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Long time 6.5 project almost done

RockyMtnMT

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Joined
Mar 25, 2007
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Location
Montana
I have bit my tongue for a long time on this because we just did not know if it would work. I should probably still be quiet.....I can't.:D

This Idea started in a wall tent 3 yrs ago on a hunting trip in a blizzard that kept us inside for 3 days. We aren't the first ones to try this, we just did it a little different.

Here is what we did. We are just calling it what others have in the past, 6.5 Ultracat.

We took the 300/7mm ultramag put a 40deg shoulder on it and took out most of the taper. We did two rifles with 30" barrels in 7 twist with the small pain killer brake. We put in extended mag box and set the bullets at 3.85 oal to mag feed. Actions both are Rem 700 squared up. Topped both with Night Force NXS 5.5-22 NP-R2 scopes. Both in McMillan sporter stocks. Jewel trigger set at 6oz.

Here is where it gets different. We designed the bullet during that time in the wall tent also. So we proto typed a 130g mono metal bullet to run in this monster. We are figuring this bullet to have .63 bc and built as a dedicated hunting bullet. I will be shooting it at extended range this coming weekend to see how it does.

We did load development yesterday with half a dozen different powders and settled on US869 at 106g. This produced 3900fps in one and 3950fps in the other. Both rifles shot sub 1" at 200 yards.

The icing on the cake with this is it is an absolute dream to shoot. The Pain Killer brake on this setup is so efficient that there is literally almost no recoil. I would let any young kid shoot it. I shot 40 shots yesterday with free recoil and felt nothing. One of the rifles is going out tonight with a 12 year old boy to shoot a bear. Video and pics hopefully to follow.

Before you all start saying that the barrels are already burnt up from load development, I think we have a solution to that in the bullet we built. Time will tell in that. We will make an effort to burn one of them up and document how many shots we put through it. It is designed to be a long range hunter so I will not be scorching the barrel. Never more than 3 or 4 consecutive shots.

This combo makes a point blank to 500 yards and still carries 1400 ft lbs of energy at 1200 yards. We have got a lot of hunting coming up very soon. These rifles will be getting a work out, and we will document as much as we possibly can to share with you all.

Steve
 
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We are doing our own bullets. The plan is that we will go into production in the near future. Hopefully very near. I will let it be known here before any place else when we get up and fully running. This is the part that I have been biting my tongue over. I didn't want to say anything until we were at that point but yesterday was too cool not to let some of the cat out of the bag.

Steve
 
I would have two questions both about the bullet. First how did you decide to go with the 130 grain weight? I would assume because of OAL length of bullet? Second is how did you come up with the estimated BC? It just seems significantly higher then similar weight bullets out there. I look forward to seeing your results as I am a fan of the hot rod cartridges.
 
A G1 of .630 at 3900 FPS might be possible, but it will probably drop off a lot down around 3000-2500 FPS. An average G1 BC of .630 would ROUGHLY be a G7 of .320, that means that your bullet would have to have a G7 Form factor of less than 0.85, which is do able, but insane. I have only seen one bullet reach that and it was designed with some pretty advanced formulas. If you can get that, awesome! But I have a hard time believing it. I love the concept though, the best of luck!
 
I would have two questions both about the bullet. First how did you decide to go with the 130 grain weight? I would assume because of OAL length of bullet? Second is how did you come up with the estimated BC? It just seems significantly higher then similar weight bullets out there. I look forward to seeing your results as I am a fan of the hot rod cartridges.

Bullet is 1.572" long, so it is as heavy as we could go and still stabilize. We needed to increase twist to a 7 or this. The bc is an estimate at this point, but I feel comfortable it should be pretty close based on the form of the bullet. The size of the bullet if it were lead core would probably be around 160g or so. So the calculated bc is less than if it were heavier because of the lack of weight. But that helps get the velocity up to make up for the lack of weight.

We will see this weekend how it drops as far as I can. I am sure the limiting factor will be the nut behind the gun. (me) If the wind is good I can get a target out to about 1500 yards. Based on the data that I have put together for the shooting this weekend that will be 23moa. Although I will be up 2000 more feet to 5000 ft elevation so it should be a bit less.

I am very anxious for the weekend to get here. Day jobs suck.

Steve
 
I will try to get some pics and video this weekend. I am not so good at this, but I need to.

By the way no bears came into the orchard the other night. May have a chance for that this weekend.

Steve
 
Ok, I think we may have this thin figured out. We had to scrap the US-869, it was giving huge pressure swings with small temp increases. Settled today on Retumbo. Have burnt a lot of powder the last couple of weeks to figure this girl out. Running 90g to push the 130 to 3850fps. Not nearly as sexy sounding as before but still pretty impressive. At that speed the .63bc still looks good to 1070yrds. Will be able to work that out a little better at the next session. Wind was a bit tricky today but was able to shoot consistent 4" groups at 635yrds and shot about 8" at 1070yrds. No more powders this year, but would really like to try Ramshot Magnum if it ever comes available.

Over all feeling pretty good about how the day went. Should be able to go out next time and just fine tune drops and get ready for the soon to come hunting season.

Steve
 
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