7mm RM pressure problems

[bteate]

While working up my 7mm RM, started low and working my way toward max, when I got to 62 gr IMR4350 groups got pretty good. When I got to 63.5, groups were .583 (I can live with that!) but my velocity was 3070 with 150 AB. Then I proceeded to try to see where my groups started opening up. 64 gr- about 1" but it was pretty windy and I didn't feel good about my shooting and my chronograph didn't have enough light to work. At 64.5 gr- felt good but bad group, and a sticky bolt. I wasn't that close to max and my velocity was low for a 150 gr. I'm .010 off lands, should I change powder or seat deeper or what? I was looking for +/- 3150-3200 fps. Is that to much to ask for, or is that all I can expect? I'm sticking with 63.5gr for now because I've got a whitetail hunt in 5 days. Any suggestions?

 

[JD338]

It sounds like you found the MAX for your rifle. After your hunt, I would suggest you try RL 22. :wink:

JD338

 

[DrMike]

Actually, the sticky bolt lift was telling you that were were above max charge. Regardless of what the guide says, you are customizing a load for your rifle. It is doubtful that any whitetail will ever know the difference between 3070 fps and 3150 fps. Sounds as if you have a pretty good load. The accuracy will suffice for game anytime over the velocity.

 

[rick smith]

I would try IMR-7828.Rick.

 

[bteate]

really, the lift wasn't sticky, bolt lifted smooth. It was the pulling back on the bolt that was tough. It took a little bump to slide out, I put the spent case back in and it bolted fine, bolt lift smooth, again had to give slight bump to start back. It is on a Tikka M595 and they have one of the smoothest actions I have ever felt. thanks

 

[Bruce Mc]

Even though the Nosler Manual shows super velocity with the IMR-4350/150gr bullet combo I too haven't been able to duplicate the velocity without pressure signs early on. About 3100 is the most I can get from my 26" barrel. The bump to open the bolt is probably from the case head over expanding. Measure some of the fired cases around the belt and just in front of the belt and compare to some known samples. You might also mic your primer pocket to make sure they're not expnading too.

I've gotten good results with the 150gr and Reloder 22 also. Same for H-4831sc. Velocities have been in the 3150 range.

 

[bteate]

hey guys, at the risk of sounding like a D.A., I'm using 140 gr AB's.in a 24" barrel. I don't know what I was thinking! My mistake . I'm finishing up my .308 that I'm using 150's in. I've got alot going on this week trying to get ready. I guess @ 3070 with a 150 would be great for me. Ha! sorry for the mix-up

 

[Bruce Mc]

You can really smoke the 140 AccuBond with Reloder 22. You can get a tad better than 3300 fps even in a 24" barrel. Work up carefully. I've gotten extremely good groups with loads above 3300 fps.

 

[john-brennan]

I use 68 gr. H4831 in my 7mm RM with 140gr accubonds and with a 24'' barrel I max out at 3300 fps and .350''-.500'' groups. R22 is about the same but not as good accuracy till 160gr then it gets better.

 

[FOTIS]

You did find the max for your gun.

4350 series powders are in fact too fast for this combo. The factory 150 gr 7mm mag features IMR 7828. About 68 gr if I remember correctly. Velocity in my Sako 75 was about 3170 or so.

Try H4831 and slower powders. RL22 RL25 MRP 7828 etc.

 

[YoteSmoker]

My "7" loves IMR4350 w/ 140s and RL22 w/160s. Both bullets will shoot ragged holes at 100.

 

[roysclockgun]

Best groups in my Browning, 26" bbl. 7mmRemMag. 140gr. AB. 70gr. of either IMR7828 or MagPro, produce same results. Used Fed215 Primers.
Provides 3200fps, MV.
Zeroed at 300 yds. the impact at 400 yds., is right at 8 inches low, so no problem holding just a bit over the deer's elbow at that range.
At 150 yards, I am about 3 inches high, which again is not a problem, even if I do not think about it.
I have not recovered any bullets from white tails, mule deer and pronghorn as all hits were through and through. This past season I recovered the bullet from the off side of a mature boar's shoulder and the bullet still weighed 90gr. which IMO is great performance.
IMO IMR4350 is too fast. Use a slower burning propellant to maximize MV in your 24 inch bbl.
Could the hard extraction be from a dirty chamber?
Steven A.

 

[SJB358]

I will vouch for the others, the RL22 works very well for me in my 7mm Mags. Those 140's would be dynamite on deer and probably do very well on elk also. Scotty

 

[Ridge_Runner]

I have way too much lot to lot varience with re-22, my love affair with it is over, I'd try H-1000 or maybe even retumbo.
RR

 

[bteate]

well guys, my hunt is long gone by now and no blood, literally. I shot a monster non-typical 10 point whitetail and no exit with the 140 AB. Here's the short story- 110 yards quartering hard away, couldn't turn him, leaving field, bullet placement was behind the last rib to take out off-side shoulder (I've taken this shot on several deer before with good success), not the shot I wished for but never the less it was my only shot or dream about this deer forever. Shot rang out and WHAP! hit hard, bucked like a bronc, tucked his tail and dove into the willows. NO EXIT . I had 3 other hunters in the area from 1200-2000 yards away and they all heard the hit. I think I'll go with 160 AB's on the next load and scrap( or use for foulers) the 140's. Thanks for all of the input. Try not to blast me to hard for taking a marginal shot to begin with.

 

[JD338]

bteate

I take it that you didn't recover the deer, too bad.
You won't be disappointed with the 160 gr AB. Go with RL 22 and you will find a sweet load.

JD338

 

[bteate]

no, JD338 I didn't . The willows were thick as hair on a dogs back and with no blood, I didn't have anywhere to start. Looked for 2 hours.

 

[SJB358]

Man, thats tough. Sorry to hear you didn't recover the deer. I would think 160's would do better for that kind of penetration. It didn't sound like a horrible shot, that is easily doable with the right bullet. Still surprised the 140 didn't exit on a deer. Must have gotten into alot of bone or something. JD is right though, 160's and RL22 will net you something good most likely. Scotty

 

[Guest]

I don't think you took a marginal shot. If you know your rifle, which it sounds like you do, and you know your game, which it sounds like you do from your description of how you placed the shot, at that relatively short distance, I'd take that shot with a lot less rifle than a 7mmRemMag, and for sure with a 7mag. Sorry the deer found a quiet place to hide out in the thick stuff.

It's long been my opinion that unless you're looking to go stem to stern on a giant bull elk, the 7mmRemMag and the 160gr AccuBond are a match made in heaven. I can't think of a white-tail that would not respond generously to the offer of a long nap from that combination. Good luck with the load development.

 

[sask boy]

I am jumping in a little late but we use 160gr. ABs in 3 diferent 7mm mags and the same powder IMR 4350 on Nosler site it states the most accurate load.
I load 60grs in all three and all three have sub MOA.
If I am not mistaken the vel. is around 3000ft per second.
That is plenty quick in my opinion :wink: