Sierra 88 TMK Load Data

[Formidilosus]

Interesting. I must either have a bad lot of BH or my gun just doesn’t like it. It groups horribly but the speeds are there.

Recent lots have been very erratic. The last 2-3 have been 3+ MOA from known guns.

 

[KyleR1985]

I want to make the 88s work, as they just look like they should be shot at an elk... but even with the 7 twist barrel in my Savage, I'm just not sure I can get enough velocity to justify them without pushing things. Or AI'ing it. Or both. But the 77 is no slouch... and I'd probably never shoot at big game beyond 500 anyway.

Seeing some folks get up into 2700 without AI gives me some hope, but the throat in my Savage is only going to allow 2.40ish OAL so that may hold me back (but also feeds from factory mags).

I ordered 500 77 TMKs recently, but I'm still trying 88s in the mean time.

How long does the mag/mag box allow you to load?

It takes about a half an hour to cut a longer throat and costs 60.00.

Sample size of 1, but the gun got more accurate after throating (controlling for jump, velocity, etc.).

If you can feed 2.5” reliably, there’s nothing holding you back on 88’s.

 

[WDR]

How long does the mag/mag box allow you to load?

It takes about a half an hour to cut a longer throat and costs 60.00.

Sample size of 1, but the gun got more accurate after throating (controlling for jump, velocity, etc.).

If you can feed 2.5” reliably, there’s nothing holding you back on 88’s.

2.40ish maybe 2.45 ... I purposely avoided AICS, and stuck with factory mags, when I "built" this gun because I hate crap sticking out of the bottom of the gun for hunting. There is a spacer at the rear of the mags, that is riveted in, that I might be able to mess with, but I don't want to ruin feeding reliability. I'm using the old style metal mags, not their new all polymer ones. I am curious if the new mags would allow longer length or be easier to modify, but haven't seen one in person yet.

Having the gun throated and maybe AI'd is something Ive considered.

I was able to make it to the range today and test a few more charges of N540 from 22.5 up to 23.6 grains... 23.6 was getting a little warm maybe. But all the rounds I fired were hitting the 320yd steel in about a 3" or so group. My shooting buddy was pretty impressed. They smack steel a bit harder than the 80gr ELDs I was also shooting. I didn't chronograph them yet. I may back down to 23.5 (same as my 80 ELD load) and load a few up to chrono and shoot for groups.

I did sling one at the 1000 yard target, but mirage was bad, wind was bad, and I don't have any verified dope. Pretty sure it was a miss.

 

[Thegman]

2.40ish maybe 2.45 ... I purposely avoided AICS, and stuck with factory mags, when I "built" this gun because I hate crap sticking out of the bottom of the gun for hunting. There is a spacer at the rear of the mags, that is riveted in, that I might be able to mess with, but I don't want to ruin feeding reliability. I'm using the old style metal mags, not their new all polymer ones. I am curious if the new mags would allow longer length or be easier to modify, but haven't seen one in person yet.

Having the gun throated and maybe AI'd is something Ive considered.

I was able to make it to the range today and test a few more charges of N540 from 22.5 up to 23.6 grains... 23.6 was getting a little warm maybe. But all the rounds I fired were hitting the 320yd steel in about a 3" or so group. My shooting buddy was pretty impressed. They smack steel a bit harder than the 80gr ELDs I was also shooting. I didn't chronograph them yet. I may back down to 23.5 (same as my 80 ELD load) and load a few up to chrono and shoot for groups.

I did sling one at the 1000 yard target, but mirage was bad, wind was bad, and I don't have any verified dope. Pretty sure it was a miss.

Check your mag; I think it should take 2.5" which is pretty acceptable for the 88s. I say that about the mag as I used to have a Savage 223 with the metal bodied mags and it accepted up to 2.5".

 

[Moose83]

16” factory barrel, 2.490” coal. 2,608fps MV.


View attachment 1083573

Are there conditions at which you think those of us using 8 twist barrels should be monitoring for increased instability? I am not well versed in the minutiae of twist rates, conditions, and stability, but I've always heard that a 7 twist was mandatory for anything over 80 gr at .223 velocities

 

[cq0302]

Finally got around to playing with these in my tikka 1:8 22-250, factory barrel. Was out of n560 so settled on staball 6.5. Quick pressure ladder from 34-38, all was well at 38, went to 37.5gn as it was close enough to the 3100fps I was looking for (3076 fps mv). Loaded 5 to ~.030 jump and went out for a quick group. Now that I know they shoot I’ll load up a bunch and go shoot some distance.

Factory tikka 1:8 22-250
Lapua brass with fed. 210M
37.5gn staball 6.5 with mv 3076

Top left group

 

[TradLife406]

16” factory barrel, 2.490” coal. 2,608fps MV.


View attachment 1083573

Well if I use this as a baseline in my AI I should be able to get 2750-2800 in my 18".
But I've got n540 running really good.

 

[TradLife406]

It's nice when you let one out of the cluster to remind us you're still only human

 

[Formidilosus]

Are there conditions at which you think those of us using 8 twist barrels should be monitoring for increased instability? I am not well versed in the minutiae of twist rates, conditions, and stability, but I've always heard that a 7 twist was mandatory for anything over 80 gr at .223 velocities

Yes, I’m sure there is. The first rifles true drhem in grouped fine at 3,000ft DA, but had wild shots at -3,000ft DA. I had thought it was due to losing stability, even though the trace looked fine (just bullets missing animals widely). However, that barrel has been found to be bad. So, I’m not sure.

 

[Formidilosus]

It's nice when you let one out of the cluster to remind us you're still only human

The funny part is that it was the last bullet, and the one that I repeatedly reseated and crushed the tip on. Told Mikey and Zack before I shot it that it will probably be jacked. Haha.