Checked chamber lengh for my 1893 Spanish Mauser and got 3.165" to the lands...

[Jeffrimerman]

Hey guys,
I'm taking this ole girl to the range and getting massive groups like10" at 50 yards. I got a case and cut 2 slits and dropped a bullet on top then chambered to see where the lands pushed it back to and got 3.165". Should I be loading at 3.13" vs 3.00"? Could this be the source of my inaccuracies? I've only shot it 3 times. Once with the rear iron sight and got maybe the same or maybe 8" spread I forget. Then put on the rear sight rail which I hear isn't that great but I checked it after shooting and it's on there solid. I slugged the bore and got .276 and .275" should be the factory bore so pretty close still. I see visible crisp rifling. Has anyone noticed their old Mauser to have a "deep throat"? Did you also need to load a lot longer?

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[Patrick Chadwick]

If the case length will permit it, then seating the bullet to be about 0.010“ off the lands would be a good start. However, if the rifle has a deep throat this may not be possible, as there should be at least 1 caliber of bullet length in the case neck to hold it reliably and consistently. A very good reason to use Spitzer or round-nose bullets. In my experience boat-tails are useless in Mausers of this vintage, as you just cannot seat them properly without being way off the lands. These old Mausers were designed for bullets with a good cylindrical back end, not boat tails.

[Jeffrimerman]

That's a good point. I should have got the flat bottom bullets. I have a few that someone else sold me but I'll probably need to use up what I have or try to trade. When I shoot 123g .310 bullets with Enfield they shoot fine so as long as I get get a snug fit I should get better groups. I'll report back with the results. Thanks Patrick.
Jeff

[bob q]

You need to get the groove measurement , that is most likely your problem . What bullets are you using ? The groove will matter much more than the throat .

[Jeffrimerman]

Thanks Bob. The spec for the barrel is .275" for a 7mm Mauser and it slugged at .276" at the lands which I'm told is fine. The bullets I'm using are .284" but are 139g boat tail bullets which seem to be too short for loading long just off the lands but they seem to barely work. I loaded some at 3.135" COL but I want to get the 173g flat back that should easily load longer to maybe 3.15". The grooves are supposed to be .285" but not sure what mine are. The rifling looks good visually. I'll shoot them long and report back what the results were.

[bob q]

You need to know the groove size . If you have a .288 + groove your short boat tails will not ride the rifling straight and you will have poor accuracy . I have seen that a lot on 7mm military rifles . I once bought a M-95 from a guy who was shooting Rem 139 BT's with the same result as you , he sold it cheap since it would not shoot . With the right bullet in handloads it shot 2 inch groups at 100 for me . What something is supposed to be and what they really are can be two different things .

[Jeffrimerman]

Thanks Bob, I'm hoping that's the case. I don't plan on selling it and I have some flat base bullets to try. I got a care package from a felling 7x57 guy <3 hehe. 139g spire point flat base, 120g spire HP flat base, 140g spt X flat base, 150g spcl flat base. I'm going to order some 173g and hoping they are flat base so waiting to hear back from the shop. I was thinking seating out would help and didn't realize bullet obturation would help also. If I load close to the lands with flat base bullets crossing toes that does the trick. Thank you

[bob q]

Something else that will help with the fb light bullets is a light load with a fast burning powder . That will give them a " kick in the pants ' to help with obturation , the light bullets are usually varmint types with thin jackets and soft cores .

[Jeffrimerman]

I'll use the WC747 I have. It's a little faster than W748. It's made in the same factory. I already tested it for safety with the other 139g bt bullets so it's good to go. Thank you Bob

[Jeffrimerman]

I used my homemade took which is a case with 2 slits so I can pop a bullet on and test to see how long before it hits the lands. I must have had some crust or something before or just didn't notice. I put a 140g flat base spire bullet and it measured 3.26". After chambering it still measured 3.26". I then got a 150g hp fb bullet and it measured 3.33". After chambering it still measured 3.33". Do these throats open wide then tapper down or mine is just so worn I just need to load as long as possible before the bullet falls off? When I used my bore scope things looked to be in the right place. I could see the shoulder and neck in the chamber and where the neck ends. Things probably weren't precise in 1893-98?