75 gn Amax in 224

[Optomist]

Hi folks I'm currently trying to work up an accurate load in 223 using 75 gn Amax's using T3 tika tac 1:8 twist. I have already got very good loads using SMK 69 and 77gn bullets touching grou ps at 100 yds, even with my eyesight.
Tried varget and N140 and usual .5 mm off lands but cant get better than 1 inch plus groups.

Any ideas? std length or max length.
Regards Optomist
.

[bullbarrel]

Could be the rifel just doesn't like the bullets.

I'd take a mid point in the powder stakes then start 10 thou off the lands and work back 10thou for 5 or 6 groups.

If none of them work I'd stick to the 77s.

Out of interest are you using a sled to single load or just fiddling with the long rounds?

[junkyard dog]

I've used them in my A-Bolt varmint with a 1 in 8 twist, 22.2gn of N140 and 15 thou off the lands. They key holed at 100yds but wouldn't fit in the mag so no use to me. I now use the 77gn smks with the same results.

[223AI]

I've used them in my A-Bolt varmint with a 1 in 8 twist, 22.2gn of N140 and 15 thou off the lands. They key holed at 100yds but wouldn't fit in the mag so no use to me. I now use the 77gn smks with the same results.

They entered the target sideways? as that is my understanding of keyholing, the shape left by an unable bullet that passes through the target sideways

[bullbarrel]

They entered the target sideways? as that is my understanding of keyholing, the shape left by an unable bullet that passes through the target sideways

I think we all know he meant a close, tight group. I've noticed a few people use the term keyholing for this, when like you say, I take it to mean going sideways and making the impression of a keyhole.

[223AI]

I think we all know he meant a close, tight group. I've noticed a few people use the term keyholing for this, when like you say, I take it to mean going sideways and making the impression of a keyhole.

That's why I queried it, seems to have different meanings for different people, opposite meanings in fact!

Clover leaf is a tight group with bullet holes close or touching, looks like a clover leaf.

Keyhole bulket enters along its length, leaves a long, narrow keyhole shaped hole.

Then we get onto one hole groups, which some take to mean bullets through the same hole and others lots of bullets with all holes merging tighter in to one big hole. I'm an expert at 1 hole groups, trick is to fire a single round!

[DedIdick]

I've used them in my A-Bolt varmint with a 1 in 8 twist, 22.2gn of N140 and 15 thou off the lands. They key holed at 100yds but wouldn't fit in the mag so no use to me. I now use the 77gn smks with the same results.

I use the Hornady 75gn HPBT(not the A-max) for mag length and they work very well with about 24gns of Varget behind them.

[Optomist]

Hi folks, in reply unfortunately single loading which is a real pain on the tikka as many will know, but extra long mag on its way so should eliminate another prob. thanks for load info my last batch gave best accuracy was 24.5 varget. I may evewn load to mag length get the best load then faf about with length by which time the barrel is shot!! some wisdom in sticking with SMK's

Cheers Optomist

[223AI]

They do a bob sled single loading block for the tikka I believe

[larro]

They do a bob sled single loading block for the tikka I believe

Yep they do. I use one and it is smashing. Darran.

[bewsh]

Hi folks I'm currently trying to work up an accurate load in 223 using 75 gn Amax's
I have already got very good loads using SMK 77gn bullets

Your 75's are longer than the 77's
you might be running on the edge of stability

75gr Hornday A-Max® 1.105"
77gr. SIERRA TMK 1.070"

if you want to eliminate that possibility pull the tips on a couple of the AMax
I had this issue with 52gr Amax in a 1:14 barrel, couldn't get the groups under an inch at 100yds
pulled the tips and the touch

its a bullet length not bullet weight issue when it comes to long/heavy bullets

[223AI]

Your 75's are longer than the 77's
you might be running on the edge of stability

75gr Hornday A-Max® 1.105"
77gr. SIERRA TMK 1.070"

if you want to eliminate that possibility pull the tips on a couple of the AMax
I had this issue with 52gr Amax in a 1:14 barrel, couldn't get the groups under an inch at 100yds
pulled the tips and the touch

its a bullet length not bullet weight issue when it comes to long/heavy bullets

Learn something new every day, I thought it was the length of the bearing surface that made the difference but thinking about it that has no bearing (see what I did there ) on the stability once it has left the barrel!!

[Parabuteo]

That's why I queried it, seems to have different meanings for different people, opposite meanings in fact!

Clover leaf is a tight group with bullet holes close or touching, looks like a clover leaf.

Keyhole bulket enters along its length, leaves a long, narrow keyhole shaped hole.

Then we get onto one hole groups, which some take to mean bullets through the same hole and others lots of bullets with all holes merging tighter in to one big hole. I'm an expert at 1 hole groups, trick is to fire a single round!

They are mixing up bughole with keyhole Scott. Bughole is a yank term though.

Like you say, you usually see keyholes at Stickledown when folk try to stretch it that bit too far...if they manage to get on the board. Been a long time since I have been up there though.

[andrew375]

Your 75's are longer than the 77's
you might be running on the edge of stability

75gr Hornday A-Max® 1.105"
77gr. SIERRA TMK 1.070"

if you want to eliminate that possibility pull the tips on a couple of the AMax
I had this issue with 52gr Amax in a 1:14 barrel, couldn't get the groups under an inch at 100yds
pulled the tips and the touch

its a bullet length not bullet weight issue when it comes to long/heavy bullets

I use the 75gr. A-max in my 1 in 9" .223 Savage. They are marginal in that in normal conditions they perform very well, but when I shot them in below freezing weather they went through the target sideways. This was due to the greater air density.

Just a thought, how do you know your barrel is 1 in 8"?

I only ask as I have encountered two people now who had been sold .223 rifles with "fast twist" barrels, but were in fact the usual 1 in 12! Easy enough to measure. Push a tight patch in to the barrel. Make a mark on your cleaning rod opposite some datum point on the receiver, push the rod in until it has rotated one full turn. Take the rod out and measure between the marks.

[Optomist]

I use the 75gr. A-max in my 1 in 9" .223 Savage. They are marginal in that in normal conditions they perform very well, but when I shot them in below freezing weather they went through the target sideways. This was due to the greater air density.

Just a thought, how do you know your barrel is 1 in 8"?

I only ask as I have encountered two people now who had been sold .223 rifles with "fast twist" barrels, but were in fact the usual 1 in 12! Easy enough to measure. Push a tight patch in to the barrel. Make a mark on your cleaning rod opposite some datum point on the receiver, push the rod in until it has rotated one full turn. Take the rod out and measure between the marks.

Thanks Andrew 1:8 stamped on barrel and yes done the rod test and no doubt you only need to look down the barrel to confirm 1:8 just ran the Berger stability calculation and should be marginally stable with a value of 1.25 less than 1 unstable more than 1.5 comfortably stable
Regards Optomist