Need suggestion in correcting 375H&H COL

gitrdun

gitrdun

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I sheepishly admit to make a mistake when setting up my COL. I checked good chambering. Fired rounds at the range with chambering each round individually. But in my haste to produce a good load for an upcoming hunt, I forgot to check that my rounds would cycle through the magazine. So, I have a great shooting single shoot in a Win70 XTR. Yeah, I know...don't worry, I'm trying to figure out a way to kick my own arss. :redface:

Anyways, here is my load and what I propose to do since I have 30 rounds loaded and I'd like to not pull them all and start at the beginning (if I can avoid it).

First my load: 375 H&H - 300gr TSX - 63.0gr IMR4895

The COL with bullet touching the lands = 3.792"
The current single shot load COL = 3.717" (0.075" from lands)
The desired load to cycle thru COL = 3.550" (0.242" from lands).

Now, here are my questions:

1. does 0.242" from the lands not seem like a mile? I know Barnes like a bit of a jump to the lands, but isn't this 2 much?

2. rather than pulling bullets and charging with a lesser amount of powder and seating to 3.550", I was thinking of seating 5 bullets deeper in increments of 0.050" until I have 5 bullets with one at the desired depth. Of course I would observe each for signs of over pressure. Once and if the last one (3.550") shoots with no excess pressure, then I do one more but with a factory crimp. And then check if this last one shows signs of pressure. Everything being OK, I still have to then establish a grouping, but 3.550" is the max lenght I can use to cycle thru the action.

Do you fellows think this is a good approach or do you have better suggestions. Safety always being most important of course.:)
 
My data books show your are 4 grains below max and the col listed for a speer bullet is 3.440. I think you are okay to seat the bullet back to fit in the mag and have no pressure problems. The only thing that could go wrong is your accuracy may not be what it was and you may have to do a work up load again at the new desired col. I shoot two target rifles with a huuuge lead and am still sub moa out at five hundered meters so i don't think you will have an issue with the jump.
 
.242" is a lot but there's not much you can do about it - the rounds have to fit the mag.

If it were me, I'd just seat the bullets to the 3.55" COL and hope they shot okay. It appears that your load is below book max(Hodgdon site shows 61 gr IMR4895 with a COL of 3.6") so pressures should be ok.

FWIW, my 9.3X62 has a very long free-bore and it shoots very well.
 
So you guys don't think I need to seat progressively deeper, just go to 3.550" and it should be good? I do see your point, with being 4 gr. under, but remember those Barnes TSX are a pretty long bullet and seat deeply. I think I might still play it safe and progress with a couple of rounds though.
 
how far down the neck and passed the shoulder do you figure you will be?
as far as just doing it it is not a problem and because of the small shoulder and tapered case plus long bullet it should be well stabilized still as it enters the lands.
 
i just looked up my old data and when i was loading 300 grain tungsten solids to a col of 3.450 there was quite a bit of bullet below the shoulder, biggest problem being the short neck on the 378 ouch and ouch. You will be fine.
 
Good point yodave. The bullet seats .750" in past the shoulder. It'll still be .500" in deep when it hits the lands. See...this is why I check here first ;)

If my grouping needs improvement, then I can start increasing powder charge. I have just bought a Lee factory crimp die for this caliber as I think that it will keep COL intact for the rounds in the mag, but according to the literature that comes with the die, it also helps accuracy by providing more consistency in peak pressure. I just don't like crimping with a seating die anymore ever since using a factory crimper for my .444
 
don't crimp unless you have a cannelured bullet, ithink that is one of the first three rules of bullet seating isn't it??? pointy end up being the first
 
lol: pointy end first...that's a good rule to follow. The TSX bullets have 5 grooves. My shoulder will end up just inside the last one, so I'm OK to crimp. The instruction sheet that comes with the Lee factory crimp dies states that a cannelure is not needed with this die as it will form one. Otherwise, using a seating die to crimp, it most likely is a good idea to use a cannelure.
 
Them TSX's not having a lead core might be a little harder to crimp into, although the die info says it doesn't need a canalure I wonder if the TSX might present a little too much resistance. Good idea to go back in stages just to see what happens, although it will probably be alright. Keep us updated.
 
I'm surprised that you can't seat that bullet out to 3.6". 3.6" pretty much defines 'full-length magnum', and it's the standard max COL for the .375 H&H...

That said, if she'll only take 3.55" then crunch them all down to 3.55" and expect some shifting of groups. Probably not a ton, but it's likely to have an effect.
 
I just pulled a couple of dummy rounds and re-seated to 3.600" - She just won't swallow them down the mag. It's got to be 3.550" for feeding without hang ups. I'll have to give them a try at this lenght, and yes I'll keep you updated. Just wondering if I should consider having a good smith open up the mag a bit. I'll bet if I take it apart and have a good close look I might even be able to do it myself though.
 
Just seat them to the correct OAL to fit the mag and feed properly and go hunting.

I'll bet the POI doesn't change a quarter of an inch. $20 -- If I lose, I'll square it up with you next month. :)

Ted
 
A .375 isn't a varmint rifle, and I think trying to wring out the last quarter minute from a powerful rifle is a bit obsessive. I seat all my .375 stuff to the cannular. Full length resizing, prepping the primer pockets and flash holes, and crimping my bullets seems to produce good accuracy for me. I believe function trumps accuracy, but most of my loads are MOA for 3 shots, some are better and some don't quite make it but are close. The point is that big game animals are large targets, and you don't get to shoot off a bench out there anyway. Accuracy is a confidence builder, but how well you shoot from field positions with a 2 minute rifle is what determines if there is meat in the freezer.
 
Boomer said:
A .375 isn't a varmint rifle, and I think trying to wring out the last quarter minute from a powerful rifle is a bit obsessive. I seat all my .375 stuff to the cannular. Full length resizing, prepping the primer pockets and flash holes, and crimping my bullets seems to produce good accuracy for me. I believe function trumps accuracy, but most of my loads are MOA for 3 shots, some are better and some don't quite make it but are close. The point is that big game animals are large targets, and you don't get to shoot off a bench out there anyway. Accuracy is a confidence builder, but how well you shoot from field positions with a 2 minute rifle is what determines if there is meat in the freezer.
Click to expand...

I'm with you on that 100% Boomer. That isn't my goal though. I'm having to shorten the rounds due to magazine lenght. I mainly want to do so safely, this mistake that I made was not trying to make my .375 shoot like my .223 ;)
 
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