Crown issues? Boat tail vs. flat base ** Update **

[Just Say Moe]

I bought a used 6mm Remington (Zastava Mauser) a while back and once I sorted out scope issues, I have confirmed it doesn't like boat tailed bullets. Any BT from Nosler 95 ballistic tips, Hornady 100 BTSP's, to Speer 85 BT's shot from 1.5-2 inch groups at best (minute of deer) to mostly 4-5 inch shotgun patterns. Nosler 100grain partitions and Sierra 100gr Pro Hunters shot some groups 0.5 - 0.75 inch. Aside from the obvious shoot the flat base bullets and be done with it, could the crown be of issue?

You can see from these pictures that some of the crown is smooth, and some has a little chatter, but the depth of it is even all around. Would polishing out the chatter help (or hurt) or would recutting it be a better option?

Also the last two pictures are the shoulder area of the chamber that looks like it was cut with a dull pocket knife! I guess they got in a hurry on this one.

 

[Walt Krafft]

Used gun, you have nothing to lose recrowning it. Will it make a big difference? IDK.

 

[Dusty Stevens]

Id say the twist is probably wrong and the BT is just a tad too long. If its a 12 or more it just isnt going to shoot them. Try a 65-68bt and youll see. Not sure where you are but if you come around central ark ill give you a fist full to try

 

[Just Say Moe]

Id say the twist is probably wrong and the BT is just a tad too long. If its a 12 or more it just isnt going to shoot them. Try a 65-68bt and youll see. Not sure where you are but if you come around central ark ill give you a fist full to try

Sorry - should have added - it's 1 in 8. I have some 68 and 70 match bullets I can try but this will be a deer rifle and I don't feel comfortable going less than 90gr.

 

[Dusty Stevens]

Sorry - should have added - it's 1 in 8. I have some 68 and 70 match bullets I can try but this will be a deer rifle and I don't feel comfortable going less than 90gr.

Try something like a 103-108vld then. They shoot better than the bricks.

 

[tobnpr]

Factory rifle, you found something it likes that'll print 1/2-3/4 minute- so that indicates to moi that it's likely not a chambering or crown issue. Everything would shoot like crap if it were.
Maybe room for improvement, but I'd keep expectations realistic.

 

[spitfire_er]

I would re-crown it. Easy enough. Get rid of that chamfer. The shoulder looks like crap, but as long as it extracts fine, shouldn't be a bid deal. Looks like they used a really dull reamer and forced it to cut that shoulder.

How's the throat area look? That's what I would be more concerned about. See how concentric the throat is. I've taken several barrels with non-concentric throats, set them back and turned them into shooters.

 

[Just Say Moe]

The throat looks good. It has rifling up to the throat even all the way around with no fire cracking. It doesn't appear to have been shot much. I'm gonna try some 105's I have just for fun before I recrown it.

 

[Bill K]

#1, I would have that crown redone, it can not hurt. Especially if you did the Q-tip test and fibers clung to the bore/crown edge.
#2, remember, it is generally agreed that a flat base bullet is best up to around 300 yrds, and then the boat tail bullets start working best. But each rifle will show what it likes best. You just have to do a little shooting and grouping at those ranges to see which works in your rifle best.

 

[Ggmac]

is it marked 6 mm Remington or thats what fits . 244 Remington and 6 mm are the same BUT the early 244 Remington has a slow twist and the 6 mm has a 1-9 twist to accommodate 100gr bullets OF THE DAY , which were hunting bullets with a flat base .

 

[Djfergus]

I bought a used 6mm Remington (Zastava Mauser) a while back and once I sorted out scope issues, I have confirmed it doesn't like boat tailed bullets. Any BT from Nosler 95 ballistic tips, Hornady 100 BTSP's, to Speer 85 BT's shot from 1.5-2 inch groups at best (minute of deer) to mostly 4-5 inch shotgun patterns. Nosler 100grain partitions and Sierra 100gr Pro Hunters shot some groups 0.5 - 0.75 inch. Aside from the obvious shoot the flat base bullets and be done with it, could the crown be of issue?

You can see from these pictures that some of the crown is smooth, and some has a little chatter, but the depth of it is even all around. Would polishing out the chatter help (or hurt) or would recutting it be a better option?

Also the last two pictures are the shoulder area of the chamber that looks like it was cut with a dull pocket knife! I guess they got in a hurry on this one.

View attachment 1315637View attachment 1315639View attachment 1315642View attachment 1315641

Have you physically measured the twist rate. Just asking cause I've ran across a pile of barrels that aren't the advertised/stated twist rate. If it is indeed an 8 twist... It should shoot well with a 105 hybrid berger or 108 eld. I do believe that a flat based bullet is more likely to overcome a bad crown than a boat tail. You don't have much to loose by getting it recrowned. Good luck!

 

[Just Say Moe]

Have you physically measured the twist rate. Just asking cause I've ran across a pile of barrels that aren't the advertised/stated twist rate. If it is indeed an 8 twist... It should shoot well with a 105 hybrid berger or 108 eld. I do believe that a flat based bullet is more likely to overcome a bad crown than a boat tail. You don't have much to loose by getting it recrowned. Good luck!

I used the cleaning rod method multiple times - it's 8 or maybe 9 but definitely not a 12.

 

[Scrumbag]

Id say the twist is probably wrong and the BT is just a tad too long. If its a 12 or more it just isnt going to shoot them. Try a 65-68bt and youll see. Not sure where you are but if you come around central ark ill give you a fist full to try

I'd have said this might be your issue. One of the noted problems with 6mm Rem was the twist was slow.

Best wishes,

Scrummy

 

[Djfergus]

I used the cleaning rod method multiple times - it's 8 or maybe 9 but definitely not a 12.

If it's a 9 twist, you will most likely have a hard time getting 105gr & up bullets to shoot well. 95 or 100 gr would be the upper limit for a 9 twist in most circumstances.

 

[Just Say Moe]

I purchased a brass polishing spud and used some scope ring compound and polished up the crown where it meets the rifling. Removed the chatter marks and got it nice and shiny.

I had some Nosler 105 and Sierra 70 MK boat tails and tried them - good news - no shotgun patterns and averaged about 1.5" even though I screwed up the best group that would have been <1."

I also tried some 95gr Hornady SST flat base and they averaged a little over 1."

I didn't have any of the other Boat tails that shotgunned (4-5" groups) to retest but I am satisfied that at least the BT Match bullets shoot pretty good (even the long 105's) and all of the flat base hunting bullets are whitetail accurate enough even with the crappy chamber!

thanks for replies!

 

[jelenko]

Congrats!