Stupid question. What is "soft setting" a target?

[LR1955]

22" criterion barreled ar. Pushing the atip that fast seems like an insurmountable task with the barrel length and cartridge length limitations. Maybe a 26" and a modified magazine would get me there?

As I have stated before, I am not a smart person. I do stupid things all the time, this is just another example. The only "smarts" I have is to realize that I am dumb, so thanks for your patience and guidance.

Dumb? Not sure about others here but I sure would have expected to knock a ram down with that load.

LR-55

[grayfox]

OK, between consulting meetings I have racked my brain and finally it seems as though this can be solved by conservation of momentum, but you have to make some assumptions. So anybody who could do some reality-verification of loads that don't work as well as loads that do, then we can tweak and come up with a good answer.

Basically, conservation of momentum ('55 you were on the trail but needed to go a bit further) says the M*V product of the bullet transfers to an M'*V' of the ram, no loss of momentum.
I'm assuming that the mass of the bullet is much much less than the ram so even if the 2 objects stuck together the increase in mass would be negligible (and a bullet bouncing would transfer more so I left that out too). And assuming that the Ram does not get deformed by impact. In real life the bullet may bounce and the ram would deform, but we can adjust the problem to allow for that later. Also the Ram dimensions are approx 33x27.5 as given and I called a guy that sells and ships them, he said Rams are pretty close to 50 lb weight on the money (52 lb with cardboard shipping box).
M*V of the bullet (with V the unknown), and we need the delta-distance and delta time of the Ram's center of gravity (Ds/Dt for the V of the Ram).
Looking at a mock up picture of the ram I'm estimating the center of gravity is 13.5" off the ground and it has all of the ram's "weight", and the bullet hits the ctr of grav. The feet, as per NRA rules are to be such that the cog has to travel 1.25" rearward to tip over (thanks '55 for pointing to the NRA rule book). So the c.o.g has to move 1.25", that's Delta-distance, Ds, =1.25"/12"-per-foot.
How long does it take for the ram to tip when it gets hit? That will be the Delta-time for us, Dt. I'm assuming 0.15 seconds. We need then only to calculate for V1, the impact velocity of the bullet.

So M1V1=M2(D2s/D2t), add rearranging for the unknown, V1, V1= (m2/m1)*(Ds/Dt).
For a 130 grn bullet (0.008424 kg), and 50 lb (22.67 kg) ram, the needed impact velocity comes to 1868 ft/sec.
This also assumes that the ram's c.o.g moves in a straight line... in fact it moves slightly radially but the initial angle involved is of the order of 4* (4 degrees) and for such a short distance straight-line movement is probably an ok assumption.

1868 ft/sec at 550 yds for a 130 gr bullet, you'd need, depending on the BC... somewhere in the order of 2700 ft/sec Muzzle Velocity to start with (this from my 6.5 Creed, 20" barrel, I found a bullet I have that would work). Other bullets/MV/BC combos would work, at whatever xyz elevation/humidity you have, but this gives a somewhat decent approximation.
Apparently the NRA competition can be done at either 500 m or 500 yds. For 500m I just used 550 yds, which is again, estimate I can use in my BC calc.

[grayfox]

Forgot to mention about the plate and/or bullet deformation. The ram is made of 3/8" carbon steel, and in reality there is some amount of both bullet and ram deformation. This takes some energy, or KE, away from the momentum equation, so the impact velocity would need to increase to still knock over the ram. I don't have a value for amount tied up in the deformation, so if you want you might need to raise impact velocity by 5 or 10% to account for that deformation loss and still tip over the ram.

[Zeneffect]

dumb in the sense that I didnt check to see how they were set, what the base looks like etc. I didnt do my homework at all. Just shot, see hits, and no falls. would fall on the 2nd or 3rd hit but I dont think that will be much use in competition which lead me to the soft setting rule.

With the required energy needed to knock over the ram (as calculated, thank you very much GF) I cant wrap my brain on how they can hold this sort of competition and have an ar15 class while expecting to knock down the rams. I guess maybe idea that a grendel would excel in this type of class is maybe poor judgement on my end, or there has to be something in the set... I'm not experienced enough to say one way or the other.

[Old Bob]

Full sized NRA targets 33x27.5 approximately. I can't speak for the base though as I didn't have the opportunity to reset and inspect the targets fully.

So what I'm gathering is, I'm ill equipped, and and am not making a wise shot choice (boiler shots) not taking this as a negative, but good advice to maybe make something work.

Close! Full size NRA Rams are 32"W x 27"H x 3/8" thick. The feet on the Rams are 4" x 5". I shot silhouettes for years & never knew how much they weigh. My guess after hefting & resetting them buggers for years, the Rams are around 35/40lbs.

I have no experience shooting any bullet under 400gns at Rams. But, if I were to do so & my aim was good enough, I'd try hitting the top of the horns to tip it over enough to fall over. Another thing I'd try is hitting either the Ram's nose or butt trying to push one of the feet off the stand.

[grayfox]

It is an interesting little problem. From the guy who sells/ships, 50 lb wt according to him and if you're estimating (by lifting them) at 35-40, I'd say that checks. I did see where they are 3/8" carbon steel, and the tip-over/ rear foot setup is right from the NRA rulebook. The foot stands are set up so the c.o.g is supposed to be 1.25" from tip-over to the rear. The ht/width dimensions are only important in order to find the height of the c.o.g above the feet, which is the vertical/point that has to move the 1.25" for tip-over. I estimated that most of the weight(mass) would be in the body but the body is elevated from the ground level by the ram's legs... ergo ~1/2 of the measuring ht or 13.5" was what I used. But just a guess. (For cars, rams, etc, anything to tip over, the center of gravity/force downward due to gravity, has to be outside of the "base" dimension, why low-riding cars can hug a curve without flipping over to the side so well)

Of course it's only as good as all the assumptions made in it and I had to make several.

One interesting note on this, and I didn't set out ahead of time to get to a certain bullet KE at impact, but the mass-velocity at impact actually works out to very close to 1000 ft lb of KE. So, interesting indeed!

[Old Bob]

dumb in the sense that I didnt check to see how they were set, what the base looks like etc. I didnt do my homework at all. Just shot, see hits, and no falls. would fall on the 2nd or 3rd hit but I dont think that will be much use in competition which lead me to the soft setting rule.

With the required energy needed to knock over the ram (as calculated, thank you very much GF) I cant wrap my brain on how they can hold this sort of competition and have an ar15 class while expecting to knock down the rams. I guess maybe idea that a grendel would excel in this type of class is maybe poor judgement on my end, or there has to be something in the set... I'm not experienced enough to say one way or the other.

They don't have an AR-15 class specifically. AR-15s would be lumped into the High Power Semi Automatic Military Rifle class & they would have to be 6mm or larger in caliber & not less than a 4.5lb trigger pull.

[Zeneffect]

This particular competition does.

"Classes: are based on rifle type.

As Issued Class
Match Class
MIA Open Class
AR10 Open Class
AR15 Open Class
Bench Class
As-Issued Class: Stock military rifle issued with original sights, triggers, barrels, or replacement barrel and caliber must be of original military specifications. No aftermarket triggers, muzzle brakes, or glass bedded stocks. Rifle also must be general issue for entire military. Replicas of as-issued rifles will shoot in a different class.

Match Class: Rifles that do not have stock open sights, i.e. M1-Garand with Alley aperture sights, bull barrel, national match rifles, and across the course rifles. M1A or M1-Garand chambered in .308, and replica rifles will shoot in Match Class.

Open Class: Rifles with any type of optic."

As I understand it, this make it available to "run what I brung" for the AR15 open class which seems like it would be a lot of fun. Matches arent frequent enough for me to go observe what people are using, how they are using it, and their success rate. Its all uncharted waters for me.

[grayfox]

More power to ya!
for me, at my age/condition, it would probably be bench class. But so what? should be fun and learn something...

[LRRPF52]

dumb in the sense that I didnt check to see how they were set, what the base looks like etc. I didnt do my homework at all. Just shot, see hits, and no falls. would fall on the 2nd or 3rd hit but I dont think that will be much use in competition which lead me to the soft setting rule.

With the required energy needed to knock over the ram (as calculated, thank you very much GF) I cant wrap my brain on how they can hold this sort of competition and have an ar15 class while expecting to knock down the rams. I guess maybe idea that a grendel would excel in this type of class is maybe poor judgement on my end, or there has to be something in the set... I'm not experienced enough to say one way or the other.

What elevation (altitude) is the range at?

If you have LEVERevolution, you might be surprised at what speeds you can get from a 22”.

What magazines are you using?

With CProducts mags, I can load longer than normal.

[myrifle]

Cz 527
25.5 inch barrel
Starline case
Cci450 primer
129 able
H4895 powder
Coal length 2.355
Average velocity 2612 fps

And full life size 3/8 thick steel rams would only drop at 600 yards if I placed the shot in the high back or head.

[Zeneffect]

elevation at range is 195ft.

I do use leverevolution for just about everything 123gr and heavier. Nothing will get me to the 1000fpe mark @ 550yds that is within reasonable limits for a gas gun according to quickload + ballistics calculator... even if I switch to a 24 or 26" barrel it seems there just isnt enough case capacity or I hit the 52000psi limit before desired speed is achieved. It will more than likely have to come down to a combination of factors to get a working solution. My hunch is the set + shot placement + having enough energy will ALL be required to be competitive. Determining which is the most though I think will be a pretty fun day at the range. the fpe handicap is really making this something id like to persue even more to be fair.

[ramslamer]

https://www.sacvalley.org/clubs/semi-aut...ilhouette/

I want to do this sort of competition. Seems fun and something I could be well suited for. I found out today that at the 550yd(ish) mark I'm not knocking down the rams consistently with a 130gr norma GT doing 2465 at the muzzle. I didn't set them up so I'm not sure how they are placed but the rules (linked) say it's acceptable to soft set them. I don't know what this means exactly, can anyone elaborate? Is it like sort of hanging them at the edge of their platform so it's easier to knock down?

I have shot a lot of silhouette in my 25+ years of competition. I used a grendel bolt gun last year at the nationals. I am using the 147 eld-m at 2440 fps , I didn’t “ring” a ram all week. But you can lose a ram with anything. I believe you need more speed and weight to be more consistent with rams. I tried a 6.5 br with the 130 gr eld, had a few ringers, didn’t have the twist to run heavier. The grendel has a 1-7.5 twist and is 26 inches long. You can do all the calculations and theories you want,but the only way to “see” is shoot it. There are sooooo many variables! That’s why it is such a tough and intriguing game! At least to me

[LR1955]

I have shot a lot of silhouette in my 25+ years of competition. I used a grendel bolt gun last year at the nationals. I am using the 147 eld-m at 2440 fps , I didn’t “ring” a ram all week. But you can lose a ram with anything. I believe you need more speed and weight to be more consistent with rams. I tried a 6.5 br with the 130 gr eld, had a few ringers, didn’t have the twist to run heavier. The grendel has a 1-7.5 twist and is 26 inches long. You can do all the calculations and theories you want,but the only way to “see” is shoot it. There are sooooo many variables! That’s why it is such a tough and intriguing game! At least to me

RS:

Thanks for the feedback on the heavier 6.5 bullet for rams. I thought it would have a better chance than a 130, even if shot at a slower speed. No Go with that one.

I had my barrel maker make a 6.5 BR barrel for my Tubb 2K. Didn't do what I wanted but an interesting cartridge. Not a lot more powder capacity than a Grendel though. 31 or 32 grains is about it if I can remember correctly.

I mention this because as long as I have been shooting competitively, you are the only other guy I know who owned and shot a 6.5 BR.

LR-55

[Zeneffect]

Well, in the spirit of being dumb. The 200M chickens won't fall with .22LR cci minimag either. I think this one is pretty obvious though.

[LR1955]

Well, in the spirit of being dumb. The 200M chickens won't fall with .22LR cci minimag either. I think this one is pretty obvious though.

ZE:

So, what will you use now?

LR-55

[Zeneffect]

Grendel still. Considering more barrel, the 22 fun was just that. Being dumb and having fun. To put my 22 setup into perspective, 350 rds + optic + mount + bipod + case + range fee + cost of rifle isn't even $250. Good cheap fun is all, wanted to see if I could even get to the target was the goal.

Waiting on reply from Krieger regarding a 28" and will keep trying to contact PF regarding a 26." I am expecting Krieger lead time to quote 12-18 months. Based on the "class" of this local competition and rules (3000fps speed limit etc) I feel like grendel is still going to give the best chance. I'm staring down the rabbit hole on this one and am getting ready to jump in.

[LRRPF52]

Grendel still. Considering more barrel, the 22 fun was just that. Being dumb and having fun. To put my 22 setup into perspective, 350 rds + optic + mount + bipod + case + range fee + cost of rifle isn't even $250. Good cheap fun is all, wanted to see if I could even get to the target was the goal.

Waiting on reply from Krieger regarding a 28" and will keep trying to contact PF regarding a 26." I am expecting Krieger lead time to quote 12-18 months. Based on the "class" of this local competition and rules (3000fps speed limit etc) I feel like grendel is still going to give the best chance. I'm staring down the rabbit hole on this one and am getting ready to jump in.

If you go anything over 22”, I recommend using an Extended Length Gas System with 2 more inches of port location away from the chamber. It will really help you with pushing loads without causing early unlocking.

28” will allow you to bite the heels of 24” 6.5 Creedmoor. You can also do a gain-twist with Bartlein. I think PF has one for sale here right now with a gain twist.

[Zeneffect]

28" krieger varmatch 1-8 order submitted. will update this in about a year or so whenever it actually arrives. the advantage of gain twist (as I understand) is a pressure thing which leads to velocity. standard twist rate for me, I am not at the level to realize the benefits of gain twist etc. Ill figure out if my cleaning rod is long enough when I get to that point.

Edit

Looks like the wait might be shorter and free fluting

[LRRPF52]

28" krieger varmatch 1-8 order submitted. will update this in about a year or so whenever it actually arrives. the advantage of gain twist (as I understand) is a pressure thing which leads to velocity. standard twist rate for me, I am not at the level to realize the benefits of gain twist etc. Ill figure out if my cleaning rod is long enough when I get to that point.

Edit

Looks like the wait might be shorter and free fluting

Make sure it gets a +2” Extended Length Gas System, not standard Rifle Length Gas System.