would help with what you are describing but my bet is that is just pressure ring expansion.They all do it in the 45-70 unless it is something like a 400 grain factory load.The more it expands/swells the more pressure..Garrets semi mild loads also expand/swell at under 35,000 CUP and Buffalo Bores expand/swell more.

When using the same brass as a known load,I have measured the expansion for comparison...Nothing to worry about if your within the data.

Which 45-70 brass are you using?

Jayco

yes, just talkin about the typical expansion ring we all see on overloaded or bad headspaced cases.


just shot some factory Hdy and it came out fine.....still confused.

I wouldn't think brass length would matter much on a non-bottlenecked case, but measured anyways and it's just fine.

That is because the pressure is at SAAMI levels for the 45-70 aka 28,000 or less.Remington factory ammo had no expansion either but once you start getting over 28,000 the brass is going to expand at the pressure ring.There is nothing wrong with it at all and when you resize the brass,it goes back to normal.

Garretts expand and so do Buffalo Bores because both exceed the 28,000 SAAMI for the 45-70.If you watch and measure the expansion,you will notice it gets larger as the velocity/pressure increases..Garretts are rated at 35,000 CUP or less and Buffalo Bores at supposedly 40,000 CUP or slightly less(according to Brian Pierce)and there expansion at the ring is quite different with Buffalo Bores being more and both using Starline brass.

Mine do and my loads are under 40,000 CUP which the modern Marlin 45-70 is unofficially rated at.Maybe that is why they put a belt on the 450 Marlin.

Jayco

lc-

I'll take your word for it...just a little suprised that the expansion ring is normal at near starting loads for Hdy#7.

Here is a link to the same question on another forum with pictures..Pay attention to what Dr A says..Good guy and knows his stuff.

http://www.thefiringline.com/forums/showthread.php?p=3072106

Good luck

Jayco

My pet load in my GG is 47.5 grains of 3031 pushing the Hornady 350 RN. It iz amazingly accurate. 3/4-1" groups with regularity and 1/2 inch when i do my part. I am tending to the mild side with that load. Your 54 grains sounds pretty darned stout, but no way should you be having pressure problems at 48.

The load is about mid range as far as pressure is concerned for that size bullet in a Marlin. I'm guessing a slightly oversized or oblonged chamber.

If the case ejects without problems, no sticking, flat primers or extruded primer material around the firing pin indent etc and the accuracy is good then I would just live with it. Ive had quite a few factory chambers that were "wobbled" but didn't interfer with hunting accuracy.

Depending on how you have your sizing die set up or how well the die fits the fired brass, the longevity of the brass is probably the only issue.

YOU'RE SURE that your powder weigh scale and other equipment is calibrated and not totally screwed up?????

Did you measure the fired and sized case with a micrometer or caliper at the buldge?????

FWIW...my NEF BC 45-70 now 45-120 liked H4895 with the Hornady 350 bullet...it gave the highest velocity and best accuracy and lower pressures than the faster burning powders (RL7, H4227, H4198 etc) usually listed for this case. A couple of other powders AA2230 and AA2460 gave even better results, case longevity etc shooting 45-70, 45-90 anc 45-10 cased loads in my 45-120 and 458 American.

I double checked my rcbs scale with my Hdy digital and their right on. The bulge measures .005". The more I research this the more I see it just may be indicative of the Marlin chamber. Thanks anyways.

The Hodgdon manual states that the 350 Hornady bullet can be loaded up to 60 gr of 3031 in the .45-70 with about 35 KSI chamber pressure. You are at 80% of maximum load (48 vs. 60 grs.) which with a canistered powder may be too low a loading density. Sometimes pressure is higher with too low a density of cannistered powders. Try using 4198 if you want to load slower loads.