H4350 or VV N165 for 20 shot strings with 7 SAUM

[maxpower]

I had great luck with my 7 SAUM (with H4350) in 2+ 15 shot strings which is normally all I fire. Sometimes often it was around shot 16-17 that my last shots often leaked out or at least not hold in the X ring. During some recent 20 shot matches I found that the last few were starting to lose accuracy. It was not a fouling issue as the same barrel shot great again for 16 shots or so in the next target once it cooled down. Talking to some other shooters they were suggesting maybe N165 might be good for the 20 shot strings as it is cooler burning, but my thoughts were that I will need to put more powder in, going from 56gns to 59gns with N165, which might start causing more heat again. Has anyone actually taken any barrel temperatures to see which ends up running cooler in long shot strings out of smaller doses of H4350 or larger doses of N165?

 

[dkhunt14]

Are you sure it is not the heat mirage getting to your scope? I know when I shoot strings my sight picture gets worse as the gun heats up. Now this is benchrest where I can actually see it because I never leave the scope. Matt

 

[maxpower]

Are you sure it is not the heat mirage getting to your scope? I know when I shoot strings my sight picture gets worse as the gun heats up. Now this is benchrest where I can actually see it because I never leave the scope. Matt

I am fairly sure that barrel heat is not the main cause. I noticed the barrel getting mighty hot during 15 shot strings and so first of all used target Board as a mirage sheid and it now wears a mirage shield at all times. I realise that some mirage haze will effect the sight picture but my 300 WSM holds together well in 20 shot strings but not this SAUM.

 

[maxpower]

I am fairly sure that barrel heat is not the main cause. I noticed the barrel getting mighty hot during 15 shot strings and so first of all used target Board as a mirage sheid and it now wears a mirage shield at all times. I realise that some mirage haze will effect the sight picture but my 300 WSM holds together well in 20 shot strings but not this SAUM.

FWIW, my 300wsm barrel in the same gun that will go well for unlimited sightseers and 20 shots is a different brand and is running H4831sc powder. It still seems to get darn warm but accuracy stays good all the way through. I do not have anything to compare barrels temps scientifically.

 

[nhm16]

In addition to H4831SC, consider regular H4831. It's been more available than the short cut version, and in my 7mm Walker (.284 Win. derivativebarrels, more accurate. Has done well in the Texas summers with unlimited sighters and 20 for record.

 

[tclaunch]

I had great luck with my 7 SAUM (with H4350) in 2+ 15 shot strings which is normally all I fire. Sometimes often it was around shot 16-17 that my last shots often leaked out or at least not hold in the X ring. During some recent 20 shot matches I found that the last few were starting to lose accuracy. It was not a fouling issue as the same barrel shot great again for 16 shots or so in the next target once it cooled down. Talking to some other shooters they were suggesting maybe N165 might be good for the 20 shot strings as it is cooler burning, but my thoughts were that I will need to put more powder in, going from 56gns to 59gns with N165, which might start causing more heat again. Has anyone actually taken any barrel temperatures to see which ends up running cooler in long shot strings out of smaller doses of H4350 or larger doses of N165?

Do the shots leak to the same area? I shot with someone whos 6BR barrel started "walking" when it got hot, he called Broughton, they had him send it back for another heat treat, and it fixed the problem. You may get the barrel Cryo treated to see if that fixes it, for $60.00 might be well worth it.

 

[maxpower]

Do the shots leak to the same area? I shot with someone whos 6BR barrel started "walking" when it got hot, he called Broughton, they had him send it back for another heat treat, and it fixed the problem. You may get the barrel Cryo treated to see if that fixes it, for $60.00 might be well worth it.

It doesn't trend in any certain direction. By shot 16-17 the shots start filling the 10 ring. By shot 20 (including sightsers) they leak out into the 9 ring in random direction, but I think more vertical than just enlarged group. 20 minutes later when it cools again, it is back around the X ring ( in perfect conditions)

 

[maxpower]

In addition to H4831SC, consider regular H4831. It's been more available than the short cut version, and in my 7mm Walker (.284 Win. derivativebarrels, more accurate. Has done well in the Texas summers with unlimited sighters and 20 for record.

Funny you should mention your 284. While I have not tried the regular H4831 much lately, I have tried regular 284s and only ever had one which started to scatter shots at the end of long shot strings and it was not running H4831sc. I wonder if the smaller 284s are just gentle enough on barrel heating that they do not suffer from the same barrel over heat symptoms that the magnums do.
That might be a question for another post.

 

[Joe Salt]

Max what Diameter is your barrel?

Joe Salt

 

[maxpower]

Max what Diameter is your barrel?

Joe Salt

1.25" straight, 30" long.

 

[Joe Salt]

Max even with my 1.450 barrels, they heat up to were you don't want to pick it up with your bare hands after 20 shots. I think you should try and space your shots a little more if time allows and see what you get.

Joe Salt

 

[maxpower]

Max even with my 1.450 barrels, they heat up to were you don't want to pick it up with your bare hands after 20 shots. I think you should try and space your shots a little more if time allows and see what you get.

Joe Salt

That's not the option I am looking for. When conditions are right I want to be able to rattle them down range. That is why I was trying to find if anyone had tested actual barrel temps with lighter (but higher pressure) loads of H4350 or heavier (but slightly lower pressure) with Vit N165. It might help others with similar problems.

 

[kev77]

That's not the option I am looking for. When conditions are right I want to be able to rattle them down range. That is why I was trying to find if anyone had tested actual barrel temps with lighter (but higher pressure) loads of H4350 or heavier (but slightly lower pressure) with Vit N165. It might help others with similar problems.

N-165 is extremely cool burning powder, much cooler than H 1000. Starts at 62gr n165 in rem brass