H4895 reduced loads 175gr 7mm instability

[crustyrusty]

hey guys since my first post looking to Slow my rounds down so I could better enjoy my shooting experience with my 280 Remington all of the great information gleaned from here was a total wonderment and awe as to the knowledge and intelligence the collective we have here on this forum
is just staggering.. so I come to you once again looking for understanding and insight as to what I have come across.. Ok first thing first while on Loaddata .com researching good loads with H4895 for 168gr and 175gr bullets for my 280 was a slim picken at best …. but there were loads for them nonetheless and I used the 60% rule to establish my rock bottom load.. from there I added 2grs just for G.P. that turned out to be a total of 30.5gr of H4895. so I put together 20 rounds of 175 gr Hornady round noses and 20 rounds of 175gr Hornady SST's. When I got to my range to shoot,, My first target was at fifty yards and bullet of choice was my round nose.. the first 5 rounds printed a nice 3/4 inch maybe 1 inch group and I took it to 100 yards. first group was 1-1/2 5 round string...ok round noses did just fine,, Next up are the SST's When driven to 2700fps out of my rifle I get really good groups of 3/4 inch at 100 yards So now I pull the trigger on the SST's and I actually hear a THUMP.. so I go look at the target..... every round was a KEYHOLE on the target at fifty yards!!! ok so here is the question.... why would this projectile be so accurate at 2700fps and keyhole at 2100fps? it doesn't make sense the round nose didn't care what speed it was traveling it performed flawlessly fast and slow but the SST? not so much,,,, has anybody ran into this issue before?

 

[Ringostar]

I can’t say much on your keyholes. However it was my understanding that the reduced recoil idea from Hodgdon included using lighter bullets.

 

[crustyrusty]

I can’t say much on your keyholes. However it was my understanding that the reduced recoil idea from Hodgdon included using lighter bullets.

Yeah i called Hodgdon and they said I was doing it right and that as long as that there was a archived load for a particular load find the max load times it by .6 and that gives you your bottom or start point and work up from there... the load for the 168gr was listed however I did extrapolate for the 175gr bullet.. performance wise the round nose was superb just the SST's sucked wind.

 

[243winxb]

https://www.jbmballistics.com/ballistics/calculators/calculators.shtml

Longer bullets need a faster twist rate in the barrel. Or more RPM are needed for your 175 gr. More velocity.

But the instruction at Hodgdon say down load the maximum powder charge of the load the have listed on their website.

There is no maximum load listed with the 175 gr bullet and H4895 that i see.

 

[Texas10]

I would have to agree with the issue being simple velocity. The round nose bullet has a much more forward center of gravity than the pointed, therefore is less susceptible to the overturning forces at low and particularly subsonic speeds. Is the 2100 fps the velocity at the muzzle or the target?

The JPM ballistics computer mentioned above will no doubt shed some valuable light on the issue.

 

[Ringostar]

https://www.jbmballistics.com/ballistics/calculators/calculators.shtml

Longer bullets need a faster twist rate in the barrel. Or more RPM are needed for your 175 gr. More velocity.

But the instruction at Hodgdon say down load the maximum powder charge of the load the have listed on their website.

There is no maximum load listed with the 175 gr bullet and H4895 that i see.

View attachment 1106548

You bring up a great point here. The op never mentioned what his rifle is other than a 280 Rem. If it’s a factory hunting rifle, the twist rate and low velocity probably isn’t close to stability for the 175 bullets.

 

[crustyrusty]

https://www.jbmballistics.com/ballistics/calculators/calculators.shtml

Longer bullets need a faster twist rate in the barrel. Or more RPM are needed for your 175 gr. More velocity.

But the instruction at Hodgdon say down load the maximum powder charge of the load the have listed on their website.

There is no maximum load listed with the 175 gr bullet and H4895 that i see.

View attachment 1106548

your right there isn't a listed load for the 175 gr bullet I just took the 168gr data and used it in place for the 175grn the round nose was superbly accurate the longer SST keyhole on every shot.. this same bullet at 2700fps is really a accurate round just a slow speeds sucks wind key holing the target every shot

 

[crustyrusty]

so I went to lymans 49th edition and they list a lead gas check 168gr at 1800fps with 30gr H4895 and thats where I "barrowed" the data to use with the 175gr stuff. so according to that loading I actually need to go up several grains to get to my target speed of 2200-2300fps

 

[crustyrusty]

You bring up a great point here. The op never mentioned what his rifle is other than a 280 Rem. If it’s a factory hunting rifle, the twist rate and low velocity probably isn’t close to stability for the 175 bullets.

well according to JBM ballistics My 280 Remington with a twist of 1-9.5 and the 175gr SST should have been just fine although it is close to being marginal it came up with a number of 1.320 and according to the ballistics calculator 1.30 and above to 2.0 is where you want to be.

 

[dellet]

Definitely check the stability calculator for the bullet in question. Twist rate makes a much bigger difference than velocity. It’s quite possible that the bullet is marginal at 2700 fps. You may also want to verify the twist in your rifle.

Often with a stability factor of 1.3 it won’t show up until 100 yards.

There is also another possibility, and that is gas cutting the base. The pressure may be low enough that it is not expanding the base of the SST and sealing. Flatbase bullets are more forgiving at low pressure, I believe the SST is a boat tail, but not familiar with that particular bullet.

 

[crustyrusty]

ok I have a postulation to pose here... If I fire this SST at 2700fps and we track its entire flight path to the end the bullet stays stable until it hits the ground..... so why does it keyhole when fired at 2000 fps?all of the information says it should be good to go.. but its not... so where in the equation is the information is missing that explains the whole mystery?? I dont think gas cutting could be in play because the base of an SST is solid copper not lead so deformation is not in play... I did look at manufacturer twist rate recommendation for that bullet and it did say they recommended a twist of 1-9
rate.. and my rifle rate is 1-9.5 so its on the edge of twist recommendation... now when I measured the 175gr round nose it was almost 1/2 inch shorter than the SST... so basically it fly's like a coffee can in the air... and the SST was a Javelin ...ok my head hurts now

 

[dellet]

If the SST is solid copper, that is likely your problem with a spin rate that is marginal.

What you likely have is a bullet that is smaller than your bore at some point in the barrel. Lead and jacketed bullets obturate at much lower pressures than solid copper. This allows the bullet to expand to fill the void. Copper solids generally take more than 40,000 psi to obturate. Any imperfection in the bore will allow gas to blow by the bullet and start an imbalance in the spin, due to a deformed bullet.

The reason a bullet leaving a 10 twist at 2700 fps will remain stable until it hits the ground is because it will shed its velocity much faster than its rpm. It will hit the ground spinning at the same rate that it would leave the muzzle at say 2400 fps. Even if it isn’t traveling 1800 fps. (Example numbers pulled out of the air.)

The proof would be to use a bullet of the same length, that is either jacketed or lead and see it it is stable. Or move to a faster powder like Trail Boss which can easily put pressures over 50,000 psi. With the SST. Bullet shape will also come into play.

This is why when shooting solid bullets at subsonic velocities I use a faster powder. This puts the bullet under the pressure it was designed to operate. It has greatly increased subsonic accuracy and dependability.

I have been down this road many times with solid copper bullets at velocities under 1000 fps and pressures lower than 25,000 psi.

 

[crustyrusty]

cool I will try that route there were a couple of published loads for the 175 gr projectiles using SR 4759 powder in a reduced load that had high cup values...

 

[243winxb]

175gr Hornady SST

i cant find this bullet?

Increase the velocity till the bullets stabilize. But first, find load data for the correct bullet.

 

[crustyrusty]

well I THOUGHT it was a SST I bought it from Midway USA as a Blem with no name on the box

 

[thatguyshm]

I would be willing to bet that it is an ELD-X. Long bullet for those speeds. It's difficult to simply plug and play different bullet and powder combinations and expect them to all play nicely.

A 175gr ELD-X is going to be considerably longer then a 168gr lead cast bullet, or a round nose for that matter. How much longer is the round nose that is working than the 175 that is key holing?

Have you checked the diameter of the blem bullets? Are they .284" or slightly smaller?

Are you wanting to shoot the blems because you got them cheap and are looking to practice?

Bit of loading advice I learned long ago. It's better to shoot what works then to keep shooting what doesn't. Get the SST/ELD-X back up to 2700 fps and play with your round nose at reduced load charges.

 

[jim_k]

I love the reduced load capability with H4895, and have utilized it for many years, since most factory ammo goes way too fast for the 100-300 yd. shots I take. However, when I have gotten close to 60% of a book max load, I've gotten some "fizzle" rounds, that acted like they were not going to ignite, then ignited with a sizzle and a poof. Not good. I currently load at least 75% of the book max for the round, and I have not had further issues. Other than that, H4895 is the "one powder to rule them all" for my usage. Those are from .223 to .30-'06.

 

[243winxb]

https://www.midwayusa.com/product/9...in-spitzer-boat-tail-box-of-100-bulk-packaged

Blemished

Blemished Bullet Reloading Tip: Since these bullets do have slight blemishes it is always better to check bullets for defects in diameter before loading

The most likely cause , undersize.

 

[lb-ft]

I’ve shot the 175 ELD in 26” 7mm Rem Mag Sendero at max pressure & velocity.

Keyholed. Very disappointed.

However, I have developed a marvelous light recoil load that is quite accurate. 139 interlock, 4064, MAGNUM primer. It is published (print published) data but for the life of me I don’t recall the source.

Search for similar load in 280.

It turned my 7mag into a heavy barreled, low-recoil 7mm-08.

 

[crustyrusty]

I would be willing to bet that it is an ELD-X. Long bullet for those speeds. It's difficult to simply plug and play different bullet and powder combinations and expect them to all play nicely.

A 175gr ELD-X is going to be considerably longer then a 168gr lead cast bullet, or a round nose for that matter. How much longer is the round nose that is working than the 175 that is key holing?

Have you checked the diameter of the blem bullets? Are they .284" or slightly smaller?

Are you wanting to shoot the blems because you got them cheap and are looking to practice?

Bit of loading advice I learned long ago. It's better to shoot what works then to keep shooting what doesn't. Get the SST/ELD-X back up to 2700 fps and play with your round nose at reduced load charges.

yes That is exactly what I am going to do seeing as they work wonderfully well at 2700fps that is what I will shoot them at,,, its gonna take awhile to use them up at that pace cause I ordered 500 of them... of the 175 gr round noses I have 700 of them that I inherited when dad passed away and shoot superbly at any speed.. so I am gonna make a nice batch that run about 2000fps and use them up at my brothers 40 acres and the longest shot is less than 50 yards... yeah I bought the blems because they were cheap and fit within my budget constraints so I thought I could shoot more... but flinch and jerk so bad with full power loads with my 280 its just not fun to shoot .. so i turned reduced loads to fit the bill and i fell in love with my rifle all over again because of H4895 and how versatile it is ....