40 brass in 10mm

[nhyrum]

So this is a slight spin off of the shoot 40 through a 10, which is debatably unsafe. Not because of pressure, but headspace.

 

Would it be possible to load 40 brass to 10mm lengths? Mainly because 40 brass is cheaper and easier to find

 

Sent from my SM-G930V using Tapatalk

 

 

[GrumpyOne]

It doesn't matter if you load 40 to 10mm length, the brass is still the same as 40 brass, and the headspace would be the same. OAL does matter, but in this case, only in respect to head space. Your cartridge does not headspace off of the bullet.

[nhyrum]

True. But, if the bullets were seated close enough to the lands, there would be no real issue of having only the extractor hold the case in. If you seat them, so they reliably feed and function, but just barely out of the rifling, the case can't go any further in. Basically headspacing off the ogive. Same way 300 win mag precision guys load to effectively head space off the shoulder, not the belt(slightly different, but sort of similar. Does that make sense?

Now, I don't know if 40 brass is long enough for that

It doesn't matter if you load 40 to 10mm length, the brass is still the same as 40 brass, and the headspace would be the same. OAL does matter, but in this case, only in respect to head space. Your cartridge does not headspace off of the bullet.

Sent from my SM-G930V using Tapatalk

[GrumpyOne]

And if you have bullet setback when the round is chambered? What then? Headspacing a 300 Win mag off the shoulder is one thing, as that shoulder will not move...headspacing a 40 off of the bullet ogive is quite another. That bullet can move, and not to mention the pressure build up with that bullet setting right on the lands...you need to have a bit of jump...and if that round is just a wee bit longer than expected, it won't go into battery.

[nhyrum]

Sure, I get it's different, and bullets vary, brass is sized and doesn't really move after that. If they were seated 5 to 10 thou off, you could have a little room for error, get a good crimp, no set back.

I agree, it's not perfect, or really even "good"but better than running straight 40 in 10,no?

Sent from my SM-G930V using Tapatalk

[OdinIII]

The only right thing to do is use 10mm brass. Buy some once fired online or at a local range. Buy 1K and shoot minimum loads and you’ll be set for a very long time. You’ll need new 10mm brass for max loads.

[MikeyScuba]

I “bit” the bullet (lame I know...) and got the gun rebarreled for 40 from 10mm.  Bought the gun for fun (and cheap- STI Tactical 10 were being sold at a discount of $400-500).  Got into IPSC, realized my STI 9mm 3Gun wasn’t competitive and got the 10 switched over to 40.  It’s a great gun, needed 1000+ rounds to function flawlessly ( was brand new)

 Wasn’t super cheap but I imported the gun into Canada from MO and even with the import fees and then the work to switch to 40 it was hundreds less than had I bought it as a 40 New here. Plus it’s had its trigger done, much lower weight springs  and more.  I assume it’s built stronger to withstand the 10mm pressures?

[nhyrum]

I agree. My point is, bulk 10mm brass is 13 cents a case, 40 is 3 cents. For what, an eighth inch longer case? It's ridiculous. My 10mm major loads are WAY below 10mm max pressures, so they have to be safe in 40 cases, loaded to the same oal.

Sure, like I said, it's less than ideal.

The only right thing to do is use 10mm brass. Buy some once fired online or at a local range. Buy 1K and shoot minimum loads and you’ll be set for a very long time. You’ll need new 10mm brass for max loads.

Sent from my SM-G930V using Tapatalk

[nhyrum]

I “bit” the bullet (lame I know...) and got the gun rebarreled for 40 from 10mm.  Bought the gun for fun (and cheap- STI Tactical 10 were being sold at a discount of $400-500).  Got into IPSC, realized my STI 9mm 3Gun wasn’t competitive and got the 10 switched over to 40.  It’s a great gun, needed 1000+ rounds to function flawlessly ( was brand new)
 Wasn’t super cheap but I imported the gun into Canada from MO and even with the import fees and then the work to switch to 40 it was hundreds less than had I bought it as a 40 New here. Plus it’s had its trigger done, much lower weight springs  and more.  I assume it’s built stronger to withstand the 10mm pressures?

If I rebarrel my 10, it's gonna be 9x25(opposite way on brass price, I know) but man... I want one... Bad...

Sent from my SM-G930V using Tapatalk

[MikeyScuba]

I shoot in too many matches to worry about collecting my brass, I grab whatever 40 I can if the situation permits.  You don’t always have the option.