6 UM Reloading Thread

[JDMBEND]

116 TMK’s 6 UM 30. 2.9 oal, 65gr. N570 3170 fps. Zero pressure, 100 rounds on barrel. Will step up to 65.5 which should put me at 3200 fps. Currently, consistent .75 moa.
95% of the time came spot all my shots past 250.
Working on the 5%.
Love this rifle. My 6 CM feels lonely

 

[kit.critchlow]

So please forgive my ignorance with this post. Have shot factory ammo my whole life in a variety of guns. Shoot a decent amount but not as much as many do here on this site. Anyway, decided if I was going to get into reloading and custom loads, there was no better place to jump in head first than with a 6UM. Since the brass was my toughest component to source I decided to have unknown munitions load me up some their offerings. So I had them load the “production load” with the 116 TMKs. Finally went out and shot it and this is what the back of the brass looks like.
View attachment 1072054
The bolt was pretty tough to lift as well. Am I correct in my assumption that this is the ejector swipe, and that this load is too hot for what I have? I shout about 20 rounds to “break in” my barrel per Preferred Barrels recommendations. So if this is a hot load, what are my options? I have about 80 of these loaded cartridges from unknown. The tough part is, this load is crazy accurate, especially for a barrel that is just getting started.

Will it get better after “break in”? Of note this is a tikka action, 20” preferred barrels barrel with 1:7.5, with a nNomad Ti suppressor on the end.

Any thoughts or guidance would be appreciated. Thanks!!

That is definitely hot and you will probably only get 1 or 2 firings on the brass if you reload it. I would send the pic and explanation to UM for feedback.

 

[passinggas33]

It may lighten up a bit as the throat breaks in. 66 grains of N570 would be ok if you end up changing the load.

According to UM, it is already loaded at 66 grains. So should I shoot some more and see if the throat wear starts to lessen pressure? Or will I be doing damage by that point?

 

[IrkedCitizen]

Is it 30° shoulder or 40° shoulder? If it's 30° and being shot in a 40° shouldn't it be loaded light and long to jam?

 

[TradLife406]

I think their published load is 66g N570 with 115dtacs. I did a pressure test this past weekend with 2 guns shooting 116tmk’s and 6UM40 with N570 and max was 67 with one and 66.5 with another. 70 degrees out. I was starting to catch a slight lip on the ejector mark with my finger nail around 66/66.5 along with a little stiffer bolt. So I’m going to load around 66. I didn’t setup the chrono.


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I was wondering if 66 was the max. Or if a dude could go a little higher.
66 seemed to work great with the TMKs last weekend.
Going to fireform 150 cases this weekend and load TMKs for S2HU in two weeks.

Ha pretty sure this pipe will be dead when I get home. At about 300 rounds so far. Just glad the fire forming loads are mellow.

Thought about swapping pipes before I go to the school. Ive got two ready to spin on. Just dont have the tools yet.

I definitely jerked that one.

 

[passinggas33]

Is it 30° shoulder or 40° shoulder? If it's 30° and being shot in a 40° shouldn't it be loaded light and long to jam?

Was this question directed at me? Because mine is a 40. If this wasn’t directed at me, I apologize for any added confusion.

 

[wind gypsy]

Was this question directed at me? Because mine is a 40. If this wasn’t directed at me, I apologize for any added confusion.

I think the question was if the brass was already fireformed in the loaded ammo.

I sure wouldn't want those kinds of pressure signs on expensive brass that needs to be fireformed in a barrel burner. Last thing you'd want is those 100 peices to be trashed early and have to fire form more before the barrel is toast.

 

[Woodsman44]

I was wondering if 66 was the max. Or if a dude could go a little higher.
66 seemed to work great with the TMKs last weekend.
Going to fireform 150 cases this weekend and load TMKs for S2HU in two weeks.

Ha pretty sure this pipe will be dead when I get home. At about 300 rounds so far. Just glad the fire forming loads are mellow.

Thought about swapping pipes before I go to the school. Ive got two ready to spin on. Just dont have the tools yet.

I definitely jerked that one.

How long is your barrel?

I’m not sure how bad the ejector mark has to be to determine an official max for a gun. At 67 it was more than I would like for getting 4-5 reloads from this brass and the bolt was stiffer than I’d like. I’d actually consider it above max for me at that point. Because of the variation between the two rifles I’ll probably do 66.3 for one and 65.8 for the other. More testing this weekend.


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[IrkedCitizen]

Was this question directed at me? Because mine is a 40. If this wasn’t directed at me, I apologize for any added confusion.

Yes.

I think the question was if the brass was already fireformed in the loaded ammo.

I sure wouldn't want those kinds of pressure signs on expensive brass that needs to be fireformed in a barrel burner. Last thing you'd want is those 100 peices to be trashed early and have to fire form more before the barrel is toast.

This.

 

[Ryan Avery]

In a 6UM40, 66g of 570 is the sweet spot for most barrels with the 115 dtacs and 116TMKs. There are a few that will take 67g; most will not.

It looks like 116TMKs likes to jump between 90 and 120 thou.

 

[passinggas33]

I think the question was if the brass was already fireformed in the loaded ammo.

I sure wouldn't want those kinds of pressure signs on expensive brass that needs to be fireformed in a barrel burner. Last thing you'd want is those 100 peices to be trashed early and have to fire form more before the barrel is toast.

Gotcha. The brass was fire formed by unknown munitions as part of their offering. Then once fire formed, it’s reloaded and shipped to me, the customer. So not the same barrel as the fire forming.

 

[Axlrod]

According to UM, it is already loaded at 66 grains. So should I shoot some more and see if the throat wear starts to lessen pressure? Or will I be doing damage by that point?

Heavy bolt lift is over pressure. Shooting more of them and hoping the problem goes away isn't the right thing to do. Need to find out why you have over pressure.

One thing to try, is take a 6mm bullet, and see if it fits easily in a fired case. If you don't have any loose bullets, you can use one that is in a loaded cartridge. If it doesn't fit easily, this means your chamber throat is too tight for the neck on your brass. This will give you over pressure, because the bullet can't release easily from the brass.

 

[passinggas33]

Heavy bolt lift is over pressure. Shooting more of them and hoping the problem goes away isn't the right thing to do. Need to find out why you have over pressure.

One thing to try, is take a 6mm bullet, and see if it fits easily in a fired case. If you don't have any loose bullets, you can use one that is in a loaded cartridge. If it doesn't fit easily, this means your chamber throat is too tight for the neck on your brass. This will give you over pressure, because the bullet can't release easily from the brass.

I’ll give that a try. I should have some bullets floating around somewhere.

 

[Grizzle]

In a 6UM40, 66g of 570 is the sweet spot for most barrels with the 115 dtacs and 116TMKs. There are a few that will take 67g; most will not.

It looks like 116TMKs likes to jump between 90 and 120 thou.

@Ryan Avery have you found that seating depth working well specifically in the 6UM or has that been across the board of cartridges?

 

[TradLife406]

In a 6UM40, 66g of 570 is the sweet spot for most barrels with the 115 dtacs and 116TMKs. There are a few that will take 67g; most will not.

It looks like 116TMKs likes to jump between 90 and 120 thou.

They need that big of a jump?

I'm not even sure what I jumped them on those tests. Just loaded them to the same thing I had my die set for the dtacs. Figured that the sierras are pretty forgiving. I'd lost my modified case. I've got a new one coming today.

Fire forming 150 pieces of 6.5 saum tomorrow to have ammo for the university. We'll see if this pipe can last through fire forming and the class lol. At about 300 rounds so far. Figure worst case scenario I bring an extra pipe with me.

Email that info if you get a chance

 

[Experienced Novice]

Anybody load the 116’s and know how far from the lands they actually are? What’s your OAL with that distance from the lands?

6UM-30 with 116s.
I'm 3.053 at the lands, loading for a COAL of 2.910, 143 thou jump. Was shooting for 2.920 but after the first few somehow f'd something up and most ended at 2.910 for that group and they shot well enough so I left it.

 

[Cory_Shoot2Hunt]

6UM-30 with 116s.
I'm 3.053 at the lands, loading for a COAL of 2.910, 143 thou jump. Was shooting for 2.920 but after the first few somehow f'd something up and most ended at 2.910 for that group and they shot well enough so I left it.

Thank you thank you thank you been wanting this info for awhile lol

 

[Experienced Novice]

no worries