K31 Bullet Seating

[prid93]

Hey all,
I'm attempting to reload 7.5x55 swiss for the K31 rifle. I understand that these rifles normally have very shallow throats and was aware that most bullets would have to be seated very deeply to chamber correctly.
In order for the Sierra 168gr matchking bullets I have to chamber with no signs of the bullet touching the lands, it practically has to be seated so far in that there is a very very little bit of space between the top of the case and the bullet...that is what I am unsure about. Is this bad? I was able to chamber the dummy round while it was seated out a little further, but it showed signs of touching the lands (sharpie marker being rubbed off.)

I am still relatively new to handloading (started in December) so any input is greatly appreciated.

 

[Cosmoline]

I would suggest using the GP11 as the model and trying to copy it as closely as possible, including OAL.

 

[sig220mw]

Something else to worry about is might the bullet be seated so deep that the top part of the bullet where the case mouth is holding it be smaller and the case not have a good hold on it. In that case the bullet could fall down into the case. You might want to try a different brand bullet with a longer ogive
(I believe that is the correct term). I am using 165gr and 125gr nosler ballistic tips and am about to try hornady bullets in the same weights.

 

[Canuck-IL]

I would suggest using the GP11 as the model and trying to copy it as closely as possible, including OAL.

You just can't do that ... pull a GP-11 bullet and compare the shape to a typical SMK or any common US match bullet. The GP-11 has an unusually long, thin nose design unlike US fodder. The older Hornady guides listed 3.06 as an OAL and you will not get a Sierra SMK in the chamber at that length without jamming the bullet hard enough to set it back ... as the OP has noted. [The Hornady data *may* have been for the K-11 rifles, as their dies at that time were - not sure on that].

Anyway, the 168s should end up about 2.85 OAL with some other bullet designs allowing up to about 2.92.
/Bryan

 

[prid93]

Canuck,
That last line is exactly what I was hoping to hear, thank you. It comes in at about 2.87'' for me...I just wanted to be certain that the bullet being that deep was not a problem.

 

[Canuck-IL]

Should be good +/- a bit as OAL is a variable measure - noses vary a lot, even on quality bullets like SMKs - measuring to the ogive with a Stoney Point (now Hornady) or Sinclair comparator is more reliable.

Besides my own loads, I've got several pages of "screen scrapings" from the various Swiss rifle web sites and 2.84 - 2.92 is a pretty common range.

/B

 

[zfk55]

A dead match for the GP11 projectile is the 175gr Berger VLD. As long as you index on the ogive your seat depth will be correct with a nominal amout of the projectile out front.

Left to right, SMK 175, GP11, Berger VLD 175, all properly seated for the 1911, k11, k31, zfk55 and the PE57. All k31's like the projectile to be very close to the lands.

Both the SMK and VLD have been meplat trimmed and pointed.

 

[soloban]

I use 168 Gr Sierras or 167 Gr Lapuas in my 7.5 Swiss reloads. You have to seat them a lot deeper than the manuals state. This is because the manuals use the K11 and not the K31 for load development. My current K31 load:

45 Gr IMR 4320
CCI 200
OAL 2.845"

Also, using a K31 specific die helps.

 

[Canuck-IL]

A dead match for the GP11 projectile is the 175gr Berger VLD

That's nice to know!!

Also, using a K31 specific die helps.

I think that really only "helps" in that it keeps the brass from being overworked by the K11 dies - doesn't really affect seating depth and distance to the lands.
BTW, Hornady now sells a K-31 specific set of dies in addition to the Reddings that have been around for quite awhile.
/B