The 6UM

[IrkedCitizen]

Anyone have any data showing felt recoil, velo and case capacity difference between the 6um 30 & 40

Input that into a recoil calculator with your rifle weight and see what it says

 

[Castle Rock]

Anyone have any data showing felt recoil, velo and case capacity difference between the 6um 30 & 40

2/5ths of fuckall

 

[huntsd]

View attachment 868392

Input that into a recoil calculator with your rifle weight and see what it says

thanks. In an 8 lbs rifle the 30 is putting out 17.7 ftlbs and the 40 is putting out 18.9.

Are most you current 6 UM owners running a break? Seems like there is just enough recoil to justify one.

For reference I found a load on rokslide for 6.5 prc 58 gr/2933 fps/ 143 bullet its putting out 19 ft lbs in an 8 pound rifle. IMO breaks belong on 6.5 prc

 

[Axlrod]

thanks. In an 8 lbs rifle the 30 is putting out 17.7 ftlbs and the 40 is putting out 18.9.

Are most you current 6 UM owners running a break? Seems like there is just enough recoil to justify one.

For reference I found a load on rokslide for 6.5 prc 58 gr/2933 fps/ 143 bullet its putting out 19 ft lbs in an 8 pound rifle. IMO breaks belong on 6.5 prc

Brakes belong on your car, mufflers belong on your gun!

 

[huntsd]

Brakes belong on your car, mufflers belong on your gun!

hahah unfortunately I can't use a muffler where I live!

 

[hdc77]

Finally got my 6 SAUM, I guess 6 UM 30, didn’t want to deal with fire forming, 24 inches, shoots amazing, I’m at 3250 gps with 115 DTACS, non coated, and N570. Deer season can’t get here fast enough. Barrel should speed up after first 100 rounds, let’s see.

 

[Tx_6UM]

Little disappointed in speed. I have 110 rounds through this barrel so far, 18” 7.5tw. Shooting 108’s I worked up to 66.5gr of 570 today. That got me to 3125 with heavy bolt lift and swipe marks. Had my fingers crossed to hit 3300 but doesn’t look like that’s going to happen.

Edit: loaded up 10 more rounds at 66gr, average was 3131 with no signs of pressure but group opened up to 2.5 inches. Maybe carbon ring? Either way gonna try out the Dtacs now.

 

[djfergus]

What brand barrel? How many lands & grooves?

Little disappointed in speed. I have 110 rounds through this barrel so far, 18” 7.5tw. Shooting 108’s I worked up to 66.5gr of 570 today. That got me to 3125 with heavy bolt lift and swipe marks. Had my fingers crossed to hit 3300 but doesn’t look like that’s going to happen.

Edit: loaded up 10 more rounds at 66gr, average was 3131but group opened up to 2.5 inches. Maybe carbon ring? Either way gonna try out the Dtacs now.

 

[Hunter609]

Little disappointed in speed. I have 110 rounds through this barrel so far, 18” 7.5tw. Shooting 108’s I worked up to 66.5gr of 570 today. That got me to 3125 with heavy bolt lift and swipe marks. Had my fingers crossed to hit 3300 but doesn’t look like that’s going to happen.

Edit: loaded up 10 more rounds at 66gr, average was 3131but group opened up to 2.5 inches. Maybe carbon ring? Either way gonna try out the Dtacs now.

I’m at 3130 with my 18” 6prc with dtacs.

 

[Tx_6UM]

What brand barrel? How many lands & grooves?

Ace 6 groove

 

[Tx_6UM]

I think I’m going to clean the bore and shoot for pressure again. It’s not making sense to me that at 66.5 I had stout bolt lift shooting 3124 and 10 rounds at 66 was smooth sailing with an average of 3131. Makes me think something else is going on.

 

[Harvey_NW]

I think I’m going to clean the bore and shoot for pressure again. It’s not making sense to me that at 66.5 I had stout bolt lift shooting 3124 and 10 rounds at 66 was smooth sailing with an average of 3131. Makes me think something else is going on.

Fireformed vs new brass?

 

[Tx_6UM]

Fireformed vs new brass?

Fire formed

 

[djfergus]

@Tx_6UM what primers are you using

 

[Tx_6UM]

@Tx_6UM what primers are you using

Federal 215’s

 

[Tx_6UM]

I’ve got a game plan. Ordered a longer mag and gonna figure out how close I am to the lands. Right now I’m loading to a hair under factory tikka 300wsm mag length which sounds like is not ideal. Also gonna scrub the bore to get rid of any possible carbon ring. Then gonna reshoot for pressure.

 

[GoatPackr]

I’ve got a game plan. Ordered a longer mag and gonna figure out how close I am to the lands. Right now I’m loading to a hair under factory tikka 300wsm mag length which sounds like is not ideal. Also gonna scrub the bore to get rid of any possible carbon ring. Then gonna reshoot for pressure.

Make changes 1 at a time or you will never know where the problem truly was.

Also you don't need a new mag to test that idea. Just single load them until you know it's worth doing.

 

[Tx_6UM]

Make changes 1 at a time or you will never know where the problem truly was.

Also you don't need a new mag to test that idea. Just single load them until you know it's worth doing.

That’s fair.

I checked this morning and I’m 76 thousandths off the lands. Gonna load some 20thou off and reshoot for pressure tomorrow.

 

[JBahr]

6 PRC, 22” Ace, 61 grains N570, 108 eldm seated at the lands = 3450 fps, .050” off the lands = 3290 fps. ES was all over the place tickling the lands.

 

[PathFinder]

That’s fair.

I checked this morning and I’m 76 thousandths off the lands. Gonna load some 20thou off and reshoot for pressure tomorrow.

Most of us end up at either .050 or .060 off, that has been a consistent sweet spot. During testing I tried everywhere from .020 to .120 off and didn't see a lot of difference.

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